Roll Center.....again [Archive] - Nissan Road Racing Forums

WishIHadaSilvia

11-04-2008, 02:34 PM

Ok, so I've been brain storming with a friend on making some adjustments to the front control arms. We decided that a rod end - like the battle version weld in kit - instead of the rubber bushing would be ideal for the main mount.

To my knowledge (although very limited) roll center can be adjusted in two ways. By changing one of these two things (green and blue highlighted areas):

http://i25.photobucket.com/albums/c51/95KA-Turbo/rollcenter2.jpg

http://i25.photobucket.com/albums/c51/95KA-Turbo/rollcenter3.jpg

We were going to cut up a control arm and see if we could weld the green highlighted part up higher while keeping all of the factory angles that are supposed to be there. Basically cut and weld some metal in there to increase the height of where the factory sized ball joint sits, and effectively change the angle on the arm itself.

I just wanted to run that by you all on here to see what the general consensus is. Will this actually work? We'd basically measure the angle of the arm and figure out how much metal needs to be added to make the arm parallel rather then angled upward from excessive lowering.

Any help or advice is greatly appreciated.

Scores240

11-04-2008, 06:50 PM

Is there supposed to be a picture here?

cheeky14

11-04-2008, 10:31 PM

being that you guys are discussing knuckles & rollcenter adjusters, i'm curious to know if any body has used the GP Sports Hyper knuckle kit/ Super knuckle kit- heres a link to their web site http://www.gpsports.co.jp/otr/knck.html

floodo1

11-05-2008, 12:42 AM

roll center is determined by the location of the PIVOTS, more specifically the center of the rotation. so for a heim joint it is the center of the hole, and for a balljoint like the lower control arm has it is the center of the ball inside the balljoint.

This being the case the shape of the arm makes no difference.
Therefor what you need to be changing is the distance from the axle (on the spindle) to the center of the ball that connects the spindle to the lower control arm.

basically what you want to do to get the roll center under control is move the ball part of the balljoint or heim physically DOWN in relation to the axle.

If you're doing this with a heim joint what you need to do is make some sort of spacer that attches to the SPINDLE, which would space the heim downwards, and in doing so make the lower control arm flatter.
again i point out the the arm itself isnt the important part but the line from the inner pivot of the lower control arm to the outer pivot of the lower control arm (the heim).

if you dont understand this description google image search for roll center, and see how its a series of lines connected to pivot points. all that matters is that the points are connected with something, doesnt have to be straight, could be u shaped, so long as the pivots are connected by fixed "arms".
so modifying the arm does nothing, other than change the strength.

WishIHadaSilvia

11-05-2008, 08:25 AM

So, in short, of the two methods of changing the roll center I posted, the only thing that'll really change the roll center is the blue highlighted bit - or completely changing the arm altogether (rod end w/ height adjustability)?

Thanks for the info!

Def

11-05-2008, 10:59 AM

Don't think of the physical shape of the arm, imagine a straight arm between the pivots and you want to change the height of one end or the other.

WishIHadaSilvia

11-05-2008, 11:43 AM

Thanks Def, that makes perfect sense. I'll let you guys know what we come up with....there might be several months of silence, haha.

a_ahmed

11-05-2008, 12:29 PM

Interesting, but try not to be silent :P

WishIHadaSilvia

11-05-2008, 07:38 PM

My friend that I am brainstorming with lives ~1.5 hours away from me so we basically communicate through a thread on a local forum (including pictures) and the phone, haha.

He just so happens to have a S14 and S13 in his garage, on jack stands, without motors or suspensions....so he was able to get pictures immediately and he happened to have a nice set of calipers to do some measurements with.

It's looking good so far - he works very early in the AM so I have to wait for him to get back to me about a few other things before I post on here. As I don't want to post incomplete or inaccurate information.

IF I am interpreting the pictures correctly that he sent me there should be a couple of INCHES of space to move the mounting point. I'll post up when I find out.

I guess I'll ask one other question. I've been assuming the entire time that the goal of correcting the angle in the control arms is to get them to be parallel with the cross member? Is that, in fact, correct? I found a way to actually measure the roll center online - but I believe the amount of measurements it requires may be outside of my ability. Even if I did get the actual number I wouldn't know how to apply it - like what a "good" roll center is, haha. If anyone can shed some light on that for me I'd appreciate it.

WishIHadaSilvia

11-06-2008, 08:28 AM

Here's what we're thinking right now - converting the FLCA bushing end to a rod end so we have some length adjustment as well and it will give you around an inch of space to move the mounting point up. Here's the pictures so far:

http://i25.photobucket.com/albums/c51/95KA-Turbo/rollcenter5.jpg

The red/blue/green dots are just areas I wanted him to look and see how much space was there for the arm to actually move.

http://i30.photobucket.com/albums/c333/ballinnmiami240sx/mods/100_5132.jpg

There is room to move the actual stock arm up some, I am thinking the rod end will free up a little space. Would it be safe to grind one of the edges of a rod end down to allow for more clearance? I am thinking no, but just figured I'd ask. Also, what kind of loads does that particular spot see?

From the thread about the JIC time attack S15 I got this picture:

http://www.dragsport.com/issue/2007/images/0707/s15-5.jpg

It looks like there is enough room to move the rear up some as well. It actually looks like the factory position could be cut off and a new, taller/stronger one could be welded in its place.

We're working on some spindles as well. I know this will not interest the majority of the people here as they're for angle, but I just wanted to be sure I am grasping this properly.

http://i25.photobucket.com/albums/c51/95KA-Turbo/spindle1.jpg

If the tie rod mounting point is kept on the same Y and Z axis the steering input should feel the same right? Basically, I'm trying to find out if spindles can be made that have the same steering feel as a OEM unit but achieve more angle. Changing the X axis (black line in my picture) will change the angle yes? And leaving the mounting position in the exact same place will keep the steering the same right?

Please correct me if I'm wrong.

I know the RX-7 guys do this:

http://i79.photobucket.com/albums/j148/74chevynova/13b-re/Picture002-1.jpg

and get angle like this:

http://www.urbanracer.com/gallery/gallery/event_coverage/formula_drift/2008/formula_drift_irwindale_ca_10-11-08/0218.jpg

I want to make a spindle like that so I have options (factory position or super wide angle position).

a_ahmed

11-06-2008, 10:53 AM

Although I don't grasp all of it as yet, this is looking awesome, ambitious and worthwhile. But know this forum is mostly anti-drfit and pro-grip hehe.

jmauld

11-06-2008, 11:44 AM

I think drilling new holes in the subframe is a great idea. I'm going to check into that and see how difficult it will be to get those holes drilled perfectly.

Any of the suspension gurus want to take a shot at how much the arm needs to be moved, relative to how much it has been lowered?

Is moving the roll center by itself going to effect anything else?

I'm going to be picking up a few spare subframes for my engine swap project and I don't mind drilling these holes to test this idea.

WishIHadaSilvia

11-06-2008, 01:19 PM

I had to take my front wheel off to check for a nail today, so while I was there I decided to stick my head in by my LCA. There is so much room it is kind of ridiculous. I could fit two fingers in there and move them around easily. It looks like even in line w/ the factory location the arm can be moved up around 1/2 of an inch. If the arm is shortened and the hole location is moved an inch or so out there is even more room to go up.

I'm pretty excited about this and hopefully will have something done by this weekend - as my buddy has those cars up in his garage and is willing to start drilling.

We were going to get the cars on a lift that keeps the suspension from uncompressing - like an alignment lift - and take some measurements/use some string to get some numbers and see if there's enough space to completely correct the roll center.

I still would like to know what an ideal placement would be for the control arms - preferably an angle they need to be at. This way it can be applied to all S chassis and the only thing that would have to change is just how much the arm needs to move.

jmauld

11-06-2008, 01:39 PM

We were going to get the cars on a lift that keeps the suspension from uncompressing - like an alignment lift - and take some measurements/use some string to get some numbers and see if there's enough space to completely correct the roll center.

Alternatively, you can lift the front end, remove a strut and move the arm through as much motion that would reasonably represent the real world. Measure how much you can move the arm up at full compression.

I still would like to know what an ideal placement would be for the control arms - preferably an angle they need to be at. This way it can be applied to all S chassis and the only thing that would have to change is just how much the arm needs to move.
Don't fall into the "ideal" placement trap. Moving it up 1/2" may not be ideal, but it's likely better than it is now.

jmauld

11-06-2008, 02:40 PM

I just looked at my spare crossmember. The first problem you'll run into is that on the back side there is a bracket and the associated weld that is probably going to be right where you want to drill your hole.

Def

11-06-2008, 04:05 PM

I posted about this exact thing a while ago in the 240SX forum - didn't drum up much interest.

I think with a -12 rod end there you can move it up quite a bit with moving it out maybe 1/2-3/4".

jmauld

11-06-2008, 04:29 PM

I would think that the arm pivot point should stay in line where it currently is. At least I wouldn't move it until someone had a fairly accurate model of the front suspension to make sure the other arms (tie-rod and T/C rod) don't start playing badly with it.

Speaking of that, is the front T/C going to bend the arm at the mounting point based on the pivot being in a different location? If the control arm is moved up 1/2" perhaps the T/C rod should move up with it?

Def

11-06-2008, 04:42 PM

The T/C rod really should move, but there is less space on that mount. With a rod end on the control arm it shouldn't be a huge deal from a loading perspective, but the caster curve up front will change with travel.

jmauld

11-06-2008, 08:03 PM

There's plenty of room to move the control arms up at at least .5" if not .75", if you ignore that welded bracket. It also looks like the T/C rod could be moved up as well. However, you may run into interference with the swaybar by moving those up. Alternatively, It might be possible to mount the swaybar and T/C rod to the bottom of the control arm, if it were boxed in. I believe you could avoid moving the T/C rod if you did that. I don't know if that would change the arc of the T/C rod in relation to the arc of the LCA.

WishIHadaSilvia

11-06-2008, 08:38 PM

Wouldn't the effects on the sway bar and TC rod be null because I'd be returning my control arm to a more stock state? Right now I know my control arm is angled up even with no wheel on it - because of how short my front shocks are.

I mean, the TC and sway bars are meant to be moved with the arm, or they wouldn't have mounted them to a moving object - or am I completely missing something? Also, how would moving one end of the arm verses the other really effect it?

Now that I think about it, you're probably talking about the X axis movement right? By having a rod end rather then a bushing, couldn't everything remain in the same position but just have the actual mounting point of the FLC be moved out 3/4s of an inch?

RBbugBITme

11-07-2008, 07:58 AM

I hope you guys follow through with this and see some improvements however I must say that you clearly don't understand what it is you're changing and you probably won't see any improvements at all. Unfortunately suspension kinematics is not something that can be explained on a forum. FYI, moving your inner pick up points up is not the right direction to be heading. Your roll center will move up roughly as much as the pick up point does and you're screwing with lateral load transfer distribution big time as well as the magnitude of your roll couple which can severly effect handling characteristics for the worse.

jmauld

11-07-2008, 08:28 AM

There are literally hundreds if not thousands of Mustang drivers at real racing events who would disagree with your assessment. Perhaps you could give more details?

WishIHadaSilvia

11-07-2008, 08:32 AM

That's the kind of stuff I need to hear. I have no engineering background what-so-ever. I majored in biology, I just have my car as a hobby, haha.

So basically, the reason no company/really anyone has done this is because it is extremely detrimental to the entire way the suspension works? I don't know enough about any of this to refute or ask any intelligent questions, so I guess we need to modify the knuckle like every other company does - or put a rod end on the outside with a big enough adjustment range to drop the arm down.

Here's a program w/ a free demo:

http://www.performancetrends.com/rc.htm

I have a Mac so I can't use the software, but inputting numbers into that would give concrete answers.

Ruff Ryder 6

11-07-2008, 09:31 AM

I majored in biology, I just have my car as a hobby, haha.

+1

:D

RBbugBITme

11-07-2008, 09:55 AM

There are literally hundreds if not thousands of Mustang drivers at real racing events who would disagree with your assessment. Perhaps you could give more details?

Do you know why they do it? Do they know why they do it? We are talking about mustangs...

There really are to many effects the roll center has for me to go into. The gist of it is, you always want your roll center as low as possible for jacking and scrub reasons while keeping in mind lateral migration in roll, relative heights front and rear, whether or not it passes through the ground plane, making sure it moves vertically with the CG, and on and on.

jmauld

11-07-2008, 10:03 AM

Do you know why they do it? Do they know why they do it? We are talking about mustangs...

I'm waiting on you to tell me.

RBbugBITme

11-07-2008, 10:06 AM

I don't know anything about them so that ain't happening. What I do know is you never copy (or justify) taking what someone does to one car over to a totally different platform without fully understanding each of them and why it was done.

jmauld

11-07-2008, 10:30 AM

Okay, this isn't a "totally" different platform. A front mcstrut is the same basic design across most chassis. But the details are different enough that we can just drop that out of discussion.

Let's look at the "potential" advantages of raising both inner points (LCA and T/C rod) to avoid odd things happening between the T/C rod and LCA. Let's ignore moving the point in or out of the chassis for this comparison.

Advantages
- If you can get the outer joint of the LCA to point down, you get an improved camber curve.
- With the roll center closer to the CofG, you will increase roll stiffness and can utilize a softer spring, which in turn gives more compliance if the track gets a little rough.

Now, give the disadvantages, please.

Anyone else, please jump with additional pros/cons. Again, RB, I do realize that without a model of the front suspension, you can't know exactly every detail of what is going to happen. IMO when you say that raising the roll center is the wrong direction, you don't know that for certain unless you've done some modeling or testing on your own? So, if you have, do you have any plans on sharing that info?

RBbugBITme

11-07-2008, 11:53 AM

Advantages
- If you can get the outer joint of the LCA to point down, you get an improved camber curve.
In ride or roll, and which one needs improvement? The way that you do this can have positive or negative effects.

- With the roll center closer to the CofG, you will increase roll stiffness and can utilize a softer spring, which in turn gives more compliance if the track gets a little rough.
Poor comparison. If the track gets rough thats when you're going to want as little scrub as possible which is the killer of mechanical grip. Which would you prefer in a RACING situation, a rough ride or more mechanical grip?

In the end we're talking about geometry we don't know much about. I've been trying to measure it very accurately but I think for the time being I'll just get rough tape measure estimates.

floodo1

11-08-2008, 07:51 AM

OK, first, I wouldnt go around modifying suspension pickup points without understanding how suspension geometry works. This is to all you out there that heard 'the roll center is too low when you lower your car" and thought "i can fix that, i'll just move the FLCA pickup up".

what NO ONE has mentioned so far is a little thing called anti-dive which you will introduce a nice dose of if you move only the FLCA pickup and no the T/C rod with it.
This shows to me that you have no business modifying your suspension arms because you guys dont know what this is. I think this is what RBBug is trying to say. That if you dont really know what you're doing its very easy to screw your geometry up.
Take the steering angle modifications that guys are doing. Maybe it works fine for drift, but changes like that are going to mess with your ackerman, which has the potential to be an uncurable problem on the track (under grip).

That said, you do NOT always want your roll center as low as possible, "taking into account other factors". The big thing here is roll couple. The relation between the relative heights of the roll centers to the CG determines a thing called roll couple, which tells you how much roll will occur at each end......this has a big impact on oversteer/understeer and is going to be hugely impacted if you fix the front end but dont change the back to match. These are the sorts of concerns you need to be considering if you're going to mess with pickup points.

All in all though, in every way it should help out the suspension to fix the front roll center, provided you dont screw it up and adversely impact something like ackerman. it should help the camber curve and cg to roll center height (cant rememer that term, doh).

Finally, modifying the inside pickup point is a non-adjustable fix. that is, you drill a new hole in your cross member and live with the location. The adjustable fix is to fix the spindle/outer balljoint so that you can use some sort of shims or spacers between the knuckle and the outer balljoint. This way you can take your car to the track, find out that the amount you adjusted it by sucks, and then fix it.
THIS is the ONLY good way to do a mod like this. Adjusting roll center is HUGE HUGE HUGE on the track!

a_ahmed

11-08-2008, 08:20 AM

Would be nice if someone just did all that and sold kits wouldn't it lol jk.

Well it's beyond me, but imho it's a commendable effort. Would be nice if all of us put the effort in correcting this together, I mean that's what this forum is all about isn't it... exploring the possibilities of the s chassis that none saw before (except yo yo jdm dorifting)... All I am giving is a hug and a pat on the back for the effort, can't really contribute from a knowledge perspective though, it's beyond me, but I'm chiming in with my two cents of support :)...

WishIHadaSilvia

11-08-2008, 04:49 PM

floodo1 - That is exactly why I posted this before I did anything. I have absolutely no clue what I'd be doing. My only though was that I'd be straightening out the FLCA and - by simplified definition - fixing the roll center.

I'm going to state what I stated earlier again. How is the TC and sway bar placement changing? The arm moves up and down normally - currently on my car it is angled up far greater then it does at the stock height. If the arm is kept at the exact same length and even mounts in the same location, just maybe a 1/2 inch higher - wouldn't it just put everything closer to being how it is supposed to be angled to begin with? The same goes for the rear as there is plenty of room to move it back there as well. I wouldn't want to correct just one (front or back).

I understand that most of what you're talking about is complex. I mean without calculations no one can be certain. I'm going to give the link to that program to my friend and see if he can't get some measurements - even crude ones would show if moving the mounting point up would be a good or bad thing right?

Def

11-08-2008, 08:02 PM

Look up how to calculate the instant center of a front strut suspension with a locating link - basically, you're moving one pivot point, so you're changing the relationship of where the instant center is in BOTH the forward/aft plane and side to side plane.

Plus the caster curve is going to change with moving the arm height where the tension rod mounts and not changing where the tension rod is. Think about it this way, all the other arms are still all "jacked up" - with the tension rod probably pointing slightly upwards, but now the control arm is angled down(looking outboard) like it'd be with maybe 2-3" higher ride height.

What the other guys are saying is that changing only one variable is going to get you some potentially undesirable effects.

I'm not one to say the sky is falling unless I have at least a good idea that things are heading in a bad direction, and I haven't looked at the situation in detail, so no big recommendations from me to go either way.

WilloW

11-08-2008, 09:27 PM

+1

:D
+2, can't wait to see more.

WishIHadaSilvia

11-09-2008, 07:05 AM

I found these articles on Sport Compact Car:

http://www.sportcompactcarweb.com/tech/0512_sccp_making_it_stick_part_4/guide.html

I'm not 100% sure how helpful that would be in actually trying to change anything w/o paying for someone's aftermarket arms. I also imagine they're barely scraping the surface on the topics. Oh well, time to read up.

floodo1

11-15-2008, 11:03 PM

if you really want to learn, get a Steve Smith book. I learned on the late model stock car book, but there are others.

Epstein

11-16-2008, 05:44 AM

Thought I'd mention it, but SCC is doing a Time Attack S13 this month (first installment) and used the Megan roll-center adjusters. Apparently there is some actual roll-center change with these, although it is very small. They mentioned wanting the Moonface "Circuit" parts, but not wanting to shell out $600.

a_ahmed

11-16-2008, 05:53 AM

^SCC = sportcompact car magazine? Link?

The s2000 guys use those moonface things and apparently it works for them, it's beyond me, but I'm always curious, but then from all the discussion on this forum its been labeled as a bad apple that is just rotten and doesnt work, even the spl arms are not good enough to truly correct it from whats been said here. Yet no one really presents a viable solution :-/ Or rather no one's really put the effort to make a viable solution and most of us have not a clue how to lol, I sure don't. None the less I'm curious always to hear something... link to their article lets see what they've got in store.

Nothing on the front page http://www.sportcompactcarweb.com/index.html

a_ahmed

11-17-2008, 10:41 AM

And me found this picture:

http://img393.imageshack.us/img393/5076/mfrfrontrcafn9.jpg

And these are the 'hardrace' roll center adjusters lol:

http://img.photobucket.com/albums/v72/Ken200/LS14008-1.jpg

floodo1

11-17-2008, 07:02 PM

in order to change the roll center you have to move the outer balljoint IN RELATION TO THE SPINDLE. do NOT worry about how the balljoint is connected to the LCA as this has no effect on roll center.
This means, in the simplest terms, that you need a balljoint with a longer shank/stud (the part that goes into the spindle and gets a nut).

None of the standard japanese "roll center adjusters" like the ones pictured have longer shanks. they all change where the shank is in relation to the arm, but I already told you, DO NOT WORRY ABOUT THIS. They only change the angle of the arm, but NOT THE ROLL CENTER.

ok that said, there IS a reason that those things are made, which is to flatten the LCA back out so that the tension rod is at a more favorable angle. As it is on lowered cars it is twisted at ride height. Whether or not this is trivial is an exercise left to someone who cares :)

floodo1

11-17-2008, 07:03 PM

Oh yeah, the spindles linked earlier in the thread DO change the roll center, because they change where the balljoint is in relation to a stock spindle.
Furthermore they are the best solution because they are stronger than using a longer shank on a balljoint.

RBbugBITme

11-17-2008, 07:14 PM

I guess I'm having trouble seeing how the extended ball joint RC adjusters work. I thought they were longer but the pivot is still in the bottom part which would be lower relative to the spindle.

Regardless I don't think I'd ever spend money on those and this thread makes me want to get off my ass and get my suspension back together and modeled so I can try my own idea out which seems to be far superior (to me ;) ) than any options presented so far.

jmauld

11-17-2008, 07:31 PM

I suppose you're not planning on sharing that idea?

RBbugBITme

11-17-2008, 07:37 PM

I can't say I'm to comfortable putting it out there. It just sucks that school and FSAE is keeping me from working on my personal projects like this for a long time. Who knows when I'll get to it.

RBbugBITme

11-17-2008, 07:46 PM

I may actually work on this a bit over the week and have some of my senior design teammates sign off as witnesses and then I can blab all I want.

jmauld

11-17-2008, 07:57 PM

Any chance you could have someone who's worked with mcpherson strut based cars have a look at it?

Def

11-17-2008, 08:19 PM

I may actually work on this a bit over the week and have some of my senior design teammates sign off as witnesses and then I can blab all I want.

Easiest proof is to mail yourself a reasonably detailed sketch and keep it sealed.

That said, there isn't near enough money in this to fight it in any court, so it's kind of pointless to take these steps.

Also, I'd say the impediment to replicating your idea is more likely the actual fabrication rather than the idea itself. At least in any real quantity, and thus causing "lost sales."

At least that's my business plan analysis.

RBbugBITme

11-17-2008, 10:00 PM

I've been thinking about it and this industry sucks anyways and I probably wouldn't have the time to fight someone over it.

I'm not saying "use whats found in this picture." But if you can imagine something like this ( http://www.pegasusautoracing.com/bigpicture.asp?RecID=3185 ) being inserted from the bottom of the upright and bolted from the top. It would have a shoulder on the shank that butts up against the bottom surface of the upright for rigidity and to set the height. Then all you need is a straight lower control arm with a spherical bearing.

WishIHadaSilvia

11-17-2008, 11:24 PM

I guess that would be a better idea then a straight FLCA w/ two spherical bearings and a long bolt with spacers?

Forgive my crude drawing:

http://i25.photobucket.com/albums/c51/95KA-Turbo/flca.jpg

Would the set up suggested above be stronger then my drawing? My drawing would be using basically what everyone else does in their aftermarket arms. I'm just not sure how strong it would be.....it also completely defeats the purpose of fixing the problem w/ a mostly stock FLCA, because once you start making aftermarket arms you have to worry about the tension rod and sway bar placement and what not.

So I want to be clear here....will changing this blue section change the roll center?

http://i25.photobucket.com/albums/c51/95KA-Turbo/rollcenter3.jpg

I'm just wondering if actually making a new spindle with a mounting point that was spaced down further would be a feasible option?

RBbugBITme

11-18-2008, 08:51 AM

Def

11-18-2008, 10:57 AM

RBbugBITme

11-18-2008, 11:01 AM

I don't think I'm following you... by spindle I assume you mean upright? My terminology and whats used on these forums is very different. A spindle to me is just the rotating part the wheel mounts to.

Def

11-18-2008, 11:06 AM

Yea, I'm asking about the front upright. How will it rotate?

RBbugBITme

11-18-2008, 11:08 AM

At the new outboard spherical bearing, no more ball joint.

Def

11-18-2008, 11:14 AM

So what mount is in double shea if the outside mount is a spherical bearing?

RBbugBITme

11-18-2008, 11:45 AM

http://img.photobucket.com/albums/v364/iwantawd/uprightmount.jpg

quick and dirty... bearing in double shear, just need to make an arm

Def

11-18-2008, 12:19 PM

I just reread your description you posted earlier and see what you're talking about. I'm not seeing how this is a superior solution. In fact, you're now putting whatever holds the spherical bearing in single shear on both ends, and the rod is still loaded in bending just like a balljoint shank.

I'm just really not seeing what's improved in this design other than maybe allowing some limited adjustment without taking the shank off. I think the distance is so small you'd be hard pressed to put any adjustment in there and still have enough strength.

So what problems were you trying to solve with this change?

RBbugBITme

11-18-2008, 12:55 PM

Yeah the rod is still loaded in bending like the ball joint but the ball joint survives so I'm sure this will with a little FEA and some tweaking. Also, its completely not to scale, I just threw in numbers to make it look right but the shoulder would be much shorter. Right now its 4 inches which is obviously way to much length.

Positives that I see...
1) After pulling my uprights to do some suspension work I managed to mangle my ball joints when I didn't want to and have now spent to much money replacing perfectly good ball joints.

2) Possibly lighter weight and stiffer overall when you factor in the whole control arm.

3) Minor adjustment could easily be added in with shims.

4) Easier to install for the typical wrench head than replacing ball joints

I see a lot of threads about these roll center adjusters and I just came up with a different solution. Maybe its not better but only proper analysis and testing will tell, especially for #2.

Def

11-18-2008, 01:21 PM

Why not just use a bolt through a spherical bearing, or a machined shank?

Speaking of that, any disadvantage of reaming the tapered hole out and using a bolt vs a tapered fastener? I can see getting a tighter fit with a tapered hole and torquing a tapered pin into it, but a tightly fitted reamed hole can't be that far off in practice. Or is it? I see domestic guys sticking with a taper there so maybe a press fit is needed due to the stresses.

RBbugBITme

11-18-2008, 01:54 PM

probably a better design, don't mind the bolt lengths or the fact that you couldn't fit the structure for a control arm around the bearing.

http://img.photobucket.com/albums/v364/iwantawd/uprightmount2.jpg

WishIHadaSilvia

11-18-2008, 02:01 PM

Is your idea "better" or "stronger"? I don't know but mine does allow for the control arm to be in double shear. I can't say I'm to concerned with drivers that don't track their car but still wish to play with roll centers and aren't replacing all of the suspension arms anyways.

If that purple part can be made thicker then yes it would lower your outter pick up points but won't you start running out of thread for the castle nut?

I believe making a new upright is absolutely feasible on the small scale for a few serious racers. People that don't even know what they're doing and don't race drop over $2k on all the typical control arms (FLCA excluded in cost).

Cool...I wanted to be sure I was misinterpreting everything.

As far as running out of thread. I'm thinking of a completely redone spindle (upright as you say). CNCed aluminum with a lower mounting point for the FLCA and shorter arm where the tie rod attaches for greater steering angle. My friend (different friend then I talked about at beginning for this thread) is a mechanical engineer and laughed at my initial ideas and said he'd help me out over the holidays - when he has off work. I know there are a lot of things to consider when doing something like that, so I guess I'll keep you all posted. I'm not really sure what will come of this. I was surprised when he told me what it would cost to get a batch of spindles made up....it's way cheaper then I thought, but I'll have to do it in bulk.

If it doesn't work out then I'll be getting together with my other friend and welding together some FLCAs and see how that goes.

WishIHadaSilvia

11-18-2008, 02:04 PM

RBbug - let me know if I'm looking at that right. The ball joint on the bottom w/ a spacer and built in bolt to go through the upright above?

That's a nice idea for sure. Would strength be an issue though?

RBbugBITme

11-18-2008, 02:39 PM

I think you're looking at it right though I don't know what you mean by "built in bolt."

BTW after a quick and dirty FEA analysis of the last bracket I linked with just a 400lb lateral load it will absolutely fail. :D There are certainly a few ways to build on it though, I think it could work. Maximum displacement was less than 0.009" at the bottom surface and I left the arm down to the bearing too long.

RBbugBITme

11-18-2008, 04:15 PM

I rescind my previous statement, crap in = crap out. Maybe I'll get to running it again before the day is done.

SoSideways

11-20-2008, 08:04 AM

The GP Sports Hyper Knuckles are only like $1500 after all is said and done IIRC, and that's including the cost of the spacers added to the cost of the knuckles already.

The Hyper Knuckles can be used with those spacers to space the FLCA ball joint mounting point and tie rod end mounting point down, and at a maximum can space it downward 40mm.

The Hyper Knuckles themselves sell for around $1100 and the 20mm spacers are around $170 for a pair.

Now, they do make a "cheaper" version, called the Super Knuckle Kit, which are not adjustable, but they have built the knuckles that are 20mm "lower" in the mounting points section, for a price of around $750.

So unless someone can come up with a solution for less than that amount, then there is no reason to spend your time/effort trying to come up with something else, unless the cost isn't that much higher in the end and the end product is much much more superior in design in every way than the GP Sports ones.

RBbugBITme

11-20-2008, 08:29 AM

Its cast...

SoSideways

11-20-2008, 09:01 AM

Its cast...

OK, so... are you worried about the weight issue then?

I am not an engineer, so I don't see why cast knuckles would be bad?

RBbugBITme

11-20-2008, 09:04 AM

Casting is for mass production. I'm quite sure I could get the weight down and stiffness up with a machined design.

SoSideways

11-20-2008, 10:23 AM

Casting is for mass production. I'm quite sure I could get the weight down and stiffness up with a machined design.

For how much more money?

Or are you talking about selling them for less than what those GP Sports ones cost now?

Def

11-20-2008, 11:18 AM

Casting will be super expensive for a few parts. You almost surely won't be able to make these out of aluminum due to the strut mounting holes keeping the stress high in that area.

RBbugBITme

11-20-2008, 04:13 PM

Cost is dependent on a few things. I have talked it over with younger teammates and I expect to be able to come down the lab after graduating and for a small donation I'll be able to run our CNC on my own for very cheap and run enough parts out of here to satisfy all the members on this forum at least. Again, I'm not focused on mass production. If I were to outsource I don't know if I'd be able to keep it below $1500 but I don't think it would be much more than that. Entirely depends on how much of the OEM stuff you want to make use of as well.

SoSideways

11-24-2008, 07:09 AM

So I was thinking, since everyone keeps saying that if they want to fix the front roll center, to also fix the rear, or the car could handle worse and act funny.

So, if you could "fix" the front roll center by placing a 40mm spacer in the spindle to lower the ball joint mounting point by 40mm in the front relative to the same ride height, would the rear need a 40mm fix also? Or would the rear's "fix" be somehow different?

WishIHadaSilvia

11-25-2008, 09:01 AM

SoSideways

11-26-2008, 07:14 AM

Well, when my friends get more free time we're going to take measurements and see how moving the inner mounting point up will effect everything.

If that works w/o any ill effect in simulations/calculations then there is plenty of room to fix it in the back as well. Otherwise it's going to require custom control arms front and back...or custom uprights front and back. Either way it'll require a lot of PITA work and money.

Well, like someone linked to earlier, and I also touched on that subject earlier as well, GP Sports make front knuckles that is 20mm lower in the FLCA ball joint mounting point for around $750, and they make one that will allow you to put either 10mm or 20mm spacers on to space the ball joint mounting point lower on the knuckle for a maximum of 40mm of adjustment, for $1100 for the knuckle, and around $170 for a pair of the spacers.

So there really is no need to bang your head on the walls to try and figure out the knuckle method, unless you're talking about improving on their design (which, at this point, seems to be a dang good design that cannot be really improved upon other than to make it out of a chunk of billet aluminum or something for light weight, but then the cost for it would skyrocket).

Concentrate on the idea of moving the inner mounting point up, and report back on the findings.

Most importantly, see if you can devise some sort of test where you can measure the changes that you've made, either in a positive or negative way.

Maybe like a lane change test, or skid pad test, something. Something that will be able to be put onto paper and prove that yes, the changes made on the inner mounting point did help, or no, it did not help, as it hurt the times/speed here, etc.

Thanks for putting in the leg work man, you and your friend :)

Umai Kakudo

12-03-2008, 12:24 AM

Here is some extra Fuel.

1) Read the Rule Book. Some rule books prohibit modification of the uprights. You'll see a lot of SCCA cars with extended studs connected to heim joints and/or relocated inner pivots for this reason.

Here is an excellent article on constructing control arms and relocating suspension pivots on an E30 M3 using proper hardware and materials.

http://www.e30m3project.com/e30m3performance/installs/installs-3/control_arms/index.htm

http://www.e30m3project.com/e30m3performance/installs/installs-3/control_arms/pic-1.jpg

http://www.e30m3project.com/e30m3performance/installs/installs-3/control_arms/pic-2.jpg

http://www.e30m3project.com/e30m3performance/installs/installs-3/control_arms/pic-4.jpg

I'd really like to get away from the single shear setup but the only way to do that is to fabricate a custom upright. Perhaps a plate that connects the ball joint with the tie rod mounted below the rod ends would help.

SP-Tech from Japan makes fabricated upright drop spindles that are all welded steel.

http://sp-tec.com

http://sp-tec.com/shop/goods_image/A28_Z1.jpg

http://sp-tec.com/shop/goods_image/A29_Z1.jpg

One of the best designed aftermarket drop spindles is the Grigg Racing design (only $3,567.96 for a pair and is used for their SLA conversions!):

http://www.griggsracing.com/product_info.php?products_id=373
http://www.griggsracing.com/article_info.php?articles_id=15
http://www.griggsracing.com/pdfFiles/NewProductReleaseAlumSpindle.pdf

http://www.griggsracing.com/images/MDS4000.jpg

http://www.griggsracing.com/images/AlumSpindl2.jpg

Ideally you would design a modular body that would allow different balljoint/tie rods to be made so that they could be customized for ride height, ackerman, steering ratio, and other factors. That way you could keep the grip and the drift guys happy.

Now if you want an example of cost is no object just give CRP Technology a call and have them make you some cast Titanium uprights like the do for F1 and WRC teams

(Image is of rapid prototype mockups)
http://www.crptechnology.com/sito/images/stories/CaseStudies/windform-ps-2.jpg

Case Study
http://www.crptechnology.com/sito/it/rapid-casting-case-study-with-laser-sintered-polystyrene-patterns.html

For the rear I'd make a custom tubular crossmember replacement that attaches the end points like the fomula and sports racer cars do

http://dpcars.net/dp1bld/dp1147.jpg

Or better yet something with bolt on brackets for each pickup point that could be replaced or shimmed out to make ajdustments

http://dsr.racer.net/chassis/srscca/images/Hagerman/suspension_rear.jpg

I remember and article in an old Option on a JGTC 300 S15 where they redid the entire rear suspension crossmember to make it a SLA dual wishbone with toe control link and a lot less anti-squat.

Since the S series suspension is far from perfect one is tempted to go buck wild and do all sorts of crazy and expensive things to change it.

Personally - I'm just going to focus on replacing every suspension bushing with a beaning, correcting roll center back to factory for my ride height, and have fun.

Then I'll buy a DSR or F1000 car to actually go fast on a track for less time an probably less money and certainly better function.

RBbugBITme

12-03-2008, 12:46 AM

Then I'll buy a DSR or F1000 car to actually go fast on a track for less time an probably less money and certainly better function.

Not trying to be an ass but you're on crack, good luck beating a Stohr with a custom formula car that costs less than a 240sx.

a_ahmed

12-03-2008, 04:38 AM

http://sp-tec.com/shop/goods_image/A28_I1.jpg (http://66.163.168.225/babelfish/translate_url_content?.intl=us&lp=ja_en&trurl=http%3a%2f%2fsp-tec.com%2fshop%2fgoods_image%2fA28_Z1.jpg)

Aren't your love car and the arms of the underside hurray state? As for AR upright when lowering the height, the geometry change which happens is reset to correct geometry by changing the position of upright side. Cornering of strange dimension is promised by bringing close angle of the arms to proper angle when the height is lowered. Normal ratio 50mm it knocks down

lol, it's around 1000 canadian dollars, less for you guys. Not bad no?

and for the rear:

http://sp-tec.com/shop/7_29.html

http://sp-tec.com/shop/goods_image/A29_I1.jpg

Aren't your love car and the arms of the underside hurray state? As for AR upright when lowering the height, the geometry change which happens is reset to correct geometry by changing the position of upright side. Cornering of strange dimension is promised by bringing close angle of the arms to proper angle when the height is lowered. Urethane bush installation being completed. At normal ratio as for lower toe shock 45mm down. Upper 35mm down.

no z32 setup though.

Honestly if we could get a hold of one of these we could mass produce them for cheap. I mean its less than 1000 USD canadian dollar went kaput, its 1000CAD lol.. so more like 700USD or something....

If its all good, they already did their work, and we could just replicate what they did...

WishIHadaSilvia

12-03-2008, 07:50 AM

Umai Kakudo awesome post, it really solidifies what I've been thinking and brings up some good points/options out there.

Does anyone know what Option issue has that JGTC Silvia in it? I've seriously been dieing to see what they do to the suspension in those cars because they're so low they have to use special fenders on them, and they're all out grip cars.....and so, so sexy! I can't find any pictures online, I just assumed it's all top secret even though they don't use the freaking S chassis anymore!

PS the USD to Yen conversion right now is so freaking bad! It's like 93:1, when I was over there last September it was 118:1!

a_ahmed

12-03-2008, 08:26 AM

You make me wana post sexy s15 pictures in this thread including the jgtc car :P Im gona create another thraed not to pollute

float_6969

12-03-2008, 09:32 PM

Umai Kakudo

12-03-2008, 11:35 PM

Not trying to be an ass but you're on crack, good luck beating a Stohr with a custom formula car that costs less than a 240sx.

I agree ;)

I was thinking more along the lines of buying a new or used Stohr ($30K - $50K depending on spec) VS re-engineering a 240sx from the ground up and not building a runnoffs winning lowcost DSR.

The amount of money, mods, and fabrication needed to get a 240sx to do the same lap times as a F1000/DSR and have a sequential transmission would be at least $20K to $30K if not more and you'll never be able to 'add lightness' any where close to a purpose built racer.

Thinking of running costs a 240sx will use larger tires more expensive tires and due to the increased weight likely use a greater quantity of consumables (tires, pads, rotors).

To me that makes it a better 'value' for the level of performance all things considered even if the purchase price of the Stohr is higher initially. It could be done cheaper of course by using a different chassis or making your own but it would be less competitive as you pointed out.

Back on topic ~

These articles form Griggs racing is a good example of all the factors and steps required to modify a road car suspension for performance/track use.

It outlines the complexities involved in making a balanced system work together rather than just "fixing the roll center".

http://www.griggsracing.com/article_info.php?articles_id=23

and

http://www.griggsracing.com/article_info.php?articles_id=16

I really dig how they do things and operate even if they are a Mustang shop.

It should give you good fabrication ideas as well. Front SLA conversion for 240sx's anyone?

http://www.griggsracing.com/images/S197DF.jpg
http://www.griggsracing.com/images/S197PF.jpg
http://www.griggsracing.com/images/S197SPINDLE.jpg
http://www.griggsracing.com/images/S197SLABRAKE.jpg

RBbugBITme

12-04-2008, 12:30 AM

I guess I misunderstood you're point a little but no amount of money could get a 240sx to reach the lap times a good F1000 can get. Oh I'd love to get into this more but I'll save the formula series talk for another forum.

WishIHadaSilvia

12-04-2008, 06:58 AM

Has anybody considered an extension that screws onto the top of the stock ball joint to lower it in relation to the knuckle? Something like this;
http://is.rely.net/3-36-15468-l-hJQYVk0L9oPI7sRIMZT9DA.jpg
It would be VERY easy to produce on a lathe, and could easily be produced in large quantity. Steel would be a preferable material, but IDK how to figure out how much more load this would place on the ball joint, and if it could handle it.

I'm not sure how that would work load wise. Something to consider though, it would have to be relatively small and be made of a strong material, and I guess the strength of the ball joint would be a big issue.

I think making a control arm like this would be easier then making a spacer work on the spindle:

http://www.e30m3project.com/e30m3performance/installs/installs-3/control_arms/pic-1.jpg

But I don't know anything about anything so I could be wrong, haha.

Wiisass

12-04-2008, 04:38 PM

float_6969

12-04-2008, 08:57 PM

There are internal threads on the piece that the stock ball joint threads into. Like this;
http://is.rely.net/3-36-15503-l-FztflCVoFIgi8wsO8MpA.jpg
I would think the threads alone would allow you to tighten it enough to be safe, but since it's a rotating part, I would probably put some loctight on it, just to make sure it doesn't un-thread itself.

WishIHadaSilvia

12-04-2008, 09:11 PM

Yeah some red lock tight would keep it in place (haha), but would it obstruct the movement of the factory ball joint at all?

Those are very nice drawings by the way.

float_6969

12-04-2008, 09:23 PM

It shouldn't have any effect on it's movement. The only concerns to this idea in my mind are the effects of placing a "longer lever" on the ball joint (increased load) and what material to use if the increased load is acceptable. Unfortunately, I'm not in any position to figure out how much load the stock ball joint is subjected to and how much this piece would increase that load over stock.

LOL, MS Paint FTW.

Umai Kakudo

12-05-2008, 12:50 AM

So how do you tighten this piece to the stock ball joint?

Valid point - It will be very difficult to hold the lower balljoint stationary to tightly thread the adapter on without putting some sort of wrench slots in it which would weaken the now higher stressed balljoint.

Found another example of a forged aftermarket drop spindles for GM A bodies.

Made by American Touring Specilites - The 'AFX Spindle'

Full details: http://store.nexternal.com/shared/StoreFront/default.asp?CS=ats&StoreType=BtoC&Count1=979427516&Count2=896567940

http://www.bmrfabrication.com/misc/AFX-large.jpg

These are the modular steering arm links that would allow for different ones to be made to suit your retup and make the upright more universal.

http://www.bmrfabrication.com/misc/AFXSteerarm_large1.jpg

The cool thing is that these uprights are forged Aluminum but they are a reasonable $750 MSRP complete with hubs.

float_6969

12-05-2008, 06:04 AM

It shouldn't be any harder to do that putting the castle nut on it, and that doesn't require any wrench slot. All this adapter would do is duplicate the "female" portion of the knuckle on the inside and the ball joint on the outside. As I said before, loctight would be needed to keep it from un-threading.

Wiisass

12-05-2008, 03:54 PM

It's not going to work. It's not like just threading a nut on, you have to tighten it so that the inner and outer taper will seat against each other. You won't be able to do that if the ball joint is spinning. And with that design, you won't be able to hold the ball joint in place.

jmauld

12-05-2008, 04:17 PM

How difficult would it be to just convert the stock arm to a bearing with a bolt through the knuckle?

WishIHadaSilvia

12-05-2008, 04:42 PM

In my completely inexperienced/uneducated opinion making control arms like this will not be very difficult:

http://www.e30m3project.com/e30m3performance/installs/installs-3/control_arms/pic-1.jpg

Sorry I keep whoring up that picture, but it just makes so much sense, you can just measure where everything is supposed to go and make a straight pipe with rod end bungs welded on either side. Am I grossly over simplifying this?

Wiisass

12-05-2008, 05:30 PM

You could just make something, but that doesn't mean it will work. You have all the loads the arm see that you need to account for. TC rod, sway bar, normal suspension loads, etc.

So it could be made and pretty easily, but that doesn't mean it won't suck or break.

And that one you keep posting, looks alright, I guess. It would have to be unbolted to adjust, not that I like those dumb threaded adjusters that you see on most crappy control arms, but at least for the TC rod, it would be just as easy to make it a turnbuckle and not affect the strength of the part. The LCA is another case, due to the bending load the arm will see from the sway bar loads, it's hard to make it a turnbuckle because you don't want to put threads in bending or shear. It can be alright to have a rod end on the inside if it's accounted for. And the outboard pin would need to be properly designed, you can't just extend it and hope it doesn't break.

But I really don't get why people are so concerned with roll center when they don't even know what it is.

float_6969

12-05-2008, 07:09 PM

I guess I'm not understanding how this is different from threading the castle nut onto the ball joint. It doesn't present a problem with spinning in that scenario, why does it present a problem in this one? I'm not saying that you're wrong, just trying to understand.

Wiisass

12-05-2008, 07:46 PM

So you just want to loosely thread this piece on. Are you going to tighten it against anything? Or just put loctite on there and think it will be fine?

If you still don't get it, go and try and tighten a castle nut on a stock ball joint, but torque it to 30ft-lbs or try to. And then take that same ball joint and put it in the spindle and see how much torque it takes on the nut to get the taper to seat into the spindle.

float_6969

12-05-2008, 08:57 PM

I've tightened a castle nut before, and I understand how much turning force is required to seat the ball joint into the knuckle. The lack of turning force is the reason for the castle nut and cotter pin. In all honesty, I've sheared off multiple bolts trying to remove them after using a copious amount of RED loctite. Once it's been applied and sets up properly, it usually can only be removed with heat.

But if that's not enough, it would be simple enough to build the adapter in 2 pieces that would allow a pin to pass through the hole in the stock ball joint, eliminating ANY chance of it un-threading.

Now that the idea that this can't safely be attached to the ball joint has been eliminated, is there any other verifiable evidence that would show that this isn't plausible?

Wiisass

12-05-2008, 09:23 PM

You still don't get it.

You don't want the threads taking the load, that's not what they're meant for. You the body of the ball joint pin, the tapered part, to see the load. How is that going to happen if you can't tighten your piece to actually seat on the taper of the ball joint. And you won't be able to unless you can keep the ball joint pin from rotating.

You already admitted you don't understand mechanical design or how this part sees load or anything really necessary to design a part like this. So I would just stop, it's a simple idea, you just don't know how to make it work.

float_6969

12-05-2008, 09:52 PM

Wow, if you're that frustrated by my inquiry, don't respond?

If it's a 2 piece design, the threads won't take the load, the shaft of the ball joint will take the load, just as in the stock configuration. If you can't picture what I'm saying, I'd be more than happy to draw you a picture.

LOL, I didn't say I didn't understand mechanical design or how it see's load. What I don't know is how to calculate the change in force that would be applied to the stock ball joint pivot point by the lengthening the effective length of the ball joint shaft.
http://is.rely.net/3-36-15513-l-FIVuhJizp04PfQGdOtVwVQ.jpg

veilside180sx

12-05-2008, 10:10 PM

veilside180sx

12-05-2008, 10:13 PM

Float

I think the real thing is...would you trust that with your life. Realistically...that's what it comes down to. I know I trust a 3/4" stud to support my vehicle and not fail. I'm not sure if I'd trust that enough to say that.

WishIHadaSilvia

12-05-2008, 11:03 PM

I know Bill at DSG uses a control arm similar to that BMW one posted.

He's got great pictures on his site:

http://gallery.dentsport.com/cache/dsg-shopcars/bill240_001/suspension/DSCF5957.JPG_960.jpg

I'm sure you all are familiar with his set up though.

http://gallery.dentsport.com/albums/dsg-shopcars/bill240_001/suspension/DSCF5951.JPG

His rear set up:

http://gallery.dentsport.com/cache/dsg-shopcars/bill240_001/suspension/DSCF5913.JPG_960.jpg

http://gallery.dentsport.com/albums/dsg-shopcars/bill240_001/suspension/DSCF5914.JPG

I know he uses far from stock sway bars...and really everything else on his car, but the design is still there.

This may sound stupid but even if I can't make anything after all of this I still enjoy reading everyone's comments and stewing about ideas like this.

RBbugBITme

12-06-2008, 12:35 PM

http://gallery.dentsport.com/cache/dsg-shopcars/bill240_001/suspension/DSCF5913.JPG_960.jpg

Oh no, are those rod ends in bending?

WishIHadaSilvia

12-06-2008, 01:17 PM

I think that's an optical illusion? The arm bends like that but it has a straight piece of pipe welded there, I'm not sure if we're even talking about the same thing though.

RBbugBITme

12-06-2008, 01:30 PM

We're not talking about the same thing. Here is a good article for you... http://www.formulastudent.de/academy/pats-corner/advice-details/article/pats-column-rod-ends-in-bending/

Def

12-06-2008, 03:02 PM

Which rod end is loaded in bending? Looks like every rod end I see is loaded in tension or compression.

Wiisass

12-06-2008, 03:28 PM

Def, sway bar loads will put the inner rod ends in bending/shear. It's probably more of a concern in the front than the rear. But realistically for how these arms would be built, it probably wouldn't even be an issue. It's not the best design, but the adjustability out weighs that factor.

And if you know your sway bar loads, you can calculate for it and probably not even have to worry about it.

Def

12-06-2008, 03:46 PM

Oh, I suppose so, but I was expecting a more major force than the sway bar loads. It's not like you're putting your entire braking force in bending or anything.

WishIHadaSilvia

12-06-2008, 07:52 PM

That was a very interesting article to read. See now I only thought I was in over my head in this topic, now I understand that this topic is WAY over my head.

I thought this was humorous though "...Newtons Second Law. Cars that are heavier than necessary are not good designs." Hahaha!

Does this design also put the inner rod end in bending? It would technically see similar loads as the rear suspension set up in question right?

http://www.240edge.com/performance/f-l-arm-spl.jpg

RBbugBITme

12-07-2008, 02:11 PM

The line of force issue in the last pic in the article shows what I would probably be most concerned with which I'm sure is why he has the "anti-intrustion" bar to help reduce those bending forces.
http://www.formulastudent.de/uploads/RTEmagicC_image009.jpg.jpg

That funny quote is the reason I mention this, its definitely additional weight that isn't necessary. Why would you want to adjust camber from the LCA anyways? You're changing scrub radius, KPI and therefore bumpsteer, ARB rates, track width (minimally). I'm not a fan, you'd be better off with camber/caster plates to get close and eccentric bolts to dial in the set up.

Wiisass

12-07-2008, 07:20 PM

No matter where you adjust camber, you're changing kpi, scrub radius, etc. If you change it at the upper mount, you're changing roll center, kpi, scrub radius, camber gain, etc. And you're changing a lot of things if you adjust at the spindle.

As for the heavy comment, I would bet if you did the load calcs, the rod ends that you would use based on mounting hole size in the subframes, are more than enough to account for the loads the arm sees.

RBbugBITme

12-07-2008, 07:29 PM

As for the heavy comment, I would bet if you did the load calcs, the rod ends that you would use based on mounting hole size in the subframes, are more than enough to account for the loads the arm sees.

That doesn't make it a good design.

No matter where you adjust camber, you're changing kpi, scrub radius, etc. If you change it at the upper mount, you're changing roll center, kpi, scrub radius, camber gain, etc. And you're changing a lot of things if you adjust at the spindle.

Maybe I need to think about it more but how do camber bolts at the bottom of the strut change KPI? The lower ball joint isn't moving and the upper strut mount isn't moving, the only thing changing is the angle of the spindle aka upright. The strut axis shouldn't move either so the scrub radius would have a minimal change from the tire contact patch center of pressure moving with the camber adjustment.

Wiisass

12-07-2008, 07:39 PM

You're right, it doesn't make it good design, but it doesn't make it bad design. And it's funny for you to nitpick that after talking about basing control arm tubing size off of the other arms on the market.

Alright, you caught one, but you're changing roll center, camber curves, etc when you adjust at the strut/spindle mounting bolts.

RBbugBITme

12-07-2008, 07:48 PM

You're right, it doesn't make it good design, but it doesn't make it bad design. And it's funny for you to nitpick that after talking about basing control arm tubing size off of the other arms on the market.

Ok, I fail to see why starting my calcs around whats known to work is a bad idea...

Alright, you caught one, but you're changing roll center, camber curves, etc when you adjust at the strut/spindle mounting bolts.
Can you explain why RC/IC changes when you just agreed the strut axis doesn't change and the LCA isn't moving anywhere?

Wiisass

12-07-2008, 08:14 PM

Well you said good design.

You must have edited that part about strut axis while I was typing my response. Because it's wrong.

If you adjust at the where the strut mounts to the spindle, you are changing the axis of the strut. KPI doesn't change because you aren't moving the ubj or lbj. But since you're changing the strut axis, roll center/instant center/camber curve, etc will change.

RBbugBITme

12-07-2008, 08:29 PM

If the strut is able to move then how does the spindle move in order to change camber? One of the two has to be stationary and we know its not the spindle. Unless I'm wrong and the bottom of the strut axis goes through the centerline of the bolts and not the centerline of the strut.

Wiisass

12-07-2008, 09:07 PM

But one doesn't have to be stationary. The strut is pinned at the top and at the lower of the two mounting bolts and the spindle is fixed by the lbj and the lower of the two strut mounting bolts. So when you change the angle of the spindle, you're changing the location of the lower strut mounting bolt which will affect the angle of the strut axis. Unless both strut mounting holes are slotted, you won't be able to hold a strut axis angle while adjusting the spindle angle.

RBbugBITme

12-07-2008, 09:47 PM

I'll have to play with it when I get it back together. I still think the strut doesn't move much. When you turn the eccentric bolt the position of the bolt head doesn't move but the upright pivots at the LBJ. Either way we're arguing over about a half of a degree of change of strut axis angle.

Wiisass

12-08-2008, 04:54 PM

I never said it was a huge change, but changing the strut axis does affect a lot. And it's on the order of magnitude that everything you mentioned originally is.

RBbugBITme

12-08-2008, 06:06 PM

Ok so we agree that changing camber at the lower control arm affects more suspension parameters than eccentric bolts or even camber plates but the effects are so small no driver on here with our twisty frames would even notice. Good debate, whats next on our RC discussion. How about the effects of RCs that pass through the ground plane...

Wiisass

12-08-2008, 08:38 PM

RBbugBITme

12-08-2008, 09:17 PM

No, we don't agree on that. Each method of adjustment will affect the whole suspension, some ways will affect some variables more than others. It's all a compromise like any suspension adjustments, you just have to look at what you want to change and why.

But we discussed that adjusting with eccentric bolts doesn't change KPI so it does affect fewer parameters.

But I will agree, that most people won't know the difference between the different methods. But that doesn't mean that they're negligable.

Thats true but I was saying that no one could FEEL the difference on track with our old floppy chassis' and amateur driver skills.

And most roll centers are probably below ground already, unless the car is super high and running no camber adjustment at the upper mount. But we could talk about how high the roll center goes during roll.

Hopefully I'll get to work on the Mitchell model over xmas break.

mmdb

12-09-2008, 11:31 PM

After reading this thread, has anyone tried to get an OEM steering knuckle and space it out, similar to the GP sport? If anyone has a set or know someone who does let me know. If it's feasible I'll do it, and if anyone's interested I can get additional sets made.

RBbugBITme

12-10-2008, 09:13 AM

Do you have a pic of what you're talking about?

mmdb

12-10-2008, 09:34 AM

well basically it's a similar concept as the gp sports knuckle.

SoSideways

12-10-2008, 10:22 AM

well basically it's a similar concept as the gp sports knuckle.

I studied the GP Sports ones, and looked at the stock ones to see if the stock ones can be cut, drilled and tapped to accept a spacer or whatever, but there isn't enough metal on the stock one to do that with.

Not to mention the GP Sports ones actually move the arm in which the tie rod end bolts to inward a bit to achieve a little more angle.

They've also moved the mounting point for the FLCA ball joint inward a little.

mmdb

12-11-2008, 11:08 PM

I studied the GP Sports ones, and looked at the stock ones to see if the stock ones can be cut, drilled and tapped to accept a spacer or whatever, but there isn't enough metal on the stock one to do that with.

Not to mention the GP Sports ones actually move the arm in which the tie rod end bolts to inward a bit to achieve a little more angle.

They've also moved the mounting point for the FLCA ball joint inward a little.

This thread might be of some interest. http://forums.nicoclub.com/zerothread?id=349679&page=1

It was an s14 that was raced in the Speed Vision race series. You can see how his spindle was modified to adjust for bump steer, and it also looks like the spindle was modified to account for roll center as well.

http://www.fatmanracing.com/S14/08build/IMG_0524.JPG

On the side note, I found a pair of spindles near my home. I'll pick them up and take them to my machine shop and see what they say. If possible, it might be a few more weeks till I get them modified until I get my coilovers back.

Adios!

Def

12-12-2008, 12:38 AM

Rod end on the outer ball joint location is not a great idea...

SoSideways

12-12-2008, 06:32 AM

Rod end on the outer ball joint location is not a great idea...

I was just gonna say, that design just doesn't look that great to me at all...

1) it has to be pretty heavy
2) the rod end at the end of the lower arm where the ball joint is... that doesn't look safe at all, and after all the discussions between Def and Tim it's apparent that that is not such a good/safe design

If anything, you can take that idea, or rather concept, and make a custom knuckle by combining what was shown in that picture and the GP Sports Hyper Knuckle's concept.

So, instead of welding on that ginormous plate to move everything down, you can weld on maybe like, half an inch of material, maybe less. Just enough material to strengthen the bottom of the OEM knuckle, and then you can find another pair of knuckles and chop off the part where the ball joint will seat onto, and the part where the tie rod end will bolt onto, and weld a plate joining those two to essentially make something like the GP Sports Hyper Knuckle's bottom piece.

From there, you can drill 2 holes into the modified OEM knuckle (the one that was reinforced by the small plate welded onto the bottom of the knuckle) and bolt the new bottom piece up.

Now you can make various thickness "adjustment pieces" that can go between those 2 halves for an adjustable roll center and bumpsteer knuckle.

If I can find a picture of an OEM knuckle hanging out on the web later today I might be able to photoshop up a diagram or something to go along with this post.

a_ahmed

12-13-2008, 06:35 AM

This thread is finally picking up :D Interesting... :)

mmdb

12-14-2008, 10:56 PM

I was just gonna say, that design just doesn't look that great to me at all...

1) it has to be pretty heavy
2) the rod end at the end of the lower arm where the ball joint is... that doesn't look safe at all, and after all the discussions between Def and Tim it's apparent that that is not such a good/safe design

If anything, you can take that idea, or rather concept, and make a custom knuckle by combining what was shown in that picture and the GP Sports Hyper Knuckle's concept.

So, instead of welding on that ginormous plate to move everything down, you can weld on maybe like, half an inch of material, maybe less. Just enough material to strengthen the bottom of the OEM knuckle, and then you can find another pair of knuckles and chop off the part where the ball joint will seat onto, and the part where the tie rod end will bolt onto, and weld a plate joining those two to essentially make something like the GP Sports Hyper Knuckle's bottom piece.

From there, you can drill 2 holes into the modified OEM knuckle (the one that was reinforced by the small plate welded onto the bottom of the knuckle) and bolt the new bottom piece up.

Now you can make various thickness "adjustment pieces" that can go between those 2 halves for an adjustable roll center and bumpsteer knuckle.

If I can find a picture of an OEM knuckle hanging out on the web later today I might be able to photoshop up a diagram or something to go along with this post.

As long as his design is effective I wouldn't worry too much about the unsprung weight. The joints could or could not be strong enough. Since the car was kept on the track I don't think it would cause so much concern. The design does warrant a concern if it was for street usage.

Update: I found a set of front and rear spindles to be modified. I'm not sure what my fab shop will come up with, but I've always been impressed with their designs. I'll post some pix when I get it done.

Def

12-14-2008, 10:58 PM

The nature of dreaded metal fatigue is that what works fine for a while will eventually have a fairly quick failure as the metal weakens. I'd never take a design like that out on track...

Wiisass

12-15-2008, 09:52 AM

I hate the GP Sports design. Two bolts in single shear holding together the spindle. It's just crappy. I think I've posted about it before or at least some of my thoughts on here or ziptied, I don't remember which.

All this talk about modifying spindles and cutting stuff and whatever is really scaring me. Not because shops/people can't safely do the work. But no one seems to know why they want this done or how much of a space they want to add or what it will do. I think that's more important than just modifying something.

But maybe I'm being idealistic and just would like to see something done right for once.

a_ahmed

12-15-2008, 10:39 AM

SoSideways

12-15-2008, 11:09 AM

Well give us a practical solution then wiisass... rather than being skeptical, i honestly have no clue, im no ME, but in simplton terms, I'm aware geometry gets messed up with a lowered car. In a stupid ppl world, messed up things or not optimal things are wishfully resolvable... by smarter people. You are smarter, so, do something about it rather than putting people's hopes down, haha.

Agreed.

Wiisass Tim, you know your stuff for sure. But you are also very quick to dismiss something and explain why.

However, you haven't really shown anyone what YOU think would work "the best", or "ideally" how you would want to make it.

Prime example, this spindle modifying situation.

You sort of pulled the same stuff on the FLCA discussion not too long ago, but at least you gave people an idea of what would work better and what would not work, but you still never gave your idea of what you would come up with.

I mean, are you just not "showing your cards" because you want to be paid to do so or something?

RBbugBITme

12-15-2008, 11:59 AM

While we all await Wisass' response why don't all of you answer this important question. Just ball park it but how much would you be willing to pay for...

a) a redesigned upright to work with the stock suspension
b) a more in depth suspension redesign which would involve moving around inboard pickup points

Obviously, cost is the #1 factor here so there is no use talking about options that are to expensive for this community. For example, when I take the time to seriously look into redesigning the upright I would probably put a laser cut steel box design at the top of the list since its cheaper than CNC'd aluminum.

Cutting/drilling into the cast upright is scary to say the least!

SoSideways

12-15-2008, 02:01 PM

Well, the GP Sport unit, despite Wiisass' dislike for it, is the only adjustable knuckle out there on the market, and adjustability is a good thing, as ride height and alignment settings will be different from car to car (although I don't think alignment will interfere with the knuckle's height or whatever), and that unit costs around $1300 or so for just the pair of knuckles. Each spacer there after is $170 or so for a pair of them, so you're looking at ball park figure of $1500 for a comparison.

If you can do something for around $1500 that is adjustable, and have every engineer on here's approval, I don't see why it wouldn't work.

Although, just because they approve of the design, how many people are actually willing to spend $1500 on some knuckles?

WishIHadaSilvia

12-15-2008, 10:26 PM

I'm not spending 1500 dollars on some Chinese cast knuckles.

Assuming I had a well paying job and could be given a very nice warranty I'd be willing to spend ~3-600 per knuckle....but I'd want it to be CNCed aluminum or I could just spend the money on some SPL control arms and save myself the headache of messing with spindles.

The reason I made this thread was for people to brain storm/post working/workable/reliable/properly designed/ME approved knuckles/control arms that could be welded up by anyone with welding experience (I was also hoping they could be designed to help the drifting and road racing communities). The entire point being - do it yourself = saves a lot of money.

I can understand not wanting to share information because you make your lively hood off of it. However, I don't think there is a huge market in 240sx spindles/control arms. If there was there would be more then a handful of companies making those parts - and the parts would be more competitively priced.

That being said I know Tim is a very busy person and has better things to do with his time then draw up the perfect spindle/control arm mod....like get my bilsteins made, haha! So that is probably why he isn't posting anything...at least I'd hope that was why.

Wiisass

12-16-2008, 09:44 AM

I don't think it would be worth it for me to do something like this, at least not until I decide I want to do it for my own car. As people have said, there isn't enough of a market for it and people won't want to spend that much money on it to make it worth it. The only reason you'll see some aftermarket spindles for so cheap is because they're having a lot of them made. If I got 1000 spindles made, it would be a lot cheaper than getting 20 spindles made, but I have a feeling that even 20 spindles would be tough to sell.

Another reason it's not worth it is because I think there's a lot of areas of improvement on most cars that should be looked at before doing something like this. Roll center heights, camber curves, etc can be accounted for, they don't need to be brough back to stock. And does anyone even know what stock is and why it's so good? Just because Nissan designed it that way doesn't mean that it's the best. The 240 wasn't some high performance sports car. I'm sure they put some thought into it, but who knows what they're original design targets were.

And that's the other thing, no one has any design targets. It's like "I want my roll center higher." Well how much higher? No one knows and even if they think they know, they have no reason for it.

It's true, there are downfalls to the macP strut design, they're inherent and custom spindles won't fix all of those problems. It's easier to account for them than to fight them. But like I keep saying, no one knows what their roll center height is, so no one knows how much they have to account for it or how they're camber curves are going to look or how any other suspension geometry factors into everything. I really don't think many people really have any idea at all. Don't take that as an insult because I don't mean it that way.

It all comes down to design versus tuning. There was actually a good article about this in Vehicle Dynamics International a couple months back. They talked about the different outlooks and asked a lot of the top vehicle dynamics guys in the industry on their opinion. It was pretty interesting and definitely worth a read if you can find it. If I ever get my new printer/scanner/etc thing hooked up, I'll try and scan it.

In my opinion, especially on a car like this, tuning is more important. There are design flaws, but they can be worked around and accounted for if you understand them. And I don't think anyone has gone far enough with tuning, to really get to the point where the gains in redesigning the spindle outweigh the gains from more tuning.

But with all that said, if anyone is serious, I will design and have these made. I will need $10k up front and you will get 2 pairs of prototype spindles to test.

2Fass240us

12-16-2008, 12:02 PM

Just add some A-arms...it'd be cheaper anyways.

The only Tim worth a **** is this one:
http://www.virginmedia.com/microsites/movies/slideshow/top-ten-movie-wizards/img_2.jpg

Wiisass

12-16-2008, 05:45 PM

Just add some A-arms...it'd be cheaper anyways.

The only Tim worth a **** is this one:
http://www.virginmedia.com/microsites/movies/slideshow/top-ten-movie-wizards/img_2.jpg

I'm going to have to disagree with both of those statements.

mmdb

12-16-2008, 06:08 PM

Ok first off, no one is going to pay 10k to have you, me, or anyone develop a front spindle, especially for our cars. Although it might be an ideal approach I'm more inclined to taking a set of spindles, having it modified and testing/tweaking it thereafter. This might prove to be time consuming and slightly costly, but I'm sure race car engineers learn A LOT by arbitrarily sticking a product on their cars, running it, and tweaking it and proving it effective - Think about the Gurney flap. With that said I think we should use the approach of modifying an OEM spindle. It's cheap (a set runs for 180 bucks front and rear) and readily available. I have a set of front and rear spindles/uprights/knuckles coming to me this week.

From what I've been reading cars do not always have the front and rear roll center the same height. According to a book by Skip Barber Racing School a higher roll center increases roll resistance. So from what I'm concluding is public used, non-race cars have roll centers higher in the front to promote more roll resistance, and more weight transfer to the outside wheel during turns to promote understeer. So i'm assuming that the 240sx, from factory, was designed to have a much higher roll center in the front that the rear. Now as a starting point, would it be wise to space the spindles so much that the front and rear LCA pivot points are parallel to the ground, or maybe possibly higher in the rear as for weight transfer when the car is accelerating?

Wiisass

12-16-2008, 07:05 PM

Well $10k is what it would take for me to care about this. And if you understood the amount of design time that would go into something like this, it's not that unrealistic. It's 100 hours worth of my time for a project like this. Probably way under the amount of time that I would really need to spend to do something like this right.

But go ahead, cut, weld, brace, whatever. I just really hope it doesn't break on you and hurt someone.

Race car engineers who learn a log by "arbitrarily sticking a product on their cars" don't hold jobs for very long.

The gurney flap is your reasoning? Roll center and suspension geometry and mechanical design are all well known, documented and understood. You aren't trying anything new. What you're talking about is done on every car ever made.

I would keep reading if you're really going to try this. And maybe a better book than the Skip Barber Racing School book. You're missing 95% of the variables that factor into handling.

mmdb

12-16-2008, 09:20 PM

I don't doubt anything you've stated. But don't get me wrong. I'm not going into this with just "forum knowledge" or without any support. I'm relying on my chassis fabrication guys to help me out. I understand a well engineered part like this is going to cost a lot. If Griggs came up with something equal to what they offer for Mustangs I wouldn't mind shelling out 2-3k for it. But I'm working with what I have available to me. If it's cost effective and a possible solution I'm all up for it. If you got any better ideas I'm open to them.

Here's some pix of DSG's 240RS suspension setup.

Their website can be found here @ dentsport.com.

Front:

http://gallery.dentsport.com/dsg-shopcars/bill240_001/suspension/image/960/DSCF5956.JPG

Rear:

Looks like he's using the rear z32 uprights which are aluminum and use a fork type bottom shock mount.

http://gallery.dentsport.com/dsg-shopcars/bill240_001/suspension/image/960/DSCF5913.JPG

http://gallery.dentsport.com/dsg-shopcars/bill240_001/suspension/image/960/DSCF5914.JPG

floodo1

12-18-2008, 05:15 PM

The 240 wasn't some high performance sports car. I'm sure they put some thought into it, but who knows what they're original design targets were.

I bet most people don't know this, but the direct competition for the s13 was....Honda PRELUDE! Both where considered "date cars", as in good for taking girls on dates.
So you can bet that Nissan wasn't aiming towards a track car when they designed the suspension. I mean the tension rod bushing is a HUGE sign of their design goals.

RBbugBITme

12-18-2008, 06:27 PM

Wisass or anyone else, if you have accurate measurements of the suspension points I'll post up any and all results from Mitchell.

Def

12-18-2008, 08:46 PM

Engineer bidding war!!!

I'll counter with $9.9k!!!

mmdb

12-19-2008, 08:05 PM

Well anyway, I did some calling here and there. I spoke with Geoff over at Full-Race and asked if they were developing/offering suspension arms to correct roll center for the s14/s13. He said no :(. I spoke to him a a bit more and told him that I wanted to modify my spindles to correct the roll center. He then light up like a bulb, and said "that's the way to do it!!" and to, get this, take it to any off-road racing truck builder - and who better than them to take it to??? They deal with this stuff all day right??? I mean off road truck racers live on bumps... not really. Good off-road truck builders will cycle the suspension to check for camber change and bump steer and make sure the ideal setup is being achieved.

This might not be the "ideal" setup as mentioned before, but in engineering the ideal setup isn't always the most effective choice. And I'm sure some of you engineers know that unless you have an unlimited budget and time, but who does?

So there it is! Another solution to this mayhem. And I bet my left tension rod that it'll only be a fraction of the 9.9k offered bid above. I'll post an estimate tomorrow when I see one of the local chassis fab guys.

Def

12-19-2008, 08:28 PM

I've heard various opinions about the "best" location of roll centers. Lots of people like it just a bit above the ground so it doesn't "move" as much with roll, while lots of open wheel racing series seem to favor the location somewhere very close to the CG at that axle just looking at it by eyeball.

Most people aren't really talking about this - so any thoughts?

Wiisass

12-19-2008, 09:12 PM

Best roll center location is 1.577" above ground in the front and 4.112" above ground in the back. With a 17.6" CG height, stock front and rear sway bars and 575lb/in springs in the front and 425lb/in springs in the rear.

mmdb, That sounds really awesome. I can't wait to see the final product.

RBbugBITme

12-20-2008, 12:22 AM

Someone is getting sour over this....

Def, I would bet my right tension rod your eye is deceiving you and the open wheel RC's are closer to the ground than the CG. Tire scrub, and therefore mechanical grip, alone is a strong enough argument in my corner on that one.

With IC's as close to the ground as possible to reduce scrub, your RC is also going to be close to the ground. Typically I'm told you want the RC as close to the ground plane as possible without it ever passing through the plane in all motions. I'm still out to lunch on that one and whether or not I should be more concerned about the kinematic RC or the forced based RC but you also want your springs and shocks to do their job which means you want the RC as far away from the CG as possible. Still much much to learn.

As for the 240, I don't yet know what the heights are at stock ride height and its likely they are below ground on lowered cars. Their relative heights are just as important but remember they are tunable to some degree with ride height and there is no magic number like what was posted above.

Def

12-20-2008, 09:34 AM

But a magic number would be sooooo cool to have... :(

Although I will say I'm of the opinion that once you get a million things to adjust it really does take A LOT of time to get things "better," and there's a big chance you go off on a tangent and things get worse. For the majority of cars on this forum, stock geometry is fine as long as you put a decent/good damper on the car and get a reasonable amount of roll stiffness.

Wiisass

12-20-2008, 09:38 AM

Not sour, I just decided that it was better to share information than to just knock everything all the time.

But seriously, comparing a car like the 240 to an open wheel car is worthless. Totally different intent.

Ryan, are you really concerned that much with tire scrub? Enough to use that as a justification? I would be much more concerned with rolling and non-rolling moments, instant center lengths, spring/bar rates, etc. I'm not saying I wouldn't try and minimize scrub, but it would be a lot further down on the list.

And on the 240, I would worry a lot about the lateral migration of the kinematic roll center. It's a lot. Like greater than the track width. That's a bigger concern than the actual kinematic height.

And those are magic numbers. I'm sure they would work for a car.

My whole point with this is that no one understands roll center and what it really does and effects. Without knowing what you're doing or understanding what you're asking someone else to do, how do you expect it to work right. And I'm sure when people start doing stupid stuff without understanding it, they won't even know if it really feels better or if they've just convinced themselves that it has to feel better so that's what they're going to say.

I still suggest, making a quick drawing and approximating roll center height. Then working out some numbers and coming up with a rough idea of spring rates and bar rates that will work. Make sure to account for anything else that you need to. And then run that. If you're numbers are close, you should be in the ball park and the car will work. If you can't handle something like this, then you shouldn't be messing with modifying spindles or having people modify spindles or even thinking about roll center height unless you're ready to really spend the right money and have someone that knows what they're talking about design the part.

And if your way of establishing credibility of a place is that they move the suspension up and down to check if their design is right, you're going to end up with an awesome working part.

Wiisass

12-20-2008, 09:40 AM

Def

12-20-2008, 09:58 AM

This is the best thing I've seen posted in this thread that I didn't write.

It's why I haven't crunched any numbers on this - that and I get bored with dynamics.

RBbugBITme

12-20-2008, 12:36 PM

Ryan, are you really concerned that much with tire scrub? Enough to use that as a justification?
Umm yes... Its one point of many I could have made to settle a simple question and I think enough people on here realize RC affects numerous things. Scrub is certainly one that wouldn't be as low on my list as yours when we're talking about majority street/autox drivers where low speed corners are most common and mechanical grip is paramount.

And on the 240, I would worry a lot about the lateral migration of the kinematic roll center. It's a lot. Like greater than the track width. That's a bigger concern than the actual kinematic height.
I know but he was asking about RC heights...

And I'm sure when people start doing stupid stuff without understanding it, they won't even know if it really feels better or if they've just convinced themselves that it has to feel better so that's what they're going to say.
Unfortunately thats what makes the aftermarket industry go round. The butt dyno reviews are what sell parts to 99% of kids screwing with their cars. I tried just like you've said you've tried to educate people on other forums and you get attacked by everyone that knows better so why don't you let kiddies have their theoretical discussion and add depth to it sometimes. I doubt anyone on here is actually going to make an upright or study these topics using real resources.

mmdb

12-20-2008, 03:23 PM

Just got back from the chassis fab shop. For the front we decided to make a custom arm using spherical bearings and a spacer to move the spindle higher, and the arm parallel to the ground; and also modify the bump steer. As for the rear we decided it wasn't a good idea.

Modifying the front spindle seemed OK because the spindle's geometrical movement is dictated by the strut, tension arm, and lower control arm. Spacing the spindle higher would not impact the suspension's much, if any it would be negligible.

When we reviewed the rear suspension a concern about modifying any of the rear arms is that it will ruin the other arm's geometrical movement. This could possibly cause binds. A solution to this is to custom build a spindle while keeping the same pickup points and moving the hub up a bit. Another solution would be to modify the rear subframe.

Either of these would prove pricey, and tuning and tweaking it would take a bit of time. So instead I decided to have them install spherical bearings into the suspension arm mounting points and use more money on track days.

If anyone is interested in having a set of front arms made I can get a few extra sets built. The bearings themselves will be high quality and the build would be top notch stuff. Keep in mind I'm not trying to start a business. So if you're interested LMK.

Def

12-22-2008, 12:54 PM

I tried just like you've said you've tried to educate people on other forums and you get attacked by everyone that knows better so why don't you let kiddies have their theoretical discussion and add depth to it sometimes. I doubt anyone on here is actually going to make an upright or study these topics using real resources.

I don't think I'd throw this forum into that class. Teach away if you feel the need.

I'll freely admit I don't know everything there is about suspension dynamics, but it's not THAT hard to pick up a book and get the basics, and I'd hope anybody making an upright themselves would at least familiarize themselves with the potential pitfalls. Sure is nice to learn on a forum for free though. :cool:

SoSideways

12-22-2008, 01:14 PM

Alright well, if you guys want any measurements off of the front suspension, my car's front is off the ground, as I am replacing the worn/old stock FLCAs with brand new OEM FLCAs with ES bushings pressed in.

Brand new ball joints are awesome also.

So yeah, I'm doing this, so while I'm down there, I could probably measure a few things for you guys.

RBbugBITme

12-22-2008, 01:35 PM

but it's not THAT hard to pick up a book and get the basics

HA its not but still no one does it. I'm not saying people are dumb or anything like that but not everyone is an engineer or wants to be and I wouldn't expect anyone to read through a 900 page vehicle dynamics book (which still only really covers the basics). If I expected that from a public forum I'd stick to the FSAE forums or my alumni email chain.

With that said, people still have ideas and want to see if they'll work which I guess I enjoy seeing on here otherwise I wouldn't be here and hopefully those who have done a bit of studying on the topic can help out.

Sosideways, since your car is off the ground you won't have accurate heights but relative distances are fine. I'm going home today so I can take some and we'll compare before I put them in the program. By relative distances I mean its probably the most accurate to, for example measure to the top of each strut and take half that distance as the Y location from chassis centerline instead of trying to measure from a point to everything. Use the inboard FLCAs to establish a longitudinal plane to measure X distances from since it should be very close to the fore-aft position of the tire contact patch. Maybe use that point to set your height as well and then just add the distance from there to the ground based on your specific ride height. FYI if you haven't figured it out already, the programs coordinate origin is at the ground through the centerline of the car.

SoSideways

12-22-2008, 01:54 PM

Well, I figured, if we can figure out the lengths and what not of some components, we can probably crunch some numbers and figure out the angles and what not. From there we can come up with some theoretical heights of when the car's on the ground, versus on jack stands (since I don't have a pit to go under the car with, so I can't measure stuff when the car's on the ground).

I mean, the FLCAs are static in length, so as long as we have that length from the center of the bushing to the center of the ball joint, and the distance between the 2 FLCA mounting points, we can figure out a theoretical centerline for the car and do some sort of calculations from those figures.

Also, I bought a gauge that I guess some builders use to determine angle from Sears, which can give us a rough estimate of the angle of the strut versus the FLCA while up in the air.

From there I can measure the distance between the 2 strut towers from the top, and from those numbers, we can probably come up with a rough estimate of what's going on, using some high school geometry lol

WishIHadaSilvia

12-23-2008, 07:50 AM

I have access to a drive on lift, so I can get my car up in the air with the wheels still on the ground so-to-say. What exactly do I need to measure?

I was looking at it all the other day when it was up on the lift, my front control arms don't appear to be THAT distorted...my rears actually look like they have more of an upright angle then the fronts.

I assume I'd need to measure shock height and angle of the shock to the FLCA? Angle of FLCA to front subframe/steering rack area? Total length across the front of the car (ball joint to ball joint)? What else is really important, I'll make my engineering friend go with me and help me measure everything - I was trying to explain to him what I wanted to find out and he told me it was a stupid idea but that he'd help anyway (sound familiar, haha).

I've been trying to read about race car dynamics but the book sucks and doesn't give any concrete information, just a bunch of beating around the bush about ackerman and other BS.

RBbugBITme

12-23-2008, 10:31 AM

You're best bet would be to just get XYZ coordinates to all the points and then using sweet SOHCAHTOA. Remember the origin is at the center of the car which could be difficult to make multiple measurements from so I'm going to try and measure across the car to the same point on each side. I may be the only one able to do this though since I don't have my engine in right now.

a_ahmed

12-25-2008, 10:37 AM

Woah this thread is picking up again :D I just read a page of stuff I have no idea about but it feels great :D LOL

I wonder if Geoff's R14 creation ever got a descent review. Since they converted it to a double wishbone setup and all. I wonder if they'd offer a 'kit' for just the suspension conversion. The "R13" never saw the light.

And lol@sohcahtoa its been a LONG time since I heard that :D

a_ahmed

01-01-2009, 05:08 AM

I just remembered, thought I'd throw this in. JUN made a rear subframe which changes the geometry + reinforced. Dialed in for more squat and dunno what else... all I know. Would be nice to see some pix.. However it costs around 2000 JDM dollars lol

a_ahmed

01-01-2009, 05:33 AM

Well I guess this is it... I dunno

http://www.junauto.co.jp/products/reinforcement/rear-drag-member/index.html?en

http://www.junauto.co.jp/products/reinforcement/rear-drag-member/subframe.jpg
http://www.junauto.co.jp/products/reinforcement/rear-drag-member/dragmember.jpg

mmdb

01-02-2009, 11:24 PM

Concerning the rear roll center on the s14, I purchased a pair of moon face pro roll center adjusters. It looks like they raise the pivot point about ~15mm. Maybe even a little more. I don't have a camera right now, but I'll take pictures of it when I get it back tomorrow.

Def

01-03-2009, 03:58 AM

a_ahmed

01-03-2009, 04:11 AM

Speaking of 'moonface'

What was said on freshalloy I shall copy paste:

http://www.moonface-int.com/mfr/roll/img/img7.jpg

[Maximike]
When lowered the arms are tilted up from the center of the car to the wheel. These get installed in the lower arms and with spacers makes the lower arms move level. The shank length is the difference and it spaces the arm down.

[djsilver]:The front roll-center is based on the location of three pivot points and the angles of the lines drawn when connecting them to draw a triangle; The strut's top-mount bearing, the LCA inboard pivot and the ball joint at the outboard end of the LCA. Using a ball-joint that moves the outboard end of the LCA down does not affect the roll-center unless the actual pivot-point (ball) moves down with it. To do that on the 240sx, the ball-joint assembly must leave the ball in the same location relative to the LCA and make the stud that's attached longer. In the picture that McRussellpants posted, the "Standard Model" is an example of how not to do it and the "Curcuit Model" is an example of how is should be done. Here's a picture; As you can see, moving any one of the three pivot points has some affect on the roll-center, among other things.

http://www.fromsteve.net/carstuff/suspension/camber/camber_whiteline.png

djsilver

01-03-2009, 05:00 AM

Speaking of 'moonface'

What was said on freshalloy I shall copy paste:

http://www.moonface-int.com/mfr/roll/img/img7.jpg

http://www.fromsteve.net/carstuff/suspension/camber/camber_whiteline.png

We're having fun now aren't we?:D If you look at the diagram you can see that the adjustable strut bearing plates a lot of us use can also affect the roll-center. When moving the top of the strut inboard to increase static negative camber it also changes at least two other things; The SAI/KPI (Steering Angle Inclination/Kingpin Inclination) is increased (which may be good) by increasing the amount of camber change as you steer the wheels. It also also changes the roll center by changing the intersection point of the lines in the diagram, but which way and how much depends on the angle of the line projected from the LCA. :D Another way to increase dynamic camber change with steering angle is by increasing caster, but that's a whole 'nother subject :rolleyes:

mmdb

01-03-2009, 08:46 AM

They move the pivot point or the spindle up 15mm relative to the control arm? To affect the roll center you need to have the pivot stay in the same position as the stock balljoints and then raise the spindle relative to that.

The pivot point is moved upwards to essentially push the arm down to allow the arm to sit closer to stock (that'll never happen heh). It also does increase the spacing between the arm and the spindle. Pix will be up later today.

Def

01-03-2009, 11:49 AM

The pivot point is moved upwards to essentially push the arm down to allow the arm to sit closer to stock (that'll never happen heh). It also does increase the spacing between the arm and the spindle. Pix will be up later today.

The arm is inconsequential, it's the imaginary line from the inner pivot to the outer pivot that needs to move. It needs to look like the "Circuit model" from the above pictures. The "Standard Model" is not going to change the roll center.

mmdb

01-04-2009, 12:57 AM

^ by up i meant down hehe. The MoonFace (MF) roll center spaces the knuckle and the lower control arm by increasing the length of the pillow ball shank. From what I've measured there is an increase of approximately 15mm between the knuckle and the lower control arm. It could be more, it could be less. The pivot point on the MF looks to be a nominal increase in height. It does ultimately have an effect on the roll center (brings it up).

I haven't had a chance to comment on the modification yet as I need to get an alignment. The MF center adjusters have altered the track width as well as toe, camber, etc. So I'm going in for an alignment tomorrow. Here's some pix...

Side by side of OEM vs MF

http://i7.photobucket.com/albums/y259/mmdb/moonface%20roll%20center%20january%204th%202009/IMG_0499.jpg

OEM height

http://i7.photobucket.com/albums/y259/mmdb/moonface%20roll%20center%20january%204th%202009/IMG_0517.jpg

MF height

http://i7.photobucket.com/albums/y259/mmdb/moonface%20roll%20center%20january%204th%202009/IMG_0528.jpg

Installed with other arms. Notice the trim job on the backing plate (i have z32 2 piston rear calipers)...

http://i7.photobucket.com/albums/y259/mmdb/moonface%20roll%20center%20january%204th%202009/IMG_0534.jpg

Def

01-04-2009, 02:33 PM

Doesn't look like it moves the spindle up much to me. Maybe .1-.2" since some of that distance is in the bigger balljoint housing itself.

mmdb

01-04-2009, 07:59 PM

I think it's safe to say the ball joint isn't of greater size/diameter, because the housing is of the similar size/diameter. The MF ball joint sits at the same, or very little above compared to the oem joint. Here's a pix

http://i7.photobucket.com/albums/y259/mmdb/moonface%20roll%20center%20january%204th%202009/IMG_0512.jpg

The pivot from the inner lower control arm to guesstimated pivot point in the MF joint sits almost parallel to the ground. The car is set to factory alignment. Prior, the car had the same factory alignment, same roll bar settings etc. I didn't figure I'd feel much of a difference using the MF product, but it definitely does feel different. There's less roll and it feels like the rear is heavily planted throughout the turning phases (entry, steady, and exit, power on exit). Another thing I noticed was that the wheels stick out a bit more, so it also helps with track width. I'd give this product a +1.

According to my machine shop an idea was presented by the owner to develop a custom spindle for the rear. I'm not sure how much it might be but I'll find out, and figure out what's involved.

Def

01-05-2009, 03:43 PM

Ok, the extra height of the MF housing threw me off.

What I don't understand is why 2 balljoints need to cost $300. It seems like a place like Moog or something could make a run of 100 of these things for maybe double their normal balljoint price, so about $120-150/pair. They'd probably sell pretty well.

The custom spindle sounds like it'd take A LOT of work doing calcs.

mmdb

01-05-2009, 08:29 PM

I totally agree Def. I wouldn't usually pay for a JDM brand part as I mostly try to stick with US made products for our Japanese made car (ie peak performance), or wherever there's awesome deals on high quality products. I took the dive because I was curious. Although I think this product could actually do some harm if the suspension arc was heavily tweaked because of it. It's too early for me to know. For now I'm pretty happy with the mod. I put them on par with the performance benefits having sway bars.

I don't think the rear spindle will be as difficult to develop as it was explained in prior posts. Although it was argued that developing a new spindle adds a crap load of complexity, much of which requires $10k+ more to make right :rolleyes:? I think what's been totally overlooked is that we don't need to modify the pick up points for the spindle. What was presented to me by my fab shop is that why don't we...

a. keep all the same pick up points
b. move the hub upwards?

Now of course a whole new unit will need to be made, and this will most likely interfere with the e-brake (i have z32 rears), and caliper position. But there's always the custom route of running a different ebrake setup, and the caliper can be moved slightly if need be. I think this is the best solution thus far. I'll keep ya'll posted as soon as I can speak with them when I go to pick up my front control arms.

cheeky14

01-05-2009, 09:47 PM

I spoke to an aquaintance from ERP suspension (specializes in Porsche suspensions for Rolex series cars) he mentioned an issue with changing just the lower control arm roll center & not changing the rear bumpsteer along with it, as well as the upper control arm; in other words by just changing the lower control arm roll center & not changing the rest in conjunction their is a certain amount of bind or conflicting arcs that the rest of the control arms produce in their range of motion, he mentioned this to me in passing without really fully analyzing the rear setup but it makes sense to an extent. He also mentioned to use the rule of thumb of keeping both pivot points of the lower control arm at least level to the ground at static height. But in reallity manufacturing correctlly engineered spindles is the only way to go.

mmdb

01-06-2009, 10:17 AM

Racecartech

01-08-2009, 07:04 PM

SoSideways

01-09-2009, 07:20 AM

Yes, but you didn't just change roll center on those cars, you changed a lot of other stuff too...

djsilver

01-09-2009, 11:35 AM

I totally agree. Like I said before the MF roll centers could do some damage to the suspension geometry, but how much they've negatively effected it is the question.

Although, by using the stock pick up points on the spindle and moving the hub upwards to bring the LCA pivot points parallel shouldn't damage suspension geometry.

Using the MF ball-joint on front would raise the roll-center but wouldn't help with bump-steer that comes from lowering because it wouldn't move the attachment point of the outer tie-rod end in the vertical perspective.

Using the MF ball-joint on the rear would increase both camber and toe changes through the range of motion.

That said, I think it's more important to try and raise the front roll-center than the rear roll-center. It's well-known that stock 240's have the tendency to hike the rear inside wheel in hard cornering and I think at least part of that is due to the roll-axis sloping too much downward to the front.

Racecartech

01-09-2009, 04:48 PM

wheels are meant to be round, don't try to reinvent them on your drivers. put the cars at the best ride height for your existing car. My track 240 isn't much lower than stock but runs coil overs and is corner balanced with track alignment. http://www.youtube.com/user/racecartech1 I set up several cars for several divisions in road race, oval and drag. The setups I have, won championships, many races in all divisions. and the first two cars in my previous post "ride height" roll center, and alignment were the only changes for the speed increase.

Wiisass

01-11-2009, 07:33 PM

To answer the question of roll center importance, I have 2 confirmed examples. 2 cars 1 Honda Civic, racing CASC GTC The only changes to the car was corner balance, right hieght and align. this car picked up 3.8 seconds a lap at Mosport. The second car Mustang gt in gtb, same changes this driver went 4.5 seconds faster. In both cases the cars came into me with the ridehieght too low. I raised the cars to make them faster with thier current set up. anouther car 05 mustang gt, completely redesigned to work with lowering, very fast, but complete redesign.. bumpsteer, custom lower ball joints, reolcate inner pivot pionts, relocate steering rack, relocate rear upper arm points, rear diff arm mounting points etc. much engineering

So where these cars aligned and corner balanced at their previous ride height? Or did you corner balance and align when you changed the ride height?

And you do know changing ride height doesn't just affect roll center, but also pretty much everything else as well.

You don't need a complete redesign to make a car work when lowered. It just needs to be measured and the geometry needs to be factored in. That's all, it's simple. Of course, going too low on some cars can cause some issues that are harder to account for. But just lowering a car doesn't make it bad.

mmdb

01-12-2009, 07:54 AM

And you do know changing ride height doesn't just affect roll center, but also pretty much everything else as well.

Can you explain this? Doesn't the roll center depends on pivot points, and when the car is raised the pivot points move raising the roll centers accordingly?

SoSideways

01-12-2009, 09:27 AM

Can you explain this? Doesn't the roll center depends on pivot points, and when the car is raised the pivot points move raising the roll centers accordingly?

Yes, roll center changes, but also along with like ackerman and king pin inclination and all that other stuff too, because you're moving the entire assembly down in relation to the chassis itself.

Which is what I said.

You move the ENTIRE suspension down by raising the car up a little, will affect all the geometry, not just 1 thing... as a matter of fact, it's really hard to just change 1 thing on the suspension without affecting another, or all other settings.

RBbugBITme

01-12-2009, 09:28 AM

Almost every suspension parameter acts non-linearly so lowering/raising the car to affect RC also changes the rate at which other things act. Tire scrub over bumps also changes among other things. Changing ride height changes a lot of stuff, this is what has been discussed over numerous pages of this thread.

SoSideways

01-12-2009, 09:30 AM

mmdb

01-12-2009, 12:31 PM

Yes, roll center changes, but also along with like ackerman and king pin inclination and all that other stuff too, because you're moving the entire assembly down in relation to the chassis itself.

Which is what I said.

You move the ENTIRE suspension down by raising the car up a little, will affect all the geometry, not just 1 thing... as a matter of fact, it's really hard to just change 1 thing on the suspension without affecting another, or all other settings.

Thanks for explaining. I read it wrong, thought he might've said doesn't change roll center. I'll try not to read posts early in the morning as I wake up heh.

Umai Kakudo

01-12-2009, 02:43 PM

Screw it.

Cut out the floor and raise the subframes up race car prep style.

http://www.3rauto.com/gallery_folder/erion_911sc/6.jpg
http://www.3rauto.com/gallery_folder/erion_911sc/6.jpg
http://www.3rauto.com/gallery_folder/volvo_build/pics/17.jpg
http://memimage.cardomain.com/ride_images/3/1718/3741/29294370026_medium.jpg
http://memimage.cardomain.com/ride_images/3/1718/3741/29294370029_medium.jpg
http://memimage.cardomain.com/ride_images/3/1718/3741/29294370014_medium.jpg

See http://www.cardomain.com/ride/2929437 for more inspiration on this technique.

Not very bolt on but solves a lot of issues and only has 'difficulty' with running out of room under the hood.

Def

01-12-2009, 03:55 PM

If I were to go to that length I probably wouldn't use the stock suspension geometry or stock subframe. Seems easier to make a custom subframe that would fix things than go hacking into the chassis.

SoSideways

01-13-2009, 06:15 AM

If I were to go to that length I probably wouldn't use the stock suspension geometry or stock subframe. Seems easier to make a custom subframe that would fix things than go hacking into the chassis.

That would probably cost more than $10k too lol

Def

01-13-2009, 04:24 PM

That would probably cost more than $10k too lol

More than you can afford pal, custom suspension work!

Racecartech

01-13-2009, 05:28 PM

mmdb

01-14-2009, 03:42 PM

That is way too much work for a street/track car. I thought the initial premise of this thread was correct roll center for autocross/ trackday cars, not building customs or spending thousands of dollars. the most drastic change to rollcenter and the negative impact is taking to lower arms piviots lower than the outer pivots. On the 240's not having the rear roll match the front will cause under or oversteer, depending on more or less difference in the roll. In the Latemodel Sportsman I am crewchief on, we work on a differene in 100th of a sec.

Agreed. In my persuit to modify and "fix" it, raising the rear height half an inch and adding rear roll center adjusters via moonface racing has be a big plus, although arguably pricey. Currently, my fabrication shop is modifying the OEM front arm to save cost. I opted not to go another route (ie spl parts, battle version etc) is to keep cost down and ensure what i was using was top quality. Not sure what the exact price will be, they should be done by this weekend.

So far, the FLCA involved removing the inner bushings and replacing them with bearings, welding a bearing to the outter arm where the spindle sits, drilling out the oem spindle to accept a larger diameter shank, and add the option to raise or descrease the spindle height via spacers. Pictures soon to come.

Duffman

01-14-2009, 04:22 PM

http://i492.photobucket.com/albums/rr286/iglooduck/PIC_0001.jpg

Here's a pic of my silk road RCA. Looks like it should give a little more change in lca angle than the mf one.

Def

01-14-2009, 04:55 PM

How much do the Silkroad ones run?

Duffman

01-14-2009, 08:42 PM

mmdb

01-14-2009, 09:31 PM

I got them off yahoo Japan a while ago but I'm pretty sure silk road doesn't make them anymore. I guess there wasn't enough interest in Japan. I honestly think the vast majority of JDM-land has no concept of roll center. Look at the MF "adjustable" spacers that don't actually change the roll center. Then I saw this thread on ziptied:

http://www.ziptied.com/forums/index.php?topic=23963.0

Look at the quotes from pro drivers. Some seem to have no idea what it is.

Revert back to page 18. You'll see where I measured the MF adjusters against OEM. You get about +15mm of added height to adjust the roll center. Currently the car's rear arms sits almost above parallel to the ground and about a finger diameter gap between the wheel and fender. Definitely does make a feel-able difference.

A bit surprised the japanese guys say that. Although, most of their suspension mods include the "bling" factor. Moonface racing did have an s15 that ran 58.xx seconds around Tskuba (sp?) with the adjusters, but there's more factors to weigh in than just he adjusters.

On the side note, I always wondered why japanese companies supplied their coilovers with such high spring rates. I can see now that you have to run higher spring rates to prevent roll through corners. I doubt they have the concept of ride comfort as we do here given our roads aren't so great (I work in LA). Keep in mind, with fixed roll center you can run softer springs while increasing creature comfort and minimizing roll. Next time you see a BMW notice how its arms are parallel to the ground.

Duffman

01-14-2009, 10:36 PM

I didn't mean that the MF adapters do nothing compared to stock. But the spacer that can either be below or above the LCA doesn't really adjust the pivot point. It's kind of silly to have a spacer at all. The silk road ones just have the same distance between the bottom flange and the snap ring grove as a stock ball joint.

Agree that fixing the roll center allows for more reasonable spring rates.

SoSideways

01-15-2009, 06:43 AM

On the side note, I always wondered why japanese companies supplied their coilovers with such high spring rates. I can see now that you have to run higher spring rates to prevent roll through corners. I doubt they have the concept of ride comfort as we do here given our roads aren't so great (I work in LA). Keep in mind, with fixed roll center you can run softer springs while increasing creature comfort and minimizing roll. Next time you see a BMW notice how its arms are parallel to the ground.

Because Japanese roads are nice and smooth in at least 95% of their country.

Most Asian countries are big into keeping their roads smooth.

I can tell you that Hong Kong had smooth roads everywhere... I don't recall any particular roads that were rough and jagged. No pot holes anywhere either.

a_ahmed

01-15-2009, 07:14 AM

I dont know in the states, but here in canada roads are village roads. Every time going from North York to South Western part of Toronto, I go through mine fields on the highway. Potholes.. FRICKING POTHOLES, huge rips, tears, you name it... disgusting quality. Some REALLY giant holes you have to avoid but the potholes that stick out high piss me off the most wtf.

I have pictures as PROOF that my mother's village back in eastern europe has better roads than we have here in Canada.. its so pathetic...

Whether it be highway or regular city roads... just pathetic.. it pisses me off :@

Roads in europe, north africa, middle-east, where i've driven... are like glass!

a_ahmed

01-15-2009, 07:16 AM

http://i492.photobucket.com/albums/rr286/iglooduck/PIC_0001.jpg

Here's a pic of my silk road RCA. Looks like it should give a little more change in lca angle than the mf one.
More info? I bet these are more rare than MF lol

Duffman

01-15-2009, 08:11 AM

I really don't have any info on them. I bought them off yahoo japan auctions for only $50 new plus $28 for someone to import it. That's how I got the idea that there must have been no interest in them in Japan.

Either that or they had some horrible reputation for failing, but lets hope it's the first idea. :p

a_ahmed

01-15-2009, 08:26 AM

LOL best of luck man,

Just thought I'd post this... for some who are just joining the thread... for those that need help understanding the mm standard, pro, race, whatever pic here is the stock in place now visualize the shank and the mount piece relation and how it changes and doesnt change:

http://photos-062.ll.facebook.com/photos-ll-sf2p/v355/143/71/849450062/n849450062_4573506_5277.jpg

SoSideways

01-15-2009, 09:54 AM

Yeah but you can't just "look" at something and say "it won't work", unless you have the measurements to back it up.

mmmb did some measurements, and Def agrees that it would work.

I have some more close up pics of the OEM front ball joints on the stock arm if anyone wants... if I can find them...

WishIHadaSilvia

01-16-2009, 01:21 PM

Well, has anyone thought of talking to QA1 or any other bearing company who also makes ball joints? I think they will make them in whatever size you want - wouldn't that let you buy some that actually change the roll center effectively?

http://www.qa1.net/qa1_industrial/images/ball_joint_sch1_2.gif

http://www.qa1.net/qa1_industrial/ball_joints.html

Just a thought...

SoSideways

01-16-2009, 01:34 PM

We were talking about that earlier in the thread, when we were talking about making it out of monoballs and a tapered "pin" stud thingie.

Problem was, nobody knew what the OEM ball joint's taper is. Not real sure about how to measure it either.

Def

01-16-2009, 02:19 PM

If it's the same as the tie rod taper it's 9 degrees total. Easy to measure too, just measure top and bottom diameters, length between them. Divide the difference in diameters by two to effectively get the height of a right triangle with a base the distance betweeen measurements. Take the arctangent of the height/base. If you do it in excel you'll have to convert from radians to degrees.

WishIHadaSilvia

01-16-2009, 03:05 PM

So minus the taper....what else is needed to get a set made/at least get a quote? I guess all of the measurements of the OEM ball joints and how much we need the arm to move?

Racecartech

01-16-2009, 07:08 PM

OK guys before you go too far. examine your package and deterine what else changes. first the front suspension of your 240 is macpherson strut. the roll center is mucha harder to re-locate than the rear. The ball joints in question allow you to lower the car further keeping the lower arm pivots level. but the upper arms will change thier angle.

a quick lesson, the lower arm pivot angle determines rc hieght, the upper arm pivots determine rc movement under dive & roll. if you change the rear without altering the front you will induce over/understeer. The long ball joint studs will move the rear roll center drastically under roll and cause a really loose car.

i'll bet in Japan this is popular with the drifters.

think it through

Duffman

01-16-2009, 10:38 PM

I think most people can agree that a longer ball joint in the front is a Good Thing, because the front roll center gets a lot worse than the rear on a lowered car. The rear I'm willing to leave alone, and I think if you really wanted to improve the rear roll center, direct mounting the subframe without bushings would be a better way.

I can give an estimate on the taper angle, but I don't have access to a good micrometer so it might be wrong.

It looks like its 3 - 4 ish degrees. Thats for an S13 front. S14 front is supposed to be different.

floodo1

01-16-2009, 10:59 PM

http://nissanroadracing.com/vbulletin/attachment.php?attachmentid=11&stc=1&d=1232175007

Ok guys, just in case anyone doesn't have a hastily-drawn-by-hand picture in their mind here we go.

Blue represents the lower control arm
Purple represents the spindle
Red (with a black cross inside) represents the pivot points (center of the BALL, in the balljoint) (center of screw in inner bushing)
Yellow represents the imaginary line between the inner and outer pivots (obviously horribly not to scale)

The yellow line is, for our purposes here, what affects roll center. This line represents the effective lower control arm. So when this line moves, so does the roll center.
As you can see, the line is tied to the ball in the ball joint, NOT to the housing. So that if you change the housing, by extending it to the left (bottom in real life) towards the Brown line, you do NOT change the yellow line. Therefore you do NOT change the roll center.

Now, the green line represents the distance between the ball joint and the spindle . The spindle is fixed in space because it's attached to the tires, which (for our purposes) are fixed in size. So if we make this distance longer, effectively lengthening the green line, THEN we move the yellow line....and NOW we moved the roll center!!
In order to lengthen the green line, you just make the shank longer....pretty simple :)

floodo1

01-16-2009, 11:02 PM

The spindle is fixed in space because it's attached to the tires, which (for our purposes) are fixed in size. So if we make this distance longer, effectively lengthening the green line, THEN we move the yellow line....and NOW we moved the roll center!!
In order to lengthen the green line, you just make the shank longer....pretty simple :)

This brings up a very good point. The spindle, and with it the lower ball joint, is attached to the wheel/tire. So if you want to restore some of your "not-stock" suspension issues, you may want to consider running as small of a wheel/tire package as possible. Any issues created by lowering your car are exacerbated by running larger tires.
Probably not very practical for most people, but for those running stock or smallish brakes, you may want to consider NOT putting 18's on there.

mmdb

01-17-2009, 12:08 AM

This brings up a very good point. The spindle, and with it the lower ball joint, is attached to the wheel/tire. So if you want to restore some of your "not-stock" suspension issues, you may want to consider running as small of a wheel/tire package as possible. Any issues created by lowering your car are exacerbated by running larger tires.
Probably not very practical for most people, but for those running stock or smallish brakes, you may want to consider NOT putting 18's on there.

I don't think running a smaller wheel would help roll center because of tire selection, but it would help with unsprung weight. If anything you'll gain VERY little improvement in roll center. If you do end up running a smaller wheel and tire, you might possibly gain more roll due to tire wall flex, unless you're running a crazy low tire aspect ratio. Another draw back is you're very limited on the size of brakes, so you're very limited to stopping power with smaller calipers - most of the calipers out there require a 17" diameter for clearance.

Here's a tire calculator to find out if it'll help or not. For me, the improvements were negligible.

http://www.miata.net/garage/tirecalc.html

a_ahmed

01-17-2009, 06:01 AM

Not if you're running 285/30/18 :D 24.8" tall tire :D Here's my fav tire calc with visuals: http://www.1000rims.com/rt_specs.jsp

I am trying to understand what racecartech said, i think he had a point, mind elaborating.

floodo1

01-17-2009, 02:29 PM

IIf anything you'll gain VERY little improvement in roll center. If you do end up running a smaller wheel and tire, you might possibly gain more roll due to tire wall flex, unless you're running a crazy low tire aspect ratio.

When I say run a smaller wheel/tire, I mean the overall package. If you're running some big tires on 18" wheels you could be well over 24" outside diameter of the tire. Now supposing that you dont have giant breaks and can run a 16" wheel (cuz you autoX or whatever) you might be able to drop close to 2" of outside diameter. This would drop the spindle and the car 1". So now raise your car back up to your previous ride height and you've had a pretty significant impact :)

WishIHadaSilvia

01-17-2009, 03:11 PM

Ahh, that makes sense, but it completely takes away the whole point of being aesthetically low - no wheel gap. The reason I want to correct the roll center is so I can tuck the tires on my 17s and not 100% ruin my suspension geometry. I am more then certain it is possible to get the best of both worlds. I'm fine with it not being perfect - I don't own a time attack car - I just want it better then what it is.

Racecartech

01-17-2009, 05:26 PM

OK perfect what you want is appearance, go for it. set your car where you like it and get aligned. the other thing to consider is body kit of choice, appear lower without messing up suspension

Scott

Racecartech

01-17-2009, 05:45 PM

now for those who autocross or track, the matching of roll is esential. I am sure there are several places across our nations capable of this. software programs such as performance trrends, or chasis r&d are the 2 I use. these will tell you where the r/c is located and how dive & roll effect it. that is all you get though. now it is up to the indvidual how to use it and where it should be. this is opinion, and there are several of these. Mine are based on experiance, several championships in many forms of racing in multiple classes. bottom line on all this is the best thing you can do is match your front and rear roll, this is done with correct springs, bar, ride hieght. Oh yeah tire diameter does not change roll center, it changes center of gravity.

Wiisass

01-19-2009, 09:39 PM

Changing tire diameter does change roll center height and center of gravity.

And what does matching roll mean? Roll rates? TLLTD? Roll Center heights?

SoSideways

01-20-2009, 07:27 AM

I would just like to know what "upper arms" Racecartech is referring to on the 240's front MacPherson strut suspension?

And why would drifters want a loose car? They want grip, as much as they can get, so they can accelerate while being in a drift and make tons of smoke. You don't make smoke by lifting off the gas and just letting a "loose" car slide uncontrollably on a track. That's called the USA poor kids trying hard "to drift".

Wiisass

01-20-2009, 10:02 AM

The upper arm in a MacP strut suspension is the strut.

But I don't know if that's what he's talking about, I didn't feel like looking through the posts and finding what you're referencing.

Duffman

01-20-2009, 12:40 PM

I think Racecartech was talking about the rear in that statement. I still don't understand it though, shouldnt both the upper and lower arm angles determine the roll center height.

Wiisass

01-20-2009, 01:14 PM

Yes, both arms define the roll center height and roll center migration.

WishIHadaSilvia

01-20-2009, 05:02 PM

OK perfect what you want is appearance, go for it. set your car where you like it and get aligned. the other thing to consider is body kit of choice, appear lower without messing up suspension

Scott

I'm not really sure how to read this - are you being sincere or sarcastic? If you're being sincere you missed my point - I want both aesthetics and function. It comes across more that you are being sarcastic, and I don't appreciate you being a prick if that is the case....if not just read the second sentence and ignore this one.

On a only slightly more productive note - does anyone know about how much QA1 charges to make ball joints? From everything I've read the S13 and S14 use different sized ball joints from each other and different sized ball joints from the front and rear. So doing this would require a group buy most likely - and would probably need to happen for one model (S13 or S14).

If it becomes as simple as replacing the ball joint I'd like to get it done when I swap out my whole suspension (whenever the bilsteins are done).

Out of all of my own ideas I feel this one is the most feasible and makes the most sense. Since I own a S14 I'd like to get the ball joints made for it, haha. It seems like there's a pretty good mix on this board of S13 and S14 owners though and I'd like to make sure I get accurate sizing information - I'm not sure if anyone happens to have any of this or if I need to do measurements myself - either way it is something I will share with everyone if I have to do the measurements.

a_ahmed

01-20-2009, 05:12 PM

lol guys, easy with the emotions, cmon...

Racecartech

01-20-2009, 05:31 PM

I was not being sarcastic, anytime we are trying to achieve goals with multifunction cars there will be comprimise. you said you do not do time attack, that is what my response was based on. If we all had dedicated cars for each event we want to do each one would have a different set up. many cars have to fill one bill, so the toatal package is a comprimise. I was referring to rear suspension upper arms. roll center hight is mostly effect of lower arms (sla short long arm suspension) while the upper arm angle determines migration.

I am not here to offend anyone. I am happy to be on a board where the members are researched and knowlegeable

WishIHadaSilvia

01-20-2009, 10:31 PM

I am sorry for mistaking your helpful advice as sarcasm. :o

Emocons make it ok right? :p

WishIHadaSilvia

01-20-2009, 10:41 PM

When you say the upper arm angle determines the migration....would that be a reason why they modified the toe arm on the JIC S15 Time Attack car?

http://www.dragsport.com/issue/2007/images/0707/s15-5.jpg

The camber arm appears to be mostly parallel to the LCA from the factory, but you can see in this picture how out of angle the toe arm is:

http://www.dragsport.com/issue/2008/images/1108/s15-3.jpg

I'm a very visual person (especially with information I am not familiar with) and have yet to find any decent reading with good visuals.

Also, when talking to my friend's in the engineering field and I mention correcting roll center, they always point out that there are many roll centers on the car - what specific one are we talking about? Does it have a specific name or something? This, I'm sure, sounds like a stupid question but I'm asking so I can search for things more specifically.

RBbugBITme

01-21-2009, 09:22 AM

Racecartech.... For an SLA at least, relative lengths will have a huge effect on migration. I had much longer arms on the bottom than the top in my latest suspension (1" out from centerline) and couldn't get the lateral migration any less than +/-4" no matter what I did with the top arm. I changed it to about 3.5" out from centerline on the bottom without changing the top and lateral migration is now theoretically +/- 0.81".

SoSideways

01-21-2009, 10:28 AM

http://www.dragsport.com/issue/2007/images/0707/s15-5.jpg

That looks like a Z32 rear spindle that's been modified heavily...

Racecartech

01-21-2009, 07:35 PM

Ryan, when inputting info into your software for the rear suspension, (i believe performance trends) is the one you are using, set your inner pivot matching your lower ball joint pivot. now if using extended ball joints it will move the knuckle effective leagth up, this makes the upper pivot higher. the inner upper pivot point on the chasis stays factory. the roll center under dive & roll will move less using the extended ball joints. For flat track setups this is desireable, the problem becomes matching the front roll to the rear roll. if the front rolls more than the rear the car will be slow to react entering the corner, will feel twitchy mid and loose on exit.
the modification to the spindle in the above pic, the rear toe arm mounting is to fix rear bump steer, the front upper link angle is for anti-dive, helps prevent rear wheel lock-up. Also notice the pivot point hieghts. The ride hieght of this car is set so the rear lower arm pivots are level.

Wiisass

01-21-2009, 08:37 PM

How does using an extended ball joint as the lbj raise the ubj?

Can you prove that using an extended ball joint will reduce roll center movement?

You keep saying matching roll and still didn't explain what you mean? Are you saying roll, like roll angle?

It doesn't look like that toe arm location will fix bumpsteer in the rear. It looks like they went a little too far down with it. But really depends on the lengths of the other arms. Parallel to the LCA doesn't mean zero bumpsteer. It only means zero bumpsteer if the arms are parallel and lies in the same plane and the pivots are at the same YZ locations. Meaning that the toe arm moves exactly the same as the LCA.

Racecartech

01-22-2009, 08:37 PM

If a longer lower ball joint stud is installed the distance from pivot points have to change, the car will be lower, the lowe control arm can be put back to level, the effective leagth of the knuckle increases, the inner pivot point separation stays the same, the upper arm angle increases. I will have to play some more to figure out how to copy from my roll center calulator to these post to demonstrate.

Matching front to rear is: have the front of the car want to roll the same as the back of the car. roll center is just one part of the equation. but is the part that make the reast of the parts work. The things to make the car roll are: center of gravity, tires, springs, total wieght, ect. the forces introduced when steering input is used to try to make the car turn. the grip of the tires determine the g's capable, the springs support the resultant force of the weight, the sway bars are part of the sping rate. now as all this happens the contol arm angle are changing, htese algle changes cause the roll center of the car to migrate.

My typin sucks plus this is enough for now

Wiisass

01-25-2009, 03:48 PM

The distance from the pivot points will change, but that doesn't mean the car will be lower. You aren't changing the position of the shock/spring at all.

So you just look at roll angle and not roll rates or wheel loads or suspension change rates?

mmdb

02-13-2009, 10:37 PM

Got my arms back. They'll be installed in a couple of weeks as I'm waiting for other parts to come in. On the outer arm there's a bearing welded in place. In the inner it's a bushing. A large 1/2" shank will go through the bottom of the arm to the spindle, which was drilled out for 1/2", with spacers in between to adjust the roll center. The outer tie rods (forgot to take a picture of it) has a beefy 5/8" spherical bearing and a long shank to compensate for bump steer. Should be nice and crispy handling.

http://i7.photobucket.com/albums/y259/mmdb/JDM%20TyteR240%20-%2002-13-2009/IMG_0619.jpg

http://i7.photobucket.com/albums/y259/mmdb/JDM%20TyteR240%20-%2002-13-2009/IMG_0620.jpg

http://i7.photobucket.com/albums/y259/mmdb/JDM%20TyteR240%20-%2002-13-2009/IMG_0621.jpg

http://i7.photobucket.com/albums/y259/mmdb/JDM%20TyteR240%20-%2002-13-2009/IMG_0622.jpg

http://i7.photobucket.com/albums/y259/mmdb/JDM%20TyteR240%20-%2002-13-2009/IMG_0623.jpg

Def

02-14-2009, 06:36 AM

Is that inner pivot a pure rotational bearing? The arm doesn't act like an a-arm, it needs to be able to move forward/backward.

mmdb

02-14-2009, 07:19 AM

Is that inner pivot a pure rotational bearing? The arm doesn't act like an a-arm, it needs to be able to move forward/backward.

that is a really good point... hmm... might have to hit the drawing board again.

Def

02-14-2009, 08:07 AM

that is a really good point... hmm... might have to hit the drawing board again.

Yea, the tension rod has an arc that makes the LCA move back and forth during its movement.

WishIHadaSilvia

02-14-2009, 10:08 AM

mmdb

02-14-2009, 11:30 AM

Yea, the tension rod has an arc that makes the LCA move back and forth during its movement.

Welp looks like Imma have to find a camber/caster plate that fits on top the damper rather than remove the bushing. I do like the strength of that inner bushing rather than a spherical piece.

mmdb

02-14-2009, 11:31 AM

This that outer bearing that you welded in something you just bought and welded in or is it something you had to get made? Ordering just a spherical bearing and getting that welded in seems like it would be even better/easier then getting a custom ball joint made.....and you could do it out back just as easily.

Why not go for a battle version style inner mount?

http://www.mamsparts.com/images/BV%20weld%20on.JPG

That lets you keep rod ends/spherical bearings everywhere.

The outter bearing is something that was made. I'll take some pictures of it later today. To adjust the toe the toe link end has to be removed and spun around to adjust it. A bit inconvenient, but the trade off is that I got to use a beefy 5/8" rod end.

SoSideways

02-14-2009, 03:59 PM

Welp looks like Imma have to find a camber/caster plate that fits on top the damper rather than remove the bushing. I do like the strength of that inner bushing rather than a spherical piece.

That still wouldn't work, because when the tension rod (or T/C rod) rotates up and down, it creates its own arc, pulling the FLCA forward as it goes up past horizontal, and as it comes back down from past horizontal, it will push the FLCA backwards.

You will need something like the Battle Version inner heim joint piece for the FLCAs to be able to rotate up and down as well as forward and backwards.

Sure, that huge ass bearing you got there is nice and all, but is it really necessary?

I'm sure you can find a pretty dang nice spherical bearing for not that much from Aurora's catalog that you can use for the insides of the FLCAs and still be able to have it stand up to track abuse.

WishIHadaSilvia

02-14-2009, 06:25 PM

mmdb

02-15-2009, 12:05 AM

That still wouldn't work, because when the tension rod (or T/C rod) rotates up and down, it creates its own arc, pulling the FLCA forward as it goes up past horizontal, and as it comes back down from past horizontal, it will push the FLCA backwards.

You will need something like the Battle Version inner heim joint piece for the FLCAs to be able to rotate up and down as well as forward and backwards.

Sure, that huge ass bearing you got there is nice and all, but is it really necessary?

I'm sure you can find a pretty dang nice spherical bearing for not that much from Aurora's catalog that you can use for the insides of the FLCAs and still be able to have it stand up to track abuse.

That's valid point. I might need to get that bushing out of there and put in a rubber piece. Any other alternative might not prove effective and too costly.

I like the idea that they over engineered the piece. Per request, I always say it must be safe to run on the street, and so I'm willing to pay for it. There's always other options out there though.

mmdb

02-15-2009, 12:07 AM

I guess the biggest thing would be the bolt that would go through the spherical bearing into the spindle. Does it need to be tapered like the factory ball joint? Or would it be better to just drill out the spindle so you can shove whatever you want through it, haha.

How strong would the bearing need to be? Also, is this something I can get away with on a street car? I'm just wondering what the life of the spherical bearing would be....since you have to weld it in and all (or are you just welding in something that you press the bearing into?).

That's correct. The spindle was drilled out so I can run a non-tapered bolt through it, and in between would be spacer to adjust the height. I believe the diameter is 1/2".

I'm not sure how strong, but I always, always specify that I'm running my car on the street, driven hard, track days, etc - worse case scenario. I've used their service for 2-3 years now and everything has been very reliable.

mmdb

02-15-2009, 12:08 AM

And for the tie rods. No idea how the boot is going to fit over, but there's a first for everything i guess. *shrug* The bearings used are 5/8", teflon coated bearings and HUGE. Should be good and strong.

Note: I did use peak performance's outer tie rod end and ended up snapping it. So I made sure I requested custom outer tie rods rather than use what's on the market. Not to say PP is bad, they do make great products, but I'd rather allow someone I know and trust to build stuff for me... or maybe I'm cynical :/

http://i7.photobucket.com/albums/y259/mmdb/IMG_0627.jpg

http://i7.photobucket.com/albums/y259/mmdb/IMG_0625.jpg