Roll Center Adjusters Revisited

[SoSideways]

Ok, here are the adjusters in question:

http://www.nengun.com/image/catalogue/original/nengun-1714-02-moonface-front_rollcenter_adjuster_pro.jpg
Pic courtesy of Nengun Performance.

Anyway, many have argued that they don't do anything, while giving the illusion of helping the roll center by placing the front lower arm downards, but not actually changing the pivot points.

I am still having difficulties picturing this in my head.

Would someone please draw up (or find) diagrams that explain the part where it gives the illusion of helping with roll center by moving the arm down, while not doing anything?

Also, here is how they look on the arm (Moonface sells brand new OEM arms with the bushings in them already, so it seems):

http://www.nengun.com/image/catalogue/original/nengun-1749-02-moonface-front_rollcenter_adjust_lower_arm.jpg

http://www.nengun.com/image/catalogue/original/nengun-1750-02-moonface-front_rollcenter_adjust_lower_arm_pro.jpg

I have a couple of brand new OEM S13 arms that I can take pictures of for comparison, as mine has brand new OEM ball joints on them, thus we should be able to make a valid comparison between these Moonface ball joints versus the OEM ball joints.

[Epstein]

Some US companies sell these, too. It's not that they don't work. It's that it's really easy to market a part like this that doesn't work as something that does. And no one wants to drop the money to measure the actual part and find out. Those things can work. They just need to keep the pivot in the same spot as the OEM and have a longer pin. It's just hard to tell what'd going on with that boot in there. We're not worried about the angle of the physical arm. We're worried about the angle of the mechanical arm that runs between the inner and outer pivot points.

[Def]

Judging from the length of the lower cylinder/sleeve, I'd say it keeps the pivot the same relative to the stock spindle, and just has a longer "sleeve" section. This doesn't affect the mechanical relationship between the pivots and the contact patch(which determines the instaneous center or "roll center" of the front suspension).

[SoSideways]

So in order for something like that to work, you guys are saying that the pivot on the arm side of the ball joint must be raised to above the arm for it to work positively?

Again, when you guys say that stuff to me, it would be extremely helpful to have a diagram to go with it, as I am more of a visual learner.

[Def]

Do some searches for roll center - I'm sure it'll do a better job of teaching it than I will(I hated dynamics).

But my understanding of the physics involved is that the PIVOT location is what's important. So if the balljoint just has a long sleeve on the bottom and keeps the pivot say 1" below the spindle like the stock balljoint, then it doesn't do you any good. The arm angle vs. the subframe changes, but this actually doesn't do anything, as what's "important" is an imaginary line drawn from the arm pivot on the subframe to the balljoint pivot. You can do whatever you want inbetween, but that imaginary line and the arc it forms is what dictates suspension movement/roll center height/camber curve etc.

[Wiisass]

If they don't relocate the pivot, they don't really do that much, but that's what everyone else was saying.

But changing the angle of the arm would change the way things are moving in relation to each other. I mean say you have an arm that is horizontal and one that is at a 20* angle. And in the front view, look at how each point would move over a +-1" range of travel. I'm not saying these are good parts, or that they will even do anything, but I was just thinking about this the other day.

But it's bad design so it's still stupid.

[Def]

I don't see it changing things by having the balljoint extended from the arm. Yes, the arm to subframe angle changes, but the important part that dictates camber curve is the imaginary line between the subframe pivot and the balljoint pivot.

If you raise the balljoint up, the arm is at a different angle, but the maximum lateral distance of the arm is still reached at the same rideheight.

I pictured an impossible situation of a 1' balljoint extender to see if it would change things. In my mind it really doesn't since it's effectively like having the same arm, but it's just "really bent" to get the pivot in the same location.

[Wiisass]

Def, I'm talking about dynamic camber change. If the arm is horizontal the pivot point is already extended as far outboard as its going to be, but if it's at an angle either above or below, it's going to be further inboard and then travel outboard or further inboard depending on position. So it will change it a little, how much, I don't know.

It's not enough that it would matter. I was just saying for arguments sake, that it would affect the camber curve slightly.

[Def]

Wouldn't extending the balljoint pivot affect where the actual pivot reaches its maximum outboard location? As in the arm tip itself reaches the maximum outboard location when it's parallel with the ground(and the camber curve goes to crap after the balljoint goes perpendicular with the spindle), but doesn't extending the balljoint, possibly at an angle, make the "actual arm" just an imaginary line from the subframe pivot to the balljoint pivot?

Maybe I'd just need to model something simple and rotate it about a point to prove or disprove my back of the envelope thinking...

[SoSideways]

That's what I'm saying guys, please post up something like a simple paint drawing or something lol

Actually, I know of one on FA, let me find it...

http://filebox.vt.edu/users/tomc/Pictures/Roll-Center.JPG
Pic courtesy of BlaBla on FA.

Is that pic correct, or not?

[AceInHole]

That pic works.

[WishIHadaSilvia]

How are you supposed to tell what is good and what is bad just from looking at it?

http://i10.ebayimg.com/04/i/000/7e/e8/357e_1.JPG

Those look more like the bad drawing, but in all honesty I have no clue.

[AceInHole]

Same. I can't tell if they'll work or not.... but I guess if you had bad balljoints and needed to buy something anyways they might be worth taking a shot.

The thing that sucks is: if they're the "bad" design, they'll be weaker than stock since they'll put a bending stress on the LCA.

[WishIHadaSilvia]

So basically the "ball" part of it needs to be on the bottom? I know someone who has them....would we be able to tell by looking at it installed on the arm?

[SoSideways]

So basically the "ball" part of it needs to be on the bottom? I know someone who has them....would we be able to tell by looking at it installed on the arm?

You could, you'd just have to have the person bend or move the ball joint when it's installed on the arm, then you can tell exactly where the pivot point is.

Looking at the pics though, they look like stock ball joints with a spacer below it, thus looking more and more like the "bad" part depicted in the MS Paint drawing.

[WishIHadaSilvia]

I just talked to the guy that has them. He said it kept the pivot point in the same location as stock. But he didn't have any pictures. He said he was surprised that it was "a functional piece".

[SoSideways]

From the pic of the "Hardrace" ball joints, it really does look like the rubber part's the part that pivots, whereas the shiny black part underneath that is just a spacer... which would place them in the "bad" category.

The Moonface ones, on the other hand, looks a little different. I'll post some pics here in a bit.

[SoSideways]

Here are the pics:

Regular front roll center adjuster
http://www.nengun.com/image/catalogue/original/nengun-1640-02-moonface-front_rollcenter_adjuster.jpg

Front roll center adjuster pro
http://www.nengun.com/image/catalogue/original/nengun-1714-02-moonface-front_rollcenter_adjuster_pro.jpg

Front roll center adjuster pro racing
http://www.nengun.com/image/catalogue/original/nengun-1715-02-moonface-front_rollcenter_adjuster_pro_racing.jpg
All pics courtesy of Nengun again.



Out of all of those, the pro racing ones look to be the most promising...

[Wiisass]

Def, now you're overthinking it. The pivot is important, but the physical path of that pivot is more important.

Anyway, just forget it, these balljoints do nothing good. They're crap, don't buy them even if you have horrible blown ball joints.

And that pictures, interestingly enough anouther Virginia Tech person, is right for how the "LCA" is defined when looking at Suspension Geometry.

And again, these balljoints are a marketing gimick, like most JDM coilovers, that make people think that they're helping them when they are, at best, not doing anything at all, or, at worst, hurting the handling of your car.

[Epstein]

And that pictures, interestingly enough anouther Virginia Tech person, is right for how the "LCA" is defined when looking at Suspension Geometry.

Just like my tech school, they apparently don't teach English at VPI either! :D

I was browsing Ziptied (the non-login part) and saw this as an interesting approach. Looks like a big spherical with a roundy-round pin in it.
http://www.ziptied.com/Coppermine/albums/userpics/10096/IMG_1723.JPG
http://www.ziptied.com/Coppermine/albums/userpics/10096/IMG_1710.JPG

Maybe Wiisass or Veilside or any of the other Ziptied people know more about it.

I think I like Mike Kojima's similar but different approach using a threaded rod-end. Then you can readjust the track width to dial out what you lost making the pin longer (as it points inward). For both, I'm not sure I'm too keen on reaming a new taper into my spindles, though.

[Epstein]

Does anyone know what the stock taper is? I've got one of those pins at home and I could get it lathed down to the right taper as an exercise...

[veilside180sx]

The S13 rear is a 9 degree taper, same as the B13 front. I'm not sure what the rest of the S chassis are, but I need to know as well to make the lower control arms I'll be working on soon.

[SoSideways]

Is this something I can grab from the FSM? Seeing as I have access to the S13 and S14 FSMs right now.

Only thing I see about the ball joint in the 91-94 USDM 240sx FSM is swinging force, turning torque, and vertical end play.

PS - I do have a pair of brand new OEM S13 FLCA w/ brand new ball joints in the garage that I can measure, although I probably don't have the proper instruments to measure them.

I can try my best to take a close up pic so you guys can geek it out by measuring the thing on your screen lol

[Wiisass]

You have to physically measure them to get the numbers. Or find someone who would have the actual drawings for the ball joints and convince them to give you some numbers, but they aren't supposed to give out that info, so you'll need a good story or sound official or just trick them into it.

But it's easiest just to measure them. And just knowing the taper angle won't be enough, you'll need to know the upper and lower diameters. Otherwise, you won't know where to put threads.

And that LCA, is a good idea, I don't like how they did the pin though. With the amount of load that the LCA sees, that pin should be bigger if it's going to be extended much outside of the spindle. Otherwise the shear and bending forces are going to cause a failure. Spacers can help to account for some of the load, but it can still be hard. And it sucks that the LCA mounting point is at such an angle because it makes it hard to so much with in terms of modifying the spindle to put the outboard LCA point in double shear.

But having a rod end out the outboard would be a bad idea. It puts threads in bending/shear and that's never good, especially out there. It can be alright if it's on the inboard end because the brake torque forces won't be as high. But it shouldn't be on the outboard end of the LCA. But similar idea, just a spherical bearing in a seat is much better.

Tim

[Epstein]

Same/similar pin on Mike Kojima's SE-R.

http://www.sr20forum.com/img/data/500/medium/1_relocated_ball_joint_compressed.jpg

[SoSideways]

Same/similar pin on Mike Kojima's SE-R.

http://www.sr20forum.com/img/data/500/medium/1_relocated_ball_joint_compressed.jpg

Can you find a pic of said FLCAs?

[Def]

Def, now you're overthinking it. The pivot is important, but the physical path of that pivot is more important.

Anyway, just forget it, these balljoints do nothing good. They're crap, don't buy them even if you have horrible blown ball joints.

And that pictures, interestingly enough anouther Virginia Tech person, is right for how the "LCA" is defined when looking at Suspension Geometry.

And again, these balljoints are a marketing gimick, like most JDM coilovers, that make people think that they're helping them when they are, at best, not doing anything at all, or, at worst, hurting the handling of your car.

I might model something and rotate it as a quick sanity check, but looking at that diagram it's saying the exact same thing as I am. The "effective LCA" is the path from the balljoint pivot to the pivot on the subframe.

[veilside180sx]

Can you find a pic of said FLCAs?

http://www.nittotire.com/blog_detail.asp?id=15

Here's Mike's setup

[SoSideways]

So... how hard is it to convert the OEM Nissan's ball joint design to the spherical bearing design that Mike K. used on that Sentra?

Battleversion, aka Alex Pfeiffer sells a kit that eliminates the need for a bushing on the FLCA, that you can use to adjust the scrub radius, and in a sense, that's a lot like what Mike K. did, but on the other side of the FLCA.

So... who would like to take on this project? I might have a pair of S13 FLCA to donate here soon for the cause.

[Wiisass]

Def, you're missing what I'm saying. I'm not saying that the effective LCA will be any different. I'm talking about it's path when moving with the wheel will be slightly offset.

Think of it similar to the way that ackerman will change with the position of the steering rack while the outboard point stays the same. Same kind of idea.

[Wiisass]

So... how hard is it to convert the OEM Nissan's ball joint design to the spherical bearing design that Mike K. used on that Sentra?

Battleversion, aka Alex Pfeiffer sells a kit that eliminates the need for a bushing on the FLCA, that you can use to adjust the scrub radius, and in a sense, that's a lot like what Mike K. did, but on the other side of the FLCA.

So... who would like to take on this project? I might have a pair of S13 FLCA to donate here soon for the cause.

Don't do it like Kojima. Did you not read what I had posted. Rod ends on the outboard of an arm like that are a bad idea and even worse on a front wheel drive car like Kojima's.

And adjust scrub radius? That's all you think of when you look at an adjustable length lower control arm? There's a lot more going on than adjusting scrub radius.

[SoSideways]

Don't do it like Kojima. Did you not read what I had posted. Rod ends on the outboard of an arm like that are a bad idea and even worse on a front wheel drive car like Kojima's.

And adjust scrub radius? That's all you think of when you look at an adjustable length lower control arm? There's a lot more going on than adjusting scrub radius.

Sorry, it's been a long day. I read this:

But similar idea, just a spherical bearing in a seat is much better.

Tim

And then looked at Mike K.'s setup, and put those 2 sentences together, like you said it was a good idea, that's all.

As for the adjustable length lower control arm bit, no, I do not just think about adjusting scrub radius. Off the top of my head, I can imagine it might have something to do with the camber curve, as it probably changes the angle between the FLCA and the spindle, and roll center might also be affected. Probably wheel rates too.

I don't know what ALL will change, but that's why there are guys like you around, to tell us noobs :)

Hey, if I didn't want to learn about this stuff, I wouldn't have followed AceInHole and Def's advice and signed up on here :)

[AceInHole]

But having a rod end out the outboard would be a bad idea. It puts threads in bending/shear and that's never good, especially out there. It can be alright if it's on the inboard end because the brake torque forces won't be as high. But it shouldn't be on the outboard end of the LCA. But similar idea, just a spherical bearing in a seat is much better.

Tim

Just say monoball so people can look it up :P

It's too bad no one makes a monoball housing that'll just press/ clip into the stock LCA *cough* Rich *cough*. For now you can just weld one in like everyone else does.

[veilside180sx]

Just say monoball so people can look it up :P

It's too bad no one makes a monoball housing that'll just press/ clip into the stock LCA *cough* Rich *cough*. For now you can just weld one in like everyone else does.

It'd be nice if I didn't have a normal job...taking up my time lol:D

[Wiisass]

Spherical bearing, monoball, whatever, it's all the same thing and people on here should know that.

[AceInHole]

Yeah but Google pulls up different results for each. I looked up "spherical bearing" for a while before finding the "monoball" housings I was looking for.

[Bdizzle]

I was reading this thread and I found this website that sells monoballs. http://www.ubmachine.com/balljoints.html My question is which one should I buy in order to weld into the LCA?
The 40-3221 looks like a good choice. What do y'all think?

[AceInHole]

I'd go with:
48-1010..... $12.50
5/8" MONOBALL HOUSING HAB-10T -
1-3/4" OD x 7/8" LONG x 1-3/8" ID

You basically clip in a spherical bearing/ COM bearing/ monoball, and add a stud (for which you may need to ream the spindle to 10deg taper).

[a_ahmed]

how about 'rose joint' suspension

[veilside180sx]

I'd go with:
48-1010..... $12.50
5/8" MONOBALL HOUSING HAB-10T -
1-3/4" OD x 7/8" LONG x 1-3/8" ID

You basically clip in a spherical bearing/ COM bearing/ monoball, and add a stud (for which you may need to ream the spindle to 10deg taper).

I prefer 3/4" monoball studs, rather than the 5/8" just for added security.

UB are good people though.=)

[SoSideways]

OK, I found the 48-1010 under "rod end" on ubmachine.com (thanks bdizzle).

But there are a few 3/4" monoball pins on that site, and their monoball selection is rather.... dismal?

[Def]

Anyone know what the ubmachine "metric taper" for studs actually is in units that don't involve ambiguous terms like "metric?"


It's not the best thing from a stress standpoint, but one could always ream out the stock spindle to some SAE size close to the lower diameter and try to find a bolt/stud/spacer that would work for that, but I think keeping the stock taper would be a good idea. Or if enough people were interested you could always buy a reamer with the correct taper together and just "pass it around."

[Bdizzle]

What stud would you use if wanted to use a spacer to adjust the roll center?
Also what about just welding a spacer to the bottom of the spindle, drill out the hole enough to fit a socket and use some thread lock to keep the nut from coming off?

[SoSideways]

What I'm wondering here is, I've seen some FC guys do work to their spindles for more angle for drifting.

If it works for drifting, which place a pretty good load on the spindle where the tie rod ends bolt to since they're constantly going from lock to lock, then there should be a way to modify and reinforce the mounting point for where the ball joint connects to the spindle?

I can hear Tim walking towards the keyboard to take me to school again...

[Wiisass]

FC guys are modding the tie rod pickup point. To adjust roll center you would need to modify the LCA mounting point which sees much more load than the tie rod mounting point will see under any situation.

I'm not saying it can't be done, but if not done right, it would cause some big problems. A custom designed spindle would be a much better solution to this problem.

As for different tapers and such, the best way would to make a pin that would fit the stock taper and can be used with whatever spherical bearing you're putting into the LCA. Other than that, I would drill out the stock taper to a through hole and run a good bolt through it.

But like I said before, the biggest problem is going to be the bending and shear that the pin will be due to the design of the mounting. So you need a strong enough pin that this will not be a problem. The other issue is the angle at which the pin would come out of the spindle. This limits how long of a pin you can run due to rotor clearance unless you were to do more extensive modifications to the spindle that would change the angle of the pin.

So just try and take some of this stuff into consideration before you have a pile of parts sitting in front of you that you can't make work because you missed one of the design constraints.

Tim

[AceInHole]

FC guys are modding the tie rod pickup point. To adjust roll center you would need to modify the LCA mounting point which sees much more load than the tie rod mounting point will see under any situation.

I'm not saying it can't be done, but if not done right, it would cause some big problems. A custom designed spindle would be a much better solution to this problem.

A custom designed spindle would get rid of a LOT of problems!! I'd imagine it wouldn't be too difficult to fabricate, especially if you use a 350z/ G35 front hub (or similar) with a bolted flange similar to the 240's rear (no need to machine a new axle portion).

[a_ahmed]

You know about two years ago i was on some japanese website selling custom spindles for S13s, S14s, S15s, Z32, etc... they were powdercoated/painted black all shiny and it was meant for lowered cars, I can only assume thats what we'd want right there.. problem is i lost the link lol.. it cost something like 800$ a pair... not bad considering adjustable LCAs from SPL/orange-tree/yashio factory almost reach that realm, im sure if it was local made it could cost less...

[WishIHadaSilvia]

Ikeya Formula makes some amazing suspension parts for our cars. You can get the fronts and rears for around 600-650 a piece lightly used or around 900-1000 a piece brand new.

By piece I mean for a front pair or rear pair.

[Def]

Front and rear what? New spindles?


I talked to Richard a few weeks ago about what it would take to come up with a casting or even if you could CNC out some new spindles. Looking at the dimensions, it looks like you'd need to a cast a new one.

I've also thought about machining somewhat cheap spacers to get just a hair more angle on the arms to adjust the roll center. Essentially make a thin "cone" out of 4130 that sits on top of the stock balljoint. Of course you can't get too thick with this or you run out of thread, but it could probably give you a few degrees and make things not "quite as bad" while not really affecting anything else.

[WishIHadaSilvia]

Sorry I had just woken up...LCA are what I'm talking about.

http://www.upgarage.com/upgarage/gazou/0704/0704154001745/0704154001745s0.jpg

Those are the fronts, derr, and have the tension rods attached to them.

[AceInHole]

[Space reserved for witty comment about having suspension parts for my S14 made by a certain site owner]

Those sway mounts look both weak and off center (as though they contribute to torquing the LCA). I wonder if you'd be able to relocate the mount to a tab on the strut, like the BMW's have, and if it'd increase the front swaybar's effective stiffness.

[a_ahmed]

those look like the orange tree/ikeya flcas... the SPL ones are like this:

http://www.splparts.com/main4/parts/NissanShared/Suspension/Multilink/SPLFrontLowerArm.jpg

[WishIHadaSilvia]

Yeah those were Ikeya Formula.

I shouldn't even post this...but I can assume these are one of those "you get what you pay for" situations?

http://cgi.ebay.com/ebaymotors/95-96-97-98-240SX-S14-TCS-FRONT-LOWER-CONTROL-ARMS_W0QQcmdZViewItemQQcategoryZ33583QQihZ023QQite mZ360034909259QQrdZ1QQsspagenameZWDVW

http://cgi.ebay.com/ebaymotors/ORANGE-VERSION-LOWER-CONTROL-ARM-S14-SILVIA-240SX-JDM_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 QQcategoryZ33583QQihZ011QQitemZ320206365015QQrdZ1Q QsspagenameZWD1V

[Wiisass]

Those ones you're saying were Ikeya arms look and most likely are exactly the same as the Battleversion/Orangetree/TC sportline ones that you posted in the last post. I have them, they suck. Everyone I know who has used them got rid of them. The biggest problem is that lower ball joint bearing. It's some weird size and way too tight causes the steering to stick and things to just feel crappy. I still have them on my car right now because my lowers got put on another car I built so it could compete and I haven't had time to get them back yet.

PJ, you could run a mount on the strut for the sway bar. But it would call for a weird designed sway bar or you would have no steering angle. But it would bring the installation ratio of the sway bar closer to 1.

As for designing and manufacturing a spindle or upright, it's not out of the realm of possibility. I was seriously considering doing it, but the whole design/prototype/test/production process is a lot for something like that and I don't know if it would be worth it. There are some custom spindles out there on the market, but I don't really trust what they did. The lack of information that JDM companies provide for their "custom" designed parts, I interpret as ignorance and that they don't really know what they're doing. I may be wrong in this, but if it follows the trends of all their other suspension "engineering" endeavors, I'm not far off the mark. With that said, there aren't many people that I would trust to design something like this. A lot of people have an idea of what needs to change, but don't understand all the implications of what changing one point will do to the rest of the suspension.

But if it's something that you guys would really be interested in and would be willing to pay for, I can start looking into it again.

Tim

[Def]

Round about how much do you think a pair of spindles would go for? I looked at material pricing, and I'm guessing they'd have to be cast and then have some machining done to them.

[veilside180sx]

I have been debating making spindles for quite a while. I think they would probably be in the $700/pair range though for casting and machining. I'd have to finish up my drawings and get quotes back on them though.

[Epstein]

Anyone who designs these things should make sure the brake mounting points will accomdate drilling out for 14mm caliper bolts.

For a rear roll-center change with Z32 uprights, I saw these from Moonface. They're only $100.

http://www.nengun.com/moonface/rear-rollcenter-adapter

[Def]

Anyone who designs these things should make sure the brake mounting points will accomdate drilling out for 14mm caliper bolts.

For a rear roll-center change with Z32 uprights, I saw these from Moonface. They're only $100.

http://www.nengun.com/moonface/rear-rollcenter-adapter

Are those used with the stock balljoints? The engrish isn't that detailed.

That's a somewhat similar idea to what I had on the fronts, but I would definitely get something like that machined on a CNC lathe.

[Epstein]

These replace the steel inserts on the rear z32 uprights. The sit on top of the ball-joint, under the upright.

[Def]

Yea, I know what they are, I'm just assuming they are thicker/longer, so that you lower the end of the LCA and raise the roll center. I just don't know how much play you have on the stock balljoints to do something like that and not run out of thread.

[Epstein]

oh yeah, sorry. The conical part is the same as the stock insert. The extra bit at the bottom is what they've added. It looks like about 1/4" as far as the scale goes. IIRC, there's about that much space on the threaded portion if a shorter nut is used (if you're keeping the cotter pin). I actually ran a washer between the nut and upright on mine and still had space.

[Bdizzle]

Any updates?