S13/S14 Rear Koni's

[veilside180sx]

As many of you know I've been recommending/setting people up with OEM based shocks for the rear of the S chassis. In the next few weeks I'll have a new housing available to run Z32 uprights with either a 8610 SA or 8611 DA insert. The 8611 compression adjuster knob will be easy to access as well, but I would like to try and build in an adjuster for it to avoid worrying about losing small tools. I'm currently waiting for the lower mounts to come in and then I'll take some pictures. Just thought I'd give everyone a heads up. The S13 housing will be 14" total housing length and have just under 6" of shaft travel. While the S14 housing will use one of the longer inserts and have 7" of shaft travel and be 17" long. iirc. Pricing should be the same as the front housings. There are other options as well, but I think this works out a little cheaper.

[veilside180sx]

Here's pictures of the tubes with the new lower brackets for the Z32 rear mounts http://nissanroadracing.com/files/images/CIMG1287.preview.JPG

[2Fass240us]

Good stuff. I look forward to seeing the finished product. Realistically, it will be another year or two before I'm ready to make a switch. I'd like to get the cage in for safety and to stiffen things up so I can run a ludicrous spring rate compared to the current one. 8) -Andy

[a_ahmed]

Pardon my ignorance... I intend to have you make me S13 front and rear 8611s... and i intend to get z32 aluminum uprights.. hence the need for a fork type rear... but... i am curious one part... Would the extra travel length make the s14 rear end superior to the s13 rear end due to this design difference... plus an s14 has a wider track.. making it more stable... Very ignorant of me but I need an explanation :( I want to go all out on my s13.. and have spent plenty as is on it... would suck to hear otherwise :( lol I want maximum grip out of this car... :(

[veilside180sx]

The strut length difference is more due to chassis stamping than an advantageous geometry. Although the LCA has less anti dive on the S14 than the S13, which is better. You can accomplish the same thing by relocating one point on it though.

[spool_sample]

Any plans on rear housings for the 86-series that will fit the standard S-chassis spindles?

[veilside180sx]

It's not much different than the Z32. I just weld a heim on the bottom instead of the bracket. I figure if you are going to take the time to swap to a nice set of Koni's...you may as well drop some unsprung weight for $50 on a set of uprights.=) If someone really wants them though...they are definately doable.

[a_ahmed]

i want to do the 8611 with z32 fork type bottom as ive mentioned in an above post... i am wondering where i can get the z32 aluminum uprights though... i want to buy them... any clue?

[McCoy]

i am wondering where i can get the z32 aluminum uprights though... i want to buy them... any clue? They pop up on Zilvia and FA all the time for decent prices. maybe even consider putting a request in the wanted adds on either of the sites. Of course a call to your local salvage yard or a visit on car-parts.com will probably be quick also.

[veilside180sx]

Ta da....we have completion. They are at the powdercoaters and will hopefully be done this weekend. (PJ's christmas present might be a little late...lol) http://nissanroadracing.com/files/images/CIMG1584.preview.JPG

[Blair]

Any plans on rear housings for the 86-series that will fit the standard S-chassis spindles? It's not much different than the Z32. I just weld a heim on the bottom instead of the bracket. I figure if you are going to take the time to swap to a nice set of Koni's...you may as well drop some unsprung weight for $50 on a set of uprights.=) Z32 uprights might not be legal for some autocross classes, and would probably take points for NASA TT. If you did weld a heim joint on, would the bearing section be replacable?

[veilside180sx]

Yeah I'd use something with a replaceable bearing MTL Any plans on rear housings for the 86-series that will fit the standard S-chassis spindles? It's not much different than the Z32. I just weld a heim on the bottom instead of the bracket. I figure if you are going to take the time to swap to a nice set of Koni's...you may as well drop some unsprung weight for $50 on a set of uprights.=) Z32 uprights might not be legal for some autocross classes, and would probably take points for NASA TT. If you did weld a heim joint on, would the bearing section be replacable?

[AceInHole]

Crap! I better start pressing in bearings on my Z32 spindles!! That and I have an engine to swap :)

[turtl631]

I'm jealous. I think I might try to do the full 8610 setup over spring break. Do those MCP bearings fit in the spindles?

[vw_nissan]

When will you have the s13 front and rear (for stock spindle) available? Eagerly waiting for Koni setup...

[veilside180sx]

I'm still bugging my guys for the front spindle flanges out of the correct material.=) I'll order the heim joints for the rear pretty soon as well. S13 uses the same insert front/rear, so that's not a big deal.

[Def]

I'm jealous. I think I might try to do the full 8610 setup over spring break. Do those MCP bearings fit in the spindles? Yep, but the lower Z32 shock bushing is just a hair under 46mm. The 46mm bearing from MCP has a 20mm ID, so I was planning on shimming it down with some 20mm OD 16mm ID pipe. I was also concerned with the increased bending stress due to the smaller bearing area on the bolt, so I think the 16mm bolt on the lower mount is a good idea towards increasing the safety factor over the 12mm factory bolt.

[turtl631]

So it should just take some sanding of the bearing carrier in the spindle to get the 46mm MCP ones to fit? I like the idea of using a 16mm bolt instead, although finding some nice Grade 8 ones will likely be a bitch for me unless I buy in bulk. I'm guessing McMaster sells some 20mm/16mm sleeves you could use to drop the inner diameter down?

[veilside180sx]

I received the housings back from the powdercoater today, so I'll post some pics of them when i get home with my camera. The color of the new ones came out closer to a Teal color, which looks nice although it's not the same. We changed manufacturers of paint because we couldn't get the same color in a time crunch.

[veilside180sx]

Here's the pics: With flash http://nissanroadracing.com/files/images/CIMG1610.preview.JPG No flash http://nissanroadracing.com/files/images/CIMG1609.preview.JPG

[Def]

Housings look nice. :) As for the MCP sphericals in the Z32 upright - I'm not 100% satisfied with how it's going. ALL the bushing holes on the upright are slightly undersized, which is good when you press in a 30mm rubber bushing, but bad when you're pressing in a 30mm spherical bearing. Without any sanding the fit is tight enough to completely bind the bearings up. Lots of sanding with a sanding drum and a drill with frequent checks can get it pretty good, but ideally you want a really loose fit to get the bearings moving freely. That said, this brings me to the solution I didn't want to use(due to the unknowns) - drilling and tapping a #8-32 hole for each bearing in the upright, then drilling an indention in each bearing and using a set screw to ensure the bearing doesn't move. I've got some reservations about this method, especially since you're likely to load up the bearings with a proper preload and cause some binding just like the too tight fit, but I haven't tested it out yet. All the sanding and checking is a time consuming process, since you need to keep the hole very circular, and the tolerance seems to be about 0.1-0.05mm between a too tight hole and a loose hole. Hopefully this will be worth it. My other option was to get a 1-3/16" reamer I believe and get the MCP 5/8" COM bearings, as that would be a quick operation on each to get the fit, and would likely necessitate the set screw. Then you can use MCP misalignment inserts and get the right width and go with 1/2" bolts. I didn't want to mess with the reamer, but looking at it now, it might be the easier way if you take on the extra cost of it and the bolts/nuts.

[turtl631]

Are you replacing all the bearings in the uprights? Sounds like quite a project, post some pics if you have any.

[Def]

I'll probably mess with it some more in the next few days. I'll toss up a few pics after I get happy with the end result.

[AceInHole]

I'm about to take on the same project, except my preference would be to cut a groove for a snap ring to hold the bearings. Hopefully it can be done with a dremel and a couple cut-off wheels stacked on each other.

[Def]

A snap ring sounds good... but I keep thinking about the loading on the upright being increased by about 3x as much. It's starting to make me a bit nervous, as I have no idea how much safety factor they gave the arms. I imagine something like that is in the 5+ range for the most they could see the car doing on sticky street tires at the time, and an S chassis being lighter than a Z32 chassis helps the situation out slightly. I just worry that you get a couple of track days on 'em and split the upright right in the center due to fatigue.

[turtl631]

Does going from rubber to spherical increase the loading in and of itself, due to the decreased compliance and higher impulse? I'm trying to use Physics I/II here, cut me some slack if I'm way off base.

[Def]

No, it's not the change in bearing/bushing material, it's that the MCP COM bearings in this size are 12mm wide, whereas the stock bushing is 32mm wide. So you're distributing the same load over about 2.7 times less area. Machining a snap ring groove only makes the problem worse by putting a stress riser right at the edge of the loaded area, as well as taking away material. Not sure a set screw is really much better either...

[turtl631]

Would it be better to use two set screws, one on each side of the bearing, rather than one that penetrates into the bearing? At least you wouldn't be applying tension to the bearing doing it this way.

[Def]

I thought about that, but I think it'd be tough to get a tight fit on it. The snap ring sounds like it could work without too much trouble. I'm still undecided if I'm going with the bearings. I did a few very rough calcs looking at the arms and I believe they'd be OK from a strength standpoint, but they're not going to have much of a safety factor.

[AceInHole]

I just worry that you get a couple of track days on 'em and split the upright right in the center due to fatigue. On a cast aluminum spindle, there shouldn't be too much fatigue. Realistically, you're reducing the total load going through the spindle since there's near zero torque loading on the pivots (as there would be from bushing bind) and everything should be isolated as vector forces. Extra vibration shouldn't be a huge deal on a fairly ductile material, especially since I think the spindles are forged. I'd worry more about the bearings seizing and putting a bending stress on the upper arms more than anything. If they fail they're fully captured by the fork, so that's not as much of an issue. Another thought for the bearings would be to retain them with epoxy. It'd make it a pain in the ass to replace down the line, but it'd be better than a force fit or a set screw. I wouldn't want any sort of load that might change the bearing race tolerance. Groove and snap ring is still going to be the best bet, though. Easy enough to do with a dremel and a router-like peice to hold it.

[Def]

It's the bearing stress on the pivot bore that's increased. You're effectively taking a 32x30mm area and then making it a 12x30mm area. That's going to cause the tensile stresses in that upright pivot area to go up by a factor of about 2.6ish since you're now involving much less material in the tensile loading that locates the uprights. The uprights also look cast to me, given the distinct mold lines all around it. There are even pushpin indents on the inboard area further indicating it's a casting. I did some rough analysis, as the factory setup stresses about 0.4 sq in of aluminum in tension on the smallest part of the upright, while the factory steel links have about 0.18 sq in in tension. Given that's a little over 2 times as much cross sectional area, it makes sense given what the strength is likely to be. When you put in these 12mm wide COM bearings, you're now loading 0.15 sq in of aluminum in tension with the same load that the factory engineers thought fit to put even more steel to resist. The aluminum - especially cast - isn't very ductile either, and it has a finite fatigue limit. So load it enough, and it will continue to drop in strength until failure, unlike steel which has an infinite ultimate fatigue strength it will reach. The failure mode on a piece of aluminum is also going to be more of a brittle fracture instead of a ductile deformation like a steel upright would. So if it's going to let go, it's just going to catastrophically rip apart one of the upright pivots. I'm still thinking of giving it a go, but there isn't much safety factor by my calcs given the type of forces you'd be likely to see. The only saving grace is that there are 3 links to resist the lateral traction generated by the tires, so hopefully that will keep loading to a safe level.

[roccon31]

theoretically, should one find a good price on a set of front and rear s13 struts/springs, all that would need to be done is buy new rear dampers for the s14 and drill the holes out for the fronts? the springs are the same length for both cars? i ask because i could find a s13 setup a whole lot easier than an s14 setup, and then when it is time to buy new dampers, i could just buy the correct ones for the s14, buying me some time before i have to shell out big bucks on koni's, correct?

thanks,
jeremy

[Def]

S13 rear dampers are much shorter than S14s - I hear somewhere around 4" but don't know for sure.

The only difference in the front is the S14 using larger spindle bolts, so yes, you just have to drill those out.

[LigouriRd]

Any plans on rear housings for the 86-series that will fit the standard S-chassis spindles?
Did the rear housings for the Standard s14 spindles ever come to fruition? I heard mention of simply welding helm joint to the end of a 8610 strut but what about the 8611? I imaging such a housing would have to come off in order to adjust the compression damping.

[veilside180sx]

Did the rear housings for the Standard s14 spindles ever come to fruition? I heard mention of simply welding helm joint to the end of a 8610 strut but what about the 8611? I imaging such a housing would have to come off in order to adjust the compression damping.

Nope, it's just too much hassle to find a 20mm bearing along with a pre-threaded tube.