Z31 to S14 front suspension --- discussion thread

[Jason84NA2T]

Benedict wrote: Zmech you chose S14 knuckles because 5-lug is typically cheaper correct?


Zmech/Buter...
Is there enough difference in S13/14 knuckles and coilovers to doubt that this conversion could be done using S13 parts?

reason being, in my case, I already have dibs on complete S13 front and rear suspension for free.


I know the balljoint is different (S13 smaller than S14, but is S13 smaller or larger than Z31?) If there's no conclusive answer I guess I'll just have to start bolting stuff up and see.

5 lug is MUCH more expensive and desirable.

No, you cannot use S13 spindles because the front axel centerline is different; the spindle is offset from the center of the strut changing wheelbase, along with caster and SAI dramatically. S13 5 lug is also an expensive conversion.

[Benedict]

5 lug is more desirable (wheel options) but I meant more expensive starting out with S13 (most are 4 lug) vs S14 (most are 5 lug)....moot point, anyway

ok, so S13 spindle is out.

I'm all for swapping to S-chassis suspension and coilovers front and rear but am reluctant to cut up the Z. Butter was forced into some serious cutting/welding because S14 rear coilovers are so long. S13 rear coils are shorter.

I'm trying to figure out the mix of S13/14 parts that will work with minimal fab work on the unibody and using the same coilovers front and rear.

-S14 spindles will work in front.
-S14 rear coilovers require rebuilding the top mount if using S14 IRS.

ideas/questions
1. If S13 coilovers can bolt up to the S14 spindles then S13 IRS and coilovers can be used in the rear without modifying the rear upper strut mounts like Butter did (this is what I'm hoping)
2. What about S13 coilovers with S14 IRS? (why? I don't know. Just asking)

Like I said, I am reluctant to cut up my Z (because it's an 86 slicktop) but if it needs to be done for the S-chassis suspension then so be it.

[wilson101]

So the thing that screws up the geometry is the placement of the spindle and not LCA because it just affects the camber?

[zmech]

z

[2+2turbo]

so Zmech you don't think you are going to have to hack up the rear shock mounts like butter had to? i think what benedict want's to know is this. from what iv'e seen, the s13 rears are alot shorter than the s14 coilovers(butter used s14 coilovers this is why he had to chop up the top shock mounts)...

[Benedict]

2+2turbo...yes you caught my drift.

Zmech, yes your write up is simple and if the issues you and Butter were discussing work out in your set-up's favor then it is simple and effective.

I know you intend to use the S14 rear coilovers with the Z31 IRS. I was hoping someone/anyone would have insight into the combinations I mentioned.

"Limited time, space and MONEY... "

^^^ That's why I'm asking so many questions instead of providing answers, lol.

[Butter]

Benidict-
You CAN use S13 coilovers with the S14 spindles. S14 uses bigger bolts to attach it though, so you have to either drill the coilover holes bigger to use the bigger bolts or buy the spacers from PDM racing to use the smaller ones.

Jason brought up another point. Note spindle axis position between S-chassis and Z31. This is what I saw that made me think twice about using it. The axis on z31 is forward of the steering axis and centered on s-chassis.

[Benedict]

yeah, the difference in spindle placement worries me.

maybe a combination of yours and Zmech's approach would be best.

Z31 strut tube cut down with added support (collar) tube like yours. Slide coilover in. Fabricate bracket to side of modified Z31 strut/spindle to secure coilover by using the bolt holes intended for the S-chassis spindle.

This way the steering is not afected (downside to Zmech's method) and the coilover is easily removed for replacement or refurbishing (downside to your method)

Of course there is a downside to this idea as well. External diameter of the coilover is probably different from whichever manufacturer choosen so swapping to another model or brand would probably require creating a new bastardized Z31 spindle. But you would have to do that to so whatever. Or forget the collar, leave the bottom of the coilover exposed and bulk up the mounting bracket.

lol, damn I wish I had the resources to try all this retarded shit.

[Butter]

maybe a combination of yours and Zmech's approach would be best.

Z31 strut tube cut down with added support (collar) tube like yours. Slide coilover in. Fabricate bracket to side of modified Z31 strut/spindle to secure coilover by using the bolt holes intended for the S-chassis spindle.
ROFLMFAO!
You mean like this bastard I made?



Didn't work BTW.

Of course there is a downside to this idea as well. External diameter of the coilover is probably different from whichever manufacturer choosen so swapping to another model or brand would probably require creating a new bastardized Z31 spindle. But you would have to do that to so whatever.

Not really! They are all pretty much the same since many are made in the same factory. I could swap out my Tanabes with Stance external resevoir by simply unscrewing them.

[Benedict]

no, not like that at all.

Your final version.

Same idea, but instead of securing the coilover into the modified Z31 spindle by welding the two together, fab a bracket welded to the side of the modded Z31 spindle and bolted to the coilover (using existing holes that would bolt up to the S-chassis spindle).

but if swapping/replacing is as easy as you say then my idea becomes kind of redundant.

[Butter]

Not enough room/strength.

[Benedict]

phuck it.

your approach is the best working, although a little more "custom" than I'd hoped.

so I'm just gonna shut up until I have some real info to provide.

[G-E]

if you were to cut the tube completely off the z31 strut and replace it with a coilover arm .... the arm would be easy to make out of ~1" plate with a plasma cutter and drill

still custom but at least much cheaper than getting s-chassis knuckles/hubs

[james]

G-E wrote: if you were to cut the tube completely off the z31 strut and replace it with a coilover arm .... the arm would be easy to make out of ~1" plate with a plasma cutter and drill

still custom but at least much cheaper than getting s-chassis knuckles/hubs

GE is onto it it may be custom but its a no nonsenence approach and it should be fairly easy for any good engineer to fab up.

....this is the route i intend to try

[Kennedy]

Butter wrote:

Are those axels removeble?

If they are maybe there is custom knuckle time. That part should be easy to fab. if axel can be remove.

Z31 measuments and axel, but strut tube place has coilover connection.