Another upper arm design. Discuss

The design as it is in that picture won't fit a Zed. Z32 FUCA's are straight and Skyline ones are offset, that's why all genric after market arms have the main shaft too one side, rather than centered; put in straight for Z32, rotate 90* for Skyline. Those won't rotate 90*.

 

the issue for me is heim joints on street cars, they dont last.

 

Nah, the guys at GK Tech said it'll fit Z32s fine. I asked them about that when they first put the CAD pix up.

 

They also seemed pretty confident they could work the R32 front drop knuckles into a Z32 despite the offset hub placement between the two.

Methinks GKTech don't know the Z32 suspension as well as they could, and are developing Skyline parts while marketing them to suit both chassis. Which is fair enough really, the Skyline market is where the money's going to be at. The only reason they're even bothering to mention the Z32 is because it the products could possibly (through no deliberate action) fit. I can hardly blame them for that, there's little reason to bother with the Z32 especially here.

Here's an R32 FUCA:



Here's a Z32 FUCA:



Notice that the R32 unit is offset while the Z32 is straight.

Here's the UAS V1 FUCA that, like most after market adjustable units, can be fit to either chassis with the rotation of an end. In this pic one end is rotated and the other not.



I'm not saying nothing could be done to make these fit a Z32; just that as pictured, they won't.

See whatta mean jellybean?

 

My old Stillen style (but UAS made I think???) arms are still going strong, no rust, no flogged out bushes, no cracks ..... maybe I'm doing something wrong?

Can't comment on the GKtek product, had death threats for releasing facts and data in the past although I will say this:

As the J arm travels through its arc and twists the end of the upper control arm it will make the secondary arm they have incorperated move through a small arc in relation to the main body. So you will have two arms swinging in arcs at 90 degrees to each other - something is going to have to give.

Seems like a patch up on the original designs, I'm sure many many people have thought of this before & not gone ahead because of the same reason I just listed.

Maybe they have crunched the numbers on the good ole computer & figured it will be OK, should only be a small movement, with coil overs with short travel it might not be an issue.

 

I'm at the other end of the spectrum Glenn. I've had 4 sets of the old UAS/Stillen type arms(all distorted or split). In fact, the ONLY UAS arms that I have NOT used/tried are the current "swivel styled" items(the previous "swivel type" ones bent in the middle section, on the trip to Warwick, QLD(a couple of years ago).:br:

 

Yeah, I know what you're talking about. I'm curious to know how critical the difference would be though.

I do wonder if the offset difference is so extreme that you'd lose suspension travel due to the shape of the suspension tower. I also wonder if using Skyline arms would result in an easy caster gain on a Z32 (provided the outboard end is further rearward than the inboard end. I have no idea which way R32 arms are oriented).

 

They haven't actually 'designed' these, they're a copy of the arms developed for the group A GTR's that raced in the 90's.

Probably very little number crunching involved.

 

I don't know exactly but it doesn't sound like a smart idea. The hubs, FUCA's and castor rods for a start I know are different.

 

I should like to add that the differences in FUCA design may vary between R32 GTS-Ts and R32 GTRs. I am not sure if they do, but I know the caster rods are different. GTS-T models have straight style ones (like our cars) and GTRs kinked. Ask me how I know...

 

They will still need to twist during the movement of the suspension & if the materials are not designed to handel it then there will be issues.
They look like a bitch to adjust as well

There is a really simple fix to the issue:
Run adjustable caster arms with rod ends on the front (rather than bushes like some have) & shift the pivot point up in the front mount.
Maybe not ideal suspension geometry but it will reduce the forward movement (& increase in caster) as the wheel comes up in relation to the chassis.

Make sure you have bump stops fitted that will prevent the top arm hitting the mount on the chassis.

Don't run a weak assed single rod where the factory installed a pretty decent box section member.

Don't run your Z so low on the street that it breaks suspension parts & then try to find a fix for it :rofl:

 

I swear I must be having a brain fart here. I just don't get this.

How can two rose joints bolted in parallel twist in unison? Is this not exactly like screwing the end of the arm of a clock down and expecting it to still go around?

 

Short answer Martin, THEY CAN'T!!!:agree::br::zlove: