Why Nobody Makes Front Upper Arms That Sit Further Backwards?

[Duncan]

Well.....back to the original question....we were looking into this for the custom upper arms for the nugget.

If pulling the bottom of the hub forward increases caster, surely pushing the rear of the hub backwards acheives the same.

The r32 upper arm is an I shape, why not make it more like L instead?

[Sydneykid]

Well.....back to the original question....we were looking into this for the custom upper arms for the nugget.

If pulling the bottom of the hub forward increases caster, surely pushing the rear of the hub backwards acheives the same.

The r32 upper arm is an I shape, why not make it more like L instead?

Why not move the inner pivot point of the front upper control arm rearwards?

You could also fix some of the gross misalignment at the same time

Cheers

Gary

[djr81]

Here are a couple of drawings and three photos.

The first shows what Nismo do to the standard upper link bracket to allow for more castor/camber. Essentially it is a stock component but with the holes drilled differently - the front moved closer to the centreline of the car & the rear lower. Thus the upper link is rotated on two axes - allowing for more castor.

The second shows a stock LHS bracket.

The third shows the Nismo bracket installed with a stock upper arm. Interestingly (or not) the bracket ends up giving you less camber for the same arm length. The shot was taken before I installed some new arms that I had made.

The fourth is a drawing of a Cusco arm - these are 10mm shorter than the stock arms. Note the trail. Unfortunately I don't have a drawing of a stock arm. Mostly due to being lazy.

The last shows the whole lot bolted up with the new arm - in rattle pack black, no less. I drew the arms to use the Whiteline bushes.

As an aside note that Nismo used to do a sliding bracket for the R32, but now all you get is a stock item with harder bushes. Also their castor rods are approx 5mm shorter than the stock items.

Edited August 13, 2009 by djr81

[Sydneykid]

the front moved closer to the centreline of the car

Wouldn't that decrease the caster ie; move the upper outer pivot point forwards?

the rear lower

That would help with the misalignment problem.

Cheers

Gary

[djr81]

Wouldn't that decrease the caster ie; move the upper outer pivot point forwards?

Cheers

Gary

Yes it would. But I don't think (ie don't really know) that it amounts to a big difference. IMHO the (mis)alignment issues in the front end are what constrains the amount of castor you can run - that & the tyre hitting the plastic at the front of the guard.

Importantly it increases camber - which sounds contradictory given you end up with less with a Nismo bracket.

As an aside it means you cannot fit an offset inner bush to the Nismo bracket. The arm binds if you try it. The brackets are a &*%$ to get out too. You start by removing the abs system.....

Edited August 13, 2009 by djr81

[Beer Baron]

Yes it would. But I don't think (ie don't really know) that it amounts to a big difference. IMHO the (mis)alignment issues in the front end are what constrains the amount of castor you can run - that & the tyre hitting the plastic at the front of the guard.

Importantly it increases camber - which sounds contradictory given you end up with less with a Nismo bracket.

As an aside it means you cannot fit an offset inner bush to the Nismo bracket. The arm binds if you try it. The brackets are a &*%$ to get out too. You start by removing the abs system.....

agreed! the first time I replaced R32 upper arms by myself I had trouble getting the f**kers out of their brackets so I had a bright idea. why not just remove the bracket and arm together.... it was a piece of cake on the drivers side. passenger side was a CNT! I did manage it without removing the abs. may have moved it around a bit though, i've blocked the memory of that bright idea...

I like your little arms you've made. very nice. I might have to get some made myself... it seems to be the way to go.

[Sydneykid]

Never had a problem, then again none of the R32's that I have anything to do with have ABS. Nor plastic inner guards for that matter.

I have redrilled the holes in the standard brackets to fix the missalignment problems. But I haven't tried it for more caster, maybe something for next time. Plus redrilling for more caster would give more room (not less) so I could retain the inner adjusters, which are essential for the amount of camber changes we make.

Cheers

Gary

[Duncan]

great diagrams, thanks. been wondering what the exact differences are stock to nismo, and voila!

[djr81]

Never had a problem, then again none of the R32's that I have anything to do with have ABS. Nor plastic inner guards for that matter.

I have redrilled the holes in the standard brackets to fix the missalignment problems. But I haven't tried it for more caster, maybe something for next time. Plus redrilling for more caster would give more room (not less) so I could retain the inner adjusters, which are essential for the amount of camber changes we make.

Cheers

Gary

I should try & clarify something I wrote a couple posts back. I used to run a stock arm with a Whiteline offset kit on the outer & a home built (er, sorry, fully sik custom) offset pin on the inner. The inner pin meant a 3mm shorter arm length. But the drillings on the front of the Nismo bracket meant the arm bound when you tried to run an offset bush. So no offset bush meant less neg camber.

If you compare like for like you do get more neg camber with a Nismo bracket.

I fixed it by making the new arms that little bit shorter again.

Gary, In your redrillings have you played around much with the inclination of the upper arm to change the roll centre? Or is it something best left for the LCA?

The problem is that Nismo only sell the stuff as a kit in which you get a bracket, a lower control arm (stock drilled differently & painted silver) and some shorter castor rods. They no longer sell adjustable length arns hence the reference on their website about the benefits of running Nismo arms makes no sense any more.

[Sydneykid]

I should try & clarify something I wrote a couple posts back. I used to run a stock arm with a Whiteline offset kit on the outer & a home built (er, sorry, fully sik custom) offset pin on the inner. The inner pin meant a 3mm shorter arm length. But the drillings on the front of the Nismo bracket meant the arm bound when you tried to run an offset bush. So no offset bush meant less neg camber. If you compare like for like you do get more neg camber with a Nismo bracket.

I have always been in favour of more caster and less camber. So that's where I have concentrated my efforts. Plus, in general there is a bit too much emphasis on maximising the static camber. I prefer to keep that to a minimum as most of our overtaking is under brakes and too much negative camber ruins that opportunity. In GTR's we also get too much corner exit wheelspin and power understeer when we run too much camber.

I fixed it by making the new arms that little bit shorter again.

I have tried a few inner pivot point positions to get rid of the usual R32 bush distortion problem, plus optimising the camber curves. Only at Philips Island did I struggle to get enough static camber with the inner and outer offset crush tubes. By concentrating on the optimisation of the camber curves I have removed even that problem. For the long, high G force corners I aimed for 1 to 1 ie; 1 degree of roll = I degree of camber change, and it's pretty close to that.

Gary, In your redrillings have you played around much with the inclination of the upper arm to change the roll centre?

You can, but it screws around to much with the camber curve and I ended up just going around in circles.

Or is it something best left for the LCA?

As per above, my experience has beem to do the lower control arm outer rather than the upper control arm inner.

The problem is that Nismo only sell the stuff as a kit in which you get a bracket, a lower control arm (stock drilled differently & painted silver) and some shorter castor rods. They no longer sell adjustable length arns hence the reference on their website about the benefits of running Nismo arms makes no sense any more.

I don't have that problem, all of the categories we race in require standard control arms. With replacement bushes OK in Production Cars and bushes plus redrilling of mounts OK in Improved Production. The other things is we don't run the cars very low, so they operate close to their design parameters.

Cheers

Gary

[haw001]

Can I ask why everyone is persisting with bushes on either end of the control arm? Seems to me to be a waste on a pure track car. There are crush tubes inside the bushes and they are greased, so even from factory on a road car doing 100's of 1000's of kms there seems to be no need for even a bearing.

Eliminating the bushes reduces the necessary size of the end of the control arm giving you a mountain of extra options for relocation. That was my plan for the nugget anyway, so I'm interested in hearing arguments.

Given the simplicity of construction, I was not even going to bother with adjustability, and instead build several different sets with different characteristics to try. Simple construction of the correct inner diameter tube (thick walled) for the ends and some rectangular tube notched to the tube diameter at both ends for the arm.

I can't remember the exact measurements, but with the smaller diameter I think you can raise the mounting points on stock chassis mounts by about 25-30 mm and drop the mounting points on the other side (can't remember the name right now) by about 20-25mm. This would allow a car like ours which will be lowered by 40mm or so (hopefully) to keep a square geometry without adding a lot of bump steer and other problems associated with a lowered road car.

The back, as has been discussed in another thread, is not so limited as we modified the cradle and dropped the whole thing a good 25mm without changing the geometry at all. Be nice to be able to do this in the front, but that would mean cutting the chassis rails and still not fix the top.

Brad, I'm glad to hear that building a new setup from scratch turned out not to be worth it, not because I wanted it to fail, but because I was seriously thinking that this would be such a big improvement that we would have no choice but to do it as well!

As much as suspension setup is a science, it's still very much a trial and error black art. You try something and it feels good but times are slower and sometimes you hate it but the times are better. My best times are often when I have no idea what I've done different and thought that the setup and tyres are terrible. But that could just be the driver

[Beer Baron]

sounds good to me mark. I can't see why it wouldn't work. I guess there has to be some kind of wear component in there somewhere but as long as the arms tube is softer than the bracket then I guess you just have to replace that when they get a bit sloppier than when you started...

[haw001]

sounds good to me mark. I can't see why it wouldn't work. I guess there has to be some kind of wear component in there somewhere but as long as the arms tube is softer than the bracket then I guess you just have to replace that when they get a bit sloppier than when you started...

Good point, I had thought of that and I have some high tensile washers with the same ID which I will weld to the outside of the brackets on both ends. This should insure that the tube wears before the brackets which are mild steel I think and would otherwise wear first.

It's hard to guess how much they will wear anyway. Unless the car is used in an enduro (something I doubt as we built it and I don't think all parts will stand the test of time!) the actual running time will be rather short and the amount of travel fairly limited. With a lowered car on firm suspension the movement around either end couldn't be more than 20 or 25 degrees. Any more and the car will be bottoming out.

I have flogged a set of Nismo bushes on my other car, but I think the wear is due to lateral stress and not rotational stress. A basically solid mount will still have the same forces on it, but *should not* wear but either be strong enough or simply crack the welds, cause a catastrophic accident, with great big balls of flaming death. But Duncan will be driving when that happens, so

[Sydneykid]

Can I ask why everyone is persisting with bushes on either end of the control arm?Seems to me to be a waste on a pure track car.

Can't speak for the other guys but the categories we race in don't allow the changing of control arms.

There are crush tubes inside the bushes and they are greased, so even from factory on a road car doing 100's of 1000's of kms there seems to be no need for even a bearing.

Factory is bonded rubber, so they accommodate rotation within their natural construction. R32's have terrible front control arm geometry that causes distortion in the bushes. Nissan recognised this, that's why R33's and R34 have the wide spread upper wishbone style control arm.

Eliminating the bushes reduces the necessary size of the end of the control arm giving you a mountain of extra options for relocation. That was my plan for the nugget anyway, so I'm interested in hearing arguments.

What is the lubrication method to prevent galling?

Given the simplicity of construction, I was not even going to bother with adjustability, and instead build several different sets with different characteristics to try. Simple construction of the correct inner diameter tube (thick walled) for the ends and some rectangular tube notched to the tube diameter at both ends for the arm.

We would change camber settings 3 or 4 times over the course of a race weekend. Rotating an eccentric crush tube takes far less time than removing and replacing upper control arms everytime. Especialy when working inside a hot wheel arch.

I can't remember the exact measurements, but with the smaller diameter I think you can raise the mounting points on stock chassis mounts by about 25-30 mm and drop the mounting points on the other side (can't remember the name right now) by about 20-25mm. This would allow a car like ours which will be lowered by 40mm or so (hopefully) to keep a square geometry without adding a lot of bump steer and other problems associated with a lowered road car.

What about the dynamic camber curves? Roll centre? Drive shaft angles? Scrub radius?

The back, as has been discussed in another thread, is not so limited as we modified the cradle and dropped the whole thing a good 25mm without changing the geometry at all. Be nice to be able to do this in the front, but that would mean cutting the chassis rails and still not fix the top.

But the standard rear geometry in an R32 is not the best. The anti squat built into the lower control arm pivot points for example. Nisan recognised this, that's why R33's and R34 have far superior rear geometry.

As much as suspension setup is a science, it's still very much a trial and error black art. You try something and it feels good but times are slower and sometimes you hate it but the times are better. My best times are often when I have no idea what I've done different and thought that the setup and tyres are terrible. But that could just be the driver

Driver feel is important but the hard data is the truth serum for that feel. The car may feel better but if it turns in slower lap times, over a race distance, doesn't generate the same G forces, longitudinal and/or lateral, then the data doesn't lie.

Cheers

Gary

[haw001]

Can't speak for the other guys but the categories we race in don't allow the changing of control arms.

Factory is bonded rubber, so they accommodate rotation within their natural construction. R32's have terrible front control arm geometry that causes distortion in the bushes. Nissan recognised this, that's why R33's and R34 have the wide spread upper wishbone style control arm.

Yep certainly is better in the 33

What is the lubrication method to prevent galling?

I'm going to try some high density grease, similar to the stuff you get with the urethane bush kits. I've got a dozen or so packets somewhere, so I'll start with that.

We would change camber settings 3 or 4 times over the course of a race weekend. Rotating an eccentric crush tube takes far less time than removing and replacing upper control arms everytime. Especialy when working inside a hot wheel arch.

Agreed, not ideal if changing often, but I'm not at that level of sophistication. I'll usually test a few different settings then not touch anything over a weekend for fear of screwing it up.

What about the dynamic camber curves? Roll centre? Drive shaft angles? Scrub radius?

Hun, what, who? No seriously, I know what they are, at least in theory, but not far enough along in testing to deal with them yet. Primary goal is to lower the car and increase the camber and castor without introducing a huge amount of bump steer. Once we've got the approximate location I'll think of making some parts that are more finely adjustable.

But the standard rear geometry in an R32 is not the best. The anti squat built into the lower control arm pivot points for example. Nisan recognised this, that's why R33's and R34 have far superior rear geometry.

Agreed, but I think we've fixed a lot of that with the adjustable mount point modifications to the rear cradle. There are some photo's in the other thread.

Driver feel is important but the hard data is the truth serum for that feel. The car may feel better but if it turns in slower lap times, over a race distance, doesn't generate the same G forces, longitudinal and/or lateral, then the data doesn't lie.

Again I agree, and that was sort of the point I was making. Feel does not equate to times. Need to test and test and test.

[Gts-t]

Gary,

is there anything that can be done to fix this...

But the standard rear geometry in an R32 is not the best. The anti squat built into the lower control arm pivot points for example. Nisan recognised this, that's why R33's and R34 have far superior rear geometry

And also what can be done to fix the front, or do you jsut need to keep replacing the bushes?

I really dont want to change to a 34 to fix these issues

Thanks mate

[Duncan]

yeah the main difference in the 32 vs 33/34 subframe is the front mounting point of the lower control arm. we had ours moved from the 32 location to the 34 location, and also put in roll centre/ride height adjustment and replaced hicas with regular tie rods at the same time.

check out the Mark and Duncan build thread in the build section for details and pics.

[Gts-t]

thanks for the tips dunc, ill have a look tomorrow

given that alot of us arent bound by the rules gary runs to, id like to see a solution to the front upper arm, and also being able to get some decent castor.

this is just from a technical/engineering viewpoint, it would most likely be wasted on me since im such a hack at the wheel

[Duncan]

well....

1.if you are racing the car with CAMS you probably can't change upper arms (3e, 3j) unless you have built a sports sedan (3d) in which case you can do anything.

2.If its a road car I think you need to expect compromises and use a standard arm with offset bushes.

3.If its a track only or AASA/MRA/Irace car....then I'd personally keep it legal for CAMS as well...goto 1

4.If its none of those or you know you never want to do something CAMS go for upper arms with rose joints. rose joints move easily in 2 directions and since there is only 1 upper arm the design needs to control that somehow. But they do allow much more adjustment. UAS are about to release a good, cheap, 3rd gen upper arm for r32/z32 based on what they have learned from previous designs.

5.If you are mad like Mark just try out any idea on a nugget and see if it works. if it it does, cackle maniacally while driving in a pair of thongs.

[haw001]

Hey, I resemble that comment. And just so you know, I only use FIA approved, fire retardant thongs for welding and driving.