Why Nobody Makes Front Upper Arms That Sit Further Backwards?

[bradsm87]

Just wondering why nobody makes an upper arm for skylines that positions the outer bushes further backwards and tilted to get more positive caster without crazy bush deflection?

They could be used in conjunction with caster rods to get like 5.5 degrees of caster in a GTR without huge rubbing problems couldn't they?

Just very interested to know why nobody does them???

[_Ryan_]

If you need for your s14, I had some made for my Datto(LCA's, too suit macpherson strut car) that were also camber adjustable. Machined from billet, will upload photos when I get home. Randy at Nissco in Vic can arrange them for you. Www.Nissco.com.au

[bradsm87]

If you need for your s14, I had some made for my Datto(LCA's, too suit macpherson strut car) that were also camber adjustable. Machined from billet, will upload photos when I get home. Randy at Nissco in Vic can arrange them for you. Www.Nissco.com.au

Nothin to do with the S14. They don't even have front upper arms. Question applies to skylines only.

[djr81]

Just wondering why nobody makes an upper arm for skylines that positions the outer bushes further backwards and tilted to get more positive caster without crazy bush deflection?

They could be used in conjunction with caster rods to get like 5.5 degrees of caster in a GTR without huge rubbing problems couldn't they?

Just very interested to know why nobody does them???

There are a number of reasons.

1. Castor is nice to have, but of much less importance than camber.

2. R32 GT-R's only have 3 degrees stock & increasing this to 4 or even 5 only gives you a small gain.

3. There are problems with increasing castor as it rotates the upright & stresses the bushes by forcing them to rotate on an axis somewhat different to the geometry they have. Doesn't much matter if you do it by pushing the bottom arm forward (which is easier) or pulling the top arm back.

4. No one makes a decent upper arm for camber, let alone for castor.

[bradsm87]

1. Castor is nice to have, but of much less importance than camber.

Not true at all in my opinion. More caster gives u more camber on the outside wheel when cornering (when you need it) and allows U to run less static negative camber so better braking grip and better traction for 4WD's.

2. R32 GT-R's only have 3 degrees stock & increasing this to 4 or even 5 only gives you a small gain.

So a way to DOUBLE the standard 3 degrees to 6 degrees is a small gain?

3. There are problems with increasing castor as it rotates the upright & stresses the bushes by forcing them to rotate on an axis somewhat different to the geometry they have. Doesn't much matter if you do it by pushing the bottom arm forward (which is easier) or pulling the top arm back.

That's why I said the angle of end of the upper arm has to be different to make up for the caster. I can't see why it can't be done easily.

4. No one makes a decent upper arm for camber, let alone for castor.

There are some decent ones out there like the ikeya formula bush type ones but pricey (well worth it IMO)

Edited August 3, 2009 by bradsm87

[djr81]

Not true at all in my opinion. More caster gives u more camber on the outside wheel when cornering (when you need it) and allows U to run less static negative camber so better braking grip and better traction for 4WD's.

I run quite a bit of neg camber on my R32 R. The contribution the 4 degrees castor makes to the tyres camber angle when you have turned the steering wheel 90 degrees is not very much. You can do the sums if you want & you will get the same result.

As for braking grip there is no shortage of front end grip with this setup. Nor traction particularly. But as the GT-R doesn't even have a front LSD standard it is a meaningless argument.

So a way to DOUBLE the standard 3 degrees to 6 degrees is a small gain?

Going from three degrees to four degrees is less influential than going from eight to nine, for example.

That's why I said the angle of end of the upper arm has to be different to make up for the caster. I can't see why it can't be done easily.

So what are you going to do for the upper link bracket that is fixed to the chassis? Nismo offer a one of thse as part of a kit. Unsurpisingly it rotates the axis around which the upper arm moves. But is costs far too much for a modified stock component.

There are some decent ones out there like the ikeya formula bush type ones but pricey (well worth it IMO)

Well you have to like running suspension without bushes. Which isn't good on the road, nor with poor geometry.

Edited August 3, 2009 by djr81

[bradsm87]

I run quite a bit of neg camber on my R32 R. The contribution the 4 degrees castor makes to the tyres camber angle when you have turned the steering wheel 90 degrees is not very much. You can do the sums if you want & you will get the same result.

As for braking grip there is no shortage of front end grip with this setup. Nor traction particularly. But as the GT-R doesn't even have a front LSD standard it is a meaningless argument.

Going from three degrees to four degrees is less influential than going from eight to nine, for example.

I think 5.5 - 6 degrees is acheivable which has gotta make a difference.

So what are you going to do for the upper link bracket that is fixed to the chassis? Nismo offer a one of thse as part of a kit. Unsurpisingly it rotates the axis around which the upper arm moves. But is costs far too much for a modified stock component.

With urethane bushes and coilovers with relatively short suspension travel, just having the end of the upper arms 'turned' compared to the inner part of the arm would be more than sufficient without causing much deflection of the bushes at all. Changing the position of the bracket wouldn't be necessary. I am more thinkin for an R33 or R34 anyway.

Well you have to like running suspension without bushes. Which isn't good on the road, nor with poor geometry.

That's why i said the bush type ones. They make both pillow ball and bush type arms.

[djr81]

I think 5.5 - 6 degrees is acheivable which has gotta make a difference.

With urethane bushes and coilovers with relatively short suspension travel, just having the end of the upper arms 'turned' compared to the inner part of the arm would be more than sufficient without causing much deflection of the bushes at all. Changing the position of the bracket wouldn't be necessary. I am more thinkin for an R33 or R34 anyway.

Even the Whiteline stuff will get you those sort of numbers on an R33, ie 5.5 degrees castor. They have more castor stock than the R32's & better front suspension anyway.

[bradsm87]

Yeh it'd be possible but would require modifying stuff for clearance. Would be nice to get lots of caster and no rubbing anywhere. Also I dunno how far u can go without stuffin up the angle of the front driveshaft.

[_Ryan_]

Nothin to do with the S14. They don't even have front upper arms. Question applies to skylines only.

thats what i was thinking haha

[Risking]

djr81 is 100% correct with pretty much everything his stated about the GTR.

[bradsm87]

djr81 is 100% correct with pretty much everything his stated about the GTR.

And how is that? Be specific.

So because u have a quick gtr mean's there's no point thinkin outside the box to make it quicker?

I guess audi, porsche, mercedes, R35 GTR etc Have it all wrong then. Caster must be useless.

[bradsm87]

Ok for r33/r34 GTR only then.

[zebra]

they are a completly different chassis all together, like comapring apples to the sydney harbour bridge.

[_Ryan_]

Even the Whiteline stuff will get you those sort of numbers on an R33, ie 5.5 degrees castor. They have more castor stock than the R32's & better front suspension anyway.

stagea gets around 5deg easily too

[Sydneykid]

For about 6 months now I have been trying some eccentric crush tubes in the inner pivot points of an R33/34 front upper control arm. It's based on a design that I have used in double wishbone Hondas for many years. Moves the top outer pivot point rearwards enough to get 6 to 7 degrees caster without excessive drive shaft angles. I don't know that it will ever go into mass production as there probably isn't enough demand for it.

It's R32's that have the real issue with their narrow spaced upper control arm inner pivots. That's why they chew through bushes and spherical bearings in a rapid fashion. No easy solution there, that's why Nissan changed the design in the R33/34's.

Cheers

Gary

[bradsm87]

For about 6 months now I have been trying some eccentric crush tubes in the inner pivot points of an R33/34 front upper control arm. It's based on a design that I have used in double wishbone Hondas for many years. Moves the top outer pivot point rearwards enough to get 6 to 7 degrees caster without excessive drive shaft angles. I don't know that it will ever go into mass production as there probably isn't enough demand for it.

It's R32's that have the real issue with their narrow spaced upper control arm inner pivots. That's why they chew through bushes and spherical bearings in a rapid fashion. No easy solution there, that's why Nissan changed the design in the R33/34's.

Cheers

Gary

Do it man. That really sounds IDEAL.

[cazman]

For about 6 months now I have been trying some eccentric crush tubes in the inner pivot points of an R33/34 front upper control arm. It's based on a design that I have used in double wishbone Hondas for many years. Moves the top outer pivot point rearwards enough to get 6 to 7 degrees caster without excessive drive shaft angles. I don't know that it will ever go into mass production as there probably isn't enough demand for it.

It's R32's that have the real issue with their narrow spaced upper control arm inner pivots. That's why they chew through bushes and spherical bearings in a rapid fashion. No easy solution there, that's why Nissan changed the design in the R33/34's.

Cheers

Gary

Superpro sell these off the shelf. They are easy to buy.

[Sydneykid]

Superpro sell these off the shelf. They are easy to buy.

Not quite, they are designed to be adjusted in tandem, ie; for camber, hence the inner pivot points on upper control arm are parrallel to the inner guards. When aiming for more caster the outer pivot point on the upper control arm needs to be moved rearwards, so the inner pivot points are no longer parrallel to the inner guards. The solution is for the bushes and/or eccentric crush tubes to be offset to compensate. I tested the offset eccentric crush tubes first because they are easily machined up. But the geometry is such that the bushes themselves have to accommodate the misalignment. Those were machined out of a slug of polyurethane, which is OK for testing, but not cost effective for selling. For production volumes you would needot have them moulded in the usual fashion, that's where the lack of potential volume would be a killer.

Cheers

Gary

[Risking]

And how is that? Be specific.

So because u have a quick gtr mean's there's no point thinkin outside the box to make it quicker?

I guess audi, porsche, mercedes, R35 GTR etc Have it all wrong then. Caster must be useless.

Oh thats funny.

My GTR is so outside the box its ridiculous.

There is not one original suspension pick up point on the R32, everything is custom from the mounting locations to the arms themselves. The angles, roll centers, everything is totally different to the original car

We totally redesigned the suspension to run a wishbone style upper and lower arm. It works well but not well enough to warrant the cost should you have to pay someone to do it for you.

There is nothing that wrong with the original car and id not build another that way again.