Front Control Arms - Shorter Upper, Or Longer Lower Arms?

[evil_weevil]

Hey guys,

Just wondering what most of you guys have done for more camber on the fronts of your skylines?

Shortened the upper control arms or lengthened the lower arms? (I currently have some whiteline bits on the car from the GB threads)

Whats the most effective for cost wise, installation, and setting up?

Cheers,

Chris

[Sydneykid]

Changing front lower control arms (their location or their length) means you will need to carry out bump steer and Ackerman correction. This can (and usually does) cost way more in time and parts than the actual change to the lower control arm itself. Plus correcting bump steer and Ackerman are not something that can be learnt overnight, it is somewhat complex and not an easy DIY. Hence why I would always suggest achieving the result with upper control arm modifications.

Cheers

Gary

[evil_weevil]

Cheers Gary, your help and answers is always appreicated mate!

What sort of upper control arms and modifications would you go for with my set up?

Cheers!

[Duncan]

but....

shorter upper arms means you don't get the benefits of wider track. wouldn't it be worth developing a lengthed arm with the correct spacers for get the bump steer right? I know a race team can afford to but it would be great if someone had the time to get the basic figures right.

[BHDave]

Just a quick question on this.

In a 32GTSt which has shorter lower control arms than a 33 or s14 etc, how badly will the ackerman angles be affected if you jam the longer LCA's into a 32 with the corresponding tie rods? couldn't you just play with your toe angles?

The inner mounting points are identical, obviously the hub is different (but by how much? could you use an r33 lower half maybe?), and i know that r33/s14 caster rods are a fair bit longer but if the 2 arms are moving in the same plane i'd have thought that would have a no noticable effect on bump steer.

[Sydneykid]

Just a quick question on this.

In a 32GTSt which has shorter lower control arms than a 33 or s14 etc, how badly will the ackerman angles be affected if you jam the longer LCA's into a 32 with the corresponding tie rods? couldn't you just play with your toe angles?

The inner mounting points are identical, obviously the hub is different (but by how much? could you use an r33 lower half maybe?), and i know that r33/s14 caster rods are a fair bit longer but if the 2 arms are moving in the same plane i'd have thought that would have a no noticable effect on bump steer.

The simple stuff first;

You would have to use the R32GTST radius rods otherwise you would loose all of the caster. From memory the bolt positioning on the R32 radius rod is different to that on the R33, so you may have to redrill one, or both, of them.

The SAI on the R33's is different to the R32's, the lower ball joint and upper control arm orientation to the upright (hub) are quite different. If you change the lower control arm (to the R33 style) you would end up with a lot of scrub radius (positive SAI) unless you also changed the upright (hub) and upper control arm. The upright is easy, but an upper control arm change would require new brackets being welded onto the inner guards, which would also require R33 style reinforcing.

Now for the complex stuff;

Keeping the above in mind, the change in scrub radius also means unavoidable changes in the Ackerman. Which is not easy to fix, you could rebend the steering arms, provided you keep the metallurgy in mind. Or you could space the tie rod end away from the steering arm, that's a test, modify and check process that can take 6 or 7 iterations before you get it right. The alternative would be to move the steering rack, further forward would be my first guess. That, of course, means changes to the steering shaft and universal.

Following on from that, once you have the Ackerman where you want it (usually around the rear diff centre line) you then have to correct the bump steer. Which will be fairly drastic by this stage, depending on the ride height . If you have moved the steering rack to fix the Ackerman then the easiest route would be to move the rack (upwards would be my guess) to eliminate some of the bump steer. Then a few minor changes with steering arm spacers should be enough to get the bump steer back to around standard tolerance.

None of the above is rocket science, but it is time consuming to fix and you need some expertise and equipment (bump steer gauge, wheel alignment facilites etc).

Cheers

Gary

[Sydneykid]

but....

shorter upper arms means you don't get the benefits of wider track. wouldn't it be worth developing a lengthed arm with the correct spacers for get the bump steer right? I know a race team can afford to but it would be great if someone had the time to get the basic figures right.

As you know, the classes we race in don't allow us to change the lower control arms, or any arms for that matter. So the market is very small, basiclly limited to track day enthusiasts with sufficient budget and the technical knowledge to understand the issues. I doubt if there would be 5 x R32GTST owners that fall into that catagory. The not inconsiderable development costs spread across that small a market means a high cost for the end user. All for something that could be easily copied and sold for much less without the need to recover the R&D costs. I did similar with a Honda caster kit several years ago, they sold for $100 but the parts were worth $80, the extra $20 was to recover my R&D time. Someone copied the kit and sold it for $80, so I never recovered my R&D time and everyone in the Honda community thought I was ripping them off because they could buy the same kit $20 cheaper from someone else.

Cheers

Gary

[BHDave]

Thanks for the comprehensive reply SK. I really appreciate it.

[Duncan]

very true Gary. that goes for pretty much any r&d work in a world of chinese factories and ebay

[MYRB30]

Hi all.

Im going through the suspension dramas on my bnr32 myself....Lots of reading and researching happening.

I originally fitted pedders camber and castor adjustable bushes. They worked well, got got adjustment for daily driver. But after some 40k kms the upper arms are squeaking like pig going to the slaughter house! lol

Now as a mechanic I am willing to try these dog bone upper arms (yes I know I will regret that in 6 months lol), but in my travels I have found that the Nismo arms and mounts are more than silver painted standard items.

For the R32 the mount where the upper arm bolts to is drilled different to minimise twisting of the arm, and the lower arm is lengthend by 4mm. http://www.nismo.co.jp/en/products/competi...ylinebnr32.html

So now Im on the hunt for some adjustable lower arms too! I know SK says it will mess with bump steer etc, but the nizmo site makes no mention of this. Is 4mm enough either side to be able to notice?????

I have to get new lower ball joints too (man they are expensive from Nissan anyone know where else I can get them).

So this wheel alignment is going to cost a bomb. Im just wanting to do it right.

[Risking]

if its just a daily driver I think its a waste of money going with the longer arms etc. you'd be far better off getting the Sydneykid whiteline kit and being done with it.

The bushes being noisy is more then likely due to insufficent lubricating when the were installed.

Jess' GTR has the full nismo suspension arm kit and honestly it makes little to no differance on the road or the track. Money could be spent so much better in other areas, particularly on a road car.