Rear camber & trailing arms.

[Erick]

Ok, recently I've been trying to figure out why is it that the wheels negative camber in so much under load with trailing arms. I'd like to basically have as little camber as possible in the back. So my two questions:

1-) How exactly does the trailing arm cause more camber under load?

and

2-) Will stiffer (polyurethane/solid) T/A bushings help solve this?

Thanks,
Erick

[jlevie]

The design on the suspension is such that negative camber will increase as the suspension is compressed (or if you lower the ride height). Worn RTABS, or bent trailing arms can yield excessive camber, even with normal ride height. A "slammed" car will have excessive camber, period!

Urethane RTABs will yield the same camber as fresh OE parts, so you can't gain anything that way. There are solutions that will reduce rear camber but the best of those require mods to the trailing arm attach points.

[Erick]

My camber wear is not bad while driving, the problem is when I'm drifting. My last two sets were worn COMPLETELY on the inner 15% of the tread pattern.

[e30 gangsta]

Buy the weld on ta kit to adjust camber. If not ask alex i belive he was trying to sell a subframe with that kit already installed.

[Erick]

I want to find out if it's the root of my problem first though.

[RyanZ06]

The root of your problem sounds like you're running the car too low.

Contact Treehouse racing, they offer ecentric rear trailing arm bushings. If you install these, it requires no welding, and you will be able to adjust the rear alignment!

[Teaguer]

The root of the problem is the fundamental design of the semi-trailing arm suspension .

[Erick]

The root of the problem is the fundamental design of the semi-trailing arm suspension .

We established the problem, now we need a (reasonable) solution. :)

[Teaguer]

Ok , lets try this : :D

1-) How exactly does the trailing arm cause more camber under load?
2-) Will stiffer (polyurethane/solid) T/A bushings help solve this?

1. As the car accelerates the tires grip/bite the road and basically pull the car down .
This squat of course makes the arms/tires folow their swing path which makes them swing in an upward and inward arc .

2. To a point yes ,...but its no magic cure-all .
If your bushings are beat then it will make a greater improvement .
But the offset bushings or making the subframe adjustable is only going to give you so much to work with .

Also keep in mind when you mess with camber you will also affect the toe .
Welcome to the world of lowered BMW's . :D


Solution is add whatever adjustabilioty you can afford and flip your tires more often .
Or get a tire sponsor . :p

[browntown]

The root of your problem sounds like you're running the car too low.

Contact Treehouse racing, they offer ecentric rear trailing arm bushings. If you install these, it requires no welding, and you will be able to adjust the rear alignment!

AKG sells them too. From what I understand the weld on kits are better since you can adjust the parameters individually and the eccentric bushings adjust both specs at once and is harder to make right.

[Brew]

There's a good chance the majority of your problem is excessive toe out and not negative camber. Your trailing arms and/or subframe may be bent. I'd get some baseline alignment specs to see where your at, then decide whether you can correct it with eccentric bushings/weld-on kit or if you'll need to replace trailing arms or the subframe.

[10/10ths]

^ That was the case with my car for about a year, I installed a used trailing arm assembly and later found out it was bent. At first I had nearly 1/2in toe-out on the left rear, It didnt take long to wear out the inside of the left rear nearly to the cords (these were fairly new azenis) and it also had a tendancy to oversteer in right hand corners.

I had it bent as much as it would go and got it to 1/4in out...which is still too much. I recently installed Kmac adjustable urethane bushings and was able to correct the problem.

[nando]

Also keep in mind when you mess with camber you will also affect the toe .
Welcome to the world of lowered BMW's . :D


Solution is add whatever adjustabilioty you can afford and flip your tires more often .
Or get a tire sponsor . :p

only with the cheaper offset bushings. the weld in kits don't have this issue.

[trent]

I have both kits sitting on my desk, a weld in kit "Ecentric", and the AKG "Acentric" kit. For ease of use, I decided to go with the AKG kit (I have no problem welding in my on things if required). I am happy with the design of the AKG product. Yes, with these, changing the inner and outer points will change both toe and camber, but who gives a fuck. You set it once and leave it. I probably should have gone with the weld in kit, but, I like these for the simplicity.

[Erick]

Good review. I'll look into them. I got the AKG offset CABs and I like them so far.