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BMW Rear Camber - Why so much? Anyone reduce from Stock spec?

3.4K views 10 replies 8 participants last post by  977  
#1 ·
Does anyone know why BMW specs so much negative camber in the rear of the e46 (-2 degrees)? Is there something inherent in the suspension design that needs more neg. camber or is it just to promote more grip in rear?

I am autocrossing a mostly-stock e46 and trying to determine the best alignment. I don't have camber plates in front so max negative camber I can get is around 1 degree. Normally, I'd want the rear camber to be the same or less than the front but the OEM spec is -2 degrees. I am considering trying -1 degree camber in the rear but am wondering if there is a reason for the higher spec.

And please no flames or "don't deviate from the spec, BMW knows best" nonsense. I am autocrossing and tracking and doing other things BMW didn't plan when they set the spec and I am willing to try something different, accept lower tire life, etc. I just want to make my car handle as well as it can without putting more parts on (at least not for now). TIA.
 
#6 ·
I took out a little of my rear negative camber.

My rear alignment is set at -1.5 camber 1/16th toe in. I also am a weekend racer like you. I am also running -3 camber up front with slight toe out with maxed caster on my camber/caster plates. I am also aware of poor tire wearing but the car handles like a dream! This is matched up to TC Kline DA Coilovers that are cornerbalanced.

Hope this helps!
 
#7 ·
OK. I got the poop straight from a former Nat'l autox champion. He said for running with OEM spec camber in front (approx. -1.0 degree), then it is beneficial to drop the rear camber well below the stock spec to somewhere closer to -0.75 degrees. This will help with the front/rear balance.
 
#10 ·
Please explain. In my experience, autox and track setups are very similar (and much more similar to each other than either is to a street setup). You might want a bit more stability, especially high speed stability, for track work where for autox you want a car that's easier to flick around cones, even to the point of being a bit darty. So, you can tolerate more front toe out and possibly a greater tendency for oversteer for autox than you might want on the track but camber and caster settings are pretty similar (both trying to maximize cornering forces and have the car be easy to control at the limit of adhesion). I typically use a hybrid setup with the toe at zero all around and the sway bars/shocks adjusted for slight understeer to neutral (then use trailing braking/throttle get the car to turn better).

What did you have in mind? Am I missing something?
 
#11 ·
I'm running 0.75 camber at the rear, and 1 at the front, 0.1 degrees of toe in at the back, and 0.1 degrees of toe out at the front, works nicely, makes the car very predictable in its loss of traction, so I can enter corners with a very slight oversteer on a wider line and get the power on nice and early before the late apex.