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In Reply to: Re: Some help posted by Skid on October 15, 2000 at 20:07:07:
You'll have to ask, I don't know. I just use the BMW 0.5 degree corrective camber mounts. Though I wouldn't be surprised if it's an additional 0.5-1 degrees from what we're running with the camber corrective mounts.
Your observation about the L/R difference is spot on - scrub is actually farther around on the left tire than the right just as might be expected with a .4deg difference. Is that unusually high?
It's noticable. I'd wouldn't worry too much though. Just take it into account.
I realize that the wear pattern from worn bushings will, under highway use be scalloping. But does that that same worn bushing under hard cornering allow in any way decreased camber?
Yes, but not to a significant amount. Those bushings are NOT supposed to have any side loading and do not affect camber. Unfortunately the geniuses who designed these cars designed in a huge amount of side movement in the upper control arm bushing - it's no wonder they don't last more than 40k or so.
I admit I haven't thought through all the forces acting on the control arms under cornering and perhaps these bushings in no way relate to dynamic camber?
The suspension geometry is such that as you turn right, for example, the left wheel gains negative camber and the right wheel gains positive camber. Ever notice how the inside wheel seems to be falling over at full lock (if you forget to straighten out after parallel parking, you'll notice it - or go out and turn the steering to full lock, you'll see what I mean.)
Now, what happens with worn upper bushings is that in increases toe out (as we've said before). This increases the situation of the wheel "falling over", in a way causing the wheels to move in a similar fashion to the inside wheel during turning. This causes increase in positive camber. But the difference is VERY miniscule. I'd be surprised if it's more than 0.1 degrees in the worst cases. And this is during cornering, or anything.
Incidentally it is this movement of the wheel during turning that causes the upper control arm to move side to side and causing the bushing to fail. The bushing has to cope with a severe amount of side loading and it fails early.
CG
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