E30 (and others) Rear Allignment

[SMILLER@xxxxxxxxxxxxxx]

I'm catching up on my Digest reading (the holidays messed up my
schedule, at least that's my excuse this time).  I noticed the thread on E30
rear allignment.  If this has already been answered, please disregard this
and scroll down now.

The car does not come from the factory with a rear camber adjustment. 
There are (I think) 2 "common" ways to make camber changes:  

1.  Offset rear semi-trailing arm bushings.  I've seen these in some of the
catalogs (Bav. Auto?  BMP?).  They're mainly meant to correct toe, I think,
but they probably also have an effect on camber.  Maybe someone
who's tried them can comment.

B.  Adjustable rear sub-frame.  Dinan $ell$ them, and probably other
suppliers do as well.  They slot some of the semi-trailing arm attachment
points.  The interesting thing about these adjustable sub-frames is that
they're usually used to REDUCE negative camber at the rear of lowered
cars.  Lowering can cause excessive negative camber.

Digressing but still kind of related:

I recently had an opportunity to drive a 635CSi which had been lowered. 
The driver thought wider rear tires would help get power down exiting a
tight turn at high RPMs, where currently the car loses rear traction under
those conditions.  However, under all other conditions the car
UNDERSTEERED a bunch.  Adding air to the front tires helped.  My
opinion is that wider rear tires will increase understeer under most
conditions, and I'd bet it doesn't do much for the power-on oversteer. 
There is too much negative rear camber, and the car rides on the insides
of the rear tires.  What the car needs is to get the rear tires flatter on the
ground during turns.  Decreasing rear negative camber would do this.

OK, enough about allignments, now back to RRRUD specs!

Scott Miller
Golden Gate Chapter
BMW CCA #44977
1990 325i/is hybrid

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