Often times, the our pursuit for better suspension performance (i.e. lowering, tire changes, etc.) we overlook how our adaptations can negatively affect the performance the BMW engineers already built into our cars. Namely we make our changes using the best possible information and experience out there only to find that the smooth, driving performance characteristics that we’ve come to know and love about BMW, have vanished from our car.
After lowering the CSi with Eibach springs and installing Bilstein HD valved shocks and strut inserts, the ride improved from a controllability perspective but some of its ‘surefootedness’ vanished; and it bugged me to no end – especially on unstable ground that we all encounter every day.
Lowering your car will have a negative impact on the geometry already built into the E31 suspension. And luckily, thanks to the support from our more senior members of the E31 community, there is a solution that brings back that BMW ride quality. These bump steer plates are one of those solutions.
So I installed these nifty custom made plates in the CSi today and MAN what a different it makes with the Eibach springs! Went over many bumps and a little washboard in the road and the car felt more like itself, more sure of itself in general and especially at turn in.
I’m not understanding all the geometry but it sure made the car feel more solid! Other enthusiasts believe that the greatest felt effect comes from toe change/bump steer, and that’s the best benefit the plates have to offer.
Credit to 8Tech at Bimmerforums for his write up that makes adding these spacers easy: http://forums.bimmerforums.com/forum/showpost.php?p=21656294&postcount=11