In Reply to: Suspension Gurus: Pls help... posted by Eugene Ong on October 06, 1999 at 01:15:50:
: When you lower the M3, many people forget to cut the rear bump stops, the Bilstein Sport is barely stiffer than stock, so it cannot handle the forces from the bump stop and the spring combined. This lack of rebound makes the car feel floaty. You will note the many posts regarding cutting bump stops with H&R. The Ground Control front spring is 300 lbs/in, almost 3 times the stock rate, so I think your spring rate is stiff enough. The rear springs are also stiffer, but not as much to avoid progressiveness. These spring rates are both stiffer than the H&R street, so I think your body roll and floatiness are not because of the springs themselves. Did you have the car realigned? If there is any toe out the car will act weird. H&R street: F200, R380; GC Street F300, R450; H&R race F345, R515; GC race F550, R700.