In Reply to: Not the valve posted by RJK on April 17, 1999 at 18:13:12:
: The valve corrects the wheels "quick-twitch" which is a one-time jerk motion of the wheel when the brakes are applied. There is another problem: it's induced at higher speeds and is a pronounced shaking of the wheel when the the brakes are lightly or moderately stepped on. It feels like warped rotors but that's not the problem. Wish BMW would admit there's a problem; that would go a long way to solving it.
You are right about the vibration not being caused by the rotors, although in this case it may be. But if the vibration is at high speeds (60+), alright I admit it, I don't drive very fast, then it has to do with clearances in the floating rotors and spindles, pads and pistons, and calipers and spindles. At high speeds, even small clearances become more pronounced. I still don't know which one(s) are causing the problem, but BMW employs the best when it comes to braking systems and they probably are on it.
Engineering is not easy, I think ya'll have to go out every now and then and rent a Ford Escort for a day.