5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
in a technical sence the rotors can be machined but BMW does not machine thier rotors they just replace them. it is likely a warped rotor or it could also be loose lower control arms sometimes if the lower balljoint gets too loose it will shake the steering wheel when braking.
If its a E39 around 100K miles I'd bet the control arm bushings are gone. If its brand new rotors they could be more than 00.5 out from the factory its happened to me. You could lift the front tires one at a time and spin the wheel. If you hear a change in the brake pad pressure on the rotor, its the problem.
Best case scenario is a simple build up of brake dust. BMWs are notorious for this. Seen this same thing happen on a high mileage car. Sprayed EVERYTHING with a can of brake clean and then later blasted them again with a pressure washer... shudder gone.
__________________ 1992 325ic *sold*
1984 320 *sold*
1986 325 5sp sedan, 175,000 Great car!
1986 535 5sp sedan, 172,000 Awesome!
1978 530 AT sedan, 275,000 still runs and drives
1997 740il AT sedan, 125,000 Like a newly wed!
Other than the rotors, the other possibility could be control arm bushings. Have you at any time had some clear mineral oil leak, not much, just drips, but they disappeared after a while? If you did, that was the hydraulic oil from the control arm bushing. When that casing inside the bushing breaks, the little amount of oil inside leaks out, then it would still go for some time until one of the symptoms show...which is what you described when braking.
So, just be prepared as your dealer might just recommend replacing the rotors, and then find out later that they were not the cause! All at your expense of course! And they'll tell you, "Well, the rotors need to be replaced anyway..."
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.