Warped rotors for sure. Comes from overheating. Replace with slotted rotors. Cross drilled are better (and they look really cool), but they rust quicker due to more exposed surface area.

The NASCAR boys are slowing down a car of similar weight, and they use slotted discs with some serious Brembo calipers.

 

I was just doing some research, and found this. Interesting reading.

The "Warped" Brake Disc and Other Myths of the Braking System.

 

Wow that's cool dear.....i like this car..........

 

Have you ever turned your rotors or even changed pads? If rotors have been turned then chances are the pads could be the cause of the issue. No joke. But then again, how hard are you breaking? Is it like an ABS shudder or what? Speaking of ABS I almost had the side of a little 1er stuck to the front end of my car...without ABS we both would have definitely been losers.

edit: just seen your post. glad you figured it out.

 

+3

If you're not experiencing any shaking while driving but only during braking, then I'd have to agree. My Toyota did the same thing. I bought new rotors and all was good.

 

+4 warped rotors

 

I had this problem. It was caused by imprinting the discs with pad material as mentioned before. The discs are very durable and difficult to warp. I was stopping at a toll booth from a high speed run and kept my foot on the brake (auto gearbox) while waiting for the barrier to lift. The heat transfer imprinted the discs. I replaced them and could see and feel an exact pad imprint on the old discs. New discs (Brembo) are cheap and easy to fit.
Regards
Greg

 

If warped discs do not exist, as suggested by the article, then how come my new discs that vibrated after 5000 miles were replaced by the manufacturers under warranty due to warping?

 

Brake discs can and do warp from time to time for a variety of reasons. And BMW control arm bushings do wear at an early age. So, while some minor warp-caused vibration is usually dampened out by a car's suspension, it can actually be exaggerated by worn suspension bushings. If you are still under warranty I recommend having your dealer inspect both areas for issues.

 

In my experience, dealer are very quick to blame any issues on after suspensions. Such as in my case.