Like many of you I have had chronic problems with my brakes since the car was new. After every brake change and after maybe half the pad life I brought the car back to the dealer who can't find anything wrong with the car. If they put on new rotors new pads it fixes the problem but it appears that some of the brake pad material is being transferred to the disk so while the disc is not out of round it is grabbing the disk differently on different places, causing a pulsing and shutter. While I don't race the car I am a spirited driver.
What's the best upgrade for disks and pads, do they accept the OEM wear sensors? I would appreciate any input.

 

Maybe worth a try -- I was experiencing some shudder under light braking on my C300 4Matic sedan and on a recent road trip started to feel a major vibration under braking. So, I attempted to clean the rotors by heavy braking at highway speeds. Shudder is gone.

Seems to me that the problem was an uneven buildup of brake pad material on the rotor.

YMMV.

Just another thought: BMW dealers now have a new machine to "machine/clean up" rotors without removing the rotors from the car, and after 30+ years of telling BMW drivers never to machine rotors, they now do not normally replace rotors unless the thickness is below spec. Maybe a BMW dealer could clean your rotors.

 

After three sets of OEM rotors lasting 6000 miles at the most I went with Stoptech rotors and never looked back! No more warped rotors. They are under $100 each as an added bonus!

 

I looked at Tirerack and AutoAnything and they don't have specific parts for a 2011 550 Cabriolet. They have some like front pads but no rear pads. Front rotors but out of stock on rear rotors.
Do I need to call these places to be assured fitment?

 

Go to the Stoptech web site and get part numbers then go to Amazon and look for it. That's what I did and shipping was free!