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Old 06-20-2018, 07:44 PM   #23
equ
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Join Date: Aug 2005
Carmudgeonly Ride: 981S, 340i
Posts: 9,580
Quote:
Originally Posted by rumatt View Post
I also have Zimmerman rotors.

My theory on the commonality is that we don't drive our cars every day. My theory is that the rotors get slightly rusty from rain / humidity, but not in the spot where the pads are resting on the rotors. Driving scrapes the rust off off the rest, but the rotor is never the same from that point forward.

Should I do an experiment where I remove my brake pads every time I park the car?
The 535i pads were worn and the rotors needed replacing due to heavy rust; the OEM rotors were the most rusty brakes I've ever seen on any car at 50k miles. I'm not sure if it was Baltimore (where the car lived up to 42k miles) or the material that BMW has switched to. The Zimm's on the 528i never rusted or pulsated. They were installed at 50 or 60k and going strong at 130k. The 17-year old OEM rotors on the M3 never pulsated and that car wasn't driven frequently.
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