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Old 11-25-2012, 11:41 AM   #5
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Join Date: Apr 2008
Location: Boston
Posts: 4,971
My Ride: 2003 325xi
Originally Posted by tomoyer View Post
Usually only 2 reasons that rotors warp; either the lugs are too tight and not evenly torqued OR you have a brake caliper piston hanging up and creating too much heat on the rotor. A bad wheel bearing can also cause, but usually you will hear them.
Wheel lugs should be put on by hand, hand tightened with a torque wrench.
A caliper piston that is hanging up should show signs of heat discoloration (especially if you have painted the calipers).
Two more causes of warped rotors: 1) driving through cold puddles with hot brakes and 2) poor manufacturing/quality control processes (aka buying cheap rotors).

It's really tough to beat the quality/performance/price of Genuine BMW rotors. You can get two out of three in an aftermarket rotor, but genuine really is best short of going with a nice BBK.
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