[MotoSook]

Under or marginal design and cheap castings used for replacement.

My current case: BMW 530i.

Bought STOPTECH slotted rotors for all four corners. As soon as I bedded in the new pads, STOPTECH street performance pads, I developed a vibration in the front. I thought I just over did it and it would smooth out, but it never did. I checked runout and it verified warped rotors. Had them turned and rebedded with less enthusiasm. A month later more vibration. Now the steering wheel vibrates so much it's embarrassing.


This is a case of well a designed system with poor replacement part quality.

Had problems with the Jeep Cherokee too. Poor quality rotors from FLAPS. I replaced them with Zimmermans IIRC and it fixed the problem. Fortunately, Jeep rotors are cheap. Not so the BMW rotors.

Unless you are descending a grade and/or really heating the brakes towing w/o trailer brakes, I really don't think some of the suggestions about pad deposit on a hot rotor or warping due to heat insulation by the pad are a concern. Most street driving won't generate that much heat.

Another potential problem is rusted or sticking caliper carriers or calipers. This is particularly so with single piston caliper designs that allow the caliper to float on pins (inboard side only). If you've changed enough pads you'll have noticed that the pads don't wear evenly on both sides. This tells me the pads don't work evenly and those could generate heat at different rates on each side of the rotor. It also could result in unequal force at moments.

We're all so used to opposing pistons on our Porsche calipers.