[masraum]

Originally Posted by fastfredracing

I find the whole " rotors do not warp, its just pad material deposits " theory interesting .
As someone who has turned thousands of rotors in my life, I will wholeheartedly say, that rotors do indeed warp.
You can literally see the run out when you chock them up on the brake lathe, and bring the cutting bits close to the rotor surface .
I don't cut rotors anymore, but when I did, it was pretty rare for rotors to clean up without taking less then 5 thousandths off each side . It was not pad material I was removing, it was metal .

I used to work at a FLAPS where we turned drums and rotors, and we frequently saw what you describe. I assume those were mostly under-braked cars, but not something like a Porsche. Of course, if you do hard braking on a Porsche, I assume it would be possible to warp them. There was NEVER any maintenance to our lathes. After the fact, I assumed that the issue was likely with our lathes or process for mounting.