Give me a thick brake. And no turning!
We’ve seen some (brake) rotor warping , recently, that was due to improper torqueing of wheels. The culprit is usually an impact gun, being used in, let’s say a harsh way. The result will be a shimmy in the steering wheel when you press down on the brake pedal. Not good.
BMW specs require that rotors be replaced when doing a brake job. There was a time, (long ago in brake lathe land) when rotors were “turned or machined”. Not the case with BMW’s for some time.
OK, why not machine the rotors? After all, isn’t that a less expensive way to go? Glad you asked that question.
The machining or turning of the rotors will essentially “shave off” some of the thickness. So, even if the rotors initially appear to have enough left on them, (to last a bit longer), after careful machining, there is usually not enough material left on the rotors, “to meet specs”. The material that has been worn down by your brake usage, has now been even made thinner by the machining process. Once again, we are at the mercy of those “pesky specifications”. (Keep in mind, this is where the heat dissipates in your brakes and if there’s not enough “stuff” to work properly, you can also get rotor warping).
New materials, new manufacturing processes and different specs have changed what used to be a very common practice in brake repair. Enjoy the road!