Turning/machining the brake rotors

[xtmsports]

Hey guys, I have heard that the BMW rotors can't be turned. i found this out after I paid to have it turned by Pep Boys, and they said that it falls within acceptable specs, so they did it.

Is this completely insane? Do I really need new rotors? What are the problems with having the rotors turned? What kinda problems am I looking at?

[Kalevera]

How do they brake? If they're smooth and aren't messed up....I'd keep 'em.

[632 Regal]

the theory is that the stock roters are a specified thickness, with wear the pads grind up the rotor to a thinner width and thus cant be turned. This is why thay say to replace the rotors when there is a wear lip on the edge, usually too thin. I have read a lot about this braking thing and you should do a search on "brake bedding". It's all new to me but does make a lot of sence and might be your problem.

Also no need to double post the same issue, when someones on here they will answer you if they have an idea of whats going on. Weekends are slim here with Fridays between 6-8 being the busiest.

[Blitzkrieg Bob]

Is rare for BMWs, they are already at a narrow tolerance and once you have run out, warpage, liping, or blueing....that's it...time to get a new set.

[bill g]

My experience with my wifes E36 325 - very obvious steering shake and brake pedal pulsation when braking. The front rotors looked OK (no wear lip) and were not warped, but they did vary in thickness 0.04mm (just 0.0015"), measured at different positions around them. I had them machined accurately and this completely fixed the problem. Well, no sign of it in 18 months driving since.

Bill G

[liquidtiger720]

how long should rotors last? I changed pads and rotors about 2 years ago. I can already feel a lip on my rotors, but breaking power is uneffected, no shimmies...just nothing. The pads are winding down...so should I replace my rotors..again?

[Scott C]

how long should rotors last? I changed pads and rotors about 2 years ago. I can already feel a lip on my rotors, but breaking power is uneffected, no shimmies...just nothing. The pads are winding down...so should I replace my rotors..again?

For what it is worth, I picked up a new PAIR of Brembo rotors for $69 (incl shipping) from Ebay and consider it well worth the delta cost over grinding which is usually about $10 a side plus the drive/wait. My front rotors had a pretty big lip (but were still silky smooth). I considered reusing them but suspected they were beyond the min thickness and was afraid that at inspection time (next month) I would fail.

I really do not consider it a safety issue (running at min thickness) in my case since I only drive on the street and don't push the car. Warping of rotors would be a slight concern.

Scott