Turning Brake Rotors

[90_Shelby]

Do shops still turn brake rotors that are warped? If yes where is a good place and any idea on cost?

[GTR_Auto]

Most places just put on new. There is a lot less warranty issues

If someone does still turn should be around 30 or so. Pending on the car a new rotor could be that or a bit more

[danno]

I have a set of rs4 rotors that need to be turned but i heard they dont turn drilled rotors??

At audi they are $830 per rotor. Managed to get some for $550 per rotor.

[snowcat]

brand new car, warped rotors at 13,000 KM. They put them on the machine. Warped again at 16,000. Put new rotors on. Should have just done it in the first place.

[90_Shelby]

Interesting article that I found on warped rotors.... Apparently it's a myth and the vibration is caused by pad material transfer onto the rotors.

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

The obvious question now is "is there a "cure" for discs with uneven friction material deposits?" The answer is a conditional yes. If the vibration has just started, the chances are that the temperature has never reached the point where cementite begins to form. In this case, simply fitting a set of good "semi-metallic" pads and using them hard (after bedding) may well remove the deposits and restore the system to normal operation but with upgraded pads. If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit.

Followed by this:

The only fix for extensive uneven deposits involves dismounting the discs and having them Blanchard ground - not expensive, but inconvenient at best. A newly ground disc will require the same sort of bedding in process as a new disc. The trouble with this procedure is that if the grinding does not remove all of the cementite inclusions, as the disc wears the hard cementite will stand proud of the relatively soft disc and the thermal spiral starts over again. Unfortunately, the cementite is invisible to the naked eye.

[revelations]

There is actual warping (which can be caused by various reasons) and then there is cementite issue as mentioned above.

I have a warped rear disc on my lowly civic, less than 2 years old and 20,000 kms (on the rear). Cause? Axial warp. Dial indicator shows too much run out.

My fault for buying cheap chinese discs for the rear. They rust like shit after 2 days of rain and I drive pretty tame as far as acceleration/deceleration (I only corner hard).

[AE92_TreunoSC]

Most of the time it is pad material, but cheap metal results in poor characteristics.

Ideally you'd use an on-car-lathe but they are typically only in dealerships.

[90_Shelby]

I think it was pad material. After some hard driving it appears to have fixed itself.