Some tips regarding resurfacing brake rotors are to know the difference between a brake rotor that may benefit from resurfacing and one that must be replaced and that, when resurfacing a brake rotor, use a dial indicator to measure the amount of runout on the mounting face after removing the rotor. The brake rotor is more commonly known as the brake disc, and is common in vehicles that have disc brakes.
Reducing runout is an important part of any brake job. If the hub is the problem, it should be replaced. However, sometimes when the runout is minor, a tapered shim can solve the problem when installed between the rotor and hub. If the rotor is the problem, resurfacing it takes care of the issue.
When possible, cut the rotors in place using an on-car lathe. This ensures the rotor gets cut in the same plane that it rotates. If the rotor must be removed, use the process below to ensure the job is done correctly.
- Measure and mark
- Mount the rotor
- Cut the rotor
Measure and mark the spot of maximum runout when the rotor is still on the vehicle.
Mount the rotor on a lathe arbor and duplicate the amount of runout on the lathe.
Cut the rotor and remount it on the vehicle. Be sure it is in the same position as before.
It is time to resurface rotors when the surface finish dips below the 40 to 50 roughness average range. When in doubt, seek the assistance of a qualified mechanic.