ddixon2327

please advise of the thickness allowed before replacing rotors. i need to replace pads not sure on rotors. 56k miles on car and no tracking. Assume would need to have turned to reuse current rotors....help appreciated. Thanks

logray

Min thickness is stamped on the hats of the rotors.

If you don't have a micrometer take the rotors off and bring them to a machine shop...

LC MotorSports

You should not turn the cross drilled rotors and you can run them down to about 26 mm in the front and 22 mm in the rear.

Macster

Chances are the rotors while not yet at the minimum thickness will be there way before the new pads are worn enough to trip the brake warning light.

It is up to you but you might consider replacing the pads and the rotors and all other hardware that is supposed to be replaced at the same time.

Or you can measure the rotor thicknesses then install new pads (and again renew whatever other hardware is called for) and then monitor rotor wear and when rotor wear has the rotors down to their minimum thickness replace the rotors leaving the replacement pads in service provided of course they are still in good shape and have suitable remaining thickness.

But the above is a lot of work for the average owner. Thus replacing all the brake hardware, pads, rotors and other hardware (and this is a good time for a brake fluid flush/bleed as well) takes the worry about the brakes away for another 50K or more miles.

Sincerely,

Macster.

Macster

Why shouldn't cross drilled rotors be turned? As long as they clean up and are not below minimum thickness after the process I'm at a loss to understand why they shouldn't be turned (or resurfaced via a grinding process)?

Sincerely,

Macster.

LC MotorSports

The Average shop will not take the time to re-chamfer the holes holes and doesn't have the experience too properly turn a rotor with so many interruptions in their cutting process. You end up with 2 issues afterwards: Sharp Edges on the holes (without breaking that sharp edge you are creating a Heat riser that will increase the Thermal shock to the holes... thus, speeding the cracking process) as well as poor surface quality from the interrupted cut. Now if you can dual grind both surfaces at the same time and then little break the sharp edge on the holes.... Go ahead and resurface them. Any shop that is capable to do all this work will charge you more then the rotors are worth. Final note: Very few automotive shops will take on the Liability of turning Drilled or Slotted Rotors!

Macster

Thanks.

I was not aware the hole chamfers would be lost. I assumed the chamfers were deep enough to provide some chamfer even if the rotors were worn to their minimum thickness.

Now I have to go out and look at my Turbo's brake rotors.

Sincerely,

Macster.