Rotor Thickness Threshold

[Reza]

Dear Friends,

I am told that my Cayenne S 2004 has 20% to 30% brake pads left on it and once this is over I need to replace front and rear rotors because the thickness is below spec (32mm).

I was curious to check it out myself with a clipper and I noticed that the current thickness is 32.82mm

Assuming the new rotor will be 34mm (Maximum thickness I will get) and the 32mm is the min. thickness (worn rotor) mine is kind of 0.8mm more than minimum (currently 32.82mm) and that is itself like 40% of the thickness to be consumed. (calculating 34mm-32mm = 2mm is 100% of the thickness to be used/worn, the 0.8 is like 40% of this 2mm).

I would like to know experts feedback on:

- whether or not I should replace the rotors at this point? May I just replace the pads now and leave the rotors for next brake job?

- Assuming I was wrong on rotor thickness and ignore replacing rotors at this point because of budgeting issues and proceed with only replacing the pads with a new set, what would be the damage? Would the result be sever shaking of steering wheel during hard brakes or worse things will happen?

Thanks for your time.

[Loren]

Sorry, to say but most of the time you replace the rotors with the pads on a Cayenne. The car is just plain heavy so the rotor wear is more than you might think.

The rears might go two pad changes but not likely the fronts.

If it makes you feel better the Cayenne rotors are half the price of the rotors on my Mercedes CLK-55 daily driver - my "other" car.

[rizzo]

FWIW... I did a pad swap on the fronts last year on my 04S and turned the rotors. There was plenty left to turn and still have more than enough to accommodate future rotor wear.

You need twenty thousands (in most cases) to resurface a rotor. If the math works out and there is still enough material left you will be fine.

No reason to spend money when you don't have to. And it never hurts to ask the service write what the specs on your rotors are and why they cannot resurface them. The notion that a Porsche rotor cannot be resurfaced (turned) is false.

I've done it and am well within spec.

$0.02

:cheers:

[rizzo]

This chart may help. Note there is 2mm worth of wear from new to minimum.

brake wear limits.pdf

[goldenwarrior1]

Just my .02 worth as well but I agree with Rizzo. I have been doing brakes for over 35 years and you don't need to replace the rotors if they meet the specs you listed. The worst that may happen is they warp from the decreased thickness. The only other factor I would consider is if you are using it as a tow vehicle.