NP993

I suspect it's about time to do a complete brake job on my car, but I'd like to measure the rotors just to be sure (and just 'cause I'm curious). I've searched and searched but can't find any mention of the minimum thickness spec for rotors. Anyone know?

epj993

Shop manual states a wear limit of 30.0 mm for the fronts, 22.0 mm for the rears.

Harvey Yancey

You usually have to worry more about cracks than thickness in my experience though ...

bart1

It should also be stamped on the rotor. Make sure you don't include any lip it will have when you measure it. Agreed on cracks. Cracks should not touch between holes.

NP993

Thanks guys, I'll take a measurement and post the results...I'll be shocked if my fronts are within spec...

epj993

As reference, here's info on determining crakced rotors. This was for a 996, but the same rationale applies to a 993.

AOW162435

Just run 'em until you start seeing the internal vent castings.


Andreas

NP993

I normally run 'em until the rotors look like pie tins and I have to use the e-brake to stop the car, but in this case I'm trying to be a more conscientious motorist. I measured them, and the fronts are right at 30mm. Time for new rotorz.

Oh yeah, I'm also re-gearing the transmission and installing a limited slip and RS clutch/flywheel, among other things. But I'll save all of that for another post.

jungleboy

Just to piggyback real quick folks... same specs for the big red/turbo rotors as well? Or different? Thanks...

bart1

Different thickness spec, I am sure. Crack spec is the same I think.

craig001

Anyone know if the pads and rotors are the same for the C4 vs C2. I have a complete set for a C4 in my garage and don't know if the next car will be a RWD or AWD.

epj993

The C2 & C4 have the same brakes. The C4S has the Turbo brakes.

NineMeister

All Porsche rotors have a 2mm wear limit from new, so if the discs start at 32mm replace them at 30, for the rears at 28mm/24mm you bin them at 26/22 respectively.