What are the minimum rotor thicknesses?

 

Already answered in previous post...

 

sorry to dig up an old thread, but I figure it is better than starting from scratch. I am getting ready to order parts to redo the brakes next weekend, but pulled the wheels off today, to get an inventory of everything I need.

I saw in one of the posts that the minimum acceptable rotor thickness, and am confused. I am measuring with a digital caliper, and my front rotors are 32.5 mm which appears to be thicker than what is quoted for new rotors... The rear rotors are 27.1 mm. I am measuring the thickness of the entire rotor from inside to outside without the small lip at the edge. I have about 5mm of pad left in the front and 8mm in the rear.

Are the numbers posted different for a C4S, or am I looking at something incorrectly? If it is just a matter of C4s vs C2, does anyone have the minimum thickness for a C4S front and rear?

 

Pelican Parts $160 for a pair of coated rotors, 996

 

32mm front, 28 mm rear min

 

Thanks Artcollinsjr, after doing some digging on Renntech I found some additional info. On one of the 997 forums, I found a post that stated that the minimum rotor thickness is stamped on the rotor hat for the 997 models, and sure enough that applies on the 996 as well (at least for my '02 C4S). I also found a thread that stated that minimum rotor thickness should be 32mm front / 26mm rear and confirmed that with the stamps on my rotors, but I am sure there can be differences.

This is the front rotor on my car:






You can see where it is stamped Min. TH. 32MM. It was hard to make out at first, but I took a piece of chalk, rubbed the edge of the hat, and wiped it clean with my finger, the stamp stood out well enough to read and photograph after that.

Hopefully this will lead to less confussion in the future for anyone wanting to know minimum rotor thickness.

 

I don't agree with changing the rotors every time the pads are changed.

It is very possible/common to blow through a pair of pads on a track day.

As you stated rotors are spec'd to a thickness and are thought to be in good working order within those specs. There are exexptions to those specs that would cause the rotors to be changed, like hard spots and warping.

- Justin Kresty

 

So I have been hearing a slight squeal when breaking intermittently for the past month or so. I figured it was the wear indicator, so I pulled my wheels to see how things looked and get an inventory of parts for a brake job. I have an 02 C4S which with minimum rotor thickness of 32mm front / 26mm rear. New rotors are 34mm front / 28mm rear.

My rotors are currently 32.75 mm front / 27.25 rear and the pads are a little over 6mm front / 8mm rear. Would you suggest doing front and rear? Just pads or pads and rotors all around? I picked up the car 2 years ago with 36k miles and it is now pushing 50k. This is my first break job on the car, so I am not sure how much wear I should anticipate on the rotors before the pads are ready to be changed again, or how quickly the pads will go. I drive the car daily, but have not had it on the track to date . I closely inspected all four rotors and do not see any hairline cracks which is another reason I am debating which way to go....

Do the dampers and caliper springs need to be replaced every time brakes are done? I know it is recommended, but just want to know if this is a real world necessity.


I am leaning towards replacing everything but do not want to throw money away unnecessarily.

 

fantastic research!! thanks for providing this to the community, IM the OP and ended up taking my car to a reputable porsche shop. They're known for insisting on doing comprehensive work, they didn't swap the parts you mentioned.

 

You have enough pad and rotor left to keep going for probably 10k more IMHO. You are above the minimums for fitting NEW pads, so see the ones you have out. The squeak may be dust (clean them) or glazed up. Do 5x 0-80-0 as fast as you can over the shortest amount of time and keep driving (to cool down the rotors) and see if the squeak is gone. Squeak is a Brembo thing, and deglazing often helps. Or do a couple of laps of your nearest race track!

The 4s brakes are huge so you may need more than 5x to get some real heat into them

 

Can 350mm discs be fitted to a 4s or calibers should be changed too?