BHMav8r

My right rear pads are starting to sing. prolly time for new pads.

Does anybody know the tolerance for disc wear/tolerance?

Thanks

gota911

I received my new front brake discs a couple of days ago. While I am not sure about the wear tolerance in mm, I can tell you that the brake disc has 15 wear indicators on the disc. There are 5 wear indicators on the inner part of the disc (near the "hat"), and 10 on the outer edge that are situated in 5 pairs of 2. In inner wear indicators are smaller than and not as deep as the outer wear indicators.

The holes are grouped in alternating rows containing either 4 or 5 holes. Every third row of 4 holes has the inner wear indicator and an outer edge wear indicator. The a following 5 hole row has an outer wear indicator only.

See pic below... and yes, I painted the "top hat" silver, which is why the inner edge of the disc looks silver. This small amount of over spray will get worn off with the first drive after I install the discs.

Hope this helps.

kkswow12

cool, how about a pic of the whole disc with the paint, or is it too late, either way...

BHMav8r

Now I'm thinking of painting my 964 while its on jacks and the wheels are off . . .

Hate the way the rusty hubs look behind the wheels.

gota911

OK, here are a couple of pics of the brake rotors.

I sanded the original paint off the sides of the "hats" but left the original paint on the flat "top" and put tape over most of the top. You can see the difference in the color between the original flat gray paint and silver paint I used and topped with a clear coat spray.

In the second pic, you can see all 15 wear "dimples." I have been considering the reason for the difference in size between the inner and outer wear "dimples." Here is what I have come up with. When the inner "dimples" disappear, you know the disc are close to being worn out. Once the outer "dimples" are gone, the discs are toast and you waited too long to change them.

Chrono

Gota911, are those Porsche rotors? I haven't seen those wear indicators on my C2S rotors.

gota911

Yes, they are. My current rotors, which are the original rotors have the wear indicators. My car is a 2010 997.2. maybe Porsche didn't have them op the 997.1 rotors.

StormRune

Back to OP's question for a moment. The min thickness is normally stamped on the rotor hat. The answer to your question depends upon the model of the car since I the brake specs are different for S and non-S models. It's also possible that any prior owners may have replaced the rotors with non-OEM parts, so it is best to look on the rotor first. You should find a number somewhere, probably in the high twenties or low thirties.

gota911

The minimum thickness is 32mm, which is stamped on the hub ("hat").

BHMav8r

Thanks all.

StormRune

...deleted my incorrect post to make sure no one is misled...

stronbl

Here is the suggested method to measure the brake disc.

Chrono

My stock S.1 no have:

gota911

Chrono,

I guess that is another enhancement Porsche added to the 997.2 that wasn't on the 997.1

Iceter

StormRune, are you sure the grooves in your pic aren't reliefs cut at the factory to balance the rotors? My non-S rotors have the depth indicator dimples as shown in gota911's pics. Plus, if you wore the rotors down to the grooves in your photo, I think the rotor would frag.

My Porsche rotors have the dimples. At 44k miles, my rotors were down almost to the point where the last of the dimples were almost worn away. When I mic'd them, the fronts were down to 26mm, which confirms that the deepest of the dimples are drilled down to this point, making them a good indicator of rotor wear.