JKay

Hello

My 997 Turbo has 29,000 Miles/47,000km on it, and during a recent service my specialist said my PCCB's were on the limit and would need replacing sometime in the not too distant future, and that a Porsche dealer would recommend I change them immediately.

Ive done a search and am still none the wiser. I understand they have wear indicators (little circles) which when visible suggest they need to be changed, but on the other hand have also read that the circles are also sometimes visible on new cars with new PCCB's? Im no technician and its all internet research so I could be wrong

Therefore was wondering if anyone here would be able to look at my wear indicators and tell me what they think, second opinion and all? I can take more pictures if necessary.

The specialist I use are good guys and well trusted, but just after a second opinion for whatever it may be worth, so any input is much appreciated.

Thank you

Both these are rear. Fronts were less (as expected) so left them out

Rear Right


Rear Left (circle is at the bottom)

Kevin

There are 3 conditions for PCCB replacement..

Wear thickness of .020" You will need to measure your rotor thickness.

Edge erosion

Surface pitting or erosion due to extended heat damage that exceeds 1 cm2

Your ceramic surface looks decent.

JKay

Thank you. I shall measure them in a moment and see what I come up with.

JKay

Tried measuring earlier and will need something better than the ruler I had

Was trying to find out what 997.1 discs thickness should be new but only managed to find 996 PCCB thickness when new. Therefore Can I confirm if the disc thickness on new discs for the 997.1 is the same as on the 996?

The Porsche maintenance manual lists the following for the 996 turbo w/ PCCB:

Front brake disk thickness new/minimum limit: 34.0mm/33.5mm (mine says 33.8 min)
Rear brake disk thickness new/minimum limit: 28.0mm/27.5mm (mine says 27.7 min)

Dennis C

You'll need a good caliper to accurately measure thickness.

strato58

Wow only 29000 miles..you must drive hard.

Kevin

As Dennis has mentioned, you need a good micrometer..

I use .020" or 0.5 mm. 0.3mm is .012" wear... Your rear rotors don't show any delamination or erosion.

Macster

My recollection (from a 3 part article on PCCBs in Total 911 -- issues 48, 49, and 50) is the discs are worn out when the circles disappear.

From the factory Turbo service manual I have the disc thicknesses and wear limits.

See attached PDFs....

MadScience

I thought they needed to be weighed, not measured for thickness.

At least I thought mine have individual weights on them. (Edit: will check that today.)

I dug into the story with the wear circles a while back. Just being able to see them is normal, even on new disks, though on some they blend better than others. They are supposed to pit (turn rough) before the rest of the disk. So as long as they appear to have the same surface, you have not triggered that indication.

TTurboRoo

I had also heard they should just be weighed and I don't think anything but tracking your car would grind down your Rotors at all in 29000 miles. They are supposed to be good for 200000 under normal street use. They also look perfect to me, I see no indication of wear at all. Now, you could think about the pads as they should be replaced at 50% wear to continue to do their job without damage to the rotors! Also remember that the rotors are OFTEN damaged by tire shops pulling the wheels without the alignment tool screwed in on the thing. They beat up the edges. I have seen many good PCCBs with ragged edges from lack of care in removing and remounting the wheels!!

MadScience

What is the alignment tool?

I've always pulled mine very carefully after stuffing a bunch of towels in there. Slight pain, but seems to work out OK.

I also would not consider handing this car to a random tire show without very explicit instructions, and an understanding that they would replace a disk they broke at their cost.

TTurboRoo

Wheel stud alignment tool is about a 5" long tool that is simply screwed into one of the missing lug bolt holes (typically on top), so that the wheels can be slid onto that, already aligned with the bolting pattern. It takes time but simply makes it easier to put the wheels back on in that last few inches in a way that tends to protect the rotors from being damaged by the wheel being put on!

MadScience

Thanks for the info on the tool! Did some searching, ordering some for the turbo, cheap enough...

MadScience

Took a look at my rotors, and they list both a thickness and a weight.

I'm pretty sure my dealer insists on weighing them, at least I seem recall a discussion where they stated that that was the only indicator they really looked at, unless there was physical damage.

TTurboRoo

You're welcome! Darn cheap insurance and if nothing else adds awareness of the need to be careful. I cant tell you how many times I have seen wheels pulled and the weight is not compensated for so they are dropped on the rotor and caliper! Way too much invested in those not to think about them!!