Gus B.

To those of you who own/have owned a Cayenne Turbo with PCCB ceramic brakes, what kind of wear have you seen on pads and discs? I know that discs are supposed to last the lifetime of the truck, but I've also seen many resurfacing companies show up and people replacing PCCBs, thus leading me to believe that these are not in fact "lifetime parts".

Reason why I'm asking is because a Turbo came up for sale locally and it is equipped with PCCB. Drove it and noticed that the brakes are VERY grabby from initial bite and perform extremely well as stopping power is concerned. Really did not like at all the noise they create when gently applying the brakes at low speed. The truck has 60K miles (mostly done in stop and go traffic). A set of discs is $28K (local prices) and a set of pads is $2.5K (again local prices). The truck has a Porsche extended warranty on it, but brakes are not covered as they are considered "wear items". Given that the truck is for sale at $25K, the replacement cost of the brakes alone is more than the purchase price!

So, what are the odds that I will face this brake bill in the next 30K miles? No tracking whatsoever, just some spirited driving and a lot of stop and go traffic....

gonzoe11

I bought my CTT with PCCB 18 months ago with 68k miles on it. On pre-purchase inspection, the pads measured 6-7mm. At my 100k mile service in February I had the brkae fluid flushed and brakes checked.. The pads measured 6mm and my tech told me they can go the life of the CTT (taken with a grain of salt). I use my CTT to commute everyday, approx 90 miles roundtrip and much of this is stop and go. The brakes are still very "grabby". Sounds like a good deal if everything else checks out.

Gus B.

So in 32K miles of commuting in stop and go you virtually had no brake pad wear? That is awesome news! Off to talk to the seller to see if we can reach a final agreement, assuming that the PPI doesn't reveal 50%+ wear on discs or pads. Thank you for sharing your information!

2PartsEther

I haven't had my pads checked (that I remember) recently, but I know the rear discs show more wear than the front discs as evidence by a more significant lip between the unworn disc surface and the worn surface. That said, this lip is really minor, maybe 0.25mm of wear in ~35k miles. What that equates to life of the disc, probably need to have someone else chime in who had theirs measured for real, since they use a total diameter measurement I believe.

Gus B.

Your PCCB discs have a lip in them? Never seen that before….

anyone know what is the proper procedure to measure pad and disc wear? I can only assume it’s measuring pad thickness as well as discs (measurements taken in multiple places per disc to get an average figure). Am I correct in my assumptions?

Quadcammer

I believe the only way to measure rotor life is to weigh them. A lip on pccbs would be news to me.

Simeon

I've also heard that the only true way to measure carbon ceramic rotor wear is to weigh it. The reason for that is that CCB rotors literally wear from the inside out as high temps cause them to essentially evaporate in the form of carbon dust particles getting released through the vent holes. So they would not get thinner the way normal rotors do but do lose material at a rate dependent on their temperature. And the lower the material left, the quicker they heat up so the process begins to accelerate over time. But for street driven cars, they should never get hot enough to really lose material at a significant rate. That's why street driven PCCBs last a lifetime but track used PCCB wear out (or perhaps if they were used for heavy towing).

Bottom line though, I doubt a regular PPI would actually remove the rotors to give you a real wear level unless you specifically request it and it might cost a little extra but still be worth it for piece of mind. I would be more concerned if there is a tow hitch that has actually been used.

Simeon

Also I'm sure once the rotors need a replacement down the line, there would be aftermarket steel rotors that could be fitted (along with proper brake pads).

f4 plt

I don’t have a turbo but instead a diesel with PCCBs and with 95000+on the vehicle and much of it cross country towing my brakes are barely worn with many thousands of miles left before any service is needed . Great brakes wet or dry and having had a previous diesel with standard Porsche brakes I can safely say the OCCBs are significantly better and standard Porsche brakes are great .

Gus B.

I did specifically request the dealer to tell me how much life is left on the pads and rotor. I wonder how they'll measure this. If someone has a tech document on this procedure, please share!

Reason why I'm a tad "paranoid" is that the replacement cost for discs and pads (locally) is +$30K which is more than the purchase price of the vehicle! I do know that PCCBs are a premium product, but to be honest, the steel rotors would better suit my needs (only street driving, no towing).

Simeon

Well it's pretty simple. They just need to weigh the rotors and there is a minimum weight inscribed on the rotor hat. As long as it's above the minimum you're good, but to get a percentage worn, you'll need to know the starting weight for a new rotor, which they should.

Gus B.

Been doing some more research and apparently rotors are weighed to determine % used.
There are signs that the wear changes as rotors get older (quicker wear when they get lighter).

Simeon

Glad you're confirming what I said above. 👍
Both in post 7 and 11.

Gus B.

Apparently there are various generation of carbon discs for Cayennes (specifically 958 model). Some "first generation" discs cannot be measured using Proceq's Carboteq measuring device (also known as VAS6813 by Porsche dealers): https://vw.snapon.com/SpecialToolsDe...at_Name=Brakes Not sure if the tech was lying or not, but I don't see a reason why he would do so as he did try and use the device on the right rear and front left corners of the vehicle to see if he could get any kind of significant measurements. Will call Proceq later on to see if in fact this is correct information (that it doesn't work with early Cayenne PCCB discs).

I was able to see that in fact the minimum thickness and weight of each rotor was different. They did not remove the rotors to weigh them as the tech said "there would be too many variables to get any kind of accurate measurement". Instead, it was merely a visual inspection to make sure there are no rough areas anywhere on the disc (none were found, all surfaces "glass smooth"). The wear indicators (3 2cm each circles 120º apart from each other on both sides) were visible (barely). No wear on the wear indicators, but the tech "guessed" these would be good for another 20-30K kilometers (truck has 95K kms on it now).

The brake pads were measured (on the aforementioned corners) and they have worn down to 4.3 and 4.5mm of pad left. This indicates an average wear of 67%.

We shall see what the final results of the PPI are and if the seller is willing to take this information into consideration.

Gus B.

Some pics from today...