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So to answer both questions/comments. I'm also amazed at how inconsistent the measurements are. Both used the same brand of tool. It just so happened that the Porsche tech I go to has his own Carboteq measuring tool (an $8,000 tool). He moved to a different Porsche facility and the new facility had their own tool so we were able to do readings with two tools in the same visit. Re: measurements on vs off the car...please read the column headings. Some were taken w/ rotors on the car, later readings with rotors off. More specifically, once I learned that with rotors on the car the measurements could be off, I decided to get the data on that. When I brought my car back for an end-of-track-season brake wear check, I asked my tech to measure the rotors while ON the car, then take them off and measure them again on a wood bench (with the same tool...his), then measure them a 3rd time with the shop's tool. Everyone but the tech thought I was nuts, but you now understand why I asked for that info. On 3 rotors, the readings taken w/ rotors on the car indicated nearly twice the amount of wear vs the same rotors measured when on the wood bench. So, yes, measuring rotors while on the car results in highly inaccurate readings.
Do you have photos of the rotors? I'd be interested to see what they look like as a visual data point. My PCCBs don't look good. They have lots of rings etched into them and 3 years of track days. But they still work lol. I haven't had a need to get the wheels removed, calipers removed, and rotors removed to get them measured. So haven't done it. And my Porsche Dealership does have the tool to measure, but they don't want to remove rotors to do it. They say you can measure on the car, even when I told the no...
Turns out it's a waste of time/money if the rotors are going to stay on the car while being measured. I don't have recent pics of my rotors, but in the next few weeks I'm going to swap over to my winter tires (yes, I drive my Spyder in the winter). I'll snap photos of the rotors and post them. They'll have roughly 4,300 track miles and about 11,000 street miles on them.
Nice job! I too have noticed the rear pads wearing slightly faster than the fronts which I suspected was due to PTV. Your report helps to confirm my conclusion that 90% of us out there doing track days are just not going to heat PCCB rotors past the point where you cause serious rotor degradation. That along with changing the pads at 5mm and there is not much to worry about IMHO.
BTW: I should also mention that I change my pads when the 'low pad' warning light comes on. At $1600 for a set of OEM pads (F & R total), I'm getting every last mm out of them. I'm sure you can see I stopped recording my pad usage. Once I realized I was going to replace pads about every 2 months, I realized tracking their thickness was pointless.
I changed my pads when the wear light came on. But I noticed the brass (?) studs were showing through the pads at that point. I don't know if this damages the rotors or not... having not just pad material but metal studs wearing the surface every time you brake. That said... pad material is metal and has copper in it. So maybe whatever metal the studs are made of doesn't harm the rotor.
yeah, I noticed the same thing. We're talking about Porsche here. With few exceptions, they do a pretty great job of engineering things, so I figured that whatever material the studs are can't be harmful to the rotors. If they were, Porsche's engineers would have either spec'd a different material or they would have made those brake sensors wear through sooner. I know...assumptions. LOL Interestingly, I found out that my wife's mini only has one pad wear sensor per end. Yup. Driver's side front (and I don't remember which side in the rear)....and even then, it's only on one pad! Geez guys. Pinch the penny much? Speaking of pinching pennies, y'know how hte pads wear unevenly...they wear more on the edge the rotor hits first so they end up wedge shaped. Well, I couldn't get a new set of pads in time for a track event at the end of my season. So I took a partially worn set of pads from earlier in the season and spun the pads around and re-installed them with the thicker end of the pad where the rotor hits the pad first. I didn't notice a difference and I'm getting more life out of them than I otherwise would. Hey, these things don't pay for themselves. ;-D
So to answer both questions/comments. I'm also amazed at how inconsistent the measurements are. Both used the same brand of tool. It just so happened that the Porsche tech I go to has his own Carboteq measuring tool (an $8,000 tool). He moved to a different Porsche facility and the new facility had their own tool so we were able to do readings with two tools in the same visit.
Re: measurements on vs off the car...please read the column headings for specifics on how and when measurements were taken and with which tool. Some measurements were taken w/ rotors on the car (first & third columns of data), later readings with rotors off (4th and 5th columns of data). More specifically, once I learned that with rotors on the car the measurements could be off, I decided to get the data on that, too (see last 3 data columns). When I brought my car back for an end-of-track-season brake wear check, I asked my tech to measure the rotors while ON the car, then take them off and measure them again on a wood bench (with the same tool...his), then measure them a 3rd time (also on the wood bench) but this time with the shop's tool. Everyone but the tech thought I was nuts, but you now understand why I asked for that info. On 3 rotors, the readings taken w/ rotors on the car indicated nearly twice the amount of wear vs the same rotors measured when on the wood bench. So, yes, measuring rotors while on the car results in highly inaccurate readings. Now, why the LF rotor's readings weren't dramatically skewed like the others...who the heck knows? I've heard that nearby steel is what throws off the reading...so maybe there's less steel near the LF rotor than there is near the RF? Doesn't look like it to me, but what do I know? I could see both back readings being thrown off by the brake heat shields, but those don't exist on the front.
Anyway, once I got these readings, I knew I could kick the 'rotor swap' can down the road for another year. Well, that year is now up. In the spring, I'll get my new readings to see how much more rotor life I burned through in 2022. All things being equal, the fronts should be 20-30% used up and the rears will probably be more like 40% used up. I plan do do a little less track time in 2023....I need to work more :-(.....so I can probably kick the can down the road for a couple more years before I need to make a decision about what to do. Based on what I know now, I'd probably just buy a replacement set of OEM PCCB's for the rear and call it a day. I love the feel of these brakes on the track and no matter how hard I brake, they never fade or overheat.
Hard to get great info out of this but I'll mention it anyway...on my 981 Cayman S w/ steel brakes, I measured rotor temps consistently just under 700 degrees during an August DE at Watkins Glen. I had to bleed my brakes after every session b/c the pedal was going soft...and I was running RBF660. Running the same track under the same conditions, but now my speeds are higher and my Spyder weighs a little more than the Cayman did, so the brakes are doing significantly more work, my PCCB rotor temps are around 300 degrees F and the pedal never goes soft...not even a little bit.
And you could also talk about the advantages of less unsprung weight and no brake dust on my silver wheels after just a 10-mile trip to fuel up. Look, someone said it earlier, better performance comes at a price. What do you feel comfortable paying?
I tracked a Cayman R with steel brakes for a year and had the same problem: fade regardless of fluid/pads at times. Turned the calipers purple. I think those cars just don't have the equivalent brake system nor the brake cooling of the GT cars.
Do you have photos of the rotors? I'd be interested to see what they look like as a visual data point. My PCCBs don't look good. They have lots of rings etched into them and 3 years of track days. But they still work lol. I haven't had a need to get the wheels removed, calipers removed, and rotors removed to get them measured. So haven't done it. And my Porsche Dealership does have the tool to measure, but they don't want to remove rotors to do it. They say you can measure on the car, even when I told the no...
Not surprised, Dealer is happy to sell you a new set of rear PCCB rotors you probably don't need. I think the rings are normal. When you start seeing chunks missing on the edges or rough fiberous looking patchs on the faces it's time to worry.
Hi guys, I am from the company Redisc from Slovenia, and we have bought the technology for refurbishment and repairs for CCB, www.redisc.si As our references, we have already made 500 pcs (including for the company that is already well known in your forums for refurbishment, as we were his main supplier.. Now we have decided to start over, we have better and improved technology, new ownership and a very professional team. We are also using Carboteq for extra quality.
If any one has any questions, you can contact us here on the forum.
RDCR: I completely agree...that was my experience. I found myself wondering (in retrospect) how much of that problem was the product of insufficient brake cooling. Hard to tell, but the problem (for me) only occurred at Watkins Glen...a track with 5 heavy braking zones per lap (say, every 2:15)...and not just heavy braking, but high-speed heavy braking....scrubbing 50, 60, 70mph from triple digit speeds. Clearly, that was a situation which exceeded the capability of the stock brakes. As disappointed as I was, you gotta give Porsche credit for making a street car with performance limits that high! ;-D
My understanding is that the company in Germany has come up with a new technology to bond the friction layer to the base rotor. It is based on heat rather than fusing it and supposedly the process is faster than the old technology. It is good to have options to buying new
Great info here! I found more info about PCCB on GT3 forum than GT4. Wondering if 991 GT3 pccb is the same as 718gt4 pccb material-wise? I am thinking about swapping to disc, but I have seen so many saying that it is fine running them on track. I am just one level above novice and do 5-6 track days a year.
which brand are you using? Original comes from BREMBO.
CARBON-CERAMIC BRAKES – CCB are manufactured at the Meitingen factory (Germany)The CCB is a disc consisting of a core of ceramic material reinforced with carbon fibre and covered with an additional ceramic layer on both friction surfaces.
Vehicles fitted with CCB DISCS: Porsche, Audi, Bentley, Lamborghini, Bugatti, AMG, BMW-M, Aston Martin, Toyota
If you have right size, I do not think it is going to be problem.
Great info here! I found more info about PCCB on GT3 forum than GT4. Wondering if 991 GT3 pccb is the same as 718gt4 pccb material-wise? I am thinking about swapping to disc, but I have seen so many saying that it is fine running them on track. I am just one level above novice and do 5-6 track days a year.
The 718 GT4/Spyder have PCCB rotor sizes as follows: Front = 410mm diameter x 36mm thick, Rear = 380mm diameter x 32mm thick.
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://newsroom.porsche.com/dam/jcr:2a73c532-e5ef-456f-b068-880d2a3a1399/2020_718_Cayman_GT4_and_718_Spyder_tech_specs.pdf
The GT3 991 and 992's share the same PCCB rotors (though not the same hat's apparently...maybe due to centerlock vs 5-bolt?). The older GT3's had smaller 350mm PCCB rotors F & R.
As for wear....see above for my postings about PCCB wear measurements with track use. At 5-6 days per year as a beginner, you'll likely wear the rotors no more than 2-3% per season. At an advanced level of driving (and admittedly hard braking), I'm wearing the front rotors at <1% per track day and the rear rotors at just over 1% per track day. There's plenty of info out there about whether or not to convert to steel, so I'm not going to weigh in unless you specifically want MY opinion. ;-D
Last edited by modernyankee; 12-02-2022 at 07:30 AM.
11-04-2022, 02:11 PM
