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The PCCB rotor is a ceramic held together by carbon fibers. Think concrete with steel reinforcing or fiberglass with epoxy resin. Both the ceramic and the carbon fibers can withstand extreme temperatures, but carbon exposed to the air will oxidize (essentially burn) when it gets very hot. As it burns away it leaves the ceramic unsupported and with tiny voids, so thickness doesn't change. And because little carbon is lost visual and weight checks are inaccurate- hence the tool, and why we need more measurements from it rather than "the rotors look good". Looking forward to more measurements...
Like concrete without rebar the rotor loses integrity when the carbon is gone.
Oxidation is a highly non-linear process. It increases exponentially with temperature, so beyond a certain point even a little more temperature will increase wear dramatically. The critical variable is how hot the brakes get, and that varies with track and driver. Good drivers will often know if they are hard on brakes or not, but not going through pads quickly is a good indication you're not getting the brakes too hot.
yes, fantastic and technical (mostly). Pretty apparent Gen3 is a new paradigm. Thank you for the feedback and advice - I'll add my data to the sample (Sebring).
Had my PCCB rotors and pads measured today the dealer -- car has 8,670 miles on it, just over 1,300 of which are track miles. I also had them checked at 4,700 and 700 miles respectively, and there is virtually no significant difference.
Not quite sure how to interpret these numbers, but I don't think if the PCCB were measured brand new that the would have read at the "new figure" level based on the changes I saw between 4,700 miles and 8,670 miles. I am encouraged that this new generation are significantly better than previous generations.
Had my PCCB rotors and pads measured today the dealer -- car has 8,670 miles on it, just over 1,300 of which are track miles. I also had them checked at 4,700 and 700 miles respectively, and there is virtually no significant difference.
Not quite sure how to interpret these numbers, but I don't think if the PCCB were measured brand new that the would have read at the "new figure" level based on the changes I saw between 4,700 miles and 8,670 miles. I am encouraged that this new generation are significantly better than previous generations.
The figures here are great, but unfortunately they're all apples to oranges... the valuable comparison would be how a given driver gets more/less mileage out of a set of rotors over a similar usage pattern.
For example, I'm almost through my third set of PCCBs on the 7.2 which has done about 10,000 track miles (+5,000 street). My first set of ceramics went at around 4,000 track miles. It'll be interesting to see what happens to the Gen IIIs on my 1 and when replacement becomes necessary.
Yes, original pads (new 12 mm) - I will post an earlier set of readings later today at just under 5,000 miles. Not much different plus or minus from the set posted above.
Car has had four days at Sebring and six days at Lime Rock. Lime Rock is not a heavy braking track at least the way I drive at just over 1:02 per lap. I have not a hard core driver which may account for least wear than other driver's experience but still hit 135 at Lime Rock and 155 MPH at Sebring.
Had my PCCB rotors and pads measured today the dealer -- car has 8,670 miles on it, just over 1,300 of which are track miles. I also had them checked at 4,700 and 700 miles respectively, and there is virtually no significant difference.
Not quite sure how to interpret these numbers, but I don't think if the PCCB were measured brand new that the would have read at the "new figure" level based on the changes I saw between 4,700 miles and 8,670 miles. I am encouraged that this new generation are significantly better than previous generations.
This is good reading but isn't pccb more about how much carbon is in the rotors more then thickness? And you have to used a special tool to measure carbon density. Correct me if I'm wrong.
This is good reading but isn't pccb more about how much carbon is in the rotors more then thickness? And you have to used a special tool to measure carbon density. Correct me if I'm wrong.
Yes, Pete outlined that and why it's a density thing. The strength of the rotor as the matrix is burned off is the driving factor of replacing, not thickness. There has to be an easy way to check though....
The need to swap from ceramics to steels is much much less with this current generation. Put on a set of Pagid RSC pads (which are made for ceramics) and...voila!... you have a great track setup...
Very useful information. The front rotors are 20% worn, based on the units shown on the right (15 units of capacity between new and minimum; you have used just under 3. So if you've done 1,300 track miles, assuming a linear rate of wear, you should be able to get a little over 6,500 track miles from your front rotors.
08-15-2015, 09:25 AM
