ajw45

Took my car in for the 2 year intermediate service and while in there asked them to do a wear read on my rotors. Readings below (FYI each rotor has 3 measurement points)

Rotor---Max---Current---Min---%Worn
LF-------49-----48.0------36----7.7
LF-------50-----48.9------37----8.5
LF-------62-----61.1------46----5.6

RF-------64-----63.1------47----5.3
RF-------60-----59.2------44----5.0
RF-------63-----61.4------46----9.4

LR-------55-----47.7------42----56.2
LR-------56-----49.0------43----53.8
LR-------53-----45.4------41----63.3

RR-------57-----49.4------43----54.3
RR-------54-----46.7------41----56.2
RR-------58-----50.6------44----52.9

The car has 13k miles, 3k of those on the 4L, and 6-8 track days running original stock pads, SRF fluid, and traction control on. Front readings are awesome (avg 7% worn), rear readings are... terrible (avg 56% worn!!!).

Could this be the result of PTV going hog wild on my rear rotors? Maybe a worn diff? I've felt PTV kick in a few times on the track and in the twisties on tight turns where the car seems to suddenly pull into the apex harder after I've already finished turning in... or maybe that's just my imagination....

Has anyone else done a carbon reading on their PCCB rotors yet? Anyone ever get PCCBs replaced under warranty for premature wear?

Alan C.

I had high percentage wear readings on my rear PCCB rotors when compared to the front. I then took the rotors off and had them measured off the car. With rotors removed the readings were a close match to the front rotors on a percentage basis. No idea why. Might be worth a try.

ajw45

Awesome, thanks Alan, I'll give it a shot. The measurements were taken with the rotors on the car and I did see a post where the measurements should be taken with the rotors off the car so the backing plates don't interfere with the tool....

Alan C.

Let us know how it works out for you.

GTgears

Traction control and PTV both have a rear brake component built into their programming. Your ABS ECU is stepping in on track and making the caliper brake when you do not have your foot on the slow pedal.

d00d

I'd like to know if the automated rear braking can be turned off, from this thread I'm not sure it can;
http://www.pistonheads.com/gassing/t...20Forum.&mid=0

ajw45

Update!

Went back to the same dealer and asked them to remove the rear rotors and measure them again. The service manager asked me 3 times if I was really sure I wanted to do it and even called the lead tech since they all thought it was a waste of time and I might be a little off in the head. However, after assuring them that if the numbers came back exactly the same I wouldn't freak out and that I would pay the tab either way the took the car....

New numbers!

Rotor---Max----On Car----Off Car----Min---New % Worn
LR-------55-----47.7-------52.5-------42----19.2
LR-------56-----49.0-------53.9-------43----16.2
LR-------53-----45.4-------50.4-------41----20

RR-------57-----49.4-------53.9-------43----22.1
RR-------54-----46.7-------51.0-------41----23.1
RR-------58-----50.6-------54.8-------44----22.9

The good news is there is a massive difference with the rotors off the car and the new readings came out to about 21% worn, less than half as bad as the original reading. If anyone is getting their PCCBs measured, definitely have them pulled off the car and thank you to everyone that suggested it.

I'm not upset that they didn't do this the first time since they didn't actually charge me for the first measurements and they are just looking to make sure the rotors are in spec vs trying to geek out and measure wear rates. However, I do wonder how many owners have had to buy new PCCBs due to misreads. I would be PISSED if I spent $10k on PCCBs cause the tech didn't measure the rotors correctly and tossed a perfectly good set of rotors in the trash.

The rate of wear on the rears is still more than double that of the fronts even with the latest readings. That still concerns me but given the front rotors weren't measured off the car and the voodoo in measuring these things, who knows what the real rate is. I'll check again next year but if the wear rate is linear and I can go 20+ years just replacing a rear set of PCCBs that sounds like a good deal to me.

Alan C.

Glad it worked out for you.

kkakonn

Thanks for sharing the info! Just recently got into a gt4 that came with pccb's. Also a track enthusiast (plan on going 8-10 times a year) Wonder if it makes sense just to change out to some steel rotors. Although I really do love how the CCB's perform on the track

Alan C.

For 8 - 10 times a year I'd go with a set of Giro Disc rotors. I sourced mine from Clark at Apex. Great service. You might also look into a set of Spiegler brake lines along with Tarett brake line and caliper studs.

ajw45

The PCCBs have been great so far, super easy, just upgrade the the brake fluid and go. I'm going to keep driving them and measuring once a year. If I ever get down to about a 1/3 left (like 4 years from now at this rate) I'll decide then whether to go iron or surface transforms... Or just keep going. By then l'll probably be driving a minivan....

johnsopa

I have between 25-30 track days on my PCCBs. I had them measured off the car at the end of last season and will do the same probably next month. If your wear rates are too high think about getting a coach to read your telemetry and make braking suggestions.

ajw45

Thanks for the tip! What were your wear rates like at the end of last season and how many track days did you have?

johnsopa

I had about 2k track miles last year and that used between 8%-15% of the PCCBs.

https://rennlist.com/forums/gt4/9770...surements.html

I’ll take them off and have them measured again probably next month.

Sven76

That’s great, ‘cause I had also c. 2k track miles and already swapped front rotors and all pads.