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I dont have hard data yet but here is my experience so far:
7 tracks days on the car (+- 1,500km or +-1,000 miles)
11,000 km total on the car (+- 7,000 miles)
Everything stock except brake fluid. Changed tires once (to help evaluate).
Before every day at the track, I was always worried about one thing: PCCB
They never missed a beat and for my usage (much less track than some other guys here) they seems very good.
Disks still looks new, pads are still a little over 50%!! I'm done for this year and will change pads/measure disk wear next time I have the car serviced
Maybe they do only feel that way cold. I'll have to pay more attention to when it feels that way. It just seems some times on hard on the pedal to get it to slow down fast but maybe I just didn't have enough heat in them. Thanks for your replies
I can't compare steel vs PCCB on the 3, I never tried one with steel. All I can say is that I love the feel/power of my current PCCB.
They did great for me and never got too hot or mushy.
PTV+ is the big user of rear brakes and there is no way to switch it off.
I have heard that as well -- you can switch off Electronic Stability Control (ESC) by itself or you can switch of ESC and Traction Control (TC), both are part of PSM - Porsche Stability Management. However I don't believe that PTV+ is considered part of PSM and I don't believe there is any way to turn it off; not sure why Porsche takes this position. Offhand, I would think PTV+ would logically be part of ESC?
ABS also cannot be turned off, I understand the legal and safety reasons for that decision.
I'd pretty much say the Gen 3s are...bulletproof (how's that for an overused phrase? )
Yep...they really are great rotors, I think that ahs been well established right here on Rennlist.
Such a great resource of info....
Quick question how different is the pedal feel from iron to pccb? I had a 997tt with iron and now a 3 with pccb, I feel like i have to push the pedal much harder with the pccb. Is that normal?
That's interesting.
One of the biggest complaints about the PCCBs (other than cost) is the pedal feel or travel.
Many say that it's too grabby, and the pedal feel is non-linear. As compared to the standard iron rotors, that is.
I have heard that as well -- you can switch off Electronic Stability Control (ESC) by itself or you can switch of ESC and Traction Control (TC), both are part of PSM - Porsche Stability Management. However I don't believe that PTV+ is considered part of PSM and I don't believe there is any way to turn it off; not sure why Porsche takes this position. Offhand, I would think PTV+ would logically be part of ESC?
ABS also cannot be turned off, I understand the legal and safety reasons for that decision.
PTV is essentially continuation of the locking diff operation - with open diff, inside wheel spins faster than outside, killing traction; with locked diff, both wheels spin the same, killing much less traction (but still killing some); with PTV+ inside wheel spins slower than outside, which is ideal for maximizing traction. It's not a nanny intruding on driver's error but rather a way car operates. It's consistent and predictable, and a good driver will be able to work with it and use it to significant advantage, just like a locking diff vs. open diff. Think of it like a better locking diff.
That's very different from PSM operation, which basically uses brakes to slow down rear wheels when you use throttle irresponsibly, or brakes front and rear wheels to correct excessive car rotation caused by unskilled driver inputs. PSM basically takes over control from a driver and "drives" the car into a safer state for you. Think of it as instructor grabbing the wheel from you because he/she is scared for life.
PTV+ does not seem to put much wear on rear rotors because drivers I know who drive reasonably well and do not rely on traction/stability control have very little rear rotor wear. I'm still on my first set of pads in the rear, but on fourth set of pads and third set of rotors at the front (that's steel rotors though).
Very important to know if these miles are ran with PASM/TC on, PASM OFF/TC On, or with all turned off. This will change the amount of wear the rotors see since the system uses the brakes to keep the car in check.
Are you sure about that? I didn't think it was possible to turn PASM off
PASM/TC were on at all times. I basically know how these systems work but I don't find them too intrusive, especially if I am driving well. If I get sloppy, they will they step in and save my butt -- I find that I can get the car a little out of shape and not have them intervene; their implementation on the GT3 seems to be more delayed that my experience seems to indicate on other 991 and 997s that I have owned. Given the value of the car, I will probably never turn them off -- a little additional rotor wear is acceptable to me.
The one time I turned them off was on an AutoX in the rain, and I was trying to master power-on oversteer. Before I knew it was happening, I spun off the track at a low speed but hit the turf hard enough to demount a rear tire but fortunately not hard enough to do other damage.
My intentions with my post was to add one more data point to the thread and how the rotors on your car were used. In no way did I intend for it to be a post about if the car should be driven with the TC on or off. From a data point it is good to know if they systems are left on.
Originally Posted by bigkraig
Are you sure about that? I didn't think it was possible to turn PASM off
Whatever Porsche wants to call their Stability Management System in the car. They change the name of it every 2 years so it is hard to keep up with what the name is now.
The new Gen 3s will meet your needs -- see data posted earlier in this thread. I have had every generation of PCCBs on multiple cars, but my current GT3 is the first car I have tracked -- I am up to 15 track days and almost 10,000 miles on my 2015 car with minimal wear to the rotors. I am probably two track days away from changing the pads which still have more that 50% life on them. If you drive as you described above, I would predict that you will get at a minimum five years of life out of the Gen 3 rotors.
Thank you for chiming in,
-I've gone over almost all threads relating to pccb and gen 3 pccb's.. I sincerely appreciate all the data points that have been provided and it helps to make an informed decision.
Much thanks to all who posted with their experiences.
I would not jump to that conclusion just yet. The picture I'm getting so far is that wear rate is going to be very track (and to a lesser extent driver) dependent.
We've got three sets of data going so far. We know the rotors will essentially last forever on the street (even the old ones that were half the surface area) so we're looking at track usage specifically. It's only under track conditions that we can generate the high peak temperatures needed to oxidize the carbon out of the rotors and hence get significant wear.
Below is an imperfect attempt to plot all three data sets in wear vs known track miles. I'm guessing at important variables here, ie how far bigkraig drove, and I'm ignoring street miles, so I'll be the first to admit that the picture below isn't correct. Be that as it may, we might still learn something.
Clearly mmm991's data is the most encouraging- ~20% wear at 1200 track miles implies an average 6500 track mile disk life, or even more if you believe wear is flattening out. However I'm inclined to believe something different- Sebring is hard enough on brakes to get rotors above the critical oxidation temperature, while Lime Rock isn't. If that's the case you'd expect one track life on Lime Rock (nearly infinite) and an entirely different one on Sebring (roughly 2500 miles). This jibes with what we know about PCCB- keep them cool and they last, get them hot and they don't. And mmm991's description seems to support this theory- only one significant braking zone on Lime Rock should leave the rotors plenty of time to cool.
In this case track life depends very much on your particular track, so predicting life will be difficult. Average all results so far and you get 2500 track miles before rear disk replacement. Take out Lime Rock, however, as I've done below, and you get 1250 miles:
Street miles will count for something, so I think this is pessimistic, but you get the point: the data we have so far supports good rotor life in mixed use, and it supports good rotor life on tracks easy on brakes. It still seems to suggest high running costs, roughly $7 per track mile, for rotors on most tracks.
This is still imperfect data and things are moving in the right direction, however- hopefully we get more measurements to fill in the picture properly. I would still budget carefully before specing PCCBs on a heavily track car, however- to me the data still suggests that they are not bulletproof.
PTV is essentially continuation of the locking diff operation - with open diff, inside wheel spins faster than outside, killing traction; with locked diff, both wheels spin the same, killing much less traction (but still killing some); with PTV+ inside wheel spins slower than outside, which is ideal for maximizing traction. It's not a nanny intruding on driver's error but rather a way car operates. It's consistent and predictable, and a good driver will be able to work with it and use it to significant advantage, just like a locking diff vs. open diff. Think of it like a better locking diff.
That's very different from PSM operation, which basically uses brakes to slow down rear wheels when you use throttle irresponsibly, or brakes front and rear wheels to correct excessive car rotation caused by unskilled driver inputs. PSM basically takes over control from a driver and "drives" the car into a safer state for you. Think of it as instructor grabbing the wheel from you because he/she is scared for life.
PTV+ does not seem to put much wear on rear rotors because drivers I know who drive reasonably well and do not rely on traction/stability control have very little rear rotor wear. I'm still on my first set of pads in the rear, but on fourth set of pads and third set of rotors at the front (that's steel rotors though).
Thank you for the explanation, this helps greatly with my understanding.
I was assuming that PTV+ was part of PSM but I see that it isn't. As you stated, PSM is primarily designed to correct understeer or oversteer -- and it's primary active mode is to to apply selective braking to individual wheels (front or back) to restore stability.
PTV+ works primarily through the "electronically regulated and fully variable differential lock" to improve traction in cornering. Porsche's general brochure on the GT3 also states that PTV+ on surfaces with less grip such as wet surfaces will "strategically" brake either the right or left rear wheel. I am not sure, but my sense is that PVT+ under hard cornering will apply brake pressure to the inside rear wheel and deliver greater torque to the outside wheel through the differential.
Seems to be some overlap in that both PSM and PTV+ will use brakes to improve performance or correct excessive body rotation.
I would describe my driving skills as intermediate on the track and have spend time on both the skid pad and the AutoX (in other cars). I can purposely rotate the GT3 in turns through lifting the throttle or trail braking, can induce and control oversteer with the throttle, and understand the importance of balance. What amazes me in that unless I really get out of shape, PSM never comes on even though the car is being rotated or I am modulating oversteer with the throttle; I don't know about PTV+ but I assume it is working all the time and I just am not sensitive to it. On the other hand, PSM has saved my butt on more than one occasion and keep me on the track.
I would not jump to that conclusion just yet. The picture I'm getting so far is that wear rate is going to be very track (and to a lesser extent driver) dependent.
We've got three sets of data going so far. We know the rotors will essentially last forever on the street (even the old ones that were half the surface area) so we're looking at track usage specifically. It's only under track conditions that we can generate the high peak temperatures needed to oxidize the carbon out of the rotors and hence get significant wear.
Below is an imperfect attempt to plot all three data sets in wear vs known track miles. I'm guessing at important variables here, ie how far bigkraig drove, and I'm ignoring street miles, so I'll be the first to admit that the picture below isn't correct. Be that as it may, we might still learn something.
Clearly mmm991's data is the most encouraging- ~20% wear at 1200 track miles implies an average 6500 track mile disk life, or even more if you believe wear is flattening out. However I'm inclined to believe something different- Sebring is hard enough on brakes to get rotors above the critical oxidation temperature, while Lime Rock isn't. If that's the case you'd expect one track life on Lime Rock (nearly infinite) and an entirely different one on Sebring (roughly 2500 miles). This jibes with what we know about PCCB- keep them cool and they last, get them hot and they don't. And mmm991's description seems to support this theory- only one significant braking zone on Lime Rock should leave the rotors plenty of time to cool.
In this case track life depends very much on your particular track, so predicting life will be difficult. Average all results so far and you get 2500 track miles before rear disk replacement. Take out Lime Rock, however, as I've done below, and you get 1250 miles
Street miles will count for something, so I think this is pessimistic, but you get the point: the data we have so far supports good rotor life in mixed use, and it supports good rotor life on tracks easy on brakes. It still seems to suggest high running costs, roughly $7 per track mile, for rotors on most tracks.
This is still imperfect data and things are moving in the right direction, however- hopefully we get more measurements to fill in the picture properly. I would still budget carefully before specing PCCBs on a heavily track car, however- to me the data still suggests that they are not bulletproof.
I think your analysis is very good directionally -- brake life will definitely be track dependent and driver dependent. We'll need a lot more data, and probably more controlled data, in order to come to a clear conclusion. Fortunately, I think everyone agrees that they are an improvement over prior generations.
I would not jump to that conclusion just yet. The picture I'm getting so far is that wear rate is going to be very track (and to a lesser extent driver) dependent.
We've got three sets of data going so far. We know the rotors will essentially last forever on the street (even the old ones that were half the surface area) so we're looking at track usage specifically. It's only under track conditions that we can generate the high peak temperatures needed to oxidize the carbon out of the rotors and hence get significant wear.
Below is an imperfect attempt to plot all three data sets in wear vs known track miles. I'm guessing at important variables here, ie how far bigkraig drove, and I'm ignoring street miles, so I'll be the first to admit that the picture below isn't correct. Be that as it may, we might still learn something.
Clearly mmm991's data is the most encouraging- ~20% wear at 1200 track miles implies an average 6500 track mile disk life, or even more if you believe wear is flattening out. However I'm inclined to believe something different- Sebring is hard enough on brakes to get rotors above the critical oxidation temperature, while Lime Rock isn't. If that's the case you'd expect one track life on Lime Rock (nearly infinite) and an entirely different one on Sebring (roughly 2500 miles). This jibes with what we know about PCCB- keep them cool and they last, get them hot and they don't. And mmm991's description seems to support this theory- only one significant braking zone on Lime Rock should leave the rotors plenty of time to cool.
In this case track life depends very much on your particular track, so predicting life will be difficult. Average all results so far and you get 2500 track miles before rear disk replacement. Take out Lime Rock, however, as I've done below, and you get 1250 miles:
Street miles will count for something, so I think this is pessimistic, but you get the point: the data we have so far supports good rotor life in mixed use, and it supports good rotor life on tracks easy on brakes. It still seems to suggest high running costs, roughly $7 per track mile, for rotors on most tracks.
This is still imperfect data and things are moving in the right direction, however- hopefully we get more measurements to fill in the picture properly. I would still budget carefully before specing PCCBs on a heavily track car, however- to me the data still suggests that they are not bulletproof.
Nice analysis, Pete.
But two points:
1. I don't think "bulletproof" is the threshold.
2. Do we have any reports of PCCB rotor replacements in a Gen 3 setup?
09-23-2015, 12:22 PM
