frayed

I had them in my S. They feel great.

Fade has been reported with the stock pccb pads. To address this, one would swap to the motorsport pad for hard track use. But, this pad is not suitable for street use due to its abrasion characteristics at low temps. This means that with PCCB, just like steel, you have to change pads for track use.

Since you have to swap pads for track use anyway. . . it seems that if your car sees a lot of track time, steel is the better choice. PCCBs don't save any aggravation for track days, and, as has been said many times before, you can go through a lot of steel rotors for the price of pccb rotors, and I know from experience that a good track pad on steels has awesome bite and modulation, not to mention they generally prevent rotor cracking on the stock cross drilled rotors.

Bottom line is this. Many people cite improved performance of PCCBs on track use due to the pedal feel and confidence going deep into corners. This is true comparing stock pccb to stock steel (at least based on my 997S experience). When you swap to a good track pad, the PCCB feel is duplicated.

So, then, what is the sense if you gotta swap pads anyway?

MJones

Un-sprung weight advantage

The last application is the same as the first...no fade
Pedal feel remains the same thru-out where as steel race brakes will encounter
a bit of pedal fade, at least thats what David Murry responded to the Steel vs PCCB question.

The tire is the real limiting factor as brake tech has gotten so good

frayed

Un sprung weight. True, but 8.8k for a few pounds? Surely some lightweight wheels and lightweight track tires like Hoosiers will be more noticable, especially since the mass reduction is further from the axis of rotatoin.

No fade? I don't think so. Not with stock PCCB pads. Real world experience reveals that you will get fade with stock pads. This means motorsport pads or their equivalent for track use. I've run a variety of quality track pads over the years on different cars, Hawks, PFs, etc. They make all the difference in the world.

Tire certainly is the limiting factor. This would dictate just going with steels.

CWay27

Un-sprung weight advantage??? If you're really serious about this then I suspect you'd be the type of guy who strips out the car once at the track and never has more then a 1/4 tank of gas.

If it were a one time investment I would say otherwise but unfortunatly, it is not the case. With that said, I would have better use of my 8.8K.

nkhalidi

No MJones, there IS fade with PCCBs. I know this from experience; I have PCCBs and I've logged plenty of track miles on street-pad 997 PCCBs with only GS610 fluid. Just like I PM'd Frayed, the first 5 hot laps are fantastic, rock-hard pedal, amazing deceleration, really dive-bombing the braking zones.

After that, the pedal remains firm, but the rates of deceleration decline. It's harder to modulate the transition into ABS; the car just doesn't slow as quickly. This is science: the pad can't handle the heat it's being forced to absorb. That said, I'm sure the motorsport pad CAN handle the heat, and, as Frayed wrote, it's a matter of changing pads out. The other option is to brake-check going into every braking zone, but at that point, it's like, why even bother with PCCBs.

My rationale for PCCBs - any Porsche sports car I buy from here on will have them - is that no matter pad choice, they still provide a larger caliper and rotor heat sink than comparable steels. I'm all about maximum OEM brakes, and the PCCBs are it.

I'd guess that, both equipped with race pads, PCCBs will outlast and outbrake steels.

The beauty of PCCB is that you don't HAVE to use race pads to have a good time at the track. Natch, I go out there on street pads, warm up one lap, take five hot laps, cool down one lap, take another five hot laps, and the session's over. Great. Can't do that with steels. At least I couldn't

Racerron

nkhalidi___, The calipers, and swept volume of the PCCB's are identical to the steels on GT3 and RS, as far as I can tell the only benefit to PCCB's is the unsprung weight factor. I use Pagid RS-19's for track and street and have never had an issue except for the G*d awful brake squeal when the pads are new, (not broken in), but this is cured by following the procedure as outlined on the Pagid site.

The cost up here in the frozen North for PCCB's is a mind blowing 13K, I'd rather spend that somewhere else. And to replace a scorched PCCB rotor is the same price as a small Toyota.

MJones

Since PCCB discs, front are 380mm vs Steel 350mm, my best guess is that the swept area for PCCB is a bit greater..

Another Brake note:
To change brake pads at the rear on the GT3.
The rear calipers will have to be removed,
This is due to the two additional bars fitted over the brake pad slot to increase rigidity.

FixedWing

Right and wrong ...

Right, the callipers are larger. But is this a good thing? It means more unsprung weight. The callipers I had on my Turbo were massively overweight.

But wrong on the rotors. They might be the same size or slightly larger but ceramics do not absorb and transfer heat anywhere near as quickly as does cast iron. This is why they use them on the space shuttle.

In fact, this is the problem with ceramics. They don't conduct heat. So much more of the heat must be transfered via the pads and callipers. That overheats the pads and fluid and, no doubt, does quite a job on the callipers themselves over time. What good are vented rotors if the heat isn't conducted through them? This is why the rotors crack on the surface too. The insides stay cool while the surface expands from the heat.

Stephen

frayed

SiC is the major compenent of PCCB rotors. It has higher specific heat (takes more energy to raise the rotor 1 degree of temperature), is dimensionally far more stable (lower coefficient of thermal expansion) and is of course less dense (lighter) than iron rotors.

It doesn't have the impact strenght of iron; hence the use of CF reinforced SiC.

More info here

http://www.sglcarbon.com/sgl_t/indus...sigrasic_e.pdf

MJSpeed

IF it's a heat issue, wouldn't switching from whatever to RS-19/29's on a pccb optioned car as well as using higher boiling point brake fluid such as SRF resolve this?

I know individuals that use RS-19's or 29's on their Gen I PCCB GT3's and Turbo's on the track and haven't had any issues. I know of one particular case in which the person's done 12-15 track days in one year. Some do use SRF as brake fluid but not sure if all do...

Bob Rouleau

Gen 1 PCCB fade with stock street pads. With sport pads, the rotor holes get plugged and when that happens the braking is poor. Using race pads helps but they get hot too and caliper seals pay the price. I have no experience personally with the Gen 2 PCCB, and after my GT2 episode I have no desire to. Cast Iron rotors and Pagids do the job at a fraction of the cost. For those who are impressed with PCCB performance, I suggest you try the same car with a set of Pagid 29s front and RS-19he back with cast iron rotors. The car slows and stops as if being held in the hand of God.

eclou

or perhaps by the face of Madeline Albright

Bob Rouleau

Yeah that too, but only if you are on R compound tires

frayed

Bob, why the different pad compounds front to back? Typically this is done where the factory brake bias is deemed lacking, or where people try to get away with a combo street/track pad out back (i.e., so they don't have to change them).

Z06

I thinks it's RS-19 F, RS-29 R, the stock 996 GT3 has more front bias.