Porsche: Installing Carbon Ceramic Brakes (PCCB) on a 911 C4S

Porsche races, and racing shows the importance of braking. As a result, production Porsches have always had brakes on the cutting edge of road-car technology.

Reliable ceramic structures are a bit of an engineering holy grail. Extremely hard, wear resistant and lightweight for their strength, most ceramic materials are also rather brittle and nearly impossible to manufacture without defects that lead to spectacular failures. For example, when GM put ceramic-turbine turbochargers into limited production in the late 1980s, the failure rate was 100%.

Thus, when Porsche made ceramic composite brakes available on the 911 GT2, it was both an outstanding technological achievement and not all that surprising. The 911 Turbo's standard, 13-in. (330mm) cross-drilled discs and four-piston, monobloc aluminum calipers generate a stopping force four times as powerful as the engine. Further, wet-weather performance is enhanced by cross-drilled discs, which enable rapid dispersal of the water vapor generated at the initiation of braking. Directional, internal venting has been a standard feature of Porsche brakes for decades. Iron-disc Turbo brakes are among the best available on any production car and are entirely adequate for the 415-bhp, 3,600-lb car.

Porsche Ceramic Composite Brakes (PCCB) use a cross-drilled, carbon fiber reinforced ceramic disc with special composite pads. During manufacture, the basic disc molding (made from a carbon-fiber and polymer mix) is silicated in a special high-vacuum process at 3,092oF (1,700oC). Like Porsche's conventional discs, the PCCB parts are cross-drilled and directionally vented. A PCCB brake disc weighs 50% less than its cast-iron counterpart despite considerably larger dimensions. Like a competition-bred conventional system, the ceramic outer disc is mated to a steel inner "hat." PCCB brakes use specially developed six-piston calipers on the front and four-piston calipers on the rear.

The PCCB pads offer a high coefficient of friction for moderate pedal efforts and unusual consistency of friction characteristics across a wider range of operating temperatures than is available with Porsche's conventional brakes. Several different pad compounds are available for street and various levels of track use.

Another key benefit of PCCB is its exceptional durability. While the actual rate of wear on all brake components--particularly pads and discs--is entirely dependent on individual driving style and vehicle usage, comparison testing reveals a much longer life expectancy with PCCB than with conventional braking systems, as long as 160,000 miles or more under normal driving conditions. It is important to note that racing and other extreme driving can significantly reduce the life expectancy of any vehicle component. After any driving event, have the vehicle, including all PCCB components, thoroughly checked and replaced as necessary.

PCCB is available from the factory on any 911 Turbo and also fits the Carrera 4S due to its sharing of the Turbo's wheel specifications. By far the most cost effective way to get them is to simply check the option box when ordering your Porsche. The price of all the individual parts comes to $23,000, but the upgrade kit we installed is a mere $17,000, which is still considerably more than the option cost. Standard 911 Turbo brakes aren't free. Clearly, even with the advantages in durability and fuel economy, one doesn't choose PCCB in order to save money.

Porsche kindly offered to install PCCB brakes for european car to test on its long-term Carrera 4S. The car's best 60 to 0 braking distance with stock brakes rounded to 112 ft (our standard braking data procedure), and its best distance rounded to 113 ft with PCCB. In both cases, performance was consistent within a few feet over five stops, with no fade. From 80 to 0, european car's long-term car stopped in 200 ft with PCCB, exactly the same as another stock Carrera 4S tested earlier at the same location. Again, there was no fade in repeated stops with either car. This braking test is clearly not a challenge for a standard Carrera 4S, and we haven't track-tested our own car with PCCB.

At our 996 Twin Turbo shootout, By Design used PCCB on its last-minute Cabriolet, with Michelin Pilot Sport Cup tires in stock sizes. By Design had neglected to properly break in the PCCB brakes on that car, due to time constraints, and after four laps on the track, the pads were literally on fire when Cort Wagner pulled into the pits. That didn't seem to hurt the brakes, as the car's best 60 to 0 distance was 99 ft and its best 80 to 0 distance was 182 ft, winning the braking portion of the event. This car weighed hundreds of pounds more than a Carrera 4S, showing that the best way to shorten stopping distance, once the brakes are as well dialed-in as a stock Porsche's, is to get stickier tires.

Subjectively, european car's Carrera 4S did ride noticeably less harshly over Orange County's freeway expansion joints with PCCB, due to the reduction in unsprung weight. There was, however, also a slight increase in noise as the pads swept over the holes in the PCCB rotors.

In the end, we can say that you'll have to use your Porsche considerably harder than we do to realize a significant benefit with PCCB. If that's you, let us know how it goes. However, any true Porsche fanatic will know that the yellow calipers signify Porsche's most advanced brake technology, so be prepared to answer questions in the paddock.

Porsche provided its own technician to install our PCCB system. It was much like any other brake conversion, but with a few extra pieces and cautions. Each rotor costs about as much as a typical aftermarket big-brake upgrade kit, and if you chip or crack it by dropping it, it will probably be destroyed. Have the system bled by an authorized workshop with a pressure bleeder. Porsche recommends at least 500 miles of moderate street driving to bed in the PCCB system before getting on it hard.