Disc Brake System: Description and Operation

Brakes

To ensure that the high requirements with regard to the braking performance of a Porsche are met even better than before, all new Cayenne models are equipped with an even larger and optimized brake system. The brake systems can be identified visually according to the familiar logic: black brake calipers identify the Cayenne, silver brake calipers the Cayenne S and red brake calipers the Cayenne Turbo. The racing-proven Porsche Ceramic Composite Brake (PCCB) is optionally available for all Cayenne models.

Brake system overview







Standard brake system







6-piston aluminum monobloc fixed-caliper brakes and integral-type brake discs with a diameter of 350 mm (+20 mm compared with the previous model) are used for the Cayenne.
The Cayenne S is equipped with composite brake discs with a diameter of 390 mm.

4-piston aluminum monobloc fixed-caliper brakes and integral-type brake discs with a diameter of 330 mm are fitted at the rear of the Cayenne and Cayenne S.

Due to its high power, the Cayenne Turbo features composite brake discs on the front axle with an aluminum pot, a grey cast-iron friction ring and a diameter of 390 mm. Larger brake discs are also fitted on the rear axle with a diameter of 358 mm.

Porsche Ceramic Composite Brake (PCCB)

As with all other Porsche models, the especially high-performance ceramic brake system Porsche Ceramic Composite Brake (PCCB) is also optionally available. The PCCB is offered for the first time for the Cayenne. It is available as from a wheel size of 20 inches for the Cayenne Turbo and as from 19 inches for the other Cayenne models. The PCCB has a brake disc diameter of 390 mm at the front and 370 mm at the rear for the Cayenne and Cayenne S. Brake discs with a diameter of 410 mm at the front and 370 mm at the rear are used for the Cayenne Turbo. All Cayenne models have 6-piston aluminum monobloc fixed-caliper brakes on the front axle and 4-piston aluminum monobloc fixed-caliper brakes on the rear axle.

Brake booster

The Cayenne and Cayenne S variants are equipped with a tandem brake booster (9/10-inch diameter) with a transmission ratio of i=7. The transmission ratio on the Cayenne Turbo is i= 8. Compared with the previous model, this is now a normal brake booster, i.e. the brake light switch and booster coil have been omitted.

Vacuum pump

Instead of a conventional sucking jet pump, a mechanical vacuum pump has been installed on the engine to provide the brake booster vacuum. This design permits a high and constant vacuum to be provided so that brake boosting is available under even the most unfavorable conditions.







Brake master cylinder

To achieve an optimum pedal feeling with a more precise pressure point, the diameter of the brake master cylinder was increased to 28.57 mm. A brake light sensor (1) is installed directly on the master brake cylinder.