Porsche Cayenne Turbo Driver Manual page 166

After a long drive over salted or gritted roads, a
coating may form on the brake discs and pads
that significantly reduces friction and thus braking
action.
f Therefore, clean the brake discs and pads
approx. every 2 weeks with a strong jet of
water. The cleaning effect of automatic car
washes is insufficient.
To prevent corrosion of the brake discs, "brake
them dry" before parking the vehicle.
f Even though the brake discs consist of alloyed
grey cast iron, they will unavoidably start to
corrode if your car is parked for an extended
period. The brakes will tend to "rub" as a
result.
The nature, extent and effects of corrosion
depend on the amount of time the vehicle was
parked, whether road salt or grit was spread
and whether grease-dissolving agents were
used in car washes.
If the braking comfort is noticeably impaired,
we recommend having the brake system
checked by experts.
Consult a qualified specialist workshop. We
recommend that you use a Porsche partner for
this work since these are staffed with trained
personnel and have the necessary parts and
tools.
166
Driving and Driving Safety
f To relieve the braking system on downhill
stretches, change down to a lower gear in
good time to obtain engine braking.
If engine braking is insufficient on steep
stretches, operate the footbrake at intervals.
Continuous braking overheats the brakes and
reduces the braking effect.
f For information on brake fluid and checking the
brake fluid level:
Please observe the chapter "CHECKING
BRAKE FLUID LEVEL AND CHANGING BRAKE
FLUID" on Page 266.
Brake pads and brake discs
Wear on the brake pads and brake discs depends
to a great extent on the driving style and the condi-
tions of use and therefore cannot be expressed in
actual miles on the road.
The high-performance brake system is designed
for optimal braking effect at all speeds and
temperatures.
Certain speeds, braking forces and ambient condi-
tions (such as temperature and humidity) therefore
might cause the brakes to "squeal".
Warning message
A warning message will appear on the multi-
purpose display of the instrument panel if the wear
limit of the brake pads is reached.
f For information on the warning message on
the multi-purpose display:
Please observe the chapter "OVERVIEW OF
WARNING MESSAGES" on Page 147.
f Have the brake pads changed immediately.
Consult a qualified specialist workshop. We
recommend that you use a Porsche partner for
this work since these are staffed with trained
personnel and have the necessary parts and
tools.