Porsche 928 S4 – Owner’s Manual |
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Model Year 1987 From
the “Porsche 928 S4 Owner’s Manual”, available from 928 Specialists. |
With one or both doors open, you can release the hatchback by pulling either the button on the left of the driver’s seat or the respective button on the right of the passenger’s seat. The hatchback will open automatically. Parking brake force is mechanically transferred to the rear wheels by means of cables. Use the parking brake only after the vehicle has come
to a full stop. To set the parking brake Press
in the release button at the end of the lever as you pull the lever up. The parking brake engages as soon as
you release the button in the raised lever. To release the parking
brake Pull
the lever slightly up as you depress the release button. Keep the button depressed as you
lower the lever.
The
central warning light and the parking brake light will go out after the
engine is started and the parking brake is fully released (see “Central warning light system”). Functioning of brake
system Your
Porsche is equipped with a power assisted hydraulic dual circuit brake system
with disc brakes at the front and at the rear. Both circuits function independently. In the unlikely event of hydraulic failure of one
circuit, push the brake pedal down firmly and hold it in that position. A mechanical linkage activates the
second circuit, and you will be able to bring the vehicle to a stop. WARNING Failure of one brake circuit will impair the braking capability resulting in an increased stopping distance. If
one brake circuit has failed, the other will still operate. However, you will notice an increased
pedal travel when you step on the brake. Should you encounter such experience, bring your vehicle
safely to a full stop. Avoid driving the vehicle and instead have it towed to the nearest authorized Porsche dealer. Brake pedal
Brake operation and brake
warning light Make
it a habit to check the operation of your brakes before driving. The
central warning light and the brake fluid warning light in the combination
instrument will flash when the level in the brake fluid reservoir is too low
(see “Central warning light system”). With
correctly adjusted brakes, and a correctly working brake system, the pedal
travel to the point of brake actuation should be 1-3/16” to 1-9/16” or 30 to
40 mm. Whenever the brake pedal
travel exceeds this distance, have the brake system checked. Keep
in mind that the braking distance increases very rapidly as the speed
increases. At 60 mph or 100
km/h, for example, it is not twice but four times longer than at 30 mph or 50
km/h. Tire traction is also less
effective when the roads are wet or slippery. Therefore, always maintain a safe distance from the car in
front of you. Brake booster The brake booster assists braking only when the engine is running. When
the car is moving while the engine is not running, or if the brake booster is
defective, more pressure on the brake pedal is required to bring the car to a
halt. Moisture or road salt on brakes affects braking. WARNING Driving through water may reduce the traction. Moisture on brakes from road water, car wash, or coating of road salt may affect braking efficiency. Cautiously apply brakes to test them after being exposed to such conditions. When the vehicle is driven on salted roads for extended periods, the brakes should be hosed down thoroughly about every 2 weeks. An automatic carwash facility cannot do this job properly. Brakes will dry after a few cautious brake applications. Brake wear Our
automobiles have excellent brakes, but they are still subject to wear,
depending on how the brakes are used.
Have the brake system inspected at the intervals recommended in your
Warranty & Maintenance booklet. New brake pads or linings Brake
pads or linings may not have the highest possible braking efficiency when
new. Therefore, allow for longer
braking distance during the initial 100 to 150 miles or 150 to 250 kilometers
of normal city driving if fewer stops are realized. ABS Brake System
(Antilock
brake system) The
ABS system represents a major contribution to the enhancement of active safety
in your vehicle. This system
prevents the wheels from locking in a panic stop on almost all road surfaces. With ABS system in your vehicle, the following areas are enhanced: Full steerability, vehicle remains steerable
under all braking forces. Good directional control, no swerving caused by
locking of wheels under braking conditions. Excellent stopping distance stopping distances are
usually reduced because controlled braking is maximized. Prevention of wheel lock up, no brake-induced sliding
and thus no localized tire wear from emergency braking. The crucial advantage of ABS system over a conventional brake system is in the area of maintaining directional control and maneuverability of the car in emergency situations, including panic braking in turns. WARNING In spite of the improved handling afforded by the ABS system, it still remains the responsibility of the driver to adapt the driving style to the prevailing road and weather conditions, as well as, obeying traffic laws. In no case, should the higher degree of safety offered by ABS be regarded as a justification for taking greater risks. Other vehicles not equipped with the ABS system may not be able to maintain control, especially on wet or poor road surfaces and thus may be more likely to impact you in the rear. To minimize that risk, use your ABS system to increase your ability to maneuver to avoid dangerous situations and not merely to try to stop in the shortest distance possible. Driving with the ABS
System A
wheel speed sensor is fitted to each of the four wheels. If wheel slippage of either of the
front wheels or the rear wheels is sensed during braking, the brake pressure
is adjusted automatically until the wheel no longer slips. The brake pressure is regulated for
each front wheel individually and for both rear wheels together. On
a road surface which is slippery on only one side, the rear wheel which is
braking on the slippery surface determines the brake pressure which will be
applied equally to both rear wheels.
This ensures that directional stability is maintained. However, if braking force approaches
the wheel locking-up point for all wheels (panic braking) the ABS system will
intervene in a way comparable with rapid rhythmic braking. The proper operation of ABS is
perceived by the driver as a pulsating brake pedal in conjunction with
audible noise and perhaps some vibration. The driver is thereby warned to reduce vehicle speed
appropriate for the prevailing road conditions. If
your ABS system should ever malfunction, the ABS system is automatically
switched off, but the normal brake system, without ABS, would remain fully
operational. Such a malfunction
would be indicated by the illumination of the central warning light, as well
as the “ANTILOCK” light on the right hand side of the instrument cluster. If the ABS system becomes inoperative, take your vehicle to your authorized dealer immediately. Due
to the hydraulic operation of the clutch, a free travel of the clutch pedal
of 0.1” or 2.5 mm is necessary. Should
this free travel suddenly become bigger, it could mean a malfunction of the
clutch. See your Porsche dealer
for rectification. Always
depress the clutch pedal fully when changing gears. Do not hold the car on a steep hill with the clutch pedal
partially depressed. This will
cause premature wear or damage. |
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