Porsche 928 S 1986 Driver Manual page 20

Handbrake
The handbrake is cable operated to the rear
wheels only. It is applied by pulling the lever
upwards.
To release the brake, the lever must be pulled
upwards slightly whilst pressing the button in
the end of the lever until the ratchet is cleared,
and then letting the lever downwards.
The central warning light and the handbrake
warning light will go out when the brake lever
is fully released. (See Automatic warning unit.)
18
Footbrake
To reduce the pedal effort necessary when
braking, your Porsche has a brake servo unit.
The vacuum necessary to operate this unit is
taken from the engine inlet manifold, when
the engine is running.
Please note that with a defective servo unit,
or when the vehicle is being towed with the
engine turned off, the braking effort required
is considerably increased as soon as the
vacuum reservoir is used up.
With properly bled and functioning brakes, the
free movement of the brake pedal will remain
constant. This free travel before the brakes
start to operate can be 20 mm (0.8 ins.).
Should this free travel suddenly become bigger,
it could be that air has entered the brake sys-
tem. Low brake fluid level is indicated by the
flashing of the central warning light (see Cent-
ral warning unit). In addition, the "brake fluid"
label in the right-hand instrument cluster lights
up.
Clutch
Due to the hydraulic operation of the clutch,
a free travel of the clutch pedal of 2.5 mm is
necessary.
Should this free travel suddenly become
bigger, it could mean a malfunction of the
clutch. Please consult your workshop for
rectification.