Limited Slip Differential - Porsche 928 GTS 1994 Owner's Manual

Porsche limited-slip differential
(PSD)
The PSD is an electronically controlled differen-
tial lock which switches on automatically without
intervention from the driver.
It is an aid to driving off on road surfaces with
varying degrees of traction and serves to im-
prove driving stability when cornering with high
lateral acceleration.
In spite of this it still remains the responsibility
of the driver to adapt his style of driving to the
prevailing road and weather conditions, as well
as to the current traffic conditions. The higher
degree of safety afforded by this system
must not be regarded as justification for
taking greater risks.
Aid for driving off
The PSD cuts in whenever a speed difference
(slip) of more than 2 km/h occurs in the drive
wheels and the speed of the vehicle is no higher
than 30 km/h (19 mph). The extent of the differ-
ential locking effect is determined by the slip of
the drive wheels. However, some skidding of
both drive wheels cannot be avoided if accelera-
tion is too severe.
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Acceleration out of corners
The PSD cuts in over the entire speed range
whenever the control unit receives a high lateral
acceleration signal when accelerating out of
corners and the inside wheel shows signs of
slipping.
The lock transmits the non-transferable driving
force of the inside wheel to the outside wheel.
The lock is opened for safety reasons if both
wheels slip.
Deceleration in corners
If the control unit receives a high lateral accel-
eration signal at speeds of over 60 km/h (37
mph), a limited-slip torque is also built up when
decelerating in corners to counteract any slew-
ing of the vehicle.
Note
A solenoid valve regulates the gentle built-up and
reduction of the limited-slip torque. The acoustic
timing noise indicates that PSD regulation is oc-
curing.
Should the control unit detect a fault in the
limited-slip differential, the PSD is switched off
for safety reasons and a fault message appears
in the information system display.
You should then have your PSD tested at an Offi-
cal Porsche Centre as soon as possible! The
switching-off of your PSD changes the driving
characteristics of the vehicle.
The switching-off of the ABS System always re-
sults in the PSD being switched off.
The PSD indicator light in the instrument
cluster lights up when the limited-slip differential
is activated or if both drive wheels slip.