Porsche 911 TURBO - 1975 WORSHOP, Manual

Page: 56 / 252

56
Controls, Safety, Instruments
Porsche Traction Management
(PTM)
With PTM, the drive power is variably distributed to
the front and rear wheels.
Power distribution between the front and rear
axles is performed by a map-controlled multiple-
disc clutch.
Distribution of the drive power also depends on
the difference in wheel speed between the two
axles.
The multiple-disc clutch always delivers sufficient
drive power to the front wheels to ensure optimum
propulsion even on an unfavourable road surface.
In combination with Porsche Stability Management
(PSM), the PTM ensures optimum handling and
high driving stability.
Danger!
In spite of the advantages of PTM, it is still the
driver's responsibility to adapt his/her driving
style and manoeuvres in line with road and
weather conditions, as well as the traffic situation.
The increased safety that is provided should not
induce you to take greater risks with your safety.
The limits set by the physics of driving cannot be
overcome, even with PTM.
Risks of accident due to inappropriate speed
cannot be reduced by PTM.
Checks on test stands
Power measurement
Performance tests on roller test stands are not
approved by Porsche.
Brake tests
Brake tests must be performed only on plate-type
test stands or roller test stands.
The ignition must be off.
The following limit values must not be exceeded
on roller test stands:
– Testing speed 8 km/h (5 mph)
– Test duration 20 seconds
Handbrake check
Handbrake tests on the roller brake tester must
only be carried out with the ignition switched
off .
Balancing wheels on the vehicle
During finish balancing of the wheels, the vehicle
must be lifted and the wheels must be free to turn.
Towing
f
Please observe the chapter “TOWING AND
TOW-STARTING” on page 231.
Wheels/tyres
The PTM control unit is adapted to the approved
tyre sizes. The use of non-approved tyre sizes may
lead to deviations in wheel speeds and it may influ-
ence handling or result in the PTM switching off.