brake sensor PORSCHE 911 TURBO 2004 4.G Information Manual

Tiptronic S also includes a warm-
up function designed to minimise
exhaust emissions. When the
car is started, the engine speed is
increased so that the catalytic
converters reach their optimum
operating temperature within the
shortest possible time. braking on descent. This, of
course, helps to reduce the
load on the braking system. If
traction is lost under braking
in the wet or on snow, the system
automatically changes up to
restore lateral grip and bring the
car back into line. there is no need to use a kick-
down function. Unlike conventional
automatic systems, Tiptronic S
does not shift up when the throttle
is released, thus enabling
optimum acceleration when exiting
a corner with no loss of stability
due to changes in load. Mid-corner
gearshifts are also prevented,
thereby enhancing stability and
safety. Under heavy braking, the
system shifts down, using engine
braking to slow the car. The
function is enabled during high-
performance use when the driver
releases the throttle to apply
the brake within a period of
1.5 seconds. These active
downshifts enhance the car’s
performance, particularly when
braking for a corner. Under
prolonged braking, additional
downshifts are performed based
on the amount of brake force
applied. An incline sensor
improves uphill acceleration and
makes better use of engine
The 911 Turbo is available with
optional five-speed Tiptronic S
offering a highly rapid gearshift
action. This versatile option offers
fully automatic five-speed
operation as well as direct manual
control.
In manual mode, you can change
gear by hand using gearshift
controls on the steering wheel.
Simply press up to change up,
and down to change down. The
clutch function is fully automatic.In automatic mode, the standard
gearshift pattern, designed
for maximum fuel economy, can
be steplessly varied up to a
dedicated ‘Sport’ configuration
for optimum high-performance
driving. Each gearshift point is
automatically selected based on
current driving style and road
conditions. Within a short space
of time, you’ll develop a feel for
the system and begin to influence
gearshifts using the throttle alone.
The benefits of Tiptronic S are
particularly apparent when
exploring the car’s potential. Even
in automatic, the rapid gearshift
action enables remarkable agility
under acceleration. The imme-
diacy of response, with virtually
no interruption in drive, is now
more than comparable with a
Porsche manual gearbox. At just
3.7 seconds, the new 911 Turbo
with Tiptronic S is 0.2 seconds
quicker to 100 km / h (62 mph)
than the standard manually
equipped car.
While still in automatic, you can
change gear by hand using the
rocker controls on the steering
wheel. If there is no manual input
for a period of 8 seconds,
the system reverts to automatic
mode.
If the car is driven more assertively,
the system automatically selects
the ‘Sport’ gearshift pattern, i.e.,
· 46 ·· 47 ·The new 911 Turbo |
Drive
Tiptronic S gear selector lever Tiptronic S control on steering wheel
Tiptronic S.
Manual and automatic in one versatile solution.

using the automatic brake
differential (ABD) function. For
optimum traction, manual gearbox
cars can also be equipped with
an optional mechanical limited-slip
rear differential (see page 56).
Assisting PTM is a new and
specially uprated version of
Porsche Stability Management
(PSM – see page 58). Combined,
these systems ensure optimum
torque distribution – and thus
optimum drive – in every type of
road scenario, including high-
speed straights, hairpin bends and
challenging, variable-grip surfaces.
Under heavy braking where ABS
is required, the multi-plate clutch
severs all front drive so that
each front wheel can be controlled
separately
by the ABS without
being influenced by the rear wheel
dynamics.
The traction benefits of the new
electronically controlled system
are particularly apparent in
the wet or on snow. In these
conditions, the new 911 Turbo
offers breathtaking acceleration.
In short, PTM offers greater
active safety, greater performance,
and even more of the positive
handling and agility you’d expect
from a 911 Turbo.
· 49 ·The new 911 Turbo |
Drive
differential (ABD) and anti-slip
regulation (ASR).
The electronically controlled clutch
is used to vary the drive torque
transmitted to the front axle. The
previous 911 Turbo had a multi-
plate clutch filled with a viscous
fluid, which ‘passively’ determined
the front/rear torque split. On
this latest evolution, the fluid is
replaced by active, electronic
control.While the viscous-fluid system
responds to relative differences in
front/rear axle speed, the new
electronic clutch offers a more
direct response to changing road
scenarios. The status of the car
is continuously monitored with the
aid of on-board sensors. These
are used to measure a range of
values, including the rotational
speed of all four wheels, the lateral
and longitudinal acceleration of
the car, and the current steering
angle. The sensor data is analysed
in ‘real time’ by PTM, enabling
immediate adjustments in front-end
drive torque as and when required.
If, for example, the rear wheels
lose traction under acceleration, a
greater proportion of drive torque
is automatically transmitted to
the front axle. The integral ASR
function is also used to minimise
wheel-spin. When
cornering,
the system controls drive to the
front wheels in order to maintain
optimum lateral grip. On variable-
grip surfaces, traction is enhanced
· 48 · Electronically controlled multi-plate clutchAll-wheel drive system
Genuine high performance calls for
more than just a powerful engine.
It also requires an effective means
of applying that power to the road.
On the 911 Turbo, this is achieved
by means of permanent all-wheel
drive and an all-new version of
Porsche Traction Management
(PTM). The key mechanical feature
within the AWD system is the
electronically controlled multi-plate
clutch. Integral functions within
PTM include an automatic brake
Electronically controlled all-wheel drive with Porsche Traction Management (PTM).
The intelligent application of power and torque.

This latest evolution of Porsche
Stability Management (PSM)
provides automatic assistance in
critical road scenarios. A powerful
driver aid, it uses a range of
sensors to monitor the direction,
speed, yaw velocity (speed of
rotation around the vertical axis)
and lateral acceleration of the car.
With this information, it can
then calculate the actual direction
of travel. If the car begins to
oversteer or understeer, PSM
applies selective braking onindividual wheels to bring it safely
back into line. Whenever PSM is
required to intervene, an indicator
light in the cockpit is illuminated.
Another scenario in which PSM is
invaluable is when applying the
throttle on wet or other low-grip
surfaces. Here, PSM uses the ABD
(automatic brake differential) and
ASR (anti-slip regulation) functions
in PTM to maintain traction and
stability.Standard equipment on the
911 Turbo, PSM assists with high-
precision inputs that enhance the
athleticism and agility of the car.
When ‘Sport’ mode is selected
on the optional Sport Chrono
Package Turbo (see page 60),
the PSM threshold is raised
higher still enabling greater driver
involvement – particularly
at speeds of up to 70 km / h
(44 mph).
The integral ABS ensures shorter
braking distances in critical road
scenarios. System inputs are
smooth and precise fo r greater
driver comfort. Active safety is
further enhanced with the aid of
two additional brake functions:
electronic brake prefill and brake
assist.
The prefill function is automatically
enabled whenever the throttle
pedal is suddenly released. The
pressure in the brake lines is
marginally increased, bringingeach of the pads into light contact
with the corresponding disc. If
the driver then decides to use the
brakes, the system can apply
the maximum force with virtually
no delay.
The brake assist function is
specifically designed for use in
emergency stops. When the
pressure on the brake pedal
exceeds a predefined threshold,the brake assist function uses
the PSM hydraulics to apply the
pressure required for maximum
deceleration. The result: shorter
braking distances.
For a more natural drive, PSM can
be manually disabled leaving only
the automatic brake differential
(ABD) in place. Although essentially
inactive, PSM remains present in
the background and can intervene
immediately under heavy braking
where at least one front wheel
requires ABS assistance. In ‘Sport’
mode, PSM will only respond
when ABS is active on both front
wheels.
In short, PSM provides the ideal
balance between electronically
assisted active safety and
freedom to enjoy the car’s
potential.
· 58 ·· 59 ·
Oversteer without PSM Oversteer with PSM
Car steers off line
Car steers off line PSM corrects
steering and
stabilises car
PSM corrects
steering and
stabilises car
Understeer without PSM Understeer with PSM
The new 911 Turbo |Chassis
Porsche Stability Management (PSM).
Enhanced stability control for the new 911 Turbo.