brake pads PORSCHE 911 2009 5.G Information Manual

Porsche Stability Management
(PSM).
PSM, an automatic vehicle sta-
bilit y control system designed to
aid the driver in critical road
scenarios, is fit ted as standard.
Sensors monitor the direction,
speed, yaw velocit y (speed of
rotation around the vertical axis)
and lateral acceleration of the car.
Using this information, it is
possible to calculate the actual
direction of travel at any given
moment. If the car begins to over -
steer or understeer, PSM applies
selective braking on individual
wheels to restore stabilit y and
optimum speed. Whenever PSM is
required to intervene, an indicator
light in the cockpit flashes.
When accelerating on wet or other
low-grip surfaces, PSM combines
with PTM and uses the automatic
brake differential (ABD) and anti-
slip regulation (ASR) functions to
maintain traction and stabilit y.
Included as standard equipment,
PSM assists with high -precision
inputs that enhance the agilit y of
each model. When ‘Sport ’ mode is selected on the Sport Chrono
Package Turbo with dynamic
engine mount system (page 58),
the PSM threshold is raised

higher still to enable greater
driver involvement – particularly
at speeds of up to 70 km/ h
(44 mph).
PSM includes ABS to help mini -
mise braking distances. System
inputs are smooth and precise
for greater driver comfort.
Active safet y is further enhanced
with the aid of t wo additional
brake functions: electronic brake
prefill and brake assist.
The prefill function is automati-
cally enabled whenever the

throt tle pedal is suddenly released.
The pressure in the brake lines
is marginally increased, bringing
each 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, by
contrast, is specifically designed
for use in emergency stops.
When the speed of brake pedal
application and the pressure on
the brake pedal exceed a prede -
fined threshold, the hydraulics
automatically apply the necessary
pressure to achieve maximum
deceleration. For a more actively involved

driving experience, PSM can be
manually disabled. PSM remains
present in the background and
will only intervene under heav y
braking where at least one front
wheel requires ABS assistance
(in ‘Sport ’ mode, if both front
wheels require assistance). The
automatic brake differential

(ABD) remains active at all times.
Vehicle yaw
Car steers of f line
Vehicle yaw
Car steers of f line PSM corrects
direction and
stabilises car
PSM corrects
direction and
stabilises carOversteer without PSM
Oversteer with PSM
Understeer with PSM
Understeer without PSM
Performance | Chassis
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Porsche Ceramic Composite
Brake (PCCB).
The new 911 Turbo S models are
equipped as standard with a
braking system that has already
proved it can withstand even
the toughest racing conditions,
such as those encountered in
the Porsche Mobil 1 Supercup.
That system is the Porsche
Ceramic Composite Brake
(PCCB). PCCB is available as an
option for 911 Turbo models. The ceramic discs have a dia
-
meter of 380 mm at the front and
350 mm at the rear. The discs
are made from a specially treated
carbon -fibre compound that is
silicated in a high -vacuum process
at 1,700 °C. The resulting mate -
rial
is not only much harder than
metal, it is also more resistant to
heat.
Even at high temperatures,
the thermal resistance of the

PCCB disc ensures excellent
dimensional stabilit y. The ceramic
material is totally resistant to
corrosion and offers excellent
acoustic damping properties.
The pads are mounted in six-
piston monobloc aluminium fixed
calipers at the front, with four-
piston units at the rear. The
resulting brake forces are both
extremely high and remarkably
consistent. The pedal response is
fast and precise with only moder -
ate input required.
PCCB enables shorter braking
distances in even the toughest
road and race conditions. Excel -
lent fade resistance ensures
greater balance when slowing
from racetrack speeds.
The key advantage of PCCB is
the total weight saving of approximately 50
% over metal
discs with similar construction
and dimensions. As well as
enhancing performance and fuel
economy, this represents a major
reduction in both the unsprung
and rotating masses. This,
of course, produces additional

benefits in terms of comfort
and road-holding on uneven
road surfaces as well as general
handling and agilit y.
Please note that circuit racing,
trackday use and other forms of
performance driving can signi -
ficantly reduce the service life of
even the most durable pads and discs. As with conventional high-
performance braking systems,

we recommend that all brake
components be professionally
inspected and replaced where
necessary after every track event.
PCCB
Responsibility | Safet y
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