The Phaeton Chassis

Service.
Self-Study Programme 277
The Phaeton
Chassis
Design and function
In top form, the Phaeton chassis fulfils even the
most challenging demands on comfort and
driving dynamics.
Through its components, including
-
Speed dependent power-assisted steering,
Four-link front suspension,
Trapezoidal wishbone rear suspension and
ESP with braking assistant,
it achieves an important contribution towards
active vehicle safety.
S277_033
NEW
The self-study programme presents the design
and operation of new developments!
Contents will not be updated.
2
Current testing, adjustment and repair
instructions may be found in the appropriate
service material.
Caution
Note
At a Glance
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Front axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Rear axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Steering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Wheels and tyres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Tyre pressure monitor . . . . . . . . . . . . . . . . . . . . . . . . . .48
Check your Knowledge . . . . . . . . . . . . . . . . . . . . . . . .59
3
Introduction
The chassis
●
●
●
Trapezoidal wishbone rear
suspension with 1612 mm
track width
Front and rear
anti-roll bars
●
Independent wheel
suspension front and
rear
●
4
Four-link front suspension with
1628 mm track width
4-corner air suspension with
regulated damping
S277_002
●
●
●
●
●
Foot parking brake
●
Braking assistant
Speed dependent
power-assisted steering
Ventilated disc brakes
Tyre pressure monitor, optional
Electronic Stability Programme, Bosch 5.7
5
Front axle
The front axle
S277_129
The Phaeton's front axle is equipped with four-link suspension.
The multitude of guide elements produces the following advantages:
-
6
Complete isolation of drive forces from the steering
High steering precision through optimised positioning of the pivot axis
Good driving comfort
Exceptional anti-squat and anti-dive performance
The component overview
Bearing block
aluminium cast part
The upper suspension links
(front and rear)
aluminium forged parts
Wheel bearing housing
steel cast part
Subframe made of
hydroformed steel
Guide link
aluminium forged part
Anti-roll bar
steel
S277_010
Bearing link
steel forged part
7
Front axle
The bolted wheel bearing
The wheel bearings are not pressed into the
wheel bearing housing as was the practice up to
now, but bolted directly to the wheel bearing
housing as a unit (bearing and bearing housing).
Wheel hub
Wheel bearing
housing
Bolted connection
This enables the wheel bearing to be installed
without removing the pivot bearing or jointed
shaft.
Wheel
bearing
Bolted
connection
S277_044
The anti-roll bar
Depending on the engine, the Phaeton has either
a solid anti-roll bar of 35 mm diameter or a
tubular anti-roll bar of 35 mm diameter and
6 mm wall thickness.
The intermediate rubber bearings and
aluminium pipe clamps are vulcanised on in this
design and cannot be replaced.
Rubber bearing with
aluminium pipe clamps
This support arrangement, which was designed
to have radially rigid and rotationally flexible
characteristics, prevents noise and wear.
S277_025
8
The subframe
The high-pressure formed subframe of tubular
steel is bolted to the body using rubber-metal
bearings. This flexible connection keeps the body
free of forces and impacts that the chassis
introduces.
The additional bolted brace ensures ample
transverse rigidity.
Brace
S277_026
The connection of the air suspension strut to the suspension link
The air suspension strut is attached to the
bearing link with a rubber-metal bearing.
Air suspension
strut
Bearing link
S277_037
9
Front axle
The virtual steering axis
1-4 Directions of the suspension links
R
Wheel centre point
A
Wheel contact point
n
Trail
nv Castor offset
p
Scrub radius
a
Road feedback lever arm
Point AS = Piercing point of the
steering axis on the
roadway
S277_029
With the four-link front suspension, the steering
axis does not run through the upper and lower
joints on the wheel bearing housing as with
previously familiar front axle designs. Instead it
runs through the intersection points formed by
extrapolating the connection lines of the two
upper and two lower suspension link joints
respectively.
Thus, the suspension link axis is in free space and
does not change position at full steering lock.
This is why we refer to it as the virtual steering
axis.
10
This arrangement enables the steering axis to be
placed close to the wheel centre plane.
This has a positive effect especially on the scrub
radius and the road feedback lever arm, and
thus produces advantages in driving behaviour.
The full steering lock positions
This axle design allows the virtual steering axis,
around which the wheel moves and whose
position determines the castor angle and the
steering swivel inclination, to be shifted much
further out. By optimising the axle geometry, it is
possible to completely isolate torque steer effects
on the steering.
S277_070
Link position for left curve
Since the wheels are located using four ball
sockets on the respective transverse links, the
pivot axis can run approximately in the wheel
centre independently of construction space
requirements. The pivot axis is designed to
change position according to the steering
movements.
The defined movement of the axis when steering
reduces the space requirements in comparison to
conventional axle systems with fixed space
steering axes.
The virtual steering axis changes position
depending on the steering movements.
S277_040
Link position for straight driving
S277_072
Link position for right curve
11
Rear axle
The rear axle, front wheel drive
In the Phaeton, the rear axle is designed with
trapezoidal (unequal length) wishbone
suspension. All wheel location elements are
mounted to a subframe that is rigid in bending,
torsion and warping.
This is connected to the body using largedimensioned rubber bearings. This type of
structure achieves exact wheel location and
good ride.
S277_101
The wheel hub
Wheel bearing
housing
Instead of the bolted constant velocity (CV) joint
pivot, the wheel bearing is prestressed with a
stub axle.
Bolted connection
The rear axle for front wheel drive vehicles is
equivalent to the axle for all-wheel drive
vehicles.
Rear axle drive and jointed shafts are not used.
Stub axle
Bolted connection
S277_046
12
The rear axle 4-motion
In the 4-motion version, the subframe holds the
rear differential at three points. Therefore, the
rear differential is doubly isolated from the body.
S277_016
13
Rear axle
Steel subframe
Transverse link
aluminium forged part
Rubber-metal bearing
Axle link aluminium
cast part
S277_068
Bolted joint
for camber correction
Bolted joint
for track correction
Wheel bearing
housing
Track rod
Coupler
Integrating a coupler into the hub carrier
connection and using a track rod has optimised
the toe-in behaviour of the rear axle.
14
S277_018
In particular, the passive steering properties and
noise insulation have consistently improved.
The anti-roll bar
Rubber bearings
An anti-roll bar made of 20 mm solid material
has been installed on the rear axle.
The rubber bearings are vulcanised on as in the
front axle. This design is free of noise and wear.
S277_031
The wheel bearing housing
With the rear axle, as with the front axle, the
wheel bearings are bolted to the wheel bearing
housing. The wheel bearings on the front and
rear axles are identical in construction.
Wheel hub
Wheel bearing
housing
Bolted connection
Bolted connection
S277_044
15
Measurement
The particularities of measurement
The Phaeton is equipped with 4-corner air
suspension as standard.
Before every measurement, the level position of
each suspension strut must be checked.
In addition, a toe-in value is set at the front axle
when the suspension is extended.
The adjustment must be made with the wheel
extended by 60 mm when the vehicle is empty.
When measuring the vehicle, the familiar
parameters, camber and toe-in, must be
adjusted on the rear or front axle.
Adjusting the toe-in curve with the wheel in an
extended state sets the toe-in curve for driving
stability.
Toe-in curve diagram
Extension in mm
-120.
-100.
-80.
-60.
-40.
-20.
60.
40.
-20.
20.
-40.
-60.
Toe-in in degrees
20.
40.
60.
80.
S277_042
16
100.
Compression in mm
The following steps are important when performing the front-end alignment:
- Setting the basic toe-in with an empty vehicle by changing the length of the track rod
- Setting the inclination of the toe-in curve by changing the height of the outer
track rod joint
S277_021
h
A
S277_020
h = Adjustment range for the toe-in curve
A = Adjustment option for independent toe-in
17
Steering system
The steering system
Overview
S277_093
The steering column
The Phaeton is equipped with an adjustable
steering column. The travel range is 50 mm in the
axial direction and 40 mm in the vertical
direction. The steering column is available with
either manual or electric adjustment.
S277_083
18
Adjustment of the steering column - mechanical adjustment
Steering tube
Disc pack
S277_066
unclamped
clamped
With manual adjustment, eight steel discs lock the steering column in place on each side of the steering
tube using a clamping mechanism. Here there are four discs for axial adjustment and four discs for
vertical adjustment per side.
The advantage: infinite adjustment with high holding forces.
Adjustment of the steering column - electrical adjustment
The electric steering column is essentially the
same in concept as the manually adjustable
steering column with reference to kinematics,
adjustment field, installation space, connection
and crash concept.
Console
The electric steering column is infinitely
adjustable in the axial and vertical directions
and is driven by electric motors.
Pull tab
Motor
for axial adjustment
Crash carriage
Spindle
for vertical adjustment
S277_081
19
Steering system
Adjustment of the steering column - circuit diagram
The comfort CAN bus carries the command
signal to adjust the steering column, and the
control unit for driver seat/mirror position
processes it.
The steering column electronics control unit
interprets and reads the driver's wish from the
steering column adjustment button and places
the signal on the comfort CAN bus.
The control unit for driver seat/mirror position
then sets the motors to the corresponding
position.
Hall sensors in the adjuster motors send the
return signal to the control unit for driver seat/
mirror position.
Switch for
steering column adjustment
± Z, ± Y
Control unit for
steering column electronics
J527
Steering column
adjustment motor, Z
Steering column Z position
Control unit for
driver seat/mirror position
J543
Steering column Y position
Steering column
adjustment motor, Y
S277_091
20
The electric steering column lock
The Phaeton uses an electric steering column lock
instead of a mechanical steering lock.
The electric steering column lock is an integrated
system with an electrical interface to the access
and start authorisation control unit and a
mechanical interface to the steering column.
Locking collar
unlock
Locking star
lock
Push rod
Worm gear
S277_074
Motor for steering
column lock, N360
Control unit with two
Hall sensors
Control unit for access and
start authorisation, J518
When the electric motor is activated, the worm gear moves the push rod in the longitudinal direction. To
lock the steering column (terminal 15, out), the inner-toothed locking collar is pushed over the conical,
outer-toothed locking star until it stops. To unlock the steering column (terminal S, in), the locking collar is
pulled away from the locking star.
21
Steering system
The Servotronic
Design and function
The Phaeton is equipped with Servotronic. This
hydraulic steering system, which is electronically
controlled and speed dependent, is distinguished
by light, comfortable steering while parking and
a safe driving feel with increasing speed.
Power-steering
pump
Servotronic
solenoid
valve, N119
S277_049
22
The Servotronic characteristic curve diagram
Pressure p (bar)
120
100
0 km/h
80
50 km/h
60
120 km/h
40
20
0
10
8
6
4
2
0
2
4
6
8
10
S277_051
Application moment (Nm)
The diagram shows how the pressure changes
with respect to application moment in relation to
driving speed.
The characteristic curve has been specifically
adjusted to the vehicle character.
The Servotronic steering system is based on
hydraulic steering.
The hydraulic steering's modified rotary valve
uses the principle of direct hydraulic reaction
(feedback).
Using an electro-hydraulic converter and
reconfiguring the steering valve accordingly has
enabled the Servotronic system to operate
according to driving speed.
23
Steering system
The electric control
The Servotronic control unit evaluates the road
speed signal from the dash panel insert and
converts the signal into modulated current.
This actuates the N119 solenoid valve.
The N119 solenoid valve determines the hydraulic
reaction at the rotary valve and thus the
application moment at the steering wheel.
The speed dependent influence on the steering
translates into minimum forces required for
steering at still stand and low speeds.
Since the hydraulic reaction changes in relation
to diving speed, the application force at the
steering wheel increases with increasing speed.
This gives the driver especially good contact with
the roadway, allowing the driver to steer
accurately.
Road speed signal
15
31
Servotronic solenoid valve, N119
S277_095
24
Safety with the Servotronic system
The steering system remains fully functional if the
vehicle electrical system fails or other electrical
faults occur.
The Servotronic system then works using the
mechanical forced opening of the N119 solenoid
valve at maximum hydraulic reaction (fast speed
characteristic curve).
If the road speed signal fails while driving, the
Servotronic system remains at the last given
control range until the ignition is switched off.
The next time the motor is started, the maximum
hydraulic reaction develops, according to the
fast speed characteristic curve.
The characteristic curve for control current to the solenoid valve
900
Converter current I [mA]
800
700
600
500
400
300
200
100
0
Tacho frequency fe [Hz]
0
0
20
20
40
60
40
80
60
100
80
120
100
140
120
160
140
180
160
S277_067
Driving speed v [km/h]
25
Steering system
The rotary valve in neutral position - vehicle stationary
The familiar hydraulic pump generates the
pressure that the Servotronic system requires,
about 130 bar, which is transferred to the rotary
valve. In the valve unit is a torsion bar, which is
pinned to the rotary valve on one side and to the
driving pinion and control bush on the other side.
The torsion bar is responsible for centering
(neutral position).
Control unit
Rotary valve
Control bush
Road speed signal
Torsion bar
Return
Torsion bar
from the pump
Pin connection
Reaction
piston
Solenoid valve for
Servotronic
Working cylinder,
left
Rotary valve
Working cylinder,
right
S277_053
Working cylinder,
left
26
Working cylinder,
right
Control bush
Pressure and flow
relief valve
The oil that the hydraulic pump supplies flows
through the connection hole in the valve region
and into the inflow radial channel. It then flows
into the cross holes in the control bush to the
inflow control channels in the rotary valve. In the
valve neutral position, the oil flows via the open
inflow control vanes into all axial channels in the
control bush. From there it flows via the open
return control vanes also into the return control
channels in the rotary valve.
From these channels, the oil can flow through
connections into the return chamber, and from
there back to the oil reservoir. At the same time,
the radial channels in the valve body and the
associated tube lines connect the right and left
working cylinder chambers.
Return
control channel
Return
control vane
Inflow
radial channel
Inflow
control channel
Inflow
control vane
Axial channel
S277_055
Radial channel
Reaction piston
Inflow radial channel
Radial channel
Reaction chamber
Return chamber
Right working cylinder
Left working cylinder
from the pump
Return
Control bush
S277_057
27
Steering system
The rotary valve in working position, left full steering lock - driving at low speed
At left full steering lock, oil must flow to the right
side of the working cylinder to assist the steering
effort.
The force at the steering wheel turns the torsion
bar in its elastic range, since it is pinned to the
rotary valve at the top and to the control bush
and driving pinion at the bottom.
The pressurised oil travels via the inflow control
vanes, which are further open, into the
associated axial channels, through the hole in
the radial channel and via a tube line to the right
cylinder chamber, thus hydraulically assisting the
steering rack to move. The pressurised oil in the
right cylinder chamber pushes the oil out of the
left cylinder chamber into the return line.
The torsion bar, which narrows in the
appropriate region, turns the rotary valve
against the control bush.
If the driver releases the steering wheel, the
torsion bar ensures that the rotary valve and the
control bush spring back into the neutral position.
Control unit
Rotary valve
Control bush
Road speed signal
Torsion bar
Return
Torsion bar
from the pump
Reaction
piston
Solenoid valve for
Servotronic
Working cylinder,
left
Pin connection
Rotary valve
Working cylinder,
right
S277_059
Working cylinder,
left
28
Working cylinder,
right
Control bush
Pressure and flow
relief valve
The servotronic control unit evaluates the road
speed signal and passes it on to the N119
solenoid valve as modulated control current.
Due to the maximum current produced in this
driving situation, the N119 solenoid valve closes
and prevents oil from flowing from the inflow
radial channel to the reaction chamber.
A baffle ensures that the return pressure level
also acts in the reaction chamber.
Thus, the Servotronic rotary valve behaves as a
normal rotary valve in this situation.
The steering is light and can be operated with
little effort since the reaction has been
eliminated.
Baffle
Radial channel
Inflow radial channel
Reaction piston
Solenoid valve for
Servotronic
Radial channel
Reaction chamber
Return chamber
Right working cylinder
Left working cylinder
Control bush
from the pump
Return
S277_061
29
Steering system
The rotary valve in working position, right full steering lock - driving at high speed
At right full steering lock, oil must flow to the left
side of the working cylinder to assist the steering
effort.
The force at the steering wheel turns the torsion
bar in its elastic range, since it is pinned to the
rotary valve at the top and to the control bush
and driving pinion at the bottom.
The torsion bar, which narrows in the
appropriate region, turns the rotary valve
against the control bush.
The pressurised oil travels via the inflow control
vanes, which are further open, into the
associated axial channels, through the hole in
the radial channel and via a tube line to the left
cylinder chamber, thus hydraulically assisting the
steering rack to move.
The pressurised oil in the left cylinder chamber
pushes the oil out of the right cylinder chamber
into the return line. If the driver releases the
steering wheel, the torsion bar ensures that the
rotary valve and the control bush spring back
into the neutral position.
Rotary valve
Control unit
Control bush
Road speed signal
Torsion bar
Return
Torsion bar
Pin connection
from the pump
Reaction
piston
Rotary valve
Solenoid valve for
Servotronic
Working cylinder,
left
Working cylinder,
right
S277_063
Working cylinder,
left
30
Working cylinder,
right
Control bush
Pressure and flow
relief valve
As the speed increases, the Servotronic control
unit reduces the control current to the N119
solenoid valve. With this, the N119 solenoid valve
takes on a certain opening position and enables
a limited oil inflow from the inflow radial channel
into the reaction chamber. A baffle prevents
large amounts of oil from flowing out into the
return chamber, so that higher pressure develops
in the reaction chamber. The increased pressure
acting on the reaction piston then generates a
greater pressing force on the balls guided by
V-ways. These balls are located between the
reaction piston and the centering piece, which is
firmly joined to the control bush.
Baffle
During straight driving, this has a positive effect
on the centering of the rotary valve, making it
particularly exact. When the rotary valve pivots,
the balls, which are now more highly loaded,
exert additional resistance against turning of the
rotary valve. Therefore, with the hydraulic
reaction in this sequence of operations, the
specifically determined application moment
required to move the steering wheel is higher.
Ball
Reaction piston
Inflow radial channel
Reaction chamber
Solenoid valve for
Servotronic
Centering piece
Cut-off valve
Return chamber
Control bush
S277_065
At high driving speeds, the N119 solenoid valve is
completely open due to the very low or zero
control current. Thus, the inflow radial channel
supplies maximum pressure to the reaction
system. When the driver turns the steering wheel
to the right, the reaction pressure also increases
corresponding to the prevailing operating
pressure and pushes the reaction piston out of
the reaction chamber.
As soon as the reaction pressure, which is
determined specifically for the vehicle, is
reached, the cut-off valve opens and the oil flows
out into the return chamber so that the pressure
does not increase further. The application
moment at the steering wheel now does not
increase further, and conveys a secure driving
feel through optimum contact with the roadway.
31
Brake system
The brake system
The Phaeton’s high performance brake system consists of newly developed front and rear wheel brakes.
Foot parking brake
Pedal cluster
Dual brake servo
ABS hydraulic unit
Front wheel brake
32
The brake system is fitted with the Bosch ABS System 5.7 with integrated ESP as standard.
It is diagonally separated into 2 circuits. The Phaeton has large ventilated brake discs front and rear.
S277_006
Rear wheel brake
Brake cables
Brake lines
33
Brake system
The brake equipment (all brake parts are made of aluminium)
Engine
Front
Rear
V6
Ø 323 mm x 30 mm
Ø 280 mm x 22 mm
V8
Ø 360 mm x 34 mm
Ø 310 mm x 22 mm
V10 TDI, W12
Ø 365 mm x 34 mm
Ø 335 mm x 22 mm
The wheel brakes
To satisfy demanding safety requirements and guarantee a high level of comfort, the wheel brakes have
been specially designed for the Phaeton.
The front wheel brakes
A new aluminium brake calliper was developed
for the Phaeton's 18" front wheel brake. This lightweight brake calliper consists of an
unseparated housing in a monoblock design with
8 pistons and 4 brake pads.
This arrangement ensures optimum conditions for
pressing the brake pads onto the brake disc. The
brake calliper design, which has a wide reach
around the friction ring, achieves a low weight
combined with optimal calliper stiffness.
S277_103
34
The front brake disc
The front brake disc is constructed from two
parts. The friction ring is attached to the brake
disc cup with sliders.
The design allows the brake disc to freely expand
radially.
This significantly improves the thermal shock
resistance, that is, it increases the life of the brake
disc. At the same time, this type of
connection has a favourable effect on the
deformation of the friction ring under
temperature loading. Thus, the noise behaviour
is also improved.
A positive spin-off of this design is the weight
saved by manufacturing the cup from aluminium.
The specially formed cooling ribs provide a
robust construction with optimal flow-through.
Specially shaped rims and an air guide part
guide the air stream directly to the brake disc.
Brake disc cup
made of aluminium
S277_012
Slider
Friction ring
The rear wheel brakes
The Phaeton's rear wheel brakes are highperformance, ventilated disc brakes. The brakes
use a newly developed aluminium brake calliper.
The parking brake feature is integrated into the
brake calliper.
S277_008
35
Brake system
Actuation of the rear wheel brakes
When the driver applies the hand brake, the brake cables actuate the parking brake lever on the brake
calliper. The actuating shaft turns and performs a stroke.
The mounting of the actuating shaft on three balls, which are positioned on a sloped disc, produces the
stroke. The stroke movement actuates the piston which clamps the brake calliper and presses the brake
pads against the brake disc.
Automatic resetting
To retain the mechanical and hydraulic function
of the brakes in this system, the increase in
clearance that results from brake pad wear must
be compensated by resetting.
A turning action of the resetting nut on the thread
of the push bar resets the clearance increase that
results from brake pad wear.
Push bar
Sloped disc
Parking brake lever
Actuating shaft
Brake pad
Housing
Compression
spring
Resetting nut
Spring washer
Piston
Brake disc
S277_108
36
S277_110
Push bar
Resetting nut
Increased clearance
When the driver applies the brakes and hydraulic pressure
develops in the brake system and brake callipers, the piston
moves in the housing towards the brake disc.
The resetting nut is carried in the piston by a spring washer.
If the clearance increases due to brake pad wear, it is
compensated in the thread between the push bar and
resetting nut. The force of the compression spring on the
resetting nut acts against the pressing direction of the piston.
This opens the cone clutch between the resetting nut and the
piston (figures A and B).
S277_112
Cone clutch
S277_114
Nominal clearance
The push bar is held by the compression spring; the turns of
the thread between the push bar and resetting nut are
engaged in this resetting sequence. The coarse-pitch thread
between the push bar and resetting nut produces a turning
moment on the resetting nut.
The cone clutch between the resetting nut and the piston
opens far enough so that the resetting nut can turn on the
thread of the push bar by the amount of the increased
clearance in the brake application direction. This resetting
process takes places also when the brake calliper is relieved,
that is, after the braking process. Thus the brake wear that
occurs while braking is directly and non-incrementally reset.
After the brake calliper is relieved, a clearance between the
brake pads and brake disc appears (figure D).
The nominal clearance is the play between the resetting nut
and push bar thread determined by tolerances (figure C).
S277_116
Clearance
37
Brake system
The foot parking brake
Release cable
Release lever
Pedal
For the first time, Volkswagen has introduced in
the Phaeton a foot parking brake, distinguished
by its low weight, minimum release force and
responsive design. The pedal cluster is
manufactured from aluminium alloy.
The parking brake is located in the left of the
footwell above the foot rest. The parking brake is
applied by pressing the pedal.
38
Control cable
S277_109
When the driver presses the foot parking brake
pedal, a control cable transfers the applied force
to a lever mechanism under the floor of the
vehicle. Here, the force is divided over two brake
cables, which operate the actuating mechanisms
on the rear wheel brakes.
The parking brake is released by pulling the
release lever below the light rotary switch by
hand.
Drum
Release cable
Coil spring
Coil spring
Cable retainer
Drum
Plastic spring
Retainer for
release cable
Control cable
S277_156
Pedal
The coil spring, which acts on a drum, takes on
the brake locking function. The spring slides on
the drum and expands due to the direction of
movement. If the counter force of the brake
moves the spring in the other direction, it pulls
together and increases the friction between the
coil spring and drum. Thus, the pedal locking
action is almost completely stepless and
noiseless.
An additional plastic spring produces the typical
click sound when the pedal is pressed.
When the driver pulls the release lever, the
retainer of the release cable is drawn upwards.
This expands the coil spring, or in other words,
the spring becomes moveable and the pedal can
return to the initial position. This principle
requires low release forces.
Expand
S277_152
Lock:
The coil spring presses against the drum when
the pedal moves in the opposing direction.
S277_154
Release:
The diameter of the coil spring becomes larger
when the spring expands. The coil spring can
move on the drum.
39
Brake system
The brake lines and brake cables
The brake line system connects the hydraulic
components of the brake system. The brake lines
consist of galvanised steel pipes, which have a
resistant surface protection provided by the zinc
plating and an additional polyamide coating.
These lines are attached to the body with plastic
holders.
A robust, hard outer shell is used for attachment.
Injected, soft elements are used for noise
insulation.
The moveable connections in the lines to the front
and rear axles are brake tubes. The inner tube
consists of a material that keeps water
absorption into the brake fluid low. For
stabilisation, this tube has several braided fibre
sleeves, which are protected against external
influences by CR rubber.
The lines in the engine compartment as well as
those in the connection lines between the ESP
unit and the brake servo are connected to plastic
tubes with braided steel sheathing. The structure
of these lines also reduces noise transfer from the
unit during operation.
The hand brake cable
Structure of the hand brake cable
Profile wire spiral made of
bare drawn stranding wire
Polyamide
Protective shell made of
polyurethane
Lining tube made of
Polyamide
Wire strand made of drawn
stranding wires
The brake cables are sheathed in polyamide and
greased to prevent corrosion and reduce friction
forces.
40
S277_102
The pedal cluster
The bearing block of the pedal cluster is made of
aluminium alloy. It is designed to break at a
specific location in the event of a crash. Thus the
driver's lower legs and feet are not endangered.
To upgrade the aesthetics, additional custom
covers are fitted to the pedals.
Pedal cluster - manual transmission
Pedal cluster - automatic transmission
S277_119
S277_117
41
Brake system
The Bosch 5.7 ABS / ESP anti-lock braking system
The Phaeton uses the Bosch 5.7 ABS system with ESP (electronic stability program) with hydraulic braking
assistant.
S277_131
42
The special characteristics of the Bosch 5.7 ABS system include:
-
The hydraulic unit and control unit are integrated into one unit.
The G201 brake pressure sensor screws directly into the hydraulic unit.
An ESP feature without preloading is provided.
The ESP has EDL, TCS and ABS features as well as a braking assistant.
Even when the active ESP function is switched off, the vehicle remains stable in critical situations
due to the application of ESP logic (“passive” ESP).
Control unit with hydraulic unit
S277_106
G201 Brake pressure
sensor
S277_104
43
Brake system
The active wheel sensor system
The speed sensor is made of a material that
changes its electrical conductivity depending on
a magnetic field.
An electronic switch converts the current
fluctuations induced in the sensor material into
voltage fluctuations at the sensor output.
If the signal wheel moves relative to the sensor,
the sensor generates a square-wave voltage
signal at the corresponding frequency
depending on the speed of rotation.
The advantage compared to previously used
systems is that it is possible to exactly detect the
speed of wheel rotation right down to zero
rotation.
Speed sensor
S277_160
Sensor housing
Sensor electronics
Signal wheel
S277_158
For more information on the active wheel sensor system, please see SSP 218 “The Lupo 3L TDI”.
44
The dual brake servo
Pressure sensor,
only in vehicles with ADC
Displacement sensor,
only in vehicles with ADC
Connection for release switch,
only in vehicles with ADC
S277_105
The brake servo is an 8/9" dual brake servo with a stroke of 36 mm.
The diameter of the main brake cylinder is 26.99 mm.
The dual brake servo has a light-weight construction and has the following features:
- The central valves of the dual main brake cylinder guarantee the shortest application distance
at the pedal combined with reliable, self-priming ESP functionality.
- The active (electrically activated) brake servo variant represents the core component for
activation with automatic delay of the vehicle in ADC operation (automatic distance control)
and guarantees regulated, automatic delay.
Vehicles with ADC have an active brake servo.
For more information, please see SSP 276 “Automatic distance control”.
45
Wheels and tyres
The wheels and tyres
The Phaeton sets standards in comfort and driving dynamics. Different wheel-tyre combinations are
available with the Phaeton.
Vehicles with V6 petrol engines are equipped
with cast aluminium wheels with dimensions 7½ J
16 ET40 and 235/60R16 tyres as standard.
S277_045
Vehicles with W12 petrol engines have 18" cast
aluminium wheels with dimensions 7½ J 18 ET40
and 235/50R18 tyres.
S277_043
One-piece cast aluminium hollow spoke wheels
are also optional for all engine types.
The 8½ J 18 ET45 wheel comes with a 255/45R18
tyre.
S277_041
46
S277_162
All normal tyres have the “Y” speed index (300 km/h) and the special designation “XL”.
(XL = EL = extra load = reinforced)
The puncture repair kit
Emergency tyre inflation
The Phaeton is equipped with puncture repair kit
as standard. A complete spare wheel with tyre
can be ordered instead of the puncture kit.
The chapter “Tips and Maintenance” in the
operating manual describes how to use the
breakdown set.
S277_039
47
Tyre pressure monitor
Tyre pressure monitor (TPM)
Combi-processor in
dash panel insert
Function selector switch in Infotainment
Receiving antenna
S277_121
Tyre valves with
wheel electronics
Control unit for
monitoring tyre pressure
Function of the tyre pressure monitor
The tyre pressure monitor continuously monitors
the tyre pressure while driving and also when the
vehicle is stationary.
The tyre pressure monitor used in the Phaeton is
a 5-wheel system.
The spare wheel is also monitored and included
in the system messages.
48
A measuring and transmitting unit mounted in
each tyre valve sends radio signals at regular
intervals to the antennas mounted in each wheel
housing.
The signals are then passed on to the control unit
for monitoring the tyre pressure.
The control unit evaluates the tyre pressures or
changes in tyre pressure and sends
corresponding system messages to the dash
panel insert. The system messages then appear
on the driver information system display.
If the driver has selected the “Vehicle” menu in
the main information display and operating unit
(ZAB), the system messages for tyre pressure
monitor are displayed.
The system recognises the following situations:
- Gradual pressure loss:
The system informs the driver in time to be
able to correct the tyre pressure.
- Sudden pressure loss:
The system warns the driver immediately
while driving.
- Excessive pressure loss when the vehicle
is stationary:
The system warns the driver immediately
after the ignition is switched on.
49
Tyre pressure monitor
The tyre pressure sensors G222...G226
The tyre pressure sensors are screwed to the
metal valves and can be reused when the wheels
or rims are changed.
The following components are integrated into a
tyre pressure sensor:
Tyre pressure sensor
Transmitting
antenna
Pressure and
temperature
sensor
Measuring
and control
electronics
Metal valve
Battery
S277_358
The pressure sensor detects the actual tyre
inflation pressure (absolute pressure
measurement). The pressure is then sent to the
tyre pressure monitoring control unit for
evaluation.
The temperature signal is used for compensating
temperature-dependent pressure changes in the
tyres as well as for diagnostic purposes.
The control unit for monitoring the tyre pressure
performs the temperature compensation.
The measured tyre inflation pressures are
normalised to a temperature of 20 °C.
50
S277_118
The pressure sensor, temperature sensor and
measuring and control electronics are integrated
into one intelligent sensor.
When the driver selects “Store pressures”, the
tyre inflation pressures are normalised to 20 °C.
To avoid making incorrect settings, pay
particular attention that the tyre inflation
pressures are checked or corrected and stored
with “cold tyres”.
The following information is sent from the
transmitting antenna of the tyre pressure sensor:
- Individual identification number
(ID code),
- Current tyre inflation pressure
(absolute pressure),
S277_120
- Current tyre air temperature,
- Condition of the integrated battery and
- The status, synchronisation and
control information necessary for secure
data transfer.
The ID codes
Each tyre pressure sensor has an individual
identification number (ID code), which is used for
“own wheel recognition”.
S277_122
0000755100
0000678500
0000675300
0000735700
0000597400
S277_121
51
Tyre pressure monitor
The tyre pressure monitoring antennas R59 ... R62
The antennas for monitoring the tyre pressure, R59 ... R62, are located in the wheel housings behind the
wheel arch shells.
S277_120
S277_123
The antennas for monitoring the tyre pressure
receive radio signals from the tyre pressure
sensors and transfer these signals to the control
unit for monitoring the tyre pressure for further
processing.
The tyre pressure monitor has 4 antennas for
monitoring tyre pressures. They are mounted in
the FL, FR, RL, RR wheel housings behind the
wheel arch shells.
The antennas receive all radio signals
transmitted in their reception and frequency
range. Each antenna receives the radio signals
of all wheel sensors that are in range.
The control unit filters and selects the radio
signals so that it can process the correct
information.
They are connected to the control unit for
monitoring the tyre pressure using high
frequency antenna lines and are allocated to
the control unit according to their location.
The spare wheel does not have a separate antenna assigned to it. The antennas receive the
radio signals that the spare wheel transmits (data messages) and transfer the signals to the
control unit for monitoring the tyre pressure. The control unit recognises and stores the “fifth
wheel” as the spare wheel using own wheel and position recognition.
52
The system overview
S277_124
The components
G222 Front left tyre pressure sensor
R60
Tyre pressure monitoring antenna,
R61
Tyre pressure monitoring antenna,
front right
G223 Front right tyre pressure sensor
G224 Rear left tyre pressure sensor
rear left
G225 Rear right tyre pressure sensor
G226 Spare wheel tyre pressure sensor
J218
Combi-processor in dash panel insert
R62
Tyre pressure monitoring antenna,
rear right
J502
Control unit for monitoring the tyre pressure
J523
Main information display and operating unit
= Input signal
R59
Tyre pressure monitoring antenna,
= Output signal
front left
= Positive
= Ground
= CAN data bus
= Gold contact
53
Tyre pressure monitor
The warnings
The strong warnings
Pressure/bar
Sudden pressure loss
Flat tyre!
S277_128
Time/s
S277_130
The wheel electronics sends data messages every
54 seconds. If the wheel electronics detects a
sudden change in pressure (>0.2 bar/min.), it
transmits in 850 ms cycles.
54
Target tyre pressure stored via the
menu.
The system calculates the target
pressures relative to 20 °C from the
respective inflation pressures.
Strong warning due to sudden pressure
loss >0.4 bar below the stored target
tyre pressure.
The pressure falls below the coded
minimum pressure of, for example, 1.9
bar for W12.
Dynamic strong warning on sudden
pressure loss >0.2 bar relative to the
last transmitted pressure value.
The soft warnings
Check
pressures!
Pressure/bar
Slow pressure loss
S277_140
Time/s
S277_142
The wheel electronics sends data messages every
54 seconds. If the wheel electronics detects a
sudden change in pressure (>0.2 bar/min.), it
transmits in 850 ms cycles.
Soft warning due to pressure loss
between 0.2 and 0.4 bar below the
stored target tyre pressure.
If the driver has inflated the tyres to
pressures critical to driving dynamics,
the system also issues warnings.
- The difference in target pressures
on one axle may not exceed 0.4 bar.
- The difference in target pressures
between the axles may not exceed
0.5 bar.
If the spare tyre pressure falls below its
stored target pressure by more than
0.4 bar, a soft warning likewise
appears.
Strong warning due to pressure loss
>0.4 bar below the stored target tyre
pressure.
55
Tyre pressure monitor
The warnings in the dash panel insert (centre display)
The small symbol is always displayed.
The large symbol only appears when the “Tyre pressure monitor” menu is open.
It disappears when another menu opens.
... Display during the learn phase
System is
learning!
S277_146
... Display when switching off
System switched
off!
S277_146
... Display during radio fault
Warning currently
not possible!
S277_146
... Display during system fault
System fault!
S277_148
... Display when faulty wheel on board
Faulty wheel on
board!
S277_148
56
The controls
“Vehicle”
function key
S277_150
TPM
Vehicle
Spare wheel
monitoring
Inflation
information
Target pressures
in [bar]
at 2° C
Adopt current
pressures
Tyre pressure monitor main menu with strong warning rear right
S277_127
The driver is responsible for correctly setting the tyre pressures to be monitored.
57
Tyre pressure monitor
The tyre pressure monitor system main menu
appears in the main information display and
operating unit (ZAB) display when the “Vehicle”
function key is pressed.
After pressing the “Adopt current tyre pressures”
function key and then confirming the pressures,
the system stores the current tyre inflation
pressures at the current tyre inner temperatures
for the respective IDs.
The following functions are stored
-
Switch on/off tyre pressure monitor system
Switch on/off spare wheel monitoring
Inflation info
Adopt current pressures
The driver can specify and set the tyre pressures
to be monitored within the limits coded
according to the vehicle series.
58
Pressing the key also starts a new learn process
for wheel assignment. To avoid receiving from
external wheel electronics while learning, the
system learns only when travelling faster than 5
km/h. The learning process is complete after
about 15 minutes driving time.
Check Your Knowledge
1. What is special about the Phaeton's wheel bearings?
a. They are bolted to the wheel bearing housing as one unit.
b. They are joined to the wheel bearing housing by optimal pressing.
c. They can be installed without removing the pivot bearing or jointed shaft.
2. Which components have advantageous effects on the scrub radius and the
road feedback lever arm?
a. The light-weight brake calliper, which consists of an unseparated housing in a monoblock
design with 8 pistons and 4 brake pads.
b. The electronically controlled and speed dependent Servotronic system.
c. The virtual steering axis.
3. Where is the antenna that receives the data messages from the tyre pressure sensor
in the spare wheel?
a. In the boot.
b. In the centre console between the driver and front passenger.
c. The spare wheel does not have its own antenna; the other antennas receive the
signals from the spare wheel sensor and identify the sensor using its unmistakable ID code.
59
1.: a, c; 2.: c; 3.: c;
277
Only for internal use © VOLKSWAGEN AG, Wolfsburg
All rights reserved
240.2810.96.20 Issued 03/02
❀ No chlorine was used to bleach this paper
during manufacture.

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