Assembly overview: Servo unit/tandem brake master cylinder — AUDI

Note:

Brake master cylinders can no longer be dismantled, i.e. no provision is made for servicing.
Use only fresh brake fluid. Refer to information on brake fluid reservoir.

Assignment of brake pipe connections:

ABS 5.0 => Page
45-11
ABS 5.3 => Page
45-26
ABS 5.3 with ESP => Page
45-33

Brake master cylinder, ø 25.4mm
Cannot be repaired. If faulty, renew complete.
Removing and installing
=>Page
47-70
.

Bolt, Torx socket T45, 25 Nm
Flanged nut, 50 Nm
Always replace

Sealing plug
Moisten with brake fluid and insert into brake master cylinder
Press brake fluid reservoir into sealing plugs

Brake fluid reservoir with float warning indicator
Functional test

With the ignition switched on, remove the cap and press with your hand on the strainer that is visible. Warning lamp in instrument cluster lights and acoustic alarm sounds.

Removing and installing
=>Page
47-70
.
Connection for hydraulic coupling is located on side
On vehicles equipped with ESP there is an additional connection for the suction hose => Page
45-35
Refer to label on reservoir before topping up brake fluid

Strainer
Securely clipped into the container

Sealing ring
Cap
Supply hose
From brake fluid reservoir to clutch master cylinder

Sealing ring
Insert into groove at brake master cylinder
Replace after removing brake master cylinder

Brake servo
Removing and installing
=>Page
47-72
.
Adjust clevis =>Page
1
.
Functional test

With the engine switched off, firmly depress the brake pedal several times (this reduces the vacuum present in the servo unit).
Now depress brake pedal with moderate force, hold and start engine. If the servo unit is working properly, the pedal will be felt to give slightly when pressed (servo assistance becomes effective).

If faulty renew complete.

Retainer
Fit onto pin

Seal
Brake servo is supplied with bonded gasket
Replace only if damaged

Bulkhead
Pedal bracket
Removing and installing
=>Page
46-90
.

Master cylinder
Replace in the event of leakage
Adjusting => Fig.
46-87
To remove detach mounting bracket => Page
46-88

Hexagon nut, 25 Nm
Always replace

Grommet
Pin
Insert in clevis and brake pedal

Vacuum hose
Insert into brake servo unit

On petrol engines the required vacuum is taken from the intake manifold.

Brake pipe, 15 Nm
Brake master cylinder/push rod piston circuit to hydraulic unit

Brake pipe, 15 Nm
Brake master cylinder/floating piston circuit to hydraulic unit

Hexagon bolt
Screw home
Unscrew to remove brake fluid reservoir

Fig.1
Adjusting clevis

a = 135mm ±0.5mm

Notes:

When measuring, the clevis should be aligned at right angles to the surface of the brake servo unit.
Dimension -a- applies to both LHD and RHD vehicles.