Tandem Brake Booster/Brake Master Cylinder Assembly Overview

Tandem Brake Booster/Brake Master Cylinder Assembly Overview

• Brake master cylinders can no longer be disassembled, i.e. no provision is made for servicing.

• Use only new brake fluid. Observe the information on the brake fluid reservoir!

• Assignment of the brake line connections.





1 - - a - Vacuum hose

• On gasoline engines the vacuum required is taken from the intake manifold and/or a mechanical vacuum pump.

• Insert into the brake booster unit

1 - - b - Vacuum hose

• On gasoline engines the vacuum required is taken from the intake manifold and/or a mechanical vacuum pump.

• An additional electrical vacuum pump is installed on vehicles where vacuum is taken from intake manifold only

• Insert into the brake booster unit

2 - Trunnion bolt, 8 Nm

• Install as far as the stop

• Loosen to remove the brake fluid reservoir

3 - Brake fluid reservoir with float warning indicator

• Functional test

• With the ignition switched on, remove the cap and press on the strainer that is visible in the reservoir with your hand. The warning lamp in the instrument cluster should light up and the acoustic alarm should sound.

• Removing and installing, refer to => [ Brake Master Cylinder with Brake Booster ] Brake Master Cylinder With Brake Booster.

• Refer to the label on the reservoir before topping off the brake fluid

4 - Cap

5 - Sealing plug

• Lubricate with brake fluid and insert into the brake master cylinder

• Press the brake fluid reservoir into the sealing plugs

6 - Brake booster

• Removing and installing, refer to => [ Brake Master Cylinder with Brake Booster ] Brake Master Cylinder With Brake Booster.

• Adjusting ball head, refer to => [ Brake Booster Ball Head Adjusting ] Adjustments.

• Functional check

• With the engine off, firmly depress the brake pedal several times (this reduces the vacuum present in the servo unit).

• Then hold the brake pedal in the applied position with moderate force and start the engine. If the servo unit is working properly, the pedal will give slightly under foot (servo assist becomes activated).

• If faulty replace the complete assembly.

7 - Pedal bracket

8 - Supply hose

• Keep both ends closed off until it is installed.

• Push on the hose as far as it will go.

9 - Bulkhead

10 - Bolt, 25 Nm

11 - Nut, 50 Nm

• Always replace

12 - Brake master cylinder

• Cannot be repaired. If faulty, replace complete assembly.

• Has to be removed and installed together with the brake booster unit.

• Removing and installing, refer to => [ Brake Master Cylinder with Brake Booster ] Brake Master Cylinder With Brake Booster.

13 - Brake line fitting, 15 Nm

• Brake master cylinder/primary piston circuit to hydraulic unit

• Brake master cylinder/secondary piston circuit to hydraulic unit

14 - Sealing ring

• Insert into the groove on the brake master cylinder

• Replace after removing the brake master cylinder