Brake Booster and Master Cylinder Assembly Overview

Brake Booster and Master Cylinder Assembly Overview

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





1 Pedal Assembly

2 Self-Locking Hex Nut

• Always replace after removal

• 25 Nm

3 Gasket

• For brake booster

4 Brake Booster

• On gasoline engines, vacuum is supplied from intake manifold.

• Vehicles with FSI engine without HBV are equipped with a pressure sensor. Refer to => [ Brake Booster Pressure Sensor ] Brake Booster Pressure Sensor

• On vehicles with a hydraulic brake booster, a vacuum sensor is installed. Refer to => [ Brake Booster Vacuum Sensor ] Brake Booster Vacuum Sensor

• Functional check:

- With engine switched off, depress brake pedal firmly several times (to exhaust the vacuum in the unit).

- Depress and hold brake pedal with average foot pressure and start engine. If brake booster is working properly, pedal will be felt to give noticeably under foot (booster assist becomes effective).

• Replace as a unit in the event of malfunction (previously, check all vacuum lines).

• Removing and installing, refer to => [ Brake Booster ] Brake Booster

5 Seal

6 Brake Booster Vacuum Sensor (G483)

• Only on vehicles with the hydraulic brake booster

• Removing and installing, refer to => [ Brake Booster Vacuum Sensor ] Brake Booster Vacuum Sensor

7 Dual Master Brake Cylinder

• Cannot be serviced. Replace as complete unit if malfunctioning.

• Removing and installing, refer to => [ Brake Master Cylinder ] Brake Master Cylinder

8 Brake Light Switch (F)

• Removing and installing, refer to => [ Brake Lamp Switch ] Service and Repair

9 Inner TORX(R) Bolt

• 5 Nm

10 Heat Shield

11 Self-Locking Hex Nut

• Always replace after removal

• 25 Nm

12 Brake Line

• 8.5 mm diameter -17 Nm

• 6 mm diameter - 14 Nm

• Master brake cylinder/secondary piston circuit to hydraulic unit

13 Brake Line

• 8.5 mm diameter - 17 Nm

• 6 mm diameter - 14 Nm

• Master brake cylinder/primary piston circuit to hydraulic control unit

14 Sealing Plugs

• Coat with brake fluid and press into brake fluid reservoir

15 Brake Fluid Reservoir

16 Cap

17 Vacuum Hose

• With check valve and, also vehicles with FSI engine without HBV, with brake booster pressure sensor (G294)

• Insert into brake booster

• Brake booster pressure sensor (G294) removing and installing, refer to => [ Brake Booster Pressure Sensor ] Brake Booster Pressure Sensor

18 Sealing Plugs

• Connection for vacuum hose