Brake Booster/Brake Master Cylinder Overview

Brake Booster/Brake Master Cylinder Overview

• Brake master cylinder and brake boosters can be replaced independently of one another.






1 - Gasket

• For brake booster

2 - Brake Booster

• Functional check

• With engine switched off, depress brake pedal firmly several times (to deplete vacuum in tool).

• 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 assistance becomes effective).

• Disconnect from brake pedal. Refer to => [ Brake Pedal and Brake Booster ] Brake Pedal and Brake Booster

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

• Removing and installing on vehicles with a S-Tronic, refer to => [ Brake Booster, with S-Tronic ] Brake Booster, With S-Tronic

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

• Replace as complete unit if malfunctioning.

3 - Seal

• Replace

4 - Brake Master Cylinder

• Cannot be serviced.

• Replace as complete unit if malfunctioning.

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

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

5 - Heat Shield

• Allocation, refer to the electronic parts catalog ETKA

6 - Nut

• Always replace after removal

• 20 Nm

• Self-locking

7 - Brake Line

• 14 Nm

• Master brake cylinder/secondary piston circuit to hydraulic unit

8 - Brake Line

• 14 Nm

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

9 - Sealing Plugs

• Coat with brake fluid and insert into brake master cylinder

10 - Brake Fluid Reservoir

• Coat with brake fluid and insert into sealing plugs in brake master cylinder

• With floating insert with integrated brake fluid level warning switch

• To replace the warning switch, remove brake fluid reservoir

• Press brake fluid reservoir into sealing plugs

11 - Cap

• With integrated floater and brake fluid level warning switch

12 - Vacuum Tube

• With check valve

13 - Sealing Plugs

Check Inner Boot at Brake Booster





- Remove the driver side storage tray.

- Make sure the boot did not slip out of the circumferential groove, as shown here.