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Home >> Audi >> 2016 >> S4 Premium Plus, Standard Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 1303 (Hydraulic Components - Brake System (Cabriolet)) >> 47 Hydraulic Components >> Brake Booster/Brake Master Cylinder >> Overview - Brake Booster/Brake Master Cylinder

Overview - Brake Booster/Brake Master Cylinder

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NOTE:

Master Brake Cylinders Can No Longer Be Disassembled, Servicing Is Not Possible.

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

Fig 1: Identifying Brake Master Cylinder Components
GWWA47-10054Courtesy of AUDI OF AMERICA, LLC
  1. 1 - Brake Fluid Reservoir
  2. 2 - Brake Fluid Reservoir Cover
  3. 3 - Cap with Seal and Brake Fluid Level Warning Switch -F34-
  4. 4 - Bolt
    • 5 Nm 
  5. 5 - Wiring to the Clutch Master Cylinder
  6. 6 - Brake Booster
    • Adjusting ball head. Refer to Fig 2.
    • Functionality test: with engine switched off, depress brake pedal firmly several times (to deplete vacuum in the 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).
    • With adhesive seal
    • If malfunctioning: replace as complete unit.
    • Removing and installing. Refer to BRAKE BOOSTER, REMOVING AND INSTALLING .
  7. 7 - Pedal Support Bolt
    • 20 Nm 
  8. 8 - Brake Pedal
  9. Brake Lamp Sensor
  10. Bolt
    • 25 Nm 
    • Connects the brake booster to the mounting bracket
  11. Hex Nut
    • 49 Nm 
    • For the brake master cylinder
  12. Brake Line
    • 14 Nm 
    • Brake master cylinder to the hydraulic unit
  13. Brake Line
    • 14 Nm 
    • Brake master cylinder to the hydraulic unit
  14. Seal
    • Replace
  15. Brake Master Cylinder
  16. Sealing Plug
    • Moisten with brake fluid and press into brake fluid reservoir
NOTE:

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

Adjusting Ball Head

Fig 2: Adjusting Ball Head
GWWA47-0136Courtesy of AUDI OF AMERICA, LLC

Left-hand drive vehicles:

-a = 164.7mm ± 0.5mm-

NOTE:

Surface -1- for measuring.

When measuring, ball head must be arranged at a right angle to surface of brake booster.

Measure to end of ball head without gasket installed.

Ball head to the push rod, 30 Nm.