Assembly overview: Hydraulic brake servo/brake master cylinder — AUDI
Assembly overview: Hydraulic brake servo/brake master cylinder on Audi: factory workshop procedure. Full factory text, tools and checks.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📋 Procedure
ℹ️ Torque figures below come verbatim from workshop data — always cross-check against your vehicle's factory manual before final tightening.
Note:
The complete brake master cylinder and brake servo can be replaced separately from each other.
Brake master cylinders cannot be dismantled any further, 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 => Repair Group 45.
Contact for brake fluid indicator
Press home in brake fluid reservoir
Functional test as of 07/92
With ignition switched on , press firmly by hand on centre of cap (diaphragm). Warning lamp in instrument cluster lights and acoustic alarm sounds.
Functional test as of 07/92
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.
Cap
Gasket
Strainer
Brake fluid reservoir
Connection for hydraulic coupling is located on side
Refer to label on reservoir before topping up brake fluid
Pressure pipe
Pressure reservoir/brake servo
Before unscrewing, dissipate operating pressure by pressing brake pedal 20 times with engine switched off
Hydraulic brake servo
Never press brake pedal with brake master cylinder removed
Leak test => Fig.
2
Return pipe
Nut
Locking clip
Replace
Clevis
adjusting => Fig.
1
Pin
Grease lightly
Gasket
Replace
Self-locking nut, 25 Nm
Renew each time after removing
Sealing plug
Moisten with brake fluid and insert into brake master cylinder
Nut, 20 Nm
Bracket
Brake master cylinder, ø 25.4mm
Cannot be repaired. If faulty, renew complete.
Double bolt
Brake pipes
Oil pressure switch, 20 Nm
For monitoring hydraulic brake servo
Drop in pressure to between 127 and 87 bar causes lamp in dash panel insert and warning signal to sound
Oil seal
Replace
Oil seal
Replace
Fig.1
Adjusting clevis
a = 230 mm ±0.5 mm, LHD
a = 233 mm ±0.5mm,RHD
Note:
When measuring, the clevis should be aligned at right angles to the surface of the brake servo unit.
Measure without gasket as far as centre of hole in clevis.
Fig.2
Checking brake servo for leaks
Unscrew return pipe from brake servo.
Note:
Hydraulic fluid will emerge from return pipe if brake servo is defective -arrow-.
Dribbling hydraulic fluid has no significance.
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
Ask about my car →Other AUDI procedures
- Removing and installing toothed belt – Audi · 56 torque figures
- Removing engine – Audi A8 D3 · 41 torque figures
- Removing camshaft timing chain from camshafts – Audi A6/A7 C7 · 38 torque figures
- Installing engine – Audi A8 D4 · 36 torque figures
- Removing and installing camshaft timing chain · 29 torque figures
- Removing and installing gearbox mounting - vehicles with dual clutch gearbox
- Removing and installing catalytic converter, vehicles from model year 2013 onwards
- Removing and installing brake master cylinder, Audi A1
- Removing and installing steering rack - vehicles up to and including model year 2014
- Checking fresh air and air recirculation flap control motor V154 - heater, manually controlled air conditioner
Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.