Assembly overview: Servo unit/brake master cylinder — AUDI
Assembly overview: Servo unit/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:
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 => Page
45-27
Brake master cylinder, ø 25.4mm
Cannot be repaired. If faulty, renew complete.
Has to be removed and installed together with the brake servo unit.
Removing and installing
=>Page
47-73
.
Bolt, Torx socket T45, 25 Nm
Flanged nut, 50 Nm
Always replace
Sealing plug
Moisten with brake fluid and insert into brake master cylinder
Press brake fluid reservoir into sealing plugs
Brake fluid reservoir with float warning indicator
Functional test
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.
Removing and installing
=>Page
47-73
.
Connection for hydraulic coupling is located on side
Refer to label on reservoir before topping up brake fluid
Sealing ring
Cap
Supply hose
From brake fluid reservoir to clutch master cylinder
Sealing ring
Insert into groove at brake master cylinder
Replace after removing brake master cylinder
Brake servo
Removing and installing
=>Page
47-73
.
Adjust clevis =>Page
1
.
Functional test
With the engine switched off, firmly depress the brake pedal several times (this reduces the vacuum present in the servo unit).
Now depress brake pedal with moderate force, hold and start engine. If the servo unit is working properly, the pedal will be felt to give slightly when pressed (servo assistance becomes effective).
If faulty renew complete.
Gasket
Brake servo is supplied with gasket bonded on
Replace only if damaged
Vacuum hose
Insert into brake servo unit
On petrol engines the required vacuum is taken from the intake manifold.
Bulkhead
Brake pipe, 15 Nm
Brake master cylinder/push rod piston circuit to hydraulic unit
Brake pipe, 15 Nm
Brake master cylinder/floating piston circuit to hydraulic unit
Hexagon bolt
Screw home
Unscrew to remove brake fluid reservoir
Fig.1
Adjusting ball head
a = 159 mm ±0.5mm
Notes:
When measuring, the ball head should be aligned at right angles to the surface of the brake servo unit.
Measure without gasket up to the end of ball head.
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.
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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.