Hydraulic unit and brake pipes — AUDI

Hydraulic unit and brake pipes on Audi: factory workshop procedure. Full factory text, tools and checks.

Workshop procedure for AUDI — the factory write-up, straight from real workshop data.

factory workshop text

📋 Procedure

ℹ️ Torque figures below come verbatim from workshop data — always cross-check against your vehicle's factory manual before final tightening.

The tightening torque for the brake lines is 15 Nm.

Bolt, 5 Nm
Cover
Relay for solenoid valves
Relay for return pump
Hydraulic unit for ABS 5.0
Different designs => Fig.
1
and Fig.
2
No repair work may be carried out on the hydraulic unit, with the exception of replacing both relays . Never unfasten bolted joints
Replacement hydraulic units are supplied pre-bled

Removing and installing the hydraulic unit

Disconnect earthing strap from battery.
Remove front half of front right wheel housing liner.
Unscrew the brake pipes and seal the connections immediately with dummy plugs.
Screw a new hydraulic unit into the bracket -
35
-.
The brake pipes should be connected in accordance with the designations on the hydraulic unit.

Hydraulic unit/pipe connections/rear => Fig.
1
and Fig.
2

Bleed brake system => Page
47-47
Perform final control diagnosis =>Running Gear Self-Diagnosis, Repair group 00

Connector, ABS wiring harness
Release and detach
The connector is part of the ABS wiring harness. Different designs are component-specifically encoded.

Brake pipe
Brake master cylinder/floating piston circuit to hydraulic unit
Different designs => Fig.
1
and Fig.
2

Brake master cylinder with servo unit
Brake pipe
Brake master cylinder/push rod piston circuit to hydraulic unit
Different designs => Fig.
1
and Fig.
2

Brake pipe
Hydraulic unit to rear left brake caliper

Brake pipe
Hydraulic unit to rear right brake caliper

Brake pipe
Hydraulic unit to front left brake caliper

Combi bolt, 10 Nm
Earth wire
Ensure good contact

Toothed lock washer
Hexagon nut, 10 Nm
Brake pipe
Hydraulic unit to front right brake caliper

Joint/brake pipe to rear right brake caliper
Position: Wheel housing - side member, front left => Fig.
3

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Joint/brake pipe to rear left brake caliper
Position: Wheel housing - side member, front left => Fig.
3

Joint/brake pipe to rear right brake caliper
right
Position: Wheel housing - side member, rear left => Fig.
4

Joint/brake pipe/brake hose
Rear right

Brake hose, rear right
Joint/brake pipe to rear left brake caliper
Position: Wheel housing - side member, rear left => Fig.
4

Joint/brake pipe/brake hose
Rear left

Brake hose, rear left
Joint/brake pipe to front left brake caliper
Position: Wheel housing - side member, front left => Fig.
3

Direction of travel
Joint/brake pipe/brake hose
Front left

Brake hose, front left
Brake hose, front right
Joint/brake pipe/brake hose
Front right

Joint/brake pipe to front right brake caliper
Position: Wheel housing - side member, front right => Fig.
5

Hexagon bolt, 15 Nm
Washer
Bracket for hydraulic unit
Insert hydraulic unit and secure.
Removing and installing bracket => Page
45-21

Fig.1
Brake pipe connections to hydraulic unit, ABS 5.0

Applies to the following vehicles:
FWD with ABS/EDL
FWD with ABS/EDL/TCS
4WD with ABS/EDL

1 -
Hydraulic unit - brake master cylinder (push rod piston circuit)
2 -
Hydraulic unit - rear right brake caliper
3 -
Hydraulic unit - front left brake caliper
4 -
Hydraulic unit - brake master cylinder (floating piston circuit)
5 -
Hydraulic unit - rear left brake caliper
6 -
Hydraulic unit - front right brake caliper

Note:

The pressure dampers are not fitted to vehicles with 4WD and EDL suction control (05.95 onwards) => Fig.
2

EDL suction control minimises control noises.

The working range of the pressure limiting valve in the hydraulic unit is raised from 90 ±25 bar to 170 ±25 bar.

Fig.2
Brake pipe connections at hydraulic unit, ABS 5.0

For models with 4WD and ABS/EDL- pressure control (up to 05 95):

Two pressure dampers are screwed into the hydraulic unit -arrows- on vehicles with 4WD and EDL pressure control.

The dampers are designed to smooth pressure peaks in the brake pipes and reduce control noises.

Counterhold at the hexagon of the pressure dampers when unfastening the brake pipes.

Note:

The operating range of the pressure limiting valve in the hydraulic unit is 90 ±25 bar.

Fig. 3
Joints in the brake pipes

1 -
Hydraulic unit - rear right brake caliper
2 -
Hydraulic unit - rear left brake caliper
3 -
Hydraulic unit - front left brake caliper

Fig. 4
Joints in the brake pipes

1 -
Hydraulic unit - rear right brake caliper
2 -
Hydraulic unit - rear left brake caliper

Fig.5
Joint in the brake pipe: hydraulic unit - front right brake caliper

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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.

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Workshop data on this page last updated 20 Sep 2026.