Hydraulic unit, brake servo/brake master cylinder - Assembly overview, Bosch 5.7 — VW
Hydraulic unit, brake servo/brake master cylinder - Assembly overview, Bosch 5.7 on VW: factory workshop procedure. Full factory text, tools and checks.
Workshop procedure for VW — 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.
VW
Polo
2002
Running gear
Brake system
Edition
10.2004
Hydraulic unit, brake servo/brake master cylinder - Assembly overview, Bosch 5.7
Master cylinder and brake servo can be independently renewed.
Brake pipe connection
Hydraulic unit to front left brake caliper
Hydraulic unit identification -VL-
Brake pipe connection
Hydraulic unit to front right brake caliper
Hydraulic unit identification -VR-
Brake pipe connection
Master cylinder of brake/pressure piston circuit for hydraulic unit.
Hydraulic unit identification -HZ2-
Brake pipe connection
Master cylinder of brake/pressure piston circuit for hydraulic unit.
Hydraulic unit identification -HZ1-
Brake fluid tank
Plug
Sealing plug
Wet with brake fluid and press brake master cylinder.
Brake servo
On petrol engines the vacuum required is taken from the intake manifold.
On diesel engines an exhauster is installed to create the required vacuum.
Functional check.
Step on brake pedal repeatedly with engine off (That eliminates vacuum remaining in the equipment).
Then hold brake pedal on braking position applying medium pressure and switch on engine. Proper operation of brake servo can be noticed on the pedal (rise is active).
If faulty renew complete.
Non return valve (in vacuum hose).
Separating from brake pedal
Chapter
Dismantling and assembling
Chapter
Seal
To servo brake
Self locking hexagon nut, 20 Nm
Master cylinder
Cannot be repaired. If faulty renew complete.
Removing and installing
Chapter
Brake fluid tank securing bolt
Insert through brake master cylinder.
Sealing plug
Connection for vacuum hose
O-ring
Renew
Self locking hexagon nut, 28 Nm
Self locking hexagon nut, 20 Nm
Bracket
Stud bolt
Stud bolt welded to body
Bolts, 8 Nm
Bolts, 8 Nm
Bracket
Self locking hexagon nut, 20 Nm
Brake pipe connection
To left rear brake caliper
Hydraulic unit identification -HR-
Brake pipe connection
To right rear brake caliper
Hydraulic unit identification -HL-
Brake pressure sensor
G201
Dismantling and assembling
Chapter
ABS hydraulic unit
N55
with
ABS with EDL control unit
J104
The
ABS hydraulic pump
V64
and the inlet/outlet valves in the hydraulic unit are checked by selfdiagnosis.
ABS hydraulic pump
V64
and valve set cannot be separated.
Removing and installing
Chapter
When renewing the hydraulic unit, close old part with plugs from
repair set
1H0 698 311 A
.
Removing and installing
ABS with EDL control unit
J104
Chapter
Connect brake, brake master cylinder (Tandem) pipes to hydraulic unit
A
Hydraulic unit to master cylinder pressure piston circuit
Hydraulic unit identification -HZ1-
B
Hydraulic unit to master cylinder floating pressure piston circuit
Hydraulic unit identification -HZ2-
1
Hydraulic unit to front left brake caliper
Hydraulic unit identification -VL-
2
Hydraulic unit to front right brake caliper
Hydraulic unit identification -VR-
3
Hydraulic unit to right rear brake caliper
Hydraulic unit identification -HR-
4
Hydraulic unit to left rear brake caliper
Hydraulic unit identification -HL-
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.