VW MKII A2 MK2 Golf Jetta Fox Service Manual - VAGLinks.com

9•2 Braking system
Rear disc brakes
Disc thickness:
New . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 mm
Minimum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.0 mm
Disc maximum run-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 mm
Pad thickness:
New - including backplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 mm
Minimum - including backplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 mm
Master cylinder
Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.65 mm
Wheel cylinder
Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.29 mm
Servo unit
Diameter:
Manual gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178.0 mm
Automatic transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228.0 mm
Torque wrench settings Nm Ibf ft
Caliper upper securing bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 19
Caliper lower securing bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 19
Master cylinder securing nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 15
Servo unit securing nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 15
Splash guard to strut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7
Backplate to rear axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 44
Rear disc brake guide pin (self-locking) . . . . . . . . . . . . . . . . . . . . . . . . . 35 26
Rear disc brake carrier bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 48
Rear disc brake cover plate-to-axle bolts . . . . . . . . . . . . . . . . . . . . . . . 60 44
Roadwheel bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 81
1 General information and
precautions
General information
The braking system is of hydraulic, dual
circuit type with discs at the front and drum or
discs at the rear. The hydraulic circuit is split
diagonally so that with the failure of one
circuit, one front and one rear brake remain
operative.
A load-sensitive pressure regulator is
incorporated in the rear hydraulic circuits on
some models to prevent the rear wheels
locking in advance of the front wheels during
heavy application of the brakes. The regulator
proportions the hydraulic pressure between
the front and rear brakes according to the
load being carried and is located on the
under-body, in front of the left-hand rear
wheel.
A vacuum servo unit is located between the
brake pedal and master cylinder. It provides
assistance to the driver when the brake pedal
is depressed. The unit operates by vacuum
from the inlet manifold and comprises a
diaphragm and non-return valve. With the
brake pedal released, vacuum is channelled
to both sides of the diaphragm. With the pedal
depressed, one side is opened to
atmosphere. The resultant unequal pressures
are harnessed to assist in depressing the
master cylinder pistons.
The handbrake operates on the rear wheels
only, its lever incorporating a switch which
illuminates a warning light on the instrument
panel when the handbrake is applied. The
same warning light is wired into the low
hydraulic fluid switch circuit.
Precautions
Hydraulic fluid is poisonous. Wash off
immediately and thoroughly in the case of skin
contact and seek immediate medical advice if
any fluid is swallowed or gets into the eyes.
Certain types of hydraulic fluid are
inflammable and may ignite when allowed into
contact with hot components. When servicing
any hydraulic system, it is safest to assume
that the fluid is inflammable and to take
precautions against the risk of fire as though it
is petrol that is being handled.
Hydraulic fluid is an effective paint stripper
and will attack plastics. If any is spilt, it should
be washed off immediately using copious
quantities of fresh water. Finally, it is
hygroscopic, that is it absorbs moisture from
the air. Old fluid may be contaminated and
unfit for further use.
When topping-up or renewing fluid, always
use the recommended type and ensure that it
comes from a freshly-opened sealed
container.
When working on the brake components,
take care not to disperse brake dust into the
air, or to inhale it, since it may contain
asbestos which is injurious to health
1081 VW Golf & Jetta
When servicing any part of the system,
work carefully and methodically. Observe
scrupulous cleanliness when overhauling any
part of the system. Always renew components
(in axle sets, where applicable) if in doubt
about their condition and use only genuine
VW replacement parts, or at least those of
known good quality.
2 Brake pads - inspection and
renewal 3
Warning: When working on
brake components, take care
not to disperse brake dust into
the air or to inhale it, since it
may contain asbestos which is injurious to
health.
Warning: Always support the
vehicle on axle stands before
removing the roadwheel to
service brake assemblies.
Front pads
Inspection
1 Refer to Chapter 1, Section 26.
Removal
2 To remove the pads, first jack up the front
of the vehicle and support it on axle stands
(see “Jacking and vehicle support”). Apply the
handbrake and remove both front wheels.