1988 OPEL CALIBRA ABS

9
System type
Models without ABS:
1.4, 1.6 and 1.8 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front discs and rear drums, with vacuum servo assistance, dual
hydraulic circuit split diagonally, pressure-proportioning valves in rear
hydraulic circuit. Cable-operated handbrake on rear wheels
2.0 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front and rear discs, with vacuum servo assistance, dual hydraulic
circuit split diagonally, pressure-proportioning valves in rear hydraulic
circuit. Cable-operated handbrake on rear wheels
All models with Anti-lock Braking System (ABS) . . . . . . . . . . . . . . . . . . Front and rear discs, with vacuum servo assistance, operated via
hydraulic modulator, dual hydraulic circuit split front/rear, pressure-
proportioning valves in rear hydraulic circuit. Cable-operated
handbrake on rear wheels
Front discs
Type:
1.4, 1.6 and 1.8 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solid or ventilated (as from 10/91)
2.0 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ventilated
Diameter:
1.4, 1.6 and early 1.8 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 mm
Late (as from 10/91) 1.8 and 2.0 litre models . . . . . . . . . . . . . . . . . . . 256 mm
Maximum disc run-out (all models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1 mm
Minimum pad friction material thickness (including backing plate):
All models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 mm
Minimum disc thickness after machining: *
1.4, 1.6 and 1.8 litre models (with solid discs) . . . . . . . . . . . . . . . . . . 10.7 mm
1.4, 1.6 and 1.8 litre models (with vented discs) . . . . . . . . . . . . . . . . 18.0 mm
2.0 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.0 mm
* When this dimension is reached, only one further new set of brake pads is permissible, then renew the discs
Chapter 9
Braking system
ABS electronic control module - removal and refitting . . . . . . . . . . .22
ABS hydraulic modulator - removal and refitting . . . . . . . . . . . . . . . .20
ABS relays (ABS-2E systems only) - removal and refitting . . . . . . . .23
ABS wheel sensors - removal and refitting . . . . . . . . . . . . . . . . . . . .21
Anti-lock braking system (ABS) - general . . . . . . . . . . . . . . . . . . . . . . .2
Brake disc - inspection, removal and refitting . . . . . . . . . . . . . . . . . .10
Brake drum - removal, inspection and refitting . . . . . . . . . . . . . . . . .11
Brake fluid pipes and hoses - general, removal and refitting . . . . . . .25
Brake pedal - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . .29
Front brake disc shield - removal and refitting . . . . . . . . . . . . . . . . . .14
Front disc caliper - removal, overhaul and refitting . . . . . . . . . . . . . . .8
Front disc pads - inspection, removal and refitting . . . . . . . . . . . . . . .4
General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Handbrake - adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Handbrake cable - removal and refitting . . . . . . . . . . . . . . . . . . . . . .27Handbrake lever - removal and refitting . . . . . . . . . . . . . . . . . . . . . . .28
Handbrake shoes (rear disc brakes) - inspection, removal and
refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Hydraulic system - bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Master cylinder - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . .15
Master cylinder (ABS) - general . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Master cylinder (non-ABS) - overhaul . . . . . . . . . . . . . . . . . . . . . . . . .16
Rear brake backplate - removal and refitting . . . . . . . . . . . . . . . . . . .13
Rear brake pressure-proportioning valves - removal and refitting . . .24
Rear brake shoes (drum brakes) - inspection, removal and refitting . .6
Rear disc caliper - removal, overhaul and refitting . . . . . . . . . . . . . . . .9
Rear disc pads - inspection, removal and refitting . . . . . . . . . . . . . . . .5
Rear wheel cylinder (drum brakes) - removal, overhaul and refitting .12
Vacuum servo - description and testing . . . . . . . . . . . . . . . . . . . . . . .18
Vacuum servo - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . .19
9•1
Specifications Contents
Easy,suitable for
novice with little
experienceFairly easy,suitable
for beginner with
some experienceFairly difficult,
suitable for competent
DIY mechanic
Difficult,suitable for
experienced DIY
mechanicVery difficult,
suitable for expert DIY
or professional
Degrees of difficulty
54321

Rear discs
Type (all models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Solid
Diameter (all models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .260 mm
Maximum disc run-out (all models) . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.1 mm
Minimum pad friction material thickness (including backing plate):
All models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.0 mm
Minimum disc thickness after machining (all models) * . . . . . . . . . . . . .8.0 mm
* When this dimension is reached, only one further new set of disc pads is permissible, then renew the discs
Minimum handbrake shoe friction material thickness (lining only)
All models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.0 mm
Rear drums
Internal diameter (all models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200 mm
Minimum shoe friction material thickness (all models) . . . . . . . . . . . . . .0.5 mm above rivet heads
Brake fluid type/specification:
All models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .See Lubricants and fluidsin “Weekly checks”
Torque wrench settingsNmlbf ft
ABS hydraulic modulator mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
ABS wheel sensor mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
ABS control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.51
Brake fluid line unions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1612
Caliper and wheel cylinder bleed screws . . . . . . . . . . . . . . . . . . . . . . . .97
Front brake disc securing screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Front brake fluid hose to caliper union . . . . . . . . . . . . . . . . . . . . . . . . . .4030
Front caliper bracket to hub carrier . . . . . . . . . . . . . . . . . . . . . . . . . . . .9570
Front caliper guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3022
Front caliper mounting (solid disc models) . . . . . . . . . . . . . . . . . . . . . . .9570
Front caliper to mounting bracket (vented disc models) . . . . . . . . . . . .3022
Handbrake lever securing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2015
Master cylinder mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2216
Master cylinder stop screw (ATE type) . . . . . . . . . . . . . . . . . . . . . . . . . .64
Pressure proportioning valve to master cylinder:
ATE type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
GMF type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4030
Rear brake backplate/stub axle spring:
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5037
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle-tighten a further 30º
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Angle-tighten a further 15º
Rear brake disc securing screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Rear caliper mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8059
Rear drum securing screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Rear wheel cylinder mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
Vacuum servo support bracket to bulkhead . . . . . . . . . . . . . . . . . . . . .2216
Vacuum servo to support bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2015
1General description
The foot brake operates on all four wheels.
Solid or ventilated disc brakes are fitted at the
front, and self-adjusting drum or solid disc
brakes are fitted at the rear, depending on
model. Actuation is hydraulic, with vacuum
servo assistance. The handbrake is cable-
operated, and acts on the rear wheels only.
The hydraulic system is split into two
circuits. On non-ABS models, the system is
split diagonally, and on ABS models, the
system is split front and rear. If there is a
hydraulic fluid leak in one circuit, the
remaining circuit will still function, so that
some braking capability remains.
The hydraulic fluid supply to the rear brakes
is regulated so that the front brakes alwayslock first under heavy braking. The fluid
pressure to the rear brakes is controlled by
two valves, one for each brake, which are
either screwed into the master cylinder or
mounted on the rear underbody of the vehicle,
depending on model.
The brake servo is of the direct-acting type,
fitted between the pedal and the master
cylinder. The servo is powered by vacuum
developed in the inlet manifold. Should the
servo fail, the brakes will still operate, but
increased pedal pressure will be required.
2Anti-lock braking system
(ABS) - general
1ABS is available as an option for all models.
When the ignition is switched on, an ‘ABS’
symbol illuminates in the instrument panel for
a short time. 2The system comprises an electronic control
unit, roadwheel sensors, hydraulic modulator,
and the necessary valves and relays. Disc
brakes are fitted to all four wheels. The
purpose of the system is to stop wheel(s)
locking during heavy brake applications. This
is achieved by automatic release of the brake
on the locked wheel, followed by re-
application of the brake. This procedure is
carried out several times a second by the
hydraulic modulator.
3The modulator is controlled by the
electronic control unit, which itself receives
signals from the wheel sensors, which monitor
the locked or unlocked state of the wheels.
The two front brakes are modulated
separately, but the two rear brakes are
modulated together.
4The ABS unit is fitted between the brake
master cylinder and the brakes, the vacuum
servo and master cylinder being of similar
type for both non-ABS and ABS models.
9•2Braking system

5If the ‘ABS’ symbol, in the instrument panel
stays lit after approximately 4 seconds, or if it
comes on sporadically or stays on whilst
driving, there is a fault in the system. Should
this occur, it is recommended that a complete
test is carried out by a Vauxhall dealer, who
will have the necessary specialist diagnostic
equipment. Due to the special equipment
required, it is not practical for the DIY
mechanic to carry out the test procedure.
6To prevent possible damage to the
electronic control unit, always disconnect the
control unit wiring plug before carrying out
electrical welding work.
7It is recommended that the control unit is
removed if the vehicle is being subjected to
high temperatures, like for instance, during
certain paint-drying processes.
8If using steam cleaning equipment, do not
aim the water/steam jet directly at the control
unit.
9Do not disconnect the control unit wiring
plug with the ignition switched on.
10Do not use a battery booster to start the
engine.
11After working on the ABS components,
ensure that all wiring plugs are correctly
reconnected, and have the complete system
tested by a Vauxhall dealer, at the earliest
opportunity.
12All models up to 1991 that were fitted with
ABS, used the ABS-2E system. From 1992
onwards an ABS-2EH system was fitted,
which can be identified by the location of the
electronic control module, which is bolted to
the hydraulic modulator.
13The main differences between the two
systems are in the electrical components and
circuits, the most obvious of these being
omission of the surge arrester relay on the
2EH system.
3Hydraulic system - bleeding
2
General
1If any of the hydraulic components in the
braking system have been removed or
disconnected, or if the fluid level in the
reservoir has been allowed to fall appreciably,
it is certain that air will have entered into the
system. The removal of all this air from the
hydraulic system is essential if the brakes are
to function correctly, and the process of
removing it is known as bleeding.
2Where an operation has only affected one
circuit of the hydraulic system (the system issplit diagonally on non-ABS models, and front
and rear on ABS models), then it will only be
necessary to bleed the relevant circuit. If the
master cylinder has been disconnected and
reconnected, or the fluid level has been
allowed to fall appreciably, then the complete
system must be bled.
3One of three methods can be used to bleed
the system, although Vauxhall recommend
the use of a pressure bleeding kit.
Bleeding - two-man method
4Obtain a clean jar, and a length of rubber or
plastic bleed tubing that will fit the bleed
screws tightly. The help of an assistant will be
required.
5Remove the dust cap and clean around the
bleed screw on the relevant caliper of wheel
cylinder (see illustration), then attach the
bleed tube to the screw. If the complete
system is being bled, start at the front of the
vehicle. When bleeding the complete system
on models with ABS, the front brakes must be
bled before the rears.
6Check that the fluid reservoir is topped up,
and then destroy the vacuum in the brake
servo by giving several applications of the
brake pedal.
7Immerse the open end of the bleed tube in
the jar, which should contain two or three
inches of hydraulic fluid. The jar should be
positioned about 300 mm (12.0 in) above the
bleed screw to prevent any possibility of air
entering the system down the threads of the
bleed screw when it is slackened.
8Open the bleed screw half a turn, and have
the assistant depress the brake pedal slowly
to the floor. With the brake pedal still
depressed, retighten the bleed screw, and
then have the assistant quickly release the
pedal. Repeat the procedure.
9Observe the submerged end of the tube in
the jar. When air bubbles cease to appear,
tighten the bleed screw when the pedal is
being held fully down by the assistant.
10Top-up the fluid reservoir. It must be kept
topped up throughout the bleeding
operations. If the connecting holes to the
master cylinder are exposed at any time due
to low fluid level, the air will be drawn into the
system, and the whole bleeding process will
have to start again.
11If the complete system is being bled, the
procedure should be repeated on the
diagonally opposite rear brake. Then on the
front and rear brakes of the other circuit on
non-ABS models, or on the remaining front
brake and then on the rear brakes on ABS
models.
12On completion, remove the bleed tube,
and discard the fluid that has been bled from
the system, unless it is required to make up
the level in the bleed jar. Never re-use old fluid.
13On completion of bleeding, top-up the
fluid level in the reservoir. Check the action ofthe brake pedal, which should be firm, and
free from any “sponginess” that would
indicate that air is still present in the system.
Bleeding - with one-way valve
14There are a number of one-man brake
bleeding kits currently available from motor
accessory shops. It is recommended that one
of these kits should be used whenever
possible, as they greatly simplify the bleeding
operations. They also reduce the risk of
expelled air or fluid being drawn back into the
system.
15Proceed as described in paragraphs 5
and 6.
16Open the bleed screw half a turn, then
depress the brake pedal to the floor, and
slowly release it. The one-way valve in the
bleeder device will prevent expelled air from
returning to the system at the completion of
each stroke. Repeat the operation until clear
hydraulic fluid, free from air bubbles, can be
seen coming through the tube. Tighten the
bleed screw.
17Proceed as described in paragraphs 11
to 13 inclusive.
Bleeding - with pressure
bleeding kit
18These are also available from motor
accessory shops, and are usually operated by
air pressure from the spare tyre.
19By connecting a pressurised container to
the master cylinder fluid reservoir, bleeding is
then carried out by simply opening each bleed
screw in turn and allowing the fluid to run out.
Like turning on a tap, until no air bubbles are
visible in the fluid being expelled.
20Using this method, the large reserve of
fluid provides a safeguard against air being
drawn into the master cylinder during the
bleeding operations.
21This method of bleeding is recommended
by Vauxhall.
22Begin bleeding with reference to
paragraphs 5 and 6, and continue as
described in paragraphs 11 to 13 inclusive.
Braking system 9•3
3.5 Removing the dust cap from a rear
caliper bleed screw - models with
ventilated discs
9
If brake fluid is spilt on the
paintwork, the affected area
must be washed down with
cold water immediately.
Brake fluid is an effective paint
stripper!

11Remove the wood and carefully withdraw
the piston.
12Carefully prise the seal from the groove in
the caliper piston bore, using a plastic or
wooden instrument.
13Inspect the surfaces of the piston and its
bore in the caliper for scoring, or evidence of
metal-to-metal contact. If evident, renew the
complete caliper assembly.
14If the piston and bore are in good
condition, discard the seals and obtain a
repair kit, which will contain all the necessary
renewable items.
15Clean the piston and cylinder bore with
brake fluid or methylated spirit, nothing else!
16Begin reassembly by fitting the seal into
the caliper bore.
17Locate the dust seal in its groove in the
piston. Dip the piston in clean brake fluid and
insert it squarely into the cylinder. Check that
the cutaway recesses in the piston are
positioned horizontally. If necessary, carefully
turn the piston to its correct position.
18When the piston has been partially
depressed, engage the dust seal with the rim
of the caliper bore, and fit the retaining clip.
19Push the piston further into its bore, but
not as far as the stop, ensuring that it does
not jam.
20If desired, the caliper body locating pin
rubbers can be renewed. Extract the nylon
compression sleeve from within each rubber,
then carefully compress the rubber shoulder,
and push the rubber through the hole in the
caliper body to remove it from the inboard
end (see illustrations).
21Fit the new rubbers using a reversal of the
removal procedure.
22Secure the caliper bracket in a soft-jawed
vice, and refit the guide springs in the
positions noted before removal.
23Engage the caliper body with the locating
pins on the bracket, then press the caliper
body into position until the locating pin
rubbers in the caliper body rest against the
bracket.
Refitting
24Refit the caliper bracket to the hub carrier,
and tighten the securing bolts to the specified
torque. Refit the dust caps to the bolts.25Reconnect the brake fluid hose union,
using new sealing rings on the union bolt.
26Refit the disc pads, as described in
Section 4.
27Remove the polythene from the brake
fluid reservoir filler neck, and bleed the
relevant brake hydraulic circuit, as described
in Section 3.
28Refit the roadwheel and lower the vehicle
to the ground. Do not fully tighten the
roadwheel bolts until the vehicle is resting on
its wheels.
Models with ventilated discs
Removal
29Proceed as described in paragraphs 1 to 4
inclusive.
30Withdraw the caliper body from the
vehicle.
31If desired, the caliper bracket can be
removed from the hub carrier by unscrewing
the two securing bolts (see illustration).
Overhaul
32To overhaul the caliper, continue as
follows. Otherwise, go on to paragraph 42 for
details of refitting.
33Brush the dirt and dust from the caliper,
but take care not to inhale it.
34Using a screwdriver, carefully prise the
dust seal from the end of the piston and the
caliper body, and remove it.
35Proceed as described in paragraphs 10
to 15 inclusive.
36Begin reassembly by fitting the seal into
the caliper bore.
37Locate the dust seal in its groove in the
piston. Dip the piston in clean brake fluid and
insert it squarely into the cylinder. Check that
the cutaway recesses in the piston are
positioned vertically. If necessary, carefully
turn the piston to its correct position.
38When the piston has been partially
depressed, engage the dust seal with the rim
of the caliper bore.
39Push the piston further into its bore, but
not as far as the stop, ensuring that it does
not jam.
40If desired, the guide bolt sleeves can be
renewed. Extract the nylon compression
sleeve from within each rubber, then carefullycompress the rubber shoulder, and push the
rubber through the hole in the caliper body to
remove it from the inboard end.
41Fit the new sleeves using a reversal of the
removal procedure.
Refitting
42Where applicable, refit the caliper bracket
to the hub carrier, and tighten the securing
bolts to the specified torque.
43Proceed as described in paragraphs 25
to 28 inclusive.
9Rear disc caliper - removal,
overhaul and refitting
3
Note: Refer to the note at the beginning of
Section 3 before proceeding. Before
dismantling a caliper, check that replacement
parts can be obtained, and retain the old
components to compare them with the new
ones
Removal
1Where applicable, remove the wheel trim,
then loosen the relevant rear roadwheel bolts
and check the front wheels. Jack up the rear
of the vehicle, and support on axle stands
(see “Jacking and Vehicle Support”)
positioned under the body side members.
Remove the roadwheel.
2Remove the disc pads, as described in
Section 5.
3Working under the bonnet, remove the
brake fluid reservoir cap and secure a piece of
polythene over the filler neck with a rubber
band, or by refitting the cap. This will reduce
the loss of fluid during the following
procedure.
4Unscrew the brake fluid pipe union nut from
the rear of the caliper, and disconnect the
pipe. Take care not to strain the pipe. Be
prepared for fluid spillage, and plug the open
ends to prevent dirt ingress and further fluid
loss.
5Unscrew the two mounting bolts and
withdraw the caliper from the vehicle, noting
that on DOHC models, the caliper securing
bolts also secure the ABS sensor bracket (see
illustrations). Take care not to strain the ABS
sensor wiring, where applicable.
Braking system 9•9
8.31 Caliper bracket securing bolts
(arrowed) - model with ventilated discs8.20B . . . then withdraw the caliper
locating pin rubber - model with
solid discs8.20A Extract the nylon compression
sleeve (arrowed) . . .
9

Overhaul
6If desired, the caliper can be overhauled as
follows. Otherwise, go on to paragraph 20 for
details of refitting.
7Brush the dirt and dust from the caliper, but
take care not to inhale it.
8Note that no attempt must be made to
separate the two halves of the caliper.
9Using a screwdriver, prise the dust seal
retaining clips from the piston dust seals, then
carefully prise off the dust seals.
10Using a clamp, secure one of the pistons
in its fully retracted position. Then apply low
air pressure (e.g. from a foot pump), to the
hydraulic fluid union hole in the rear of the
caliper body, to eject the remaining piston
from its bore. Take care not to drop the
piston, which may result in damage.
11Temporarily close off the bore of the
removed piston, using a flat piece of wood or
similar improvised tool. Then remove the
clamp from the remaining piston, and again
apply air pressure to the caliper union to eject
the piston.
12Carefully prise the seals from the grooves
in the caliper piston bores, using a plastic or
wooden instrument.
13Inspect the surfaces of the pistons and
their bores in the caliper for scoring, or
evidence of metal-to-metal contact. If evident,
renew the complete caliper assembly.
14If the pistons and bores are in good
condition, discard the seals and obtain a
repair kit, which will contain all the necessary
renewable items. Also obtain a tube of brake
cylinder paste.
15Clean the piston and cylinder bore with
brake fluid or methylated spirit - nothing else!
16Apply a little brake cylinder paste to the
pistons, cylinder bores and piston seals.
17Begin reassembly by fitting the seals to
the grooves in the caliper bores.
18Locate the dust seals in their grooves in
the pistons, then insert the pistons carefully
into their bores until they enter the seals. It
may be necessary to rotate the pistons to
prevent them from jamming in the seals.
19When the pistons have been partially
depressed, engage the dust seals with the
rims of the caliper bores, and fit the retaining
clips.
Refitting
20Refit the caliper and tighten the securing
bolts to the specified torque, ensuring that the
ABS sensor bracket is in position, where
applicable.
21Reconnect the brake fluid pipe to the
caliper, and tighten the union nut.
22Refit the disc pads, as described in
Section 5.
23Remove the polythene from the brake
fluid reservoir filler neck and bleed the
relevant brake hydraulic circuit, as described
in Section 3.
24Refit the roadwheel and lower the vehicle
to the ground. Do not fully tighten the
roadwheel bolts until the vehicle is resting on
its wheels.
10Brake disc - inspection,
removal and refitting
3
Inspection
1Where applicable, remove the wheel trim,
then loosen the relevant roadwheel bolts. If
checking a front disc, apply the handbrake,
and if checking a rear disc, chock the front
wheels, then jack up the relevant end of the
vehicle and support on axle stands (see
“Jacking and Vehicle Support”) positioned
under the body side members. Remove the
roadwheel.
2Where applicable, check that the brake disc
securing screw is tight. Then fit a spacer
approximately 10.0 mm (0.4 in) thick to one of
the roadwheel bolts, and refit and tighten the
bolt in the hole opposite the disc securing
screw (see illustration).
3Rotate the brake disc, and examine it for
deep scoring or grooving. Light scoring is
normal, but if excessive, the disc should be
removed and either renewed or machined
(within the specified limits) by an engineering
works.
4Using a dial gauge, or a flat metal block and
feeler blades, check that the disc run-out does
not exceed the figure given in the Specifications.
Measure the run-out 10.0 mm (0.4 in) in from the
outer edge of the disc. 5On all SOHC models, if the rear disc run-
out is excessive, check the rear wheel bearing
adjustment, as described in Chapter 10.
6If the front disc run-out (all models), or the
rear disc run-out (DOHC models), is
excessive, remove the disc as described later
in this Section. Check that the disc-to-hub
surfaces are perfectly clean. Refit the disc and
check the run-out again.
7If the run-out is still excessive, the disc
should be renewed.
8To remove a disc, continue as follows.
Front disc
Removal
9Where applicable, remove the roadwheel
bolt and spacer used when checking the disc.
10Remove the disc pads, (Section 4).
11On 2.0 litre models, unscrew the two
securing bolts and remove the caliper
bracket.
12Remove the securing screw and withdraw
the disc from the hub, where applicable tilting
it to clear the brake caliper (see illustration).
Refitting
13Refitting is a reversal of removal, but
make sure that the mating faces of the disc
and hub are perfectly clean, and apply a little
locking fluid to the threads of the securing
screw. Refit the disc pads, (Section 4).
Rear disc - SOHC models
14On these models, the disc is integral with
the rear hub, and removal and refitting is
described in Chapter 10.
9•10Braking system
9.5A Withdrawing a rear caliper mounting
bolt . . .10.2 Refit a wheel bolt and spacer
(arrowed) opposite the disc securing screw
(A) before checking brake disc run-out
10.12 Removing a disc securing screw -
SOHC model
9.5B . . . which also secures the ABS
sensor bracket - DOHC model

14Front brake disc shield -
removal and refitting
3
Removal
1Where applicable, remove the wheel trim,
then loosen the relevant front roadwheel bolts
and apply the handbrake. Jack up the front of
the vehicle, and support on axle stands (see
“Jacking and Vehicle Support”) positioned
under the body side members. Remove the
roadwheel.
2Remove the brake disc, as described in
Section 10.
3Using a screwdriver inserted through the
holes in the hub flange, extract the three
screws securing the disc shield to the hub
carrier.
4Using plate shears or an alternative tool, cut
a section of metal from the rear edge of the
shield to enable the shield to be withdrawn
over the hub, then remove the shield (see
illustration).
Refitting
5If a new shield is to be fitted, cut out a
section of metal, as during removal of the old
shield, to enable the shield to be fitted.
Smooth the cut edges, and coat them with
anti-corrosion paint.
6Further refitting is a reversal of removal,
remembering the following points.
7Refit the brake disc, as described in
Section 10.
8Do not fully tighten the roadwheel bolts until
the vehicle is resting on its wheels.
15Master cylinder - removal and
refitting
4
Note: Refer to the note at the beginning of
Section 3 before proceeding
Removal
1Disconnect the battery negative lead.
2Depress the footbrake pedal several times
to dissipate the vacuum in the servo unit.3Disconnect the wiring plug from the brake
fluid level sensor in the reservoir filler cap.
4If possible, use a teat pipette or an old
hydrometer to remove the brake fluid from the
reservoir. This will reduce the loss of fluid later
in the procedure.
5Locate a container beneath the master
cylinder, to catch the brake fluid that will be
released.
6Identify the brake fluid pipes for position,
then unscrew the union nuts and disconnect
the pipes from the master cylinder.
7Unscrew the two securing nuts, and
withdraw the master cylinder from the studs
on the vacuum servo unit (see illustration).
8Clean the external surfaces of the cylinder,
then using a screwdriver carefully prise the
fluid reservoir and its seals from the top of the
cylinder.
9If desired, on models without ABS, the
master cylinder can be overhauled, as
described in Section 16.
10No overhaul of the master cylinder is
possible on models with ABS, see Section 17.
Refitting
11Refitting is a reversal of removal, but use
new seals when fitting the brake fluid
reservoir, and on completion, bleed the
complete brake hydraulic system, as
described in Section 3.
16Master cylinder (non-ABS) -
overhaul
4
Note: Before dismantling the master cylinder,
check that replacement parts can be obtained
and retain the old components to compare
them with the new ones
1With the master cylinder removed as
described in Section 15, continue as follows,
according to type.
GMF type master cylinder
2Clamp the master cylinder in a soft-jawed
vice.
3Where applicable, unscrew the pressure-
proportioning valves from the base of the
cylinder.4Carefully prise out the sealing ring from the
end of the cylinder bore.
5Depress the primary piston slightly using a
piece of wood or plastic. Then hold the piston
in the depressed position by inserting a
smooth pin or rod of 3.0 mm (0.12 in) diameter
through the primary fluid reservoir port in the
cylinder (see illustration).
6Extract the circlip from the end of the
cylinder bore using a screwdriver. Take care
not to damage the piston or cylinder bore.
7Withdraw the pin or rod retaining the piston.
8Withdraw the primary piston assembly from
the cylinder, if necessary tapping the cylinder
on a wooden block to free the piston from the
bore.
9Apply low air pressure - e.g. from a foot
pump - to the front fluid reservoir port in the
cylinder, to eject the secondary piston
assembly.
10Clean all the components, in clean brake
fluid or methylated spirit only, and examine
them for wear and damage. In particular,
check the surfaces of the pistons and cylinder
bore for scoring and corrosion. If the bore
shows signs of wear, renew the complete
master cylinder assembly (see illustration).
11If the cylinder bore is in good condition,
obtain a repair kit, which will contain all the
necessary renewable items. A Vauxhall dealer
will supply a pre-assembled kit of parts, which
should be fitted as follows.
12Lubricate the cylinder bore with clean
brake fluid or brake grease, then clamp the
cylinder in a soft-jawed vice, with the bore
horizontal.
13Remove the plug from the end of the
assembly tube, and insert the short part of the
tube into the cylinder bore as far as the
shoulder on the tube.
14Use a piece of wood or plastic to push the
components out of the tube and into the
cylinder bore. Then hold the primary piston in
the depressed position by inserting the pin or
rod used during dismantling through the
cylinder primary fluid reservoir port.
15Fit a new circlip to the end of the cylinder
bore, ensuring that it seats correctly, and that
the piston is free to move.
16Depress the primary piston, and withdraw
the pin or rod from the fluid reservoir port.
Braking system 9•13
16.5 Holding the primary piston depressed
while extracting the circlip from the
cylinder body - GMF type master cylinder15.7 Master cylinder securing nut
(arrowed)14.4 Cutting a section of metal from a new
front brake disc shield prior to fitting
9

42Where applicable, screw the pressure-
proportioning valves into the base of the
cylinder.
43Refit the master cylinder, as described in
Section 15.
17Master cylinder (ABS) -
general
The master cylinder fitted to models with
ABS cannot be dismantled, and no attempt
should be made at overhaul.
If faulty, the complete unit must be
renewed, as described in Section 15.
18Vacuum servo - description
and testing
Description
1The vacuum servo is fitted between the
brake pedal and the master cylinder, and
provides assistance to the driver when the
pedal is depressed, reducing the effort required
to operate the brakes. The unit is operated by
vacuum from the inlet manifold. With the brake
pedal released, vacuum is channelled to both
sides of the internal diaphragm. However,
when the pedal is depressed, one side of the
diaphragm is opened to atmosphere, resulting
in assistance to the pedal effort. Should the
vacuum servo develop a fault, the hydraulic
system is not affected, but greater effort will be
required at the pedal.
Testing
2The operation of the servo can be checked
as follows.
3With the engine stopped, destroy the
vacuum in the servo by depressing the brake
pedal several times.
4Hold the brake pedal depressed and start
the engine. The pedal should sink slightly as
the engine is started.
5If the pedal does not sink, check the servo
vacuum hose for leaks.
6If no defects are found in the vacuum hose,
the fault must lie in the servo itself.7No overhaul of the servo is possible, and if
faulty, the complete unit must be renewed.
19Vacuum servo - removal and
refitting
4
Note: During the 1989 model year, some
vehicles were produced with the brake pedal
height incorrectly set, resulting in the brake
pedal resting approximately 15.0 mm (0.6 in)
above the clutch pedal instead of 4.0 mm
(0.16 in below). The correct pedal height can
be set by adjusting the vacuum servo
operating fork dimension, as described in
paragraphs 15 and 16
Removal
1Disconnect the battery negative lead.
2Working inside the vehicle, remove the
lower trim panel from the driver’s footwell.
3Disconnect the wiring plug from the brake
lamp switch, then twist the switch anti-
clockwise and remove it from its bracket.
4Pull the spring clip from the right-hand end
of the servo fork-to-pedal pivot pin.
5Using a pair of pliers, pull back the end of
the pedal return spring from the pedal, to
enable the servo fork-to-pedal pivot pin to be
removed. Withdraw the pivot pin.
6Remove the windscreen cowl panel, as
described in Chapter 11, then remove the
windscreen wiper motor and linkage as
described in Chapter 12.7Remove the coolant expansion tank as
described in Chapter 3.
8Pull the vacuum pipe from the brake servo.
9Unscrew the two securing nuts, and
carefully withdraw the brake master cylinder
from the studs on the servo. Move the master
cylinder forwards slightly, taking care not to
strain the brake pipes.
10Remove the two plugs covering the servo
securing bolts from the cowl panel (see
illustrations).
11Using a Allen key or hexagon bit, unscrew
the servo securing bolts and remove them
completely, then lift the servo from the
bulkhead (see illustrations).
12If desired, the mounting bracket can be
removed from the servo by unscrewing the
four securing nuts. Note that the bracket will
stick to the servo, as it is fitted with sealing
compound.
13The servo cannot be overhauled, and if
faulty, the complete unit must be renewed.
Refitting
14Before refitting the servo, check that the
operating fork dimension is correct as follows.
15Measure the distance from the end face of
the servo casing to the centre of the pivot pin
hole in the end of the operating fork. The
distance should be 144.0 mm (5.6 in). To
make accurate measurement easier, insert a
bolt or bar of similar diameter through the
pivot pin hole, and measure to the centre of
the bolt or bar (see illustration).
Braking system 9•15
19.11A Unscrew the securing bolts . . .19.15 Measuring the servo operating fork
dimension using a bolt inserted through
the pivot pin hole19.11B . . . and withdraw the servo
19.10B . . . to expose the servo securing
bolts19.10A Remove the plugs . . .
9

16If adjustment is necessary, slacken the
locknut, turn the fork to give the specified
dimension, then tighten the locknut.
17Where applicable, coat the contact faces
of the servo and the mounting bracket with
sealing compound, then refit the bracket to
the servo, and tighten the securing nuts to the
specified torque.
18Coat the threads of the servo securing
bolts with locking fluid, then fit the servo to
the bulkhead and tighten the securing bolts.
19Refit the securing bolt cover plugs to the
cowl panel.
20Refit the master cylinder to the servo, and
tighten the securing nuts to the specified
torque.
21Reconnect the vacuum pipe to the servo.
22Refit the coolant expansion tank, as
described in Chapter 3.
23Refit the windscreen wiper motor and
linkage as described in Chapter 12, then refit
the windscreen cowl panel.
24Further refitting is a reversal of removal.
On completion, test the operation of the
servo, as described in Section 18.
20ABS hydraulic modulator -
removal and refitting
4
Note: Refer to Section 2, and the note at the
beginning of Section 3, before proceeding
Removal
1Disconnect the battery negative lead.
2Remove the brake fluid reservoir cap, and
secure a piece of polythene over the filler
neck with a rubber band, or by refitting the
cap. This will reduce the loss of fluid during
the following procedure.
3Remove the securing screw, and withdraw
the plastic cover from the hydraulic
modulator.
4Remove the two clamp screws, and lift off
the modulator wiring harness clamp (see
illustration).
5Disconnect the modulator wiring plug,
levering it from the socket with a screwdriver if
necessary.6Unscrew the brake fluid pipe union nuts,
and disconnect the pipes from the modulator.
Be prepared for fluid spillage, and plug the
open ends to prevent dirt ingress and further
fluid loss. Move the pipes just clear of the
modulator, taking care not to strain them.
7Unscrew the three modulator securing nuts
(see illustration), then tilt the modulator
slightly, and withdraw it upwards from its
bracket, sufficiently to gain access to the
earth lead securing nut at the front lower edge
of the modulator.
8Unscrew the securing nut and disconnect
the earth lead, then withdraw the modulator
from the vehicle, taking care not to spill brake
fluid on the vehicle paintwork.
9If a new modulator is to be fitted, pull the
two relays from the top of the old modulator,
and transfer them to the new unit. No attempt
must be made to dismantle the modulator.
Refitting
10Before refitting the modulator, check that
the bolts securing the mounting bracket to the
body panel are tight, and that the modulator
rubber mountings are in good condition.
Renew the rubber mountings if necessary.
11Refitting is a reversal of removal,
remembering the following points.
12Make sure that the earth lead is
reconnected before fitting the modulator to its
mounting bracket.13On completion, remove the polythene
sheet from the brake fluid reservoir filler neck,
and bleed the complete brake hydraulic
system, as described in Section 3.
14Check that the ABS warning lamp
extinguishes when first starting the engine
after the modulator has been removed. At the
earliest opportunity, take the vehicle to a
Vauxhall dealer, and have the complete
system tested, using the dedicated ABS test
equipment.
21ABS wheel sensors - removal
and refitting
3
Note: Refer to Section 2 before proceeding
Front wheel sensor
Removal
1Disconnect the battery negative lead.
2Where applicable, remove the wheel trim,
then loosen the relevant front roadwheel bolts
and apply the handbrake. Jack up the front of
the vehicle, and support on axle stands (see
“Jacking and Vehicle Support”) positioned
under the body side members. Remove the
roadwheel.
3Unclip the sensor wiring connector from the
retaining clip under the wheel arch, then
separate the two halves of the wiring
connector, prising them apart with a
screwdriver if necessary (see illustration).
4Using a Allen key or hexagon bit, unscrew
the bolt securing the wheel sensor to its
mounting bracket, then carefully lever the
sensor from the bracket using a screwdriver
(see illustration). Recover the seal ring.
Refitting
5Examine the condition of the seal ring, and
renew if necessary.
6Refitting is a reversal of removal,
remembering the following points.
7Smear a little grease on the sensor casing
before fitting it to the bracket.
8Do not fully tighten the roadwheel bolts until
the vehicle is resting on its wheels.
9Check that the ABS warning lamp
extinguishes when first starting the engine
after a wheel sensor has been removed. At
9•16Braking system
20.4 ABS hydraulic modulator (cover
removed)
1 Wiring harness
clamp screws2 Earth lead
3 Relays
21.3 Front wheel sensor wiring under
wheelarch - DOHC model
1 ABS sensor connector
2 Disc pad wear sensor wiring connector
21.4 ABS front wheel sensor securing bolt
(arrowed) - DOHC model20.7 ABS hydraulic modulator securing
screws (arrowed)