1988 OPEL CALIBRA sensor

4The cut-off valve can now be removed from
the bracket.
Testing
5To test the cut-off valve a vacuum hand
pump with gauge will be required. If available,
connect to the cut-off valve and ensure that
air through-flow aperture is fully open.
Refitting
6Refitting is a reversal of removal. Ensure
valve is fitted in the correct direction.
8AIR switchover valve -
removal and refitting
3
Removal
1Disconnect the battery negative lead.
2Disconnect wiring plug from the valve.
3Mark the location of the vacuum hoses
before removing them from the valve.
4After disconnecting the hoses undo the two
bolts, and remove them from its bracket.
Refitting
5Refitting is a reversal of removal. Ensure
hoses are fitted correctly (see illustration).
9AIR pipe and non-return
valve - removal and refitting
3
Note:New air pipe washers will be required
when refitting.
Removal
1Remove the non-return valve air duct hose.
2Undo the bolts engine lifting eye bracket,
and turn the bracket on to its left hand side.
3Remove the pipe support bracket by
releasing its three bolts.
4Remove the heat shield that is secured by
two bolts.
5The air pipe can now be removed by
releasing the two securing bolts.
6If necessary the non-return valve can now
be disconnected.
7Carefully clamp the pipe using a vice with
protective jaws. Unbolt the valve from the
pipe, clean and inspect for damage.
Refitting
8Before refitting, coat the threads of the non-
return valve with sealing compound (i.e.
Vauxhall part no. 90094714).
9Use new washers when refitting the pipe,
(take care as the washers have sharp edges).
Coat the pipe mounting bolts with assembly
paste (i.e. Vauxhall part no. 90513210), before
refitting.
10Refitting is a reversal of removal.
Retighten to correct torque as shown in Spec-
ifications.
10Catalytic converter -
description, general and
precautions
Note: The catalytic converter is not a filter. It
creates a chemical reaction, but it is not
affected by that reaction.
Description
1Certain models are available with a catalytic
converter, to reduce exhaust emissions.
These models can be identified by a ‘C’ or ‘X’,
prefixing the engine code.
2The purpose of the catalytic converter is to
change potentially harmful hydrocarbon andcarbon monoxide exhaust gases into harmless
gases and water vapour. The converter
consists of a stainless steel canister containing
a catalyst-coated honeycomb ceramic. The
catalyst is a mixture of three precious metals,
platinum, palladium and rhodium.
3The exhaust gases pass freely through the
honeycomb, where the catalyst speeds up the
chemical change of the exhaust gases,
without being permanently altered itself.
4To avoid damage to the catalyst, the engine
must be kept properly tuned, and unleaded
petrol must always be used. Normal leaded
petrol will “poison” the catalyst, and must not
be used.
5To enable the Motronic engine management
system to achieve complete combustion of the
fuel mixture, and thus to minimise exhaust
emissions, an oxygen sensor is fitted in the
exhaust gas stream. The sensor monitors the
oxygen level in the exhaust gas, and sends a
signal to the Motronic module. The module
constantly alters the fuel/air mixture within a
narrow band to reduce emissions, and to allow
the catalytic converter to operate at maximum
efficiency. No adjustment of idle mixture is
therefore possible on models fitted with a
catalytic converter.
General
6Ninety-nine per cent of exhaust gases, from
a petrol engine (however efficient or well
tuned), consists of nitrogen (N
2), carbon
dioxide (CO
2), oxygen (O2), other inert gases
and water vapour (H
2O). The remaining 1% is
made up of the noxious materials that are
currently seen (except CO
2), as the major
polluters of the environment. Carbon
monoxide (CO), unburned hydrocarbons (HC),
oxides of nitrogen (NOx) and some solid
matter, including a small lead content.
7The device most commonly used to clean
up vehicle exhausts is the catalytic converter.
It is fitted into the vehicle’s exhaust system
and uses precious metals (platinum and
palladium or rhodium) as catalysts to speed
up the reaction between the pollutants and
the oxygen in the exhaust gases. CO and HC
being oxidised to form H
2O and CO2and (in
the three-way type of catalytic converter) NOx
being reduced to N
2.
8The converter consists of an element of
ceramic honeycomb, coated with a
combination of precious metals in such a way
as to produce a vast surface area over which
the exhaust gases must flow. The three-way
closed-loop type converter fitted to these
models can remove over 90% of pollutants.
9The catalytic converter is a reliable and
simple device that needs no maintenance.
However there are some facts that an owner
should be aware if the converter is to function
properly for its full service life (see
illustration).
a)DO NOT use leaded petrol in a vehicle
equipped with a catalytic converter. The
lead will coat the precious metals,
reducing their converting efficiency and
will eventually destroy the converter.
Fuel and exhaust systems - exhaust and emissions 4C•3
10.9 The catalytic converter is protected
by heat shields
8.5 AIR switchover valve
1 Connection to brake servo vacuum hose
2 Connection to cut-off valve
7.1 AIR cut-off valve
1 Connection to AIR pump
2 Connection to AIR switchover valve
3 Connection to AIR non-return valve
4C

b)Always keep the ignition and fuel systems
well maintained according to the
manufacturers schedule (see “Routine
maintenance” and the relevant Chapter).
In particular, ensure that the air cleaner
filter element, the fuel filter and the spark
plugs are renewed at the correct intervals.
If the inlet air/fuel mixture is allowed to
become too rich due to neglect, the
unburned surplus will enter and burn in
the catalytic converter, overheating the
element and eventually destroying the
converter.
c)If the engine develops a misfire, do not
drive the vehicle at all (or at least as little
as possible) until the fault is cured. The
misfire will allow unburned fuel to enter
the converter, which will result in its
overheating, as noted above.
d)The engine control indicator (the outline
of an engine with a lightning symbol
superimposed), will light when the ignition
is switched on and the engine is started,
then it will go out. While it may light briefly
while the engine is running, it should go
out again immediately and stays unlit. If it
lights and stays on while the engine is
running, seek the advice of a Vauxhall
dealer as soon as possible. A fault has
occurred in the fuel injection/ignition
system that, apart from increasing fuel
consumption and impairing the engine’s
performance, may damage the catalytic
converter.
e)DO NOT push or tow-start the vehicle.
This will soak the catalytic converter in
unburned fuel causing it to overheat when
the engine does start see (b) above.
f)DO NOT switch off the ignition at high
engine speeds. If the ignition is switched
off at anything above idle speed,
unburned fuel will enter the (very hot)
catalytic converter, with the possible risk
of its igniting on the element and
damaging the converter.
g)DO NOT use fuel or engine oil additives.
These may contain substances harmful to
the catalytic converter.
h)DO NOT continue to use the vehicle if the
engine burns oil to the extent of leaving a
visible trail of blue smoke. The unburned
carbon deposits will clog the converter
passages and reduce its efficiency; in
severe cases the element will overheat.
i)Remember that the catalytic converter
operates at very high temperatures hence
the heat shields on the vehicle’s under-
body and the casing will become hot
enough to ignite combustible materials
that brush against it. DO NOT, therefore,
park the vehicle in dry undergrowth, over
long grass or over piles of dead leaves.
j)Remember that the catalytic converter is
FRAGlLE. Do not strike it with tools during
servicing work. Take great care when
working on the exhaust system. Ensure
that the converter is well clear of any
jacks or other lifting gear used to raise thevehicle. Do not drive the vehicle over
rough ground, road humps, etc., in such a
way as to ground the exhaust system.
k)In some cases, particularly when the
vehicle is new and/or is used for
stop/start driving, a sulphurous smell (like
that of rotten eggs) may be noticed from
the exhaust. This is common to many
catalytic converter-equipped vehicles and
seems to be due to the small amount of
sulphur found in some petrol’s reacting
with hydrogen in the exhaust to produce
hydrogen sulphide (CS) gas. While this
gas is toxic, it is not produced in sufficient
amounts to be a problem. Once the
vehicle has covered a few thousand miles
the problem should disappear. In the
meanwhile a change of driving style or of
the brand of petrol may effect a solution.
l)The catalytic converter, used on a
well-maintained and well-driven vehicle,
should last for between 50 000 and 100
000 miles. From this point on, careful
checks should be made at all specified
service intervals of the CO level to ensure
that the converter is still operating
efficiently. If the converter is no longer
effective it must be renewed.
11Carbon canister - removal
and refitting
3
Removal
1Apply the handbrake, then jack up the front
of the vehicle, and support securely on axle
stands placed under the body side members
(see “Jacking and Vehicle Support”).
2Remove the front right hand wheel and
wheel arch liner.
3Note the hose and pipe connections to the
canister, or label them, to ensure that they are
reconnected to their original unions, then
disconnect them (see illustration). Unscrew
the two nuts securing the canister mounting
bracket to the vehicle body.
Refitting
4Refitting is a reversal of removal, however
ensure correct fitment of hose and pipes.
12Oxygen sensor (catalytic
converter models) - removal
and refitting
3
Note: This sensor is also known as a Lambda
sensor.
Removal
1Disconnect the battery negative lead.
2Disconnect the oxygen sensor wiring plug,
which is located behind the coolant expansion
tank.
3Apply the handbrake, then jack up the front
of the vehicle, and support securely on axle
stands placed under the body side members.
4On DOHC models, remove the engine
undershield, as described in Chapter 11.
5On models fitted with Multec injection
system, the sensor is screwed into the
exhaust manifold. Trace the wiring from the
sensor itself to the connector (either clipped
to the radiator cooling fan shroud or behind
the coolant expansion tank). Release it from
any clips or ties; disconnect the wiring before
unscrewing the sensor.
6On other models, unscrew the oxygen
sensor from the front section of the exhaust
system (see illustration). It is advisable to
wear gloves, as the exhaust system will be
extremely hot.
7Withdraw the oxygen sensor and its wiring,
taking care not to burn the wiring on the
exhaust system. If the sensor is to be re-used,
take care that the sealing ring is not lost, and
that the sensor is not dropped.
Refitting
8If a new sensor is being fitted, it will be
supplied with the threads coated in a special
grease to prevent it seizing in the exhaust
system.
9If the original sensor is being refitted,
ensure that the screw thread is clean. Coat
the thread with a lithium based copper grease
(i.e. Vauxhall Part No. 90295397).
10Refitting is a reversal of removal. Check
the exhaust system for leakage when the
engine is re-started.
4C•4Fuel and exhaust systems - exhaust and emissions
12.6 Oxygen sensor location in front
section of exhaust system - DOHC models
11.3 Charcoal canister
A Vent to atmosphere
B Vapour feed hose from filler pipe
C Vapour exhaust hose to inlet tract
D Control valve vacuum pipe from
throttle body

13Exhaust manifold - removal
and refitting
3
Note:New manifold-to-cylinder head, and
manifold-to-downpipe, gaskets must be used
on refitting. Exhaust manifolds on DOHC
models are of tubular design, which form part
of the front section of the exhaust.
Removal
1Disconnect the battery negative lead.
2Disconnect the HT leads from the spark
plugs, if necessary labelling them to ensure
refitting to the correct cylinders.
3Loosen the clamp screw and disconnect
the air cleaner hot air tube from the shroud on
the manifold, if fitted. Remove the securing
screws and withdraw the hot air shroud from
the manifold.
4Working under the manifold, unscrew and
remove the four bolts securing the exhaust
downpipe to the manifold.
5If fitted, disconnect the oxygen sensor
wiring
6Separate the downpipe from the manifold,
and support with wire or string. Do not allow
the front section of the exhaust system to hang
under its own weight. Recover the gasket.
7Unscrew the securing nuts, and withdraw
the manifold from the cylinder head (see
illustration). Recover the gasket.
8It is possible that some of the manifold
studs may be unscrewed from the cylinder
head when the manifold securing nuts are
unscrewed. In this event, the studs should be
screwed back into the cylinder head once the
manifold has been removed, using two
manifold nuts locked together.
Refitting
9Refit the manifold using a new gasket, and
tighten the securing nuts to the specified
torque.
10Reconnect the exhaust downpipe to the
manifold, using a new gasket and tighten the
securing bolts to the specified torque.
11Further refitting is a reversal of removal.
14Exhaust system - checking,
removal and refitting
2
Note: All relevant gaskets and/or sealing rings
should be renewed on refitting
Checking
1Periodically, the exhaust system should be
checked for signs of leaks or damage. Also
inspect the exhaust system rubber
mountings, and renew if necessary.
2Small holes or cracks can be repaired using
proprietary exhaust repair products, but
where more serious corrosion or damage is
evident, renewal will be necessary.
Removal
3The original factory-fitted exhaust system
consists of four separate sections, all of which
can be renewed individually.
4On models fitted with a catalytic converter,
an oxygen sensor is fitted to the front section
of the exhaust. The catalytic converter is fitted
in place of the front expansion box in the
conventional exhaust system. The
manufacturers do not specify any renewal
intervals for the catalytic converter.
5Before renewing an individual section of the
exhaust system, it is wise to inspect the
remaining sections. If corrosion or damage is
evident on more than one section of the
system, it may prove more economical to
renew the entire system.
6Individual sections of the exhaust system
can be removed as follows.
Front section - SOHC models
7On models with a catalytic converter,
disconnect the battery negative lead, and
disconnect the oxygen sensor wiring plug,
which is located behind the coolant expansion
tank.
8Raise the vehicle, and support securely on
axle stands placed under the body side
members (see “Jacking and Vehicle
Support”).
9Unscrew the two securing bolts, and
disconnect the exhaust front section from the
front expansion box or catalytic converter (as
applicable) at the flexible joint. Recover the
sealing ring and the springs (see illustration).10Unbolt the exhaust front section from the
bracket on the cylinder block (see
illustration).
11Unscrew and remove the four bolts
securing the downpipe to the exhaust
manifold, and withdraw the exhaust front
section (see illustration). Recover the
downpipe-to-manifold gasket.
Refitting
12Refitting is a reversal of removal, but use a
new gasket when reconnecting the downpipe
to the manifold, and a new sealing ring when
connecting the flexible joint. Tighten all fixings
to the specified torque.
Front section - DOHC models
Removal
13Proceed as described in paragraphs 7
and 8.
14Remove the engine undershield, as
described in Chapter 11.
15Proceed as described in paragraphs 9
and 10.
16Working in the engine compartment,
remove the bolts securing the exhaust
manifold heat shield to the cylinder head.
17Unscrew the two lower exhaust manifold
securing nuts that also secure the heat shield
brackets, and withdraw the heat shield (see
illustration).
18Unscrew the remaining manifold securing
nuts, then withdraw the manifold/exhaust
front section from the vehicle. Recover the
manifold gasket.
Fuel and exhaust systems - exhaust and emissions 4C•5
14.10 Exhaust front section support
bracket - SOHC models
14.11 Unscrewing a downpipe-to-exhaust
manifold bolt - SOHC models
14.9 Exhaust front section flexible joint -
SOHC models13.7 Unscrewing an exhaust manifold
securing nut - SOHC models
4C

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

4Front disc pads - inspection,
removal and refitting
3
Note: 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 can damage your
health.
Inspection
1Where applicable, remove the wheel trims,
then loosen the 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.
2Remove the roadwheels. Turn the steering to
full right-hand lock, and check the wear of the
friction material on the right-hand brake pads.
Check that the thickness of the friction material
(including the backing plate) is not less than the
minimum given in the Specifications.
3Turn the steering to full left-hand lock, and
check the left-hand brake pads in the same
way.
4If any brake pad is worn below the specified
minimum thickness, renew all the front pads
as a set.
5If the pads require renewal, continue as
follows according to model.
Removal
1.4, 1.6 and 1.8 litre models
6Note how the anti-rattle springs are located
(see illustration), then drive the upper and
lower pad retaining pins out from the inboard
side of the caliper, using a pin punch.
7Remove the anti-rattle springs (see
illustration).
8Push the pads away from the disc slightly,
then using a pair of pliers, withdraw the
outboard pad (see illustration).
9Withdraw the inboard pad, and the shim
that fits between the pad and the caliper
piston (see illustration).
Refitting
10Brush the dust and dirt from the caliper,
but take care not to inhale it. Carefully remove
any rust from the edge of the brake disc.11To accommodate the new thicker pads,
the caliper piston must be depressed fully into
its cylinder bore, using a flat bar of metal such
as a tyre lever. The action of depressing the
piston will cause the fluid level in the reservoir
to rise, so to avoid spillage, syphon out some
fluid using an old hydrometer or a teat pipette.
Refer to the note at the beginning of Section 3.
Do not lever between the piston and disc to
depress the piston.
12Check that the cutaway recesses in the
piston are positioned vertically. If necessary,
carefully turn the piston to its correct position.
13Apply a little brake grease to the top and
bottom edges of the backplates on the new
brake pads.
14Locate the new pads in the caliper,
ensuring that the shim is in place between the
inboard pad and the piston. Ensure that the
friction material faces the disc, and check that
the pads are free to move slightly.
15Locate the anti-rattle springs on the pads,
then insert the pad retaining pins from the
outboard side of the caliper, while depressing
the springs. Tap the pins firmly into the caliper
(see illustration).
16Repeat the operations on the remaining
side of the vehicle.
17Refit the roadwheels and lower the vehicle
to the ground. Do not fully tighten the
roadwheel bolts until the vehicle is resting on
its wheels.
18Apply the footbrake hard several times to
position the pads against the discs.
19Check and if necessary top-up the brake
fluid level.20New brake pads should be carefully
bedded in and, where possible, heavy braking
should be avoided during the first 100 miles
(160 km) or so after fitting new pads.
2.0 litre models
Removal
21Where applicable, pull the pad wear
sensor from the inboard pad, and disconnect
the wiring at the connector under the wheel
arch, next to the suspension strut (see
illustration). Note the wire routing.
22Using a screwdriver, prise the pad
retaining clip from the outboard edge of the
caliper, noting how it is located (see
illustration).
23Prise out the two guide bolt dust caps
from the inboard edge of the caliper, then
using a Allen key or hexagon bit, unscrew the
9•4Braking system
4.6 Front disc pad anti-rattle springs
(arrowed) - models with solid discs
4.8 Withdrawing the outboard disc pad -
models with solid discs
4.21 Withdrawing the pad wear sensor
from the inboard pad - DOHC model4.15 Fitting a disc pad retaining pin -
models with solid discs4.9 Withdrawing the inboard disc pad and
shim - models with solid discs
4.7 Removing an anti-rattle spring -
models with solid discs

guide bolts, and lift the caliper and inboard
pad from the bracket. Recover the outboard
brake pad (see illustrations). Suspend the
caliper body with wire or string, to avoid
straining the brake fluid hose.
24Pull the inboard pad from the caliper
piston, noting that it is retained by a clip
attached to the pad backing plate (see
illustration).
Refitting
25Proceed as described in paragraphs 10
to 12 inclusive (see illustration).
26Apply a little brake grease to the contact
surfaces of the new brake pads.
27Fit the new inboard pad to the caliper
piston, ensuring that the piston is correctly
located.
28Locate the outboard pad on the caliper
bracket, with the friction material facing the
disc.
29Refit the caliper to the bracket, and
tighten the guide bolts to the specified torque
(see illustration).
30Refit the guide bolt dust caps.
31Refit the pad retaining clip, locating it as
noted before removal.
32Where applicable, fit a new pad wear
sensor to the inboard pad, and connect the
wiring at the connector under the wheel arch.
Route the wiring as noted during removal.
33Repeat the operations on the remaining
side of the vehicle.
34Proceed as described in paragraphs 17
to 20 inclusive.
5Rear disc pads - inspection,
removal and refitting
3
Note: 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 can damage your
health.
Inspection
1Where applicable, remove the wheel trims,
then loosen the rear roadwheel bolts and
chock 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
roadwheels.2Check the wear of the friction material on
the brake pads, on both sides of the vehicle.
Check that the thickness of the friction
material (including the backing plate) is not
less than the minimum given in the Specifica-
tions.
3If any brake pad is worn below the specified
minimum thickness, renew all the rear pads as
a set as follows.
Removal
4Note how the anti-rattle spring is located,
then drive out the upper and lower pad
retaining pins from the outside of the caliper
using a pin punch (see illustration).
5Remove the anti-rattle spring (see
illustration).
6Push the pads away from the disc slightly,
then using a pair of pliers, withdraw the
Braking system 9•5
4.23B Withdrawing the caliper, inboard and
outboard pad - models with ventilated discs
5.5 Removing a rear disc pad retaining pin
anti-rattle spring5.4 Driving out a rear disc pad retaining
pin
4.29 Tightening a caliper guide bolt -
models with ventilated discs4.25 Caliper piston cutaway recess
(arrowed) correctly positioned - models
with ventilated discs4.24 Removing the inboard pad from the
caliper piston - models with ventilated
discs
4.23A Removing a caliper guide bolt dust
cap - models with ventilated discs4.22 Prising out the disc pad retaining clip
- models with ventilated discs
9

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