brakes FORD SIERRA 1993 2.G Braking System Workshop Manual

System type
Conventional braking system (except P100 models) . . . . . . . . . . . . . . . Front discs and rear drums with vacuum servo assistance, dual
hydraulic circuit split front/rear, deceleration sensitive pressure relief
valve in rear hydraulic circuit. Cable-operated handbrake on rear
wheels.
ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front and rear discs operated via electrically-driven hydraulic pump,
dual hydraulic circuit split front/rear, pressure regulating valve in rear
hydraulic circuit. Cable-operated handbrake on rear wheels
P100 models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front discs and rear drums with vacuum servo assistance, dual
hydraulic circuit split front/rear, load apportioning valve in rear
hydraulic circuit. Cable-operated handbrake on rear wheels
Front discs
Type:
1.3 and 1.6 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solid
1.8 and 2.0 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ventilated
Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240.0 mm (9.46 in)
Maximum disc run-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.15 mm (0.006 in)
Minimum pad friction material thickness . . . . . . . . . . . . . . . . . . . . . . . . 1.5 mm (0.06 in)
Rear discs
Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solid
Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252.7 mm (9.96 in)
Maximum disc run-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.15 mm (0.006 in)
Minimum pad friction material thickness . . . . . . . . . . . . . . . . . . . . . . . . 1.5 mm (0.06 in)
Rear drums
Internal diameter:
1.3 and 1.6 litre Saloon and Hatchback models . . . . . . . . . . . . . . . . . 203.2 mm (8.0 in)
1.8 and 2.0 litre Saloon and Hatchback models and all Estate models .228.6 mm (9.0 in)
P100 models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256.0 mm (10.1 in)
Minimum shoe friction material thickness . . . . . . . . . . . . . . . . . . . . . . . 1.0 mm (0.04 in)
Chapter 10
Braking system
Brake disc - examination, removal and refitting . . . . . . . . . . . . . . . . . .8
Brake drum - inspection and renewal . . . . . . . . . . . . . . . . . . . . . . . . .9
Brake fluid pipes and hoses - removal and refitting . . . . . . . . . . . . . .26
Brake hydraulic system (ABS) - bleeding . . . . . . . . . . . . . . . . . . . . . . .3
Brake hydraulic system (conventional braking system) - bleeding . . .2
Brake pedal - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . .30
Computer module (ABS) - removal and refitting . . . . . . . . . . . . . . . .21
Deceleration sensitive valve (Saloon, Hatchback and Estate models
with conventional braking system) - removal and refitting . . . . . . .23
Disc pads - inspection and renewal . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Fluid reservoir (ABS) - removal and refitting . . . . . . . . . . . . . . . . . . . .15
Front disc caliper - removal, overhaul and refitting . . . . . . . . . . . . . . .6
General information and precautions . . . . . . . . . . . . . . . . . . . . . . . . . .1
Handbrake cable - adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Handbrake cable - removal and refitting . . . . . . . . . . . . . . . . . . . . . .27
Handbrake lever - removal and refitting . . . . . . . . . . . . . . . . . . . . . . .29Hydraulic unit (ABS) - removal and refitting . . . . . . . . . . . . . . . . . . . .16
Hydraulic unit accumulator (ABS) - removal and refitting . . . . . . . . .17
Hydraulic unit pressure switch (ABS) - removal and refitting . . . . . . .19
Hydraulic unit pump and motor (ABS) - removal and refitting . . . . . .18
Load apportioning valve (P100 models) - adjustment . . . . . . . . . . . .25
Load apportioning valve (P100 models) - removal and refitting . . . . .24
Master cylinder (conventional braking system) - removal, overhaul and
refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Rear brake backplate (drum brakes) - removal and refitting . . . . . . .11
Rear drum brake shoes - inspection and renewal . . . . . . . . . . . . . . . .5
Rear disc caliper - removal overhaul and refitting . . . . . . . . . . . . . . . .7
Rear disc splash shield - removal and refitting . . . . . . . . . . . . . . . . .12
Rear wheel cylinder (drum brakes) - removal, overhaul and refitting .10
Vacuum servo (conventional braking system) - removal and refitting .14
Valve block (ABS) - removal and refitting . . . . . . . . . . . . . . . . . . . . . .20
Wheel sensor (ABS) - removal and refitting . . . . . . . . . . . . . . . . . . . .22
10•1
Specifications Contents
10
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

Torque wrench settingsNmlbf ft
Caliper carrier bracket-to-hub carrier bolts . . . . . . . . . . . . . . . . . . . . . .51 to 6138 to 45
Front caliper guide bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 to 2515 to 18
Rear caliper guide bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 to 3523 to 26
Rear brake backplate nuts - P100 models . . . . . . . . . . . . . . . . . . . . . . .45 to 5433 to 40
Servo-to-bulkhead nuts (conventional braking system) . . . . . . . . . . . . .35 to 4526 to 33
Master cylinder-to-servo nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 to 2515 to 18
Hydraulic unit-to-bulkhead nuts (ABS) . . . . . . . . . . . . . . . . . . . . . . . . . .41 to 5130 to 38
Hydraulic unit accumulator (ABS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 to 4625 to 34
Pump mounting bolt (ABS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 to 95 to 7
High pressure hose-to-pump union (ABS) . . . . . . . . . . . . . . . . . . . . . . .7 to 125 to 9
Wheel sensor mounting bolts (ABS) . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 to 116 to 8
General information
The braking system is of the dual circuit
hydraulic type. The front and rear circuits are
operated independently from a tandem
master cylinder, so that in the event of a
hydraulic failure in one circuit, full braking
force will still be available to two wheels
through the remaining circuit.
A deceleration sensitive valve on Saloon,
Hatchback and Estate models not fitted with
an Anti-lock Braking System (ABS), and a load
apportioning valve on P100 models, is
incorporated in the rear brake hydraulic
circuit. The valve regulates the pressure
applied to the rear brakes and reduces the
possibility of the rear wheels locking under
heavy braking.
All models are fitted with front disc brakes,
with solid or ventilated discs depending on
model. The calipers are of single piston sliding
type, which ensures that equal pressure is
applied to each disc pad.
Non-ABS models are fitted with rear disc
brakes or rear drum brakes, incorporating
leading and trailing shoes operated by
double-acting wheel cylinders. A self-adjuster
mechanism is fitted which consists of a
toothed quadrant which is kept in contact with
a toothed pin attached to the shoe strut by
means of a spring. The quadrant incorporates
an arm which locates in a slot in the leading
shoe. As the shoe linings wear the quadrant is
pulled from the pin when the footbrake is
operated, and automatically repositioned to
effectively lengthen the shoe strut.
ABS is available as an option for all models
except the P100. The system comprises an
electronic control unit, roadwheel sensors,
hydraulic actuator with electrically-driven
hydraulic pump, and the necessary valves and
switches. Disc brakes are fitted to all four
wheels. The front disc brakes are similar to
those fitted to non-ABS models, but the rear
brakes incorporate a self-adjusting
mechanism, and a mechanical handbrake
mechanism. The purpose of the system is to
prevent wheel(s) locking during heavy brake
applications. This is achieved by automatic
release of the brake on the locked wheel,followed by reapplication of the brake. This
procedure is carried out four times per second
by the control valves in the valve block. The
valves are controlled by the electronic control
unit which itself receives signals from the
wheel sensors, which monitor the locked or
unlocked state of the wheels. A pressure
regulating valve is incorporated in the rear
hydraulic circuit to maintain the desired
pressure ratio between the front and rear
circuits.
Precautions
Note: 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 also 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 (it absorbs moisture from the air)
old fluid may be contaminated and unfit for
further use. When topping-up or renewing the
fluid, always use the recommended type and
ensure that it comes from a freshly-opened
sealed container
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 is injurious to health.
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 inevitable that air will have been
introduced 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 (front or rear) of the hydraulic system,
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.
Bleeding
Two-man method
4Gather together a clean jar and a length of
rubber or plastic bleed tubing which will fit the
bleed screws tightly. The help of an assistant
will be required.
5Remove the dust cap where fitted, and
clean around the bleed screw on the relevant
caliper or wheel cylinder, then attach the
bleed tube to the screw (see illustration). If
the complete system is being bled, start at the
front left-hand caliper.
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
bleedscrew to prevent any possibility of air
entering the system down the threads of the
bleed screw when it is slackened.
2Brake hydraulic system
(conventional braking system)
- bleeding1General information and
precautions
10•2Braking system
2.5 Removing the dust cap from a wheel
cylinder bleed screw
Caution: Refer to the
precautions in Section 1.

Specifications. To do this, fix the measuring
equipment, and rotate the disc, noting the
variation in measurement as the disc is
rotated. The difference between the minimum
and maximum measurements recorded is
known as disc run-out.
5Mark the position of the brake disc in
relation to the drive flange and on Saloon,
Hatchback and Estate models, remove the
retaining screw or spire washer(s), as
applicable, and remove the disc. On P100
models, also mark the position of the wheel
adapter plate in relation to the disc and drive
flange, then unscrew the five retaining nuts
and remove the wheel adapter plate and disc.
6Refitting is a reversal of removal, but when
refitting ensure that the mating faces of the
disc, drive flange and on P100 models the
wheel adapter plate, are clean. Align the
marks made on the disc, drive flange, and
where applicable the wheel adapter plate,
during removal. Refit the disc caliper and
carrier bracket.
Rear disc
7Chock the front wheels, loosen the relevant
roadwheel nuts, then jack up the rear of the
vehicle and support on axle stands.(see
“Jacking and Vehicle Support”).Remove the
roadwheel and release the handbrake.
8Detach the handbrake cable from the
retaining clip on the lower arm.
9Unscrew the two caliper carrier
bracket-to-hub carrier bolts and remove the
caliper assembly. Support the caliper on an
axle stand to avoid straining the flexible hose.
10Proceed as described in paragraphs 3
and 4.
11Mark the position of the brake disc in
relation to the drive flange, remove the
retaining spire washer(s), and withdraw the
disc.
12Refitting is a reversal of removal, but
ensure that the mating faces of the disc and
drive flanges are clean, and align the marks
made on the disc and drive flange during
removal.
1Whenever a brake drum is removed, brush
out the dust, taking care not to inhale any, as
it may be injurious to health.
2Examine the internal friction surface of the
drum. If deeply scored, or so worn that the
drum has become ridged to the width of the
shoes, then both drums must be renewed.
3Regrinding is not recommended as the
internal diameter of the drum will no longer be
compatible with the shoe friction material
contact diameter.
Saloon, Hatchback and Estate
models
1Chock the front wheels, loosen the relevant
roadwheel nuts, then jack up the rear of the
vehicle and support on axle stands (see
“Jacking and Vehicle Support”).Remove the
roadwheel and release the handbrake.
2Remove the retaining spire washer(s) from
the wheel stud(s) and pull off the brake drum.
If the drum will not pass over the shoes, it is
possible to release the automatic adjuster
mechanism by inserting a screwdriver through
the small hole in the drum and pressing down
on the ratchet.
3Remove 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 union nut and disconnect the
fluid pipe from the wheel cylinder (see
illustration). Plug the open ends of the pipe
and wheel cylinder to prevent fluid loss and
dirt ingress.
5Pull the tops of the brake shoes apart so
that the self-adjuster mechanism holds them
clear of the wheel cylinder.
6Unscrew the two retaining bolts from the
rear of the brake backplate, and withdraw the
wheel cylinder and sealing ring.
7The wheel cylinder can now be dismantled
as follows.
8Prise the dust-excluding rubber seals from
the ends of the wheel cylinder, and withdraw
the pistons and central spring, identifying the
pistons so that they can be refitted in their
original positions.
9Prise the seals from the pistons.
10Clean all the components in methylated
spirit and allow to dry. Examine the surfaces
of the pistons and cylinder bore for wear,
scoring and corrosion. If evident, the
complete wheel cylinder must be renewed,
but if the components are in good condition,
discard the seals and obtain a repair kit.
11Dip the new seals in clean brake fluid and
fit them to the piston grooves, using fingers
only to manipulate them. Ensure that the seal
lips face into the wheel cylinder.
12Carefully insert the pistons and central
spring into the cylinder, and fit the
dust-excluding rubber seals. Ensure that the
pistons are fitted in their original positions.
13Wipe the brake backplate clean, then fit
the wheel cylinder together with a new sealing
ring, and tighten the securing bolts.14Reconnect the fluid pipe to the wheel
cylinder and tighten the union nut.
15Using a screwdriver, push the
self-adjuster toothed quadrant fully towards
the backplate to its initial setting.
16Further refitting is a reversal of removal,
but on completion apply the footbrake several
times in order to set the brake shoes in their
normal positions, and bleed the rear brake
circuit.
P100 models
17The procedure is as described in
paragraphs 1 to 16 inclusive, but with the
following differences.
18Before removing the roadwheel, mark its
position in relation to the brake drum.
Similarly, mark the position of the brake drum
in relation to one of the wheel studs. Align the
marks when refitting.
19The wheel cylinder is secured to the brake
backplate by a circlip instead of the two bolts
used on other models (see illustration).
Saloon, Hatchback and Estate
models
1Remove the rear brake shoes.
2Disconnect the handbrake cable from the
backplate by extracting the U-clip.
11Rear brake backplate (drum
brakes) - removal and refitting
10Rear wheel cylinder (drum
brakes) -removal,overhaul
andrefitting
9Brake drum -inspectionand
renewal
10•12Braking system
10.4 Fluid pipe union (1) and wheel cylinder
retaining bolts (2)
10.19 Wheel cylinder securing circlip
(arrowed)
Caution: Refer to the
precautions in Section 1.
Caution: Refer to the
precautions in Section 1.

Removal
1Chock the front wheels, jack up the rear of
the vehicle and support on axle stands (see
“Jacking and Vehicle Support”).
2The load apportioning valve is located on
the right-hand side of the vehicle underbody
above the axle.
3Remove the spring clip and clevis pin, and
detach the spring from the valve operating
lever (see illustration).
4Place a suitable container beneath the
valve to catch spilt fluid, then unscrew the
union nuts and disconnect the fluid pipes.
Plug the open ends of the pipes and valve to
prevent fluid leakage and dirt ingress.
5Unscrew the three securing nuts and bolts
from the valve mounting bracket, and remove
the valve assembly (see illustration).
Refitting
6Refitting is a reversal of removal, but note
that the fluid inlet pipe from the master cylindermust be connected to the lower valve port, and
the fluid outlet pipe to the rear brakes must be
connected to the upper valve port.
7On completion, bleed the rear hydraulic
circuit and check the valve adjustment.
Models before mid-April 1989
1The vehicle must be unladen, at normal
kerb weight (a full tank of petrol, but no driver
or load).
2With the vehicle standing on its roadwheels,
remove the spring clip and clevis pin, and
detach the spring from the valve operating
lever.
3Loosen the locknut on the abutment block
at the bottom of the spring (see illustration).
4Slide the spring through the grommet in the
bracket on the axle, until the correct “X”
dimension is obtained between the centre of
the spring eye and the centre of the valve
operating lever eye (see illustration).
5Hold the spring in position, slide the
abutment block against the underside of the
grommet, and tighten the locknut.
6Attach the free end of the spring to the
valve operating lever, and refit the clevis pin
and spring clip.
Models from mid-April 1989
7The procedure is as described above, but
note that the dimension “X” has been revised
to 92.0 mm (3.6 in) with the vehicle unladen at
normal kerb weight.
Removal
1To remove a flexible hose, always free it
from any mounting bracket(s) first by prising
out the U-shaped retaining clip, and then
using two close-fitting spanners to disconnect
the hose-to-rigid pipe union (see illustration).
2Once disconnected from the rigid pipe, the
flexible hose may be unscrewed from the
caliper or wheel cylinder union, as applicable.
Refitting
3When reconnecting pipe or hose fittings,
note that the seal is made at the swaged end
of the pipe, so do not continue to tighten a
union if it is tight, yet still stands proud of the
surface into which it is screwed.
26Brake fluid pipes and hoses
- removal and refitting25Load apportioning valve
(P100 models) - adjustment
24Load apportioning valve
(P100 models) - removal and
refitting
Braking system 10•19
10
25.3 Loosen the locknut (arrowed) on the
abutment block
26.1 Flexible hose-to-rigid pipe union. U-shaped retaining clip
arrowed25.4 Load apportioning valve adjustment
X = 77.0 mm (3.0 in) with vehicle unladen at normal kerb weight
24.5 Load apportioning valve securing
bolts (arrowed)24.3 Remove the spring clip (arrowed) and
clevis pin from the valve operating lever
Caution: Refer to the
precautions in Section 1.
Caution: Refer to the
precautions in Section 1.