brake LAND ROVER DEFENDER 1996 Manual PDF

70BRAKES
2
DESCRIPTION AND OPERATION REV: 05/99 OPERATION
Master cylinder
A tandem master cylinder, which is assisted by a light
weight, short, compact servo, is fed by a divided fluid
reservoir. The rear section supplies fluid for the
primary circuit and the front section the secondary
circuit.
When the brakes are off, the fluid can move
unrestricted between the dual line system and the
separate reservoirs in the fluid supply tank.
When the footbrake is applied, the primary plunger
assembly moves up the cylinder bore and the
pressure created acts in conjunction with the primary
spring to overcome the secondary springs, thus
moving the secondary plunger assembly up the bore.
At the same time initial movement of both plungers
takes the recuperating seals past the cut-off holes in
the cylinder chambers 'A' and 'C',see J6321, and
applies pressure to the fliud in those chambers, which
is directed to the respective circuits.
The fluid in chambers 'B' and 'D'is unaffected by
movement of the plungers and can move unrestricted
between the separate chambers and respective
reservoirs in the fluid supply tank, both before and
during brake application. When the brakes are
released, the plunger assemblies, aided by the return
springs are retracted faster than the fluid; this creates
a depression between the fluid in chambers 'A' and
'C'and the recuperation seals.
The recuperation seals momentarily collapse allowing
fluid in chambers 'B' and 'D'to flow through the holes
in the plungers, over the collapsed seals and into
chambers 'A' and 'C'respectively. The movement of
fluid from one set of chambers to the other, is
compensated for by fluid from the separate reservoirs
in the supply tank moving through the feed holes in
the cylinder. Conversely, the final return movement of
the plunger assemblies causes the extra fluid in
chambers 'A' and 'C'to move through the cut off holes
into the fluid reservoir.The servo unit provides controlled power assistance
to to the brake pedal when pressure is applied. Power
is obtained from a vacuum pump located on the RH
side of the engine cylinder block. The vacuum is
applied to both sides of a flexing diaphragm, and by
admitting atmosheric pressure to the rear diaphragm,
assistance is obtained. The servo unit is mounted
between the brake pedal and master cylinder and is
linked to these by push rods. Should a vacuum failure
occur, the two push rods will act as a single rod
allowing the brakes to function in the normal way,
although more effort will be required to operate the
brake pedal.
Hydraulic system
A brake fluid loss switch is fitted to the master cylinder
reservoir filler cap. The switch is wired to a warning
light on the vehicle fascia and will illuminate as a bulb
check when the ignition is switched on and
extinguishes when the engine is running and the
handbrake is released. A hydraulic failure in the
system will result in fluid loss, causing the warning
light to illuminate.
On 90 models a pressure reducing valve (PRV), fitted
to the RH bulkhead in the engine compartment,
maintains the braking balance, see J6322. Pressure
to the rear calipers is regulated by the PRV, this valve
is of the failure by-pass type, allowing full system
pressure to the rear brake calipers in the event of a
front (secondary) circuit failure.
NOTE: In some countries, a pressure
reducing valve may be fitted to 110 models
to conform to legal requirements.

BRAKES
3
DESCRIPTION AND OPERATION
90 Models
110/130 Models
Hydraulic system
A- Primary circuit
B- Secondary circuit
C- Pressure reducing valve (PRV)1.LH rear brake caliper
2.T connector
3.RH rear brake caliper
4.Brake servo
5.Master cylinder and reservoir
6.LH front brake caliper
7.RH front brake caliper

BRAKES
1
REPAIR GENERAL BRAKE SERVICE PRACTICE
Brake fluid precautions
WARNING: Do not allow brake fluid to
come into contact with eyes or skin.
CAUTION: Brake fluid can damage
paintwork, if spilled wash off immediately
with plenty of clean water.
CAUTION: Use only correct grade of brake
fluid. If an assembly fluid is required use
ONLY brake fluid. Do NOT use mineral oil,
i.e. engine oil etc.
CAUTION: Thoroughly clean all brake
calipers, pipes and fittings before
commencing work on any part of the brake
system. Failure to do so could cause foreign
matter to enter the system and cause damage to
seals and pistons which will seriously impair the
efficiency of the brake system. To ensure the
brake system efficiency is not impaired the
following warnings must be adhered to :-
·DO NOT use any petroleum based cleaning
fluids or any proprietary fluids containing
petrol.
·DO NOT use brake fluid previously bled from
the system.
·DO NOT flush the brake system with any fluid
other than the recommended brake fluid.
The brake system should be drained and flushed
at the recommended service intervals.
Cover all electrical terminals carefully to make
absolutely certain that no fluid enters the
terminals and plugs.FLUID LEVEL CHECK/TOP UP
WARNING: Clean reservoir body and filler
cap before removing cap. Use only fluid
from a sealed container.
1.Park vehicle on level ground.
2.Check level is between 'MIN' and 'MAX' marks.
3.If level is below 'MIN' mark top up fluid level to
'MAX' mark on reservoir, using correct fluid.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended lubricants and
fluids
CAUTION: Do not fill reservoir above
maximum line.

70BRAKES
2
REPAIR BRAKE SYSTEM BLEED
Service repair no - 70.25.02
Preparation
WARNING: Before bleeding the brake
system refer to general brake service
practice.
See General Brake Service
Practice
.
·During bleed procedure, brake fluid level must
not be allowed to fall below the MIN level.
·To bleed the hydraulic circuits, four bleed
nipples are provided, one at each caliper.
·There are two methods by which air can be
removed from the braking system:-
1. MANUAL BLEED PROCEDURE.
2. PRESSURE BLEED PROCEDURE.
Pressure bleed procedure
Purpose designed equipment for pressure filling and
bleeding of hydraulic systems may be used on Land
Rover vehicles. The equipment manufacturer's
instructions must be followed and the pressure must
not exceed 4.5 bar, 65 lb/in
2.
Manual bleed procedure
Equipment required
·Clean glass receptacle
·Bleed hose
·Wrench
·Approx 2 litres (3 pints) brake fluid.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended lubricants and
fluids
Master cylinder bleed
1.Disconnect battery.
2.Depress brake pedal fully and slowly 5 times.
3.Release the pedal and wait for ten seconds.
4.Air bubbles will rise into the reservoir during
these instructions.
5.Repeat instructions until a firm resistance is felt
at the pedal.
Complete circuit bleed
1.Disconnect battery.
2.Bleed front calipers, driver's side first. Fit bleed
hose to bleed screw.
3.Dip free end of bleed hose into brake fluid in
bleed bottle.
4.Open bleed screw of caliper.
5.Depress brake pedal fully several times until fluid
is clear of air bubbles.
6.Keeping pedal fully depressed, tighten bleed
screw, then release pedal.
7.Repeat procedure on other front caliper followed
by rear calipers.
8.Fit all bleed screw protection caps.
9.Check/top-up fluid level when bleeding is
complete
See Fluid Level Check/Top-Up.

BRAKES
3
REPAIR MASTER CYLINDER
Service repair no - 70.30.08
Before starting repair refer to general brake service
practice
See General Brake Service Practice.
Remove
1.Disconnect battery.
2.Place a container under the master cylinder to
catch escaping brake fluid.
3.Clean area round master cylinder ports.
4.Disconnect pipes from master cylinder ports.
Cover, not plug, the pipe ends to prevent entry of
dirt.
5.Disconnect electrical leads from reservoir cap.
6.Remove two nuts securing master cylinder to
servo and withdraw cylinder.
7.Remove reservoir cap and drain fluid into
suitable container for disposal.
8.The reservoir is a push fit in the master cylinder
and secured by seals. Carefully ease the
reservoir from the master cylinder by rolling it
from the seals. Note that the two seals are
different sizes.
Refit
9.Insert new reservoir seals in the master cylinder
ports and fit reservoir to master cylinder.
10.Ensuring that water ingress seal is in position, fit
master cylinder to servo. Tighten fixings to
26
Nm (19 lbf/ft).
11.Connect brake pipes to master cylinder ports
and tighten to
15 Nm (11 lbf/ft).
12.Fit electrical leads to reservoir cap
13.Fill reservoir with recommended brake fluid.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended lubricants and
fluids
14.Bleed the brake systemSee Brake system
bleed
.
15.Reconnect battery and road test vehicle.

70BRAKES
4
REPAIR PRESSURE REDUCING VALVE (PRV)
Service repair no - 70.25.21
Remove
1.Disconnect battery.
2.Clean area around reducing valve ports.
3.Place a container under valve to catch escaping
brake fluid.
4.Disconnect primary circuit pipe unions ñAñ
from valve.
5.Disconnect secondary circuit pipe unions ñBñ
from valve.
6.Cover pipes to prevent ingress of dirt.
7.Remove single retaining nut and bolt securing
valve to engine bulkhead.
8.Remove valve.
Refit
9.Fit valve to engine bulkhead. Tighten bolt to
15
Nm (11 lbf/ft).
10.Connect primary and secondary circuit pipes to
valve. Tighten to
16 Nm (12 lbf/ft).
11.Fill brake reservoir with recommended brake
fluid
See LUBRICANTS, FLUIDS AND
CAPACITIES, Information, Recommended
lubricants and fluids
.
12.Bleed the brake system
See Brake system
bleed
.
13.Reconnect battery and road test vehicle.SERVO NON RETURN VALVE
Service repair no - 70.50.15
Remove
1.Disconnect brake vacuum hose from servo non
return valve.
2.Carefully prise valve out with a screwdriver blade
between valve and grommet. Take care not to
exert too much pressure on the vacuum
chamber.
3.Remove rubber grommet but be careful not to
allow it to fall into the vacuum chamber.
4.Check the valve for correct operation; it should
not be possible to pass air through into the servo
in direction of arrow. Do not use compressed air.
Refit
5.Fit rubber grommet.
6.Smear ribs of the valve with Lucas Girling rubber
grease to assist assembly, and push valve fully
home.
7.Connect vacuum hose to the valve.
8.Road test vehicle.

BRAKES
5
REPAIR SERVO ASSEMBLY
Service repair no - 70.50.01
Remove
Before starting repair refer to general brake service
practice
See General Brake Service Practice.
NOTE: The non-return valve and grommet,
are the only serviceable components. In
event of failure or damage, fit a new unit.
1.Remove master cylinderSee Master cylinder.
2.Disconnect vacuum supply hose from servo unit.
3.At footwell, release 2 brake pedal return springs.
4.Disconnect leads from brake light switch at rear
of pedal box.
5.Remove blanking grommets from each side of
pedal box.
6.Remove split pin and clevis pin securing servo
push rod to brake pedal.
7.Remove 4 nuts and plain washers securing
servo to pedal box.
8.Remove servo assembly and rubber washer
from bulkhead.Refit
9.Locate servo assembly and rubber washer to
engine bulkhead and secure to pedal box.
Tighten fixings to
14 Nm (10 lbf/ft).
10.Fit brake pedal to servo push rod with clevis pin
and new split pin.
11.Fit blanking grommets to each side of pedal box.
12.At footwell, attach pedal return springs.
13.Connect vacuum hose to servo non-return valve.
14.Fit brake master cylinder to servo unit
See
Master cylinder
.

70BRAKES
6
REPAIR BRAKE PEDAL
Service repair no - 70.35.01 - Brake pedal
Service repair no - 70.35.03 - Pedal box
Remove
1.Remove brake servo assembly.
See Servo
assembly
.
2.Remove 6 bolts securing pedal box to engine
bulkhead.
3.Taking care not damage brake fluid pipes,
remove pedal box assembly and gasket.
4.Release return springs from pedal and pedal box
bosses.
5.Using a suitable punch, drift out retaining pin and
withdraw pedal pivot shaft.
6.Remove brake pedal complete with pivot
bushes.
7.Examine components for wear or damage,
renew as necessary.
8.If it is necessary to fit new pivot bushes, they
must be reamed out to 15,87 mm±0,02 mm
(0.625±0.001 in) after fitment.Refit
9.Lubricate pedal pivot shaft and bushes with
general purpose grease.
10.Fit pedal to pedal box, insert pivot shaft and
secure with new split pin.
11.Attach return springs to pedal and pedal box
bosses.
12.Fit pedal box and gasket to engine bulkhead.
Tighten fixings to
25 Nm (18 lbf/ft).
13.Fit brake servo assembly.See Servo
assembly
.

BRAKES
7
REPAIR REV: 05/99 FRONT BRAKE PADS - ALL MODELS
Service repair no - 70.40.02
Remove
1.Remove front road wheels .
2.Clean exterior of calipers.
3.Remove split pin from retaining pins.
4.Remove pad retaining pins and anti-rattle
springs.
5.Remove brake pads.
6.Clean exposed parts of pistons, using new brake
fluid. Wipe away excess with a lint free cloth.
7.Using piston clampLRT-70-500press each
piston back into its bore. Ensure that displaced
brake fluid does not overflow from reservoir.
Refit
8.Fit brake pads.
9.Fit pad retaining pins and anti-rattle springs.
Secure with new split pins.
10.Apply service brake pedal several times to locate
pads.
11.Fit road wheels. Tighten wheel nuts to correct
torque:
Alloy wheels -
130 Nm (96 lbf/ft)
Steel wheels -100 Nm (80 lbf/ft)
Heavy duty wheels -170 Nm (125 lbf/ft)
12.Check fluid reservoir. Top up if necessary, using
correct grade of fluid
See LUBRICANTS,
FLUIDS AND CAPACITIES, Information,
Recommended lubricants and fluids
.

70BRAKES
8
REPAIRREV: 05/99 REAR BRAKE PADS
Service repair no - 70.40.03
Service tool:
Remove
1.Remove rear road wheels.
2.Clean exterior of calipers.
3.Remove pad retaining pins and anti-rattle
springs. Note differences between 90 and
110/130 models.
4.Remove brake pads.
5.Clean exposed parts of pistons, using new brake
fluid. Wipe away excess with a lint free cloth.
6.Using piston clampLRT-70-500press each
piston back into its bore. Ensure that displaced
brake fluid does not overflow from reservoir.
Refit
7.Insert brake pads.
8.Fit anti-rattle springs and secure with retaining
pins.
9.Apply service brake pedal several times to locate
pads.
10.Fit road wheels, remove chassis stands and
jack. Tighten wheel nuts to correct torque:
Alloy wheels -
130 Nm (96 lbf/ft)
Steel wheels -100 Nm (80 lbf/ft)
Heavy duty wheels -170 Nm (125 lbf/ft)
11.Check fluid reservoir, top up if necessary, using
correct grade of fluid
See LUBRICANTS,
FLUIDS AND CAPACITIES, Information,
Recommended lubricants and fluids
.
90 Models
110/130 Models