LAND ROVER DISCOVERY 1995 Service Repair Manual

REAR SUSPENSION
1
SPECIFICATIONS, TORQUE TORQUE VALUES
NOTE: Torque wrenches should be regularly checked for accuracy to ensure that all fixings are
tightened to the correct torque.
Nm
Anti-roll[sway] bar rear
- Strap nyloc nuts 30..............................................................................
- Ball link self lock nut 68........................................................................
- Castellated nut 40................................................................................
Top link to mounting bracket 176.....................................................................
Bottom link to axle 176.....................................................................................
Bottom link to chassis 176...............................................................................
Top link bracket to rear cross member 47......................................................
Shock absorber to axle 37..............................................................................
Torque values below are for all screws and bolts used except for those that are specified otherwise.
METRIC Nm
M5 6......................................................................................................
M6 9......................................................................................................
M8 25.....................................................................................................
M10 45...................................................................................................
M12 90...................................................................................................
M14 105..................................................................................................
M16 180..................................................................................................
UNC / UNF
1/4 9......................................................................................................
5/16 24...................................................................................................
3/8 39.....................................................................................................
7/16 78...................................................................................................
1/2 90.....................................................................................................
5/8 136....................................................................................................

BRAKES
1
DESCRIPTION AND OPERATION BRAKES
Discovery vehicles have servo assisted brake
systems and the option of an anti-lock brake system.
Information in this section refers to components
relevant to both brake systems. Where the system
components are different they are referred to as ABS
or NON ABS
BRAKE SYSTEM NON ABS
Description
The servo assisted hydraulic braking system is the
dual line type, incorporating primary and secondary
hydraulic circuits.
NOTE: References made to primary or
secondary do not imply main service
brakes or emergency brakes but denote
hydraulic line identification.
The brake pedal is connected to a vacuum assisted
mechanical servo which in turn operates a tandem
master cylinder. The front disc brake calipers each
house four pistons, these pistons are fed by the
secondary hydraulic circuit. The rear disc brake
calipers each house two pistons, these are fed by the
primary hydraulic circuit via a pressure reducing valve.
A brake fluid level switch is incorporated into the
reservoir cap assembly, the switch will immediately
illuminate a warning light in the instrument binnacle
indicating low fluid or sudden fluid loss.
The brake fluid reservoir is divided, the section closest
to the servo feeds the primary circuit and the section
furthest from the servo feeds the secondary circuit.
Under normal operating conditions both the primary
and secondary circuits operate simultaneously on
brake pedal application. In the event of a failure in the
primary circuit the secondary circuit will still function. If
the secondary circuit fails the primary circuit will still
function. The brake pedal travel will be longer in the
event of a half system failure.If the servo should fail, both hydraulic circuits will still
function but would require greater pedal effort due to
the lack of vacuum assistance. The hand operated
parking brake acts on a brake drum at the rear of the
transfer gearbox and is completely independent of the
hydraulic circuits.
Hydraulic circuit non ABS
Key
A = Primary hydraulic circuit
B = Secondary hydraulic circuit
C = Pressure reducing valve

70BRAKES
2
DESCRIPTION AND OPERATION ABS COMPONENTS
Location
Key to diagram
1. ABS Modulator unit
2. Servo/Master cylinder
3. Pressure reducing valve
4. Electronic control unit5. Rear sensors/exciter rings
6. Front sensors/exciter rings
7. Diagnostic plug connection

BRAKES
3
DESCRIPTION AND OPERATION Description of components
1. ABS Modulator unit
To provide the ABS function a Modulator is positioned
within the system between the master cylinder and the
calipers. On both LHD and RHD vehicles it is sited on
the left inner wing [fender]. The Modulator has 8
solenoid valves, 2 for each wheel, 2 expanders and a
recirculation pump. It is non serviceable.
2. Servo/master cylinder
Actuation of the system is provided by a combined
master cylinder and servo assembly attached to the
pedal box, this provides pressure to opposed piston
calipers at each brake pad Twin piston at the front
axle, single piston at the rear.
3. Pressure reducing valve
To maintain the braking balance, pressure to the rear
axle is regulated by a Pressure Reducing Valve (PRV)
This PRV is of the failure bypass type, allowing full
system pressure to the rear axle in the event of a front
circuit failure. It is sited on the left inner wing [fender].
4. Electronic control unit - ECU
ABS control is provided by an electronic control unit
which is positioned on the passenger side of the
vehicle behind the dash panel/glove box.
The ECU, which is non-serviceable, is connected to
the ABS harness by a 35 way connector. non
serviceable.
The ECU continually monitors the brake system,
providing diagnostics in the event of a system
malfunction. Details of how to access the ECU
diagnostics are provided in the Electrical
Troubleshooting Manual.
5.& 6. Front and rear sensors/exciter rings - 4 off
A sensor is sited at each wheel, sensing a 60 tooth
exciter ring. When vehicle is in motion inductive
sensors send signals to ECU. Front exciter ring is
fitted to outside diameter of constant velocity joint
inside each front hub assembly. The rear exciter ring
is bolted to the rear of each brake disc bell.7. Diagnostic plug connection
A diagnostic plug is located behind the dash. To the
left of the steering column on LHD vehicles. To the
right of the steering column on RHD vehicles. It is a 5
way blue connector.
The location and identification of ABS electrical relays
are given in the Electrical Troubleshooting Manual.
For location and identification of ABS electrical fuses.
See ELECTRICAL, Repair, Fuse Box - Interioror.
See ELECTRICAL, Repair, Fuse Box - Engine
Compartment
ANTI-LOCK BRAKE SYSTEM - ABS
Manufactured by WABCO
Introduction
The purpose of ABS is to prevent vehicle wheels
locking during brake application, thus maintaining
vehicle steerability and stability. This allows vehicle to
be steered whilst brakes are applied, even under
emergency conditions, and to avoid obstacles where
there is sufficient space to redirect the vehicle.
WARNING: ABS is an aid to retaining
steering control and stability while
braking.
·ABS cannot defy the natural laws of physics
acting on the vehicle.
·ABS will not prevent accidents resulting from
excessive cornering speeds, following
another vehicle too closely or aquaplaning,
i.e. where a layer of water prevents adequate
contact between tyre and road surface.
·The additional control provided by ABS must
never be exploited in a dangerous or
reckless manner which could jeopardise the
safety of driver or other road users.
·The fitting of ABS does not imply that the
vehicle will always stop in a shorter stopping
distance.

70BRAKES
4
DESCRIPTION AND OPERATION System description
The brake system consists of dual hydraulic circuits in
a front - rear split. That is individual circuits to front
and rear axles.
Wheelspeed signals are provided by the fitting of
exciter rings to axles and speed sensors.
An ABS stop light switch is fitted to provide a braking
signal to the ECU as well as operate the stop lights.
Electrical wiring is provided as necessary with system
relays and fuses. Discovery Electrical Troubleshooting
Manual gives the location and wiring circuits of these
components.
Visual warning of system malfunction is provided via a
warning light in the instrument panel.
Hydraulic circuit ABS
Key
A = Primary hydraulic circuit
B = Secondary hydraulic circuit
C = Pressure reducing valve
D = ABS ModulatorABS System operation
During normal braking the feel of the brake pedal on
vehicles equipped with ABS will be the same as that
on non ABS vehicles. During ABS cycling the driver
will experience feedback in the form of a pulsating
brake pedal and solenoid/pump motor noise from the
Modulator.
The system is fully automatic in operation both on and
off road, and will only act when the ECU detects that
ABS cycling is necessary. The ECU continually
monitors the operation of the system.
When starting the ABS system will go through a series
of self checks, including a check of the solenoid
valves/pump motor.
WARNING LIGHT
The warning light will be on during the self check
(1.3-2 secs). If no faults are stored in the memory the
light goes out for 0.5sec,then comes on again. It will
then remain on until the vehicle is driven faster than 7
kph/5mph. This is the only time that the light will be on
without indicating a problem.
Any faults detected by the ECU will cause the warning
light to illuminate indicating that the vehicle may not
have full ABS control.

BRAKES
5
DESCRIPTION AND OPERATION BRAKE PIPE LAYOUT ABS
Left hand drive shown. On right hand drive vehicles the master cylinder and servo unit only move
position.
KEY
1. Connector double elbow
2. Rear left brake
3. Modulator to rear left brake
4. Modulator to master cylinder
5. Modulator to pressure reducing valve upper
6. Electrical connection
7. Modulator unit
8. Nut, mounting bush and cup
9. Modulator to front left brake
10. Front left brake
11. Electrical connection12. Modulator to front right brake
13. Modulator to pressure reducing valve lower
14. Master cylinder to pressure reducing valve lower
15. Front right brake
16. Bolt
17. Pressure reducing valve
18. Modulator to pressure reducing valve upper
19. Master cylinder
20. Servo unit
21. Modulator to rear right brake
22. Rear right brake

70BRAKES
6
DESCRIPTION AND OPERATION BRAKE PIPE LAYOUT NON ABS
Left hand drive shown. On right hand drive vehicles the master cylinder and servo unit only move
position.
KEY
1. T-Connector
2. Rear left brake
3. Master cylinder to pressure reducing valve lower
4. Front left brake to pressure reducing valve upper
5. Front left brake
6. Front right brake
7. Master cylinder to pressure reducing valve lower8. Pressure reducing valve
9. Front right brake to pressure reducing valve
upper
10. Master cylinder
11. Servo unit
12. Pressure reducing valve upper to both rear
brakes
13. Rear right brake

BRAKES
7
DESCRIPTION AND OPERATION BRAKE SERVO UNIT
Description
The power assistance for the brake system is
provided by a twin diaphragm suspended vacuum
servo.
A 'Suspended Vacuum' servo is one where, with the
engine running vacuum is present both sides of the
diaphragm or diaphragms when the brakes are fully
released or partially applied. The principal of having
vacuum both sides of the diaphragm has two main
advantages. First, it ensures instantaneous servo
response to the brake being applied or released and
second, it provides very accurate control of the
position of the diaphragm and therefore, the degree of
partial brake application.At full pedal depression, vacuum is present in front of
the diaphragm with atmospheric pressure on the rear.
Operation
Brakes released
With the brakes released depression is present both
sides of the diaphragms, in chambers 1,2,3 and 4.
The chambers comunicate by ports A, B, D via the
valve C which is shown fully released in RR3640M.

70BRAKES
8
DESCRIPTION AND OPERATION Brakes applied
When the brake pedal is depressed the pedal pushrod
operates valve C situated in the plastic diaphragm hub
9 and 10. Inital depression of the the brake pedal,
push rod 6 and plunger 7 compress a rubber pad 8.
This slight movement causes valve C to close port D
sealing off the vacuum to chambers 2/4 and allows
atmospheric pressure to enter the chambers through
the air filter E.
With depression in chambers 1/3 and air pressure in
chambers 2/4 the servo hub will apply the brakes via
the master cylinder push rod 13.Atmospheric pressure over the large area of the
diaphragms multiples the force applied to the master
cylinder piston, to provide the power assistance. If the
brake pedal is only partially depressed, the servo hub,
diaphragms and master cylinder push rod will stop
moving, when valve C comes to rest on the plunger 7.
At this point the valve will balance the pressure in all
the chambers, to the applied effort at the pedal and
provide proportional braking.
It is only when the brakes are fully applied that the
valve does not balance the pressures in all the
chambers, but ensures that maximum available
depression is in chambers 1/3 and full atmospheric
pressure enters chambers 2/4.
When the brake pedal is released, the pressure in all
chambers is equalised and the servo is returned to the
rest position by spring 12.

BRAKES
9
DESCRIPTION AND OPERATION Petrol engine vacuum system
The vacuum necessary to operate the brake servo on
petrol engine vehicles is provided by the engine inlet
manifold. During normal operation of the brakes only a
small volume of air is drawn from the servo and into
the inlet manifold or plenum chamber. However any
excessive air leaks due to damage in the brake servo
system or manifold hose connection, will effect the
mixture strength and ECM fuelling calculations on
engines equipped with an MFI system.
Diesel engine vacuum system
As the diesel engine inlet system does not produce
depression sufficient to operate the brake servo, it is
necessary to install an engine driven vacuum pump.
During normal operation of the brakes only a small
volume of air is drawn from the servo by the vacuum
pump. However as the pump exhausts air into the
engine crankcase atmosphere, an air leak due to
damage in the brake servo system or pump hose
connection, may cause excessive crankcase
pressure.