Land Rover Discovery. Manual - part 148

REAR SUSPENSION

SPECIFICATIONS, TORQUE

TORQUE VALUES

NOTE: Torque wrenches should be regularly checked for accuracy to ensure that all fixings are
tightened to the correct torque.

Anti-roll[sway] bar rear

- Strap nyloc nuts

..............................................................................

- Ball link self lock nut

........................................................................

- Castellated nut

................................................................................

Top link bracket to rear cross member

......................................................

Shock absorber to axle

..............................................................................

Torque values below are for all screws and bolts used except for those that are specified otherwise.

METRIC

......................................................................................................

.....................................................................................................

M10

...................................................................................................

M12

...................................................................................................

M14

105

..................................................................................................

M16

180

..................................................................................................

UNC / UNF

1/4

......................................................................................................

5/16

...................................................................................................

3/8

.....................................................................................................

7/16

...................................................................................................

1/2

.....................................................................................................

5/8

136

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BRAKES

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

BRAKES

DESCRIPTION AND OPERATION

ABS COMPONENTS

Location

Key to diagram

1. ABS Modulator unit
2. Servo/Master cylinder
3. Pressure reducing valve
4. Electronic control unit

5. Rear sensors/exciter rings
6. Front sensors/exciter rings
7. Diagnostic plug connection

BRAKES

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 - Interior or.
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.

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