51REAR AXLE AND FINAL DRIVE
4
REPAIR Refit
10.Clean stub axle. Retract ABS sensor slightly
from sensor sleeve, if applicable
11.Fit hub assembly to stub axle.
12.Fit spacing washer.
13.Fit hub adjusting nut. Tighten to
61 Nm.
Back off adjusting nut 90°. Tighten to4 Nm.
This will give the required hub end float of
0,010mm
14.Fit a new lock washer.
15.Fit locknut. Tighten to61 Nm.
16.Tab over lock washer to secure adjusting nut
and locknut.
17.Using a new joint washer fit axle shaft to hub,
secure with five bolts. Tighten to
65 Nm.
18.Fit brake caliper. Tighten to82 Nm.
Secure brake pipes to axle casing.
19.If applicable, set ABS brakes sensor.
Push sensor in until it touches sensor ring then
rotate hub to set sensor.
20.Fit road wheel, remove axle stands and final
tighten road wheel nuts to
126 Nm.
21.Operate footbrake to locate brake pads before
driving vehicle.
FRONT AXLE AND FINAL DRIVE
1
DESCRIPTION AND OPERATION DESCRIPTION
The welded steel front axle casing houses a separate
spiral bevel type differential unit, which is off set to the
right of the vehicle centre line. The differential unit
drives the front wheels via the axle shafts and
constant velocity joints which are totally enclosed in
the spherical and swivel housings.
The front axles fitted with ABS brakes or non ABS
brakes are of the same construction except for
different top swivel pins in the swivel housing and a
sensor on the constant velocity joint.
Front axle - ABS
The front wheels are pivoted on taper roller bearings
19 at the bottom of the swivel housing and a 'Rialco
bush' 25 at the top. The top swivel pin also houses the
ABS pickup (electrical connection) as shown in the
main illustration, J5367.
Front axle - non ABS
The front wheels are pivoted on tape roller bearings at
the top (see insert) and bottom of the swivel housing.
The wheel hubs on all axles are supported by two
taper bearings and driven by drive flanges which are
splined to the one piece, stub shaft/constant velocity
joint.
Lubrication
The differential, swivel pin housing and wheel hubs
are indiviudally lubricated and separated by oil seals 7
and 8 to prevent oil transfer across the axle when the
vehicle is traversing steep inclines. The wheel
bearings are lubricated with grease and the swivel
housing and differential with oil.
Ventilation
Ventilation of the differential is through a plastic pipe 2
which terminates at a high level in the vehicle on both
ABS and non ABS axles. The swivel housings
ventilate through axle shaft oil seals 8 into the
differential and the hub bearings vent via the oil seals
into swivel housing.
54FRONT AXLE AND FINAL DRIVE
4
REPAIR Refit
11.Clean stub axle and drive shaft and fit hub
assembly to axle.
12.Fit spacing washer.
13.Fit hub adjusting nut. Tighten to
61 Nm.
14.Back off adjusting nut 90°. Tighten to4 Nm.
This will give the required hub end float of
0,010mm
15.Fit a new lock washer.
16.Fit locknut. Tighten to61 Nm.
17.Tab over lock washer to secure adjusting nut
and locknut.
18.Fit a new joint washer to driving member and fit
member to hub and secure with five bolts.
Tighten to
65 Nm.
19.Fit original drive shaft shim and secure with a
circlip.
20.To check drive shaft end play mount a dial
gauge using bracket LRT-99-503 and rest pin in
a loaded condition on end of drive shaft.
21.Fit a suitable bolt to threaded end of drive shaft.
Move drive shaft in and out noting dial gauge
reading. End play should be between0,08 to
0,25 mm.
22.If end play requires adjustment, remove circlip,
measure shim thickness and fit an appropriate
shim to give required end-play.
23.Remove bolt from drive shaft, fit circlip and dust
cap.
24.Fit brake caliper. Tighten to
82 Nm.
25.Bleed brake system.See BRAKES, Repair,
Brake System Bleed
26.Fit road wheel, remove axle stands and tighten
road wheel nuts to
126 Nm.
27.Operate footbrake to locate brake pads before
taking vehicle on road.
FRONT AXLE AND FINAL DRIVE
11
OVERHAUL Fit driveshaft and stub axle
59.Insert axle shaft, and when differential splines
are engaged, push assembly in fully.
CAUTION: Take care not to damage axle
shaft oil seals.
60.Place a new joint washer in position on swivelpin
housing to stub axle mating face. Coat threads
of stub axle bolts with Loctite 270.
61.Fit stub axle with flat at 12 o'clock position.
CAUTION: Ensure that constant velocity
joint bearing journal is butted against
thrust ring on stub axle. Before stub axle
is secured.
62.Place mud shield in position and secure stub
axle to swivel pin housing with six bolts and
tighten evenly to
65 Nm.
63.Fit brake jump hoses to brake jump hose
bracket.
64.Fit front hub complete assembly.
See Repair,
Front Hub Assembly
65.Check swivel pin housing oil drain plug is fitted.
66.Fill swivel assembly to correct level, with new oil.
See SECTION 10, Maintenance, Under
Vehicle Maintenance
67.Set steering lock stop bolts to provide a
clearance of 20mm.
See STEERING,
Adjustment, Steering Lock Stops
68.Fit ABS brake sensor.See BRAKES, Repair,
Sensors - Front
57STEERING
6
FAULT DIAGNOSIS STEERING STABILITY AND VEER UNDER
BRAKING
Possible cause:
Incorrectly set, swivel pin bearing preload. There are
three different settings for these bearings dependant
on model year and if fitted with ABS brakes.
Remedy.
1.Establish model year of vehicle.
2.If fitted with or without antilock brakes.
3.Follow instructions to overhaul front stub axle,
constant velocity joint and swivel pin non ABS,
or with ABS as appropriate.
See FRONT AXLE AND FINAL DRIVE,
Overhaul, Front Stub Axle, Constant Velocity
Joint and Swivel Pin Housing Non ABS See
FRONT AXLE AND FINAL DRIVE, Overhaul,
Front Stub Axle, Constant Velocity Joint and
Swivel Pin Housing ABS
1. GENERAL STEERING
1.Carry out visual and safety checks.
See Visual
and Safety Checks
2.Road test vehicle.See Road Test Procedure
3.Is problem resolved?
YES - end
NO - continue
4.Is problem stiff steering?
YES -
See Stiff Steering Checklist
NO- Goto6.
5.Is problem resolved?
YES - end
NO - go to 8.
6.Is problem steering niggle ?
YES - Replace radius arm bushes, arm and
axle.
See FRONT SUSPENSION,
Repair, Radius Arm
NO - go to 8.
7.Is problem resolved?
YES - end
NO - continue.
8.Centralise steering box.
See Adjustment,
Centralise Steering Box
9.Is problem resolved?
YES - end
NO - continue.
10.Check, adjust if necessary, steering geometry.
11.Is problem resolved?
YES - end
NO - continue.
12.Categorise the remaining problems into one or
more of the following descriptions:
See 2. Steering Veer
See 3. Veer Under Braking
See 4. Directional Stability
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.