steering LAND ROVER DISCOVERY 1999 Owner's Guide

FRONT AXLE
DESCRIPTION AND OPERATION 54-3
Wheel hub
Section through wheel hub
1Drive shaft
2Axle casing
3Gaiter
4Upper ball joint
5Constant velocity joint
6Steering knuckle
7Hub bearing
8Hub flange9Wheel stud
10Stake nut
11ABS sensor ring
12Tension collet
13Lower ball joint
14Securing bands
15Shield
16Oil seal
Each wheel hub consists of a hub flange pressed into a hub bearing.
The hub flange is splined to accept the constant velocity joint of the drive shaft, which is secured to the hub flange
with a stake nut. Five studs are installed in the hub flange for the wheel nuts and a threaded hole is provided for the
brake disc securing screw.
The outer race of the hub bearing is bolted to the steering knuckle. The hub bearing is a sealed unit which contains
twin opposed roller bearings, pre-packed with grease during manufacture. A toothed ABS sensor ring is integrated
into the inner race of the hub bearing. An opening in the outer race of the hub bearing accommodates the ABS sensor.
Drive shaft
Each drive shaft consists of a solid rod, splined at both ends, with a constant velocity joint installed on the outboard
end. A shield is incorporated onto each rod to protect the oil seals in the axle casing. The constant velocity joint is of
the ball and socket type. A shaft on the constant velocity joint is splined to the hub flange. The constant velocity joint
is pre-packed with grease and protected by a gaiter. Two securing bands retain the gaiter in position.

FRONT AXLE
54-6 REPAIRS
9.Remove 4 bolts securing each front wheel hub
to front axle.
10.Release wheel hubs from front axle. Remove
wheel hubs and drive shafts from front axle.
11.Remove oil seal from axle casing.
12.Remove 10 bolts securing differential to axle
casing. Release and remove differential from
axle casing.Refit
1.Clean drive shaft oil seal recess, oil seal
running surface, wheel hub and axle mating
faces.
2.Using a suitable solvent, remove all traces
sealant from differential and axle mating faces.
3.Applysealant, Part No. STC 3811 to differential
or axle mating face.
4.Apply sealant, Part No. STC 50552 to threads
of differential securing bolts.
5.Fit differential to axle, fit bolts and tighten to 55
Nm (41 lbf.ft).
6.Position propeller shaft and align reference
marks. Fit bolts and tighten to 47 Nm (35 lbf.ft).
7.Lubricate oil seal lip and running surface with
clean differential oil.
+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS,
Lubrication.
8.Using LRT-54-012 and LRT-99-003, fit new
drive shaft oil seal to axle casing.
9.Apply anti-seize compound to wheel hub and
steering knuckle mating faces.
10.Ensure ABS harnesses are located in cut out in
steering knuckles.
11.Fit drive shafts in axle casing and align wheel
hubs with steering knuckles. Fit wheel hub bolts
and tighten to 100 Nm (74 lbf.ft).
12.Connect each ABS sensor multiplug and
secure harness to harness bracket and brake
hose.

FRONT AXLE
REPAIRS 54-9
Seal - oil - front axle casing
$% 54.15.04
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove road wheel.
3.Remove front brake disc.

+ BRAKES, REPAIRS, Brake disc -
front.
4.Disconnect ABS sensor multiplug.5.Release harness from brake hose and hose
bracket.
6.Remove 4 bolts securing wheel hub to steering
knuckle.
7.Release wheel hub from steering knuckle.
8.Remove wheel hub and drive shaft from axle.

FRONT AXLE
54-10 REPAIRS
9.Remove oil seal from axle casing.Refit
1.Clean drive shaft oil seal recess, oil seal
running surface, wheel hub and swivel hub
mating faces.
2.Lubricate oil seal lip and running surface with
clean differential oil.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS,
Lubrication.
3.Using tool LRT-54-012 and tool LRT-99-003,
fit new drive shaft oil seal to axle casing.
4.Apply anti-seize compound to wheel hub and
steering knuckle mating faces.
5.Ensure ABS harness is located in cut out in
steering knuckle.
6.Fit drive shaft and wheel hub to axle casing and
align wheel hub with steering knuckle. Fit wheel
hub bolts and tighten to 100 Nm (74 lbf.ft).
7.Connect ABS sensor multiplug and secure
harness to harness bracket and brake hose.
8.Fit front brake disc.

+ BRAKES, REPAIRS, Brake disc -
front.
9.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
10.Remove stand(s) and lower vehicle.
11.Check differential oil level.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.

STEERING
DESCRIPTION AND OPERATION 57-1
STEERING DESCRIPTION AND OPERAT ION
Steering system component layout
RH drive shown LH drive similar
1Fluid reservoir
2Return line
3Steering damper
4Drag link
5Drop arm
6Steering box
7Universal joint and split adapter8Universal joint and coupling
9Steering column
10Decouple joint
11Intermediate shaft
12Pressure line
13Suction (inlet) line
14PAS pump

STEERING
57-2 DESCRIPTION AND OPERATION
Steering column assembly and
intermediate shaft

STEERING
DESCRIPTION AND OPERATION 57-3
1Air bag module
2Steering wheel and nut
3Horn switch 2 off
4Radio remote control switch (if fitted)
5Column switches
6Lower nacelle
7Column tilt adjustment lever
8Steering column lock
9Ignition switch and harness
10Upper column assembly
11Lower column
12Universal joint 13Bolt
14Bolt
15Intermediate shaft assembly
16Decouple joint
17Rubber coupling and heat shield
18Bolt
19Universal joint
20Shear bolt 2 off
21Rotary coupler
22Upper nacelle
23Cruise control switch (if fitted)

STEERING
57-4 DESCRIPTION AND OPERATION
Steering box
RH drive shown, LH drive similar
1Housing with output shaft lower bearing
2Input shaft dirt shield, circlip, backup washer
and pressure seal
3Relief valve stop, seal and locknut 2 off
4Piston/rack adjuster
5Hydraulic pipe
6Piston/rack and relief valves
7Output shaft
8Seal, washer and backup seal
9Circlip and dirt shield
10Teflon and rubber seal 2 off
11Cylinder cover, seal and snap ring12Bearing adjuster, locknut and seal
13Bearing 2 off
14Worm gear and rotary control valve assembly
15Teflon seals 3 off
16Worm/valve shims
17Cover plate seal
18Output shaft adjuster
19Cover plate and bearing
20Bleed screw
21Output shaft adjuster lock nut and seal
22Cover plate bolts 4 off

STEERING
DESCRIPTION AND OPERATION 57-5
Description
General
The major steering components comprise an impact absorbing telescopic steering column, a Power Assisted Steering
(PAS) box, a PAS pump, and fluid reservoir. Hydraulic fluid from the fluid reservoir is filtered and then supplied
through the suction line to the inlet on the PAS pump. The PAS pump supplies fluid to the steering box through a
pressure line routed above the front cross member. Fluid returns to the reservoir along the same route through a
return line. On LH drive vehicles the pipe route above the front cross member is still used, the length of pipe acting
as an oil cooler.
To minimise driver's injury in the event of an accident the steering system has a number of safety features including
a collapsible steering column. An additional safety feature is an air bag located in the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.
Steering column assembly and intermediate shaft
The steering column central shaft comprises of two shafts, the upper shaft is splined to accept the steering wheel and
located in bearings in the column tube. A universal joint is located on the bottom of the upper shaft, the joint allows
for angular movement between the upper and lower shafts. The lower shaft is made in two parts, the top section of
the lower shaft is located outside of the lower section. The two sections of the lower shaft are connected by two nylon
injection moulded shear pins. The lower shaft goes through a lower bearing attached to the bulkhead, the lower shaft
is connected by a universal joint to the intermediate shaft in the engine compartment.
Steering column
An upper column tube provides for the location of the steering lock and ignition switch and also the steering switch
gear and a rotary coupler. The rotary coupler provides the electrical connection for the steering wheel mounted airbag,
switches and horn. The upper mounting bracket has two slots, a slotted metal bracket is held in each slot by four resin
shear pins.
The column is mounted on four captive studs which are located on a column mounting bracket. The captive studs
pass through the metal brackets, locknuts secure the steering column to the bulkhead. The two lower mountings are
fixed and cannot move when loads are applied to them. The upper mounting is designed to disengage or deform when
a load is applied, allowing the column to collapse in the event of an accident. The steering column must be replaced
as a complete assembly if necessary.
When an axial load is applied to the upper column tube, energy absorption is achieved by the following mechanism:
lthe mounting bracket deforms,
lthe resin shear pins holding the slotted metal brackets shear,
lthe top mounting bracket slides out of the slotted metal brackets.
The slotted metal brackets remain on the captive studs on the bulkhead. If the column mounting moves, injection
moulded shear pins retaining the two sections of the lower column shaft will shear. This allows the two sections of the
lower shaft to 'telescope' together.
In the event of a collision where the steering box itself moves, two universal joints in the column allow the intermediate
shaft to articulate, minimising movement of the column towards the driver. If movement continues energy absorption
is achieved by the following mechanism:
lthe decouple joint in the intermediate shaft will disengage,
lthe lower section of the steering column shaft will move through the lower bearing,
lthe injection moulded shear pins retaining the two sections of the lower column shaft will shear.
This allows the two sections of the lower shaft to 'telescope' together reducing further column intrusion. Protection to
the drivers face and upper torso is provided by an SRS airbag module located in the centre of the steering wheel.

+ RESTRAINT SYSTEMS, DESCRIPTION AND OPERATION, Description - SRS.

STEERING
57-6 DESCRIPTION AND OPERATION
Tilt adjustment
The column tilt adjuster lever mechanism is located on the LH side of the steering column and allows the upper column
tube, nacelle and steering wheel assemblies to be tilted up or down a maximum of 7.5° or 47 mm (NAS vehicles have
a smaller range of movement than the ROW vehicles).
The pawl of the mechanism is attached to the lower column and is allowed to pivot, a toothed quadrant is fixed to the
upper column tube.
When the lever on the LH side of the steering column is raised the mechanism releases the pawl from the toothed
quadrant, this allows the column to be moved. When the lever is released two return springs pull the pawl into
engagement with the toothed quadrant.
Steering column lock (All except NAS)
The steering column lock houses the ignition switch, ignition illumination light ring, key lock barrel and the alarm
passive coil. The steering lock is attached to the upper column with two shear bolts. The bolts are tightened to a
torque which shears off the heads of the bolts preventing easy removal of the steering lock.
The steering lock operates by a bolt, which emerges when the ignition key is turned to position 'O' and the ignition key
removed. The bolt engages in a lock collar located on the upper shaft in the upper column tube. The lock collar is
attached to the upper shaft by a 'wave form' interference ring. If a high torque is applied via the steering wheel with
the lock engaged, the lock collar will slip on the upper shaft. This prevents damage to the steering lock, yet still
prevents the vehicle from being driven.
Steering column lock (NAS only)
The steering column lock houses the ignition switch, ignition illumination light ring, key lock barrel and the alarm
passive coil. The steering lock is attached to the upper column with two shear bolts. The bolts are tightened to a
torque which shears off the heads of the bolts preventing easy removal of the steering lock.
The steering column lock operates by a bolt, which emerges when the ignition key is turned to position 'O' and the
ignition key removed. The bolt engages in a groove machined into the upper shaft in the column tube.
Steering wheel
The steering wheel comprises a cast centre and wire frame onto which the soft polyurethane foam is moulded. The
steering wheel is located on the upper column shaft by a spline and is secured with a nut. A remote radio control switch
(if fitted) is located on the LH side of the steering wheel, a cruise control switch may be located on the RH side. Horn
switches are located on each side of the centre of the steering wheel and protrude through the airbag module cover.
Both switches are connected by wires to the rotary coupler connector.
Intermediate shaft
One end of the intermediate shaft is attached to the steering column lower shaft by a splined universal joint and a bolt,
the universal joint is part of a rubber coupling assembly. The rubber coupling assembly is covered by a heat shield
and connects to the lower section of the intermediate shaft via a decouple joint. The rubber coupling reduces the
shocks felt by the driver through the steering wheel. A second universal joint on the other end of the intermediate shaft
is held in by a bolt. The universal joint is splined and engages with the splined rotor (input) shaft of the steering box.
The decouple joint consists of a metal plate that has open ended slots, the plate is bolted through the slots into the
other half of the decouple joint. The top half of the decouple joint has a slot that accepts the lower section of the
intermediate shaft. The slotted metal plate clamps the lower section of the intermediate shaft to the top section. An
indicator clip is installed between the slotted metal plate and the top half of the decouple joint.
If the intermediate shaft is compressed in an accident, the slotted metal plate in the decouple joint will disengage if
sufficient force is applied to the front end of the shaft. If the forces involved do not disengage the shaft, the red
indicator clip located in the decouple joint will break off if the shaft moves. The intermediate shaft cannot be repaired
and must be replaced as an assembly if accident damage occurs.