2002 LAND ROVER DISCOVERY wheel torque

CLUTCH - TD5
33-1-8 DESCRIPTION AND OPERATION
The dual mass flywheel is used to insulate the gearbox from torsional and transient vibrations produced by the engine.
The flywheel comprises primary and secondary flywheels with the drive between the two transferred by a torsional
damper which comprises four coil springs. The springs are located in the inside diameter of the primary flywheel. Two
of the springs are of smaller diameter and fit inside the larger diameter springs.
The primary flywheel locates the ring gear and is attached to the crankshaft flange with eight bolts. The two pairs of
coil springs are located in a recess in the flywheel between two riveted retainers. A roller bearing is pressed onto the
central boss of the primary flywheel and retained with a riveted plate. The bearing provides the mounting for the
secondary flywheel.
The secondary flywheel comprises two parts; an outer flywheel which provides the friction surface for the clutch drive
plate and an inner drive plate which transfers the drive from the primary flywheel, via the coil springs, to the outer
flywheel. The two components of the secondary flywheel are secured to each other with rivets. The inner drive plate
is located between the two pairs of coil springs and can rotate on the ball bearing in either direction against the
combined compression force of the four coil springs. Under high torque loading conditions the secondary flywheel can
rotate in either direction up to 70
° in relation to the primary flywheel.
The operating face of the secondary flywheel is machined to provide a smooth surface for the drive plate to engage
on. Three dowels and six studs and nuts provide for the location and attachment of the pressure plate.
Pressure plate
1Leaf spring
2Drive plate
3Pressure plate
4Cover
5Diaphragm
6Rivet

AUTOMATIC GEARBOX - ZF4HP22 - 24
DESCRIPTION AND OPERATION 44-7
The gearbox consists of a torque converter housing, an intermediate plate, a gearbox housing and a rear extension
housing, bolted together in series. The rear of the gearbox is supported by a rubber mounting installed between a
mounting bracket on the gearbox and the LH chassis rail. A heat shield is installed on the mounting to protect it from
the exhaust.
Sectioned view of gearbox
1Lock-up clutch
2Impeller
3Turbine
4Forward drive clutch
5Reverse drive clutch
6Brake clutch
7Brake clutch
8Brake clutch
9Epicyclic gear set10Epicyclic gear set
11Clutch
12Brake clutch
13Output shaft
14Freewheel (one way clutch)
15Freewheel (one way clutch)
16Freewheel (one way clutch)
17Stator and one way clutch
Torque converter housing
The torque converter housing attaches the gearbox to the engine and contains the torque converter. Different torque
converter housings are used to accommodate the difference between the V8 and Td5 engine interfaces. The torque
converter is connected to the engine drive plate and transmits the drive from the engine to the gearbox input shaft.
When engaged, a hydraulic lock-up clutch in the torque converter prevents slippage, to give a direct drive from the
engine to the gearbox for improved driving response.

AUTOMATIC GEARBOX - ZF4HP22 - 24
ADJUSTMENTS 44-21
ADJUST ME NTS
Cable - selector
$% 44.30.04
Check
1.Position vehicle on ramp.
2.Select position 'P'.
3.Loosen selector cable trunnion nut.
4.Ensure that gearbox selector lever is in 'P'
position, (fully forward) and tighten trunnion
nut.
5.Lower ramp.
Stall test
$% 44.30.13
Testing
1.Chock the wheels and fully apply the
handbrake.
2.Start the engine and run it until it reaches
normal operating temperature.
3.Apply the footbrake and select 'D'.
4.Fully depress the accelerator pedal and note
the tachometer reading. The figures should be
as given below. Do not carry out stall test for
longer than 10 seconds, and DO NOT repeat
until 30 minutes have elapsed.
lV8: 2200 to 2400 rev/min
lDiesel: 2600 to 2800 rev/min
5.A reading below 1300 rev/min indicates a
torque converter fault, ie stator free-wheel.
6.A reading between 1300 and 2200 rev/min (V8)
or between 1300 and 2600 rev/min (Diesel)
indicates reduced engine power.
7.A reading above 2400 rev/min (V8) or above
2800 rev/min (Diesel) indicates clutch slip.
NOTE: The figures quoted above were
measured at sea level with an ambient
temperature of 20
°C (68°F). At higher altitudes
or higher ambient temperatures, these figures
will be reduced.

REAR AXLE
OVERHAUL 51-13
22.Align setting gauge LRT-51-018/7 to setting
block, rock gauge to obtain minimum reading. If
reading is lower than required reading,
decrease shim size. If reading is higher than
required reading, increase shim size.
23.Using LRT-51-003 to restrain pinion flange,
remove bolt and washer. Remove pinion
flange.
24.Remove pinion, collect tail bearing and tail
bearing shim.
25.Remove pinion head bearing outer race and
shim. Discard shim. Ensure bearing race
recess is clean and free from burrs.
26.Fit calculated shim, and using LRT-51-018/4 fit
head bearing outer race.
27.Fit pinion, pinion tail bearing and tail bearing
shim.
28.Fit pinion flange and bolt and washer. Using
LRT-51-003 to restrain pinion flange, tighten
bolt to 100 Nm (74 lbf.ft).
29.Rotate pinion in both directions to settle
bearings.
30.Recheck pinion Torque to Turn, adjust if
necessary.
31.Recheck pinion head height.
32.Using LRT-51-003 to restrain pinion flange,
remove bolt and washer. Remove pinion
flange.
33.Discard bolt.34.Using LRT-51-010 fit pinion seal.
35.Ensure spacer and tail bearing are correctly
located.
36.Fit pinion, pinion flange and washer.
37.Fit new pinion flange bolt and tighten to 100 Nm
(74 lbf.ft).
38.Lightly oil differential bearings.
39.Ensure spring dowels are fitted in bearing caps.
40.Fit differential bearing outer races and locate
differential assembly into housing.
41.Fit bearing caps and tighten bolts to 10 Nm (7.5
lbf.ft).
42.Fit adjusting nuts, tighten crown wheel side nut
to 22 Nm (16 lbf.ft). Ensure opposing nut is
loose.
43.Position DTI to check crown wheel backlash.
Adjust opposing nut to obtain correct crown
wheel backlash.
44.Rotate pinion in both directions to settle
bearings.
45.Measure in 3 places to obtain correct crown
wheel backlash.
NOTE: Crown wheel backlash should be within
0.076 mm - 0.177 mm (0.003' - 0.007').
46.Align adjusting nuts to next roll pin slot, do not
loosen nuts to align slots.

REAR AXLE
51-14 OVERHAUL
47.Tighten bearing cap bolts to 90 Nm (66.5 lbf.ft).
48.Secure adjusting nuts with new roll pins.
49.Apply Prussian Blue to crown wheel teeth to
check tooth contact.
50.Rotate pinion several times to obtain full tooth
contact.51.A = Normal pattern, the drive pattern should be
centred on the gear teeth. The coast pattern
should be centred on the gear teeth but may be
towards the toe. There should be some
clearance between the pattern and the top of
the gear teeth.
52.B = Backlash correct, thinner pinion shim
required.
53.C = Backlash correct, thicker pinion shim
required.
54.D = Pinion shim correct, decrease backlash.
55.E = Pinion shim correct, increase backlash.
56.Note assembly Torque to Turn when checking
tooth contact. Total Torque to Turn should not
exceed 10.85 Nm (8 lbf.ft).
Reassembly
1.Fit differential assembly.

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.

STEERING
DESCRIPTION AND OPERATION 57-11
Rotary control valve in demand mode
1Worm gear
2Torsion bar
3Valve sleeve
4Pin5Input shaft and valve rotor
6Piston/rack
7Coarse spline
8Spline (torque shaft to worm gear)
When the steering wheel and input shaft is turned steering resistance transmitted to the worm causes the torsion bar
to be wound up and the valve ports in the valve rotor and valve sleeve to be aligned for a right or left turn. The
alignment of the valve ports directs fluid pressure 'A' from the PAS pump to one side of the piston/rack . The other
side of the piston/rack is now connected to return 'B' (due the valves port alignment) and displaced fluid returns to the
reservoir. The pressure difference in the cylinder on each side of the piston gives the power assistance to move the
rack and so turn the steering.
The greater the resistance of the road wheels to the steering rotary movement, the greater torque acting on the torsion
bar and input shaft causing greater changes of alignment of the ports in the valve. As the change of alignment
becomes greater, the fluid pressure passing to the applicable side of the piston/rack increases.
Only when the steering wheel stops turning and the torsion bar has unwound, will the valve rotor return to the neutral
position. In the neutral position the fluid circulates through the ports in the valve rotor and valve sleeve and back to
the reservoir where it is cooled.

BRAKES
DESCRIPTION AND OPERATION 70-5
Description
General
The brakes consist of front and rear disc brakes operated by a diagonally split, dual circuit hydraulic system with
vacuum servo power assistance. The system incorporates the following control functions as standard on all models:
lAnti-lock Brakes (ABS), to prevent road wheels locking during brake application.
lElectronic Brake Distribution (EBD), to control distribution of hydraulic pressure between front and rear axles.
Replaces mechanical pressure limiting valve of previous systems.
lElectronic Traction Control (ETC), to maintain even torque distribution to the road wheels.
lHill Descent Control (HDC), to provide controlled descent ability in off road conditions.
Hydraulic system schematic
1Master cylinder/brake servo assembly
2Brake pedal
3ABS modulator
4Rear brake
5Front brake
6Hydraulic circuit
aPrimary
bSecondary
For normal brake operation, brake pedal movement is assisted by the brake servo assembly and transmitted to the
master cylinder assembly. The master cylinder assembly converts brake pedal movement to hydraulic pressure.
Primary and secondary brake pipe circuits supply the hydraulic pressure to the brakes via the ABS modulator: the
primary circuit supplies the front left and rear right brakes; the secondary circuit supplies the front right and rear left
brakes. Vacuum for the brake servo assembly is obtained from the engine inlet manifold (V8 models) or a vacuum
pump (diesel models), through a vacuum line and non return valve. To reduce operating noise, sleeving is installed
on some of the brake pipes in the engine compartment and the pipes are located in sprung pipe clips.