1996 LAND ROVER DEFENDER Workshop Manual

FRONT AXLE AND FINAL DRIVE
1
SPECIFICATIONS, TORQUE REV: 05/99 TORQUE VALUES
NOTE: Torque wrenches should be regularly checked for accuracy to ensure that all fixings are
tightened to the correct torque.
Nm
FRONT AXLE
Hub driving member to hub 65*.......................................................................
Brake disc to hub 73.......................................................................................
Stub axle to swivel pin housing 65*.................................................................
Brake caliper to swivel pin housing 82............................................................
Upper swivel pin to swivel pin housing 78*.....................................................
Lower swivel pin to swivel pin housing 78*.....................................................
Oil seal retainer to swivel pin housing 11........................................................
Swivel bearing housing to axle case 73*.........................................................
Pinion housing to axle case 41.......................................................................
Crown wheel to differential housing 58...........................................................
Differential bearing cap to pinion housing 90..................................................
Differential drive flange to drive shaft 47.........................................................
Mudshield to bracket lower swivel pin 11........................................................
Bevel pinion nut 130........................................................................................
Draglink to hub arm 40....................................................................................
Panhard rod to axle bracket 88.......................................................................
Radius arm to axle 190....................................................................................
Radius arm to chassis side member 190.........................................................
NOTE: * These bolts to be coated with Loctite 270 prior to assembly.

STEERING
1
DESCRIPTION AND OPERATION DESCRIPTION
The steering system incorporates a compression joint
in the lower shaft and is designed to collapse on
impact. The mis-alignment of the upper steering
column with the steering box and the inclusion of two
universal joints, is also designed to prevent the
column moving toward the driver under frontal impact.
The steering box is located behind the first chassis
cross member and is connected to the road wheel
swivel housing by a drag link and track rod. A
hydraulic damper absorbs shocks in the steering,
caused by road wheel deflections when operating on
rough terrain.Power steering system
The power steering system comprises a hydraulic
pump which is belt driven from the engine and
supplied with fluid from a reservoir that also acts as a
cooler.
The steering box houses a self neutralizing rotary
valve which is part of the worm/valve assy and an
hydraulic piston/rack to assist the mechanical
operation. The rotary valve which is operated by
movement of the steering wheel, directs fluid pressure
to the appropriate side of the hydraulic piston/rack to
provide assistance.
Power steering system
1.Hydraulic pump
2.Fluid reservoir
3.Steering box
4.Upper column5.Universal joints
6.Lower shaft
7.Compression joint
8.Drag link

57STEERING
2
DESCRIPTION AND OPERATION
Power steering box components
1.Housing complete with sector shaft bearings
2.Cover plate complete with bearing
3.Sector shaft
4.Hydraulic piston/rack
5.Worm/valve and torsion bar assembly
6.Shims for centralizing worm/valve
7.Ball race
8.'Teflon' seals for valve sleeve
9.Bearing adjuster, locknut and seal
10.Worm shaft pressure seal, circlip and dirt
excluder11.'Teflon' and rubber seal for piston
12.End cover seal and snap ring
13.Adjustment components for piston/rack
14.Hydraulic pipe
15.Bleed screw
16.Sector shaft adjustment lock nut with seal
17.Cover plate bolts
18.Cover plate seal
19.Seal, washer and backup seal
20.Circlip and dust cover

STEERING
3
DESCRIPTION AND OPERATION Rotary valve operation
Rotary valve at neutral
The rotary valve assembly comprises a worm (1),
valve sleeve (2), input shaft (4) and torsion bar (5).
The valve sleeve is retained inside the worm by a trim
screw (3), and incorporates valve ports in its inner
bore. The input shaft is attached to the steering wheel
via a steering shaft and steering column and
incorporates valve ports in its outer diameter to align
with those in the sleeve.
The torsion bar, which is secured to the worm and
input shaft with pins (6) at each end, holds the valve
ports in neutral alignment when there is no demand
for assistance.No demand for assistance (Valve at neutral)
When there is no demand for assistance the torsion
bar holds the input shaft and sleeve valve ports in
neutral relationship to one another, allowing equal
pump pressure (A) to both sides of the piston/rack (9).
Any excess fluid flow from the pump returns to the
reservoir via (B).

57STEERING
4
DESCRIPTION AND OPERATION Rotary valve misaligned
Demand for assistance (Valve misaligned)
When the steering wheel and input shaft is turned,
steering resistance transmitted to the worm causes
the torsion bar to be twisted and the valve ports to be
misaligned for a right or left turn. The misalignment of
the valve ports directs all fluid pressure A to one side
of the piston only and allows displaced fluid B on the
other side.
When demanding maximum assistance, any
excessive fluid output from the pump due to high
pump speed, will circulate through the regulator valve
located in the pump unit, causing the temperature of
the fluid and the pump to rise rapidly.CAUTION: To avoid excessive fluid
temperatures which could damage the oil
seals, the steering must not be held on full
lock for more than 30 seconds in one minute.
Only when the steering wheel, and the demand for
assistance, is released, will the torsion bar return the
valve to neutral, allowing the fluid to circulate through
the reservoir where it is cooled.
In the unlikely event of mechanical failure of the
torsion bar, a coarse splined connection (7) between
the input shaft and worm, ensures steering control is
maintained sufficient to allow the vehicle to be
recovered.

STEERING
5
DESCRIPTION AND OPERATION Pump and regulator valve operation
The pump which is belt driven from the engine is an
eccentric roller type and also houses the pressure
regulator and flow control valve. The pressure is
controlled by a spring loaded ball valve (3) which is
housed inside the flow control valve piston (4).
No demand for assistance High flow through box -
Low pressure
With no demand for assistance the rotary valve in the
steering box acts as a pressure relief valve, allowing
fluid (A) to flow freely through the steering box and
back to the reservoir and pump inlet (B).
No demand for assistance
1.Reservoir
2.Pump
3.Pressure control ball valve and spring
4.Flow control valve and spring
5.Press fit plug (ball bearing)
6.Restrictor
The ball plug (5) is pressed into the valve (4)
during manufacture and determines the opening
pressure of pressure relief valve (3).No flow, through box - High pressure
When the steering is turned, the rotary valve
effectively stops all fluid flow through the steering box,
thus causing an increase in pressure (A). This
increase in pressure is felt in the flow control valve
spring chamber where, at a pre-determined pressure
the relief valve (3) will open and allow the pressure to
escape. The fall in pressure in the flow control spring
chamber, allows the flow control valve to move to the
right, which in turn allows pump output (A) to escape
directly into the pump inlet (B).
Assistance demanded
As soon as the steering wheel is released after
making a turn, the system reverts to the condition
seen in J6292 and the road wheels are returned to the
straight ahead position by the mechanical steering
geometry.
In the event of any hydraulic failure, steering control,
though heavy, will be maintained through the
mechanical components in the steering box.

STEERING
1
FAULT DIAGNOSIS INSUFFICIENT POWER ASSISTANCE
1.Is fluid level correct?
YES - go to 3.
NO - Fill/bleed sytem
2.Is problem a leak?
YES - Diagnose
See Power Steering Fluid
Leaks
.
NO - continue
3.Is drive belt tension correct?
YES - go to 5.
NO - Is drive belt worn or contaminated with oil?
See ELECTRICAL, Repair, Auxiliary drive
belt
.
4.Is problem resolved?
YES - end
NO - continue
5.Carry out pressure test at idle and 1000 rev/min.
See Power Steering System - Test.
6.Is correct pressure achieved?
YES - steering box defective
Not at any speed go to 9.
Not at idle go to 7.
7.Is idle speed correct?
YES-Goto8.
NO - Correct idle speed -
See ENGINE TUNING
DATA, Information, 300 Tdi Engine
.
8.Is problem resolved?
YES - end
NO - go to 9.
9.Bypass steering box using adaptor tap
LRT-57-001
10.Is correct pressure obtained?
YES - defective steering box
NO - defective steering pump
CAUTION: Do not hold steering wheel on
full lock for more than 30 seconds in any
one minute to avoid overheating fluid and
possibly damaging seals.
NOTE: 1. Excessive pressure in the
system is almost always caused by a
faulty relief valve in the PAS pump.
NOTE: 2. Insufficient pressure in the
system is usually caused by low fluid level
or PAS pump drive belt slip, or one of the
following: PAS system leaks, faulty PAS pump
relief valve, fault in steering box valve and worm
assembly, leak at piston in steering box, worn
components in PAS pump or box.

57STEERING
2
FAULT DIAGNOSIS POWER STEERING SYSTEM - TEST
NOTE: If steering lacks power assistance.
Check pressure of hydraulic pump before
fitting new components. Use fault
diagnosis chart to assist in tracing faults.
A. Steering box.
B. Steering pump.
C. Existing hose, steering box to pump.
D. HoseLRT-57-030.
E. Test adaptorLRT-57-001.
F. Pressure gaugeLRT-57-005.
G. Thread adaptorLRT-57-004.
H. Thread adaptorLRT-57-022.Procedure
1.A hydraulic pressure gauge and test adaptor is
used to test power steering system. This gauge
is able to measure 140 kgf/cm
2. The maximum
power steering system pressure is 77 kgf/cm2.
2.Under certain fault conditions of the hydraulic
pump it is possible to obtain pressures up to 105
kgf/cm
2. It is important to realise that pressure on
gauge is same pressure being exerted upon
steering wheel. When testing, turn steering
wheel gradually while reading pressure gauge.
3.Check and maintain maximum fluid level of
reservoir.
4.Examine power steering units and connections
for leaks. All leaks must be rectified before
attempting to test the system.
5.Check steering pump drive belt tension and
renew belt if necessary,
See ELECTRICAL,
Repair, Auxiliary drive Belt
.
6.Assemble test equipment and fit to vehicle, as
shown in RR3959M.
7.Open tap of adaptor.
8.Bleed system, take care not to overload
pressure gauge.
9.With system in good condition, pressures should
be:
(A) Steering wheel held on full lock and engine
running at 1,000 rev/min, 70 to 77 kgf/cm
2.
(B) Steering wheel held on full lock and engine
idling, 28 kgf/cm
2.
Checks should be carried out on both full lock
positions.
CAUTION: Do not maintain this pressure
for more than 30 seconds in any one
minute to avoid overheating fluid and
possibly damaging seals.
10.Release steering wheel and with engine idling.
Pressure should read below 7 kgf/cm
2.
11.If pressures differ to those given a fault exists.
12.To determine if fault is steering box or pump.
Close adaptor tap for a maximum five seconds.
13.If gauge does not register specified pressure,
pump is faulty.
14.Fit a new pump, bleed system and repeat test. If
low pressure or a substantial imbalance exists,
fault is in steering box valve and worm
assembly.