LAND ROVER DISCOVERY 1995 Workshop Manual

74WHEELS AND TYRES
2
REPAIR When the indicators appear in two or more adjacent
grooves, at three locations around the tyre, a new tyre
must be fitted.
NOTE: Do not attempt to interchange
tyres, e.g. from front to rear, as tyre wear
produces characteristic patterns
depending on their position. If tyre position is
changed after wear has occured, the performance
of the tyre will be adversely affected.
NOTE: Territorial vehicle regulations
governing tyre wear MUST be adhered to.
WHEELS INSPECTION
Regularly check the condition of the wheels. Replace
any wheel that is bent, cracked, dented or has
excessive runout.
VALVES INSPECTION
Check condition of inflation valve. Replace any valve
that is worn, cracked, loose, or leaking air.TYRE PRESSURES
Maximum tyre life and performance will be
obtained only if tyres are maintained at the correct
pressures.
Tyre pressures must be checked at least once a
month and at least once a week, preferably daily, if
the vehicle is used off road.
The tyre inflation pressure is calculated to give the
vehicle satisfactory ride and steering characteristics
without compromising tyre tread life. For
recommended tyre pressures in all conditions.
See
GENERAL SPECIFICATION DATA, Information,
Wheels and Tyres
American vehicles - A label attached to the inside
edge of the driver's door also provides tyre pressure
information.
Always check tyre inflation pressures using an
accurate gauge and inflate tyres to the
recommended pressures only.
Check and adjust tyre pressuresONLYwhen the
tyres are cold, vehicle parked for three hours or more,
or driven for less than 3.2 km (2 miles) at speeds
below 64 km/h (40 mph). Do not reduce inflation
pressures if the tyres are hot or the vehicle has been
driven for more than 3.2 km (2 miles) at speeds over
64 km/h (40 mph), as pressures can increase by 0.41
bars (6 p.s.i) over cold inflation pressures.
CheckALLtyre pressures including the spare. Refit
the valve caps as they form a positive seal and keep
dust out of the valve.

WHEELS AND TYRES
3
REPAIR WHEEL BALANCING
CAUTION: It is essential that all wheel
balancing is carried out off the vehicle.
The use of on the vehicle balancing could
cause component damage or personal injury and
MUST NOT be attempted.
NOTE: Before attempting to balance a
wheel and tyre assembly clean all mud and
dirt deposits from both inside and outside
rims and remove existing balance weights.
Remove stones from the tyre tread in order to avoid
operator injury during dynamic balancing and to obtain
the correct balance.
Inspect tyres for damage and correct tyre pressures
and balance according to the equipment
manufacturer's instructions.
Alloy wheels
Clean area of wheel rim and attach adhesive balance
weights in position shown. Cut through rear face of
weight strip to detach required weights.
CAUTION: Use only correct adhesive
balance weights to avoid damage to
aluminium wheel rim. DO NOT attempt to
use a steel wheel weight on an aluminium wheel.
Steel wheels
Clean area of wheel rim and attach balance weights in
position shown.

74WHEELS AND TYRES
4
REPAIR Static balance
Wheel tramp
A. Heavy spot.
B. Add balance weights here.
C. Centre line of spindle.
Static balance is the equal distribution of weight
around the wheel. A statically unbalanced wheel will
cause a bouncing action called wheel tramp. This
condition will eventually cause uneven tyre wear.Dynamic balance
Wheel shimmyA. Heavy spot.
B. Add balance weights here.
C. Centre line of spindle.
Dynamic balance is the equal distribution of weight on
each side of the centre line so that when the wheel
spins there is no tendency for side to side movement.
A dynamically unbalanced wheel will cause wheel
shimmy.

WHEELS AND TYRES
5
REPAIR Off vehicle balancing
Balance wheel assembly referring to equipment
manufacturer's instructions.
It is essential that the wheel is located by the centre
holeNOTthe stud holes. To ensure positive wheel
location the diameter of the locating collar on the
machine shaft must be 112.80 to 112.85 mm (4.441 to
4.443 in). This diameter will ensure that the collar fits
correctly within the centre hole of the wheel.
Where possible always use the vehicle wheel
retaining nuts to locate the wheel on the balancer, to
avoid damaging the wheel. If this is not possible, the
locating nuts must be of a similar pattern to the
original wheel nuts. The use of conical type wheel
nuts for this purpose may damage the aluminium
alloy.
Cleaning
Wash the aluminium wheels using a suitable wash
and wax concentrate correctly diluted and rinse with
cold clear water.DO NOTuse abrasives or aluminium
wheel cleaners containing acid, as they will destroy
the lacquer finish.
Tyre changing
Use only tyre changing equipment to mount or
demount tyres, following the equipment
manufacturer's instructions.DO NOTuse hand tools
or tyre levers, as they may damage tyre beads or the
aluminium wheel rim.
Puncture repair
Remove punctured tyre from wheel and repair using a
combination service plug and vulcanising patch.
Always follow manufacturer's instructions when using
a puncture repair kit.
Only punctures in tread area are repairable,DO NOT
attempt to repair punctures in tyre shoulders or
sidewalls.
Do not attempt to repair a tyre that has sustained the
following: bulges or blisters, ply separation, broken or
cracked beads, wear indicators visible and punctures
larger than 6 mm diameter.
CAUTION: Do not use tyre sealants that
are injected through valve stem to repair
punctured tyres, they may produce wheel
corrosion and tyre imbalance.
Aluminium wheel rim bead seats should be cleaned
using a non-abrasive cleaner to remove the mounting
lubricants and old rubber. Before mounting or
demounting a tyre, bead area should be well
lubricated with a suitable tyre lubricant.
TYRE FITTING
Alloy wheels
1.Install a new valve assembly.
2.Ensure wheel and tyre is adequately lubricated.
3.Mount tyre in normal manner. Inflate tyre and at
same time apply hand pressure to area around
valve to aid seating over valve first.
NOTE: Stop inflation immediately if tyre
seats opposite valve, as this will result in
valve being blocked by tyre beading,
making further inflation impossible, and carry out
following procedure.
4.Deflate tyre, unseat and rotate it around the rim
until valve is in line with that part of tyre which
seated initially. This part of beading having
seated over hump previously will automatically
seat first when tyre is re-inflated.
5.Inflate tyre to seat beads correctly, finally inflate
to correct pressure.

74WHEELS AND TYRES
6
REPAIR WHEELS
Remove
WARNING: The parking brake acts on
transmission, not rear wheels, and may
not hold vehicle when jacking unless
following procedure is used. If one front wheel
and one rear wheel is raised no vehicle holding or
braking effect is possible. Wheels MUST be
chocked in all circumstances.
Apply parking brake, select 'P' or a gear in main
gearbox and engage low gear in transfer box.
1.Loosen five wheel nuts.
2.Using a suitable trolley jack raise vehicle and
place on axle stands.
See INTRODUCTION,
Information, Jacking
3.Remove wheel nuts and carefully withdraw
wheel over studs.Refit
4.Ensure that retaining studs and nuts are clean.
5.Alloy wheels: Lightly coat wheel mounting spigot
face with a suitable anti-seize compound to
minimise possibility of adhesion between wheel
and spigot face.
6.Refit wheel taking care not to damage stud
threads. (Do not apply oil)
7.Fit wheel nuts and turn by hand for at least three
full threads before using any form of wheel
wrench.
8.Tighten nuts as much as possible using a
suitable wrench.
9.Lower vehicle and finally tighten nuts to correct
torque sequence shown. Alloy wheels and steel
wheels:
130Nm.

WHEELS AND TYRES
7
REPAIR WHEEL STUD
Remove
1.Remove wheel.
See Wheels
2.Drive stud out of driveshaft flange.
Refit
3.Position stud in flange.
4.Install a suitable spacer over stud.
5.Using a M16 x 1.5P nut, a slave wheel nut is
suitable, pull stud into flange until shoulder of
stud abuts flange.
6.Refit wheel.

SUPPLEMENTARY RESTRAINT SYSTEM
1
DESCRIPTION AND OPERATION SYSTEM COMPONENTS
1. Airbag crash sensors (distributed SRS)
2. SRS warning light (airbag)
3. Rotary coupler
4. Driver's airbag module
5. Passenger's airbag module6. Airbag diagnostic socket
7. Airbag diagnostic control unit
8. Airbag harness (distributed SRS)
9. Knee bolsters (where fitted)
10. Airbag harness

75SUPPLEMENTARY RESTRAINT SYSTEM
2
DESCRIPTION AND OPERATION OPERATION
The airbag supplementary restraint system (SRS) is a
safety device which, when used in conjunction with
the seat belt, is designed to protect the driver and
front passenger.
Two different SRS systems are fitted to Discovery.
The Distributed SRS which has two crash sensors
located in the engine compartment on the chassis
longitudinals and the Single Point Sensing (SPS) SRS
which has a single crash sensor located in the Airbag
diagnostic control unit.
The change from distributed SRS to SPS SRS
occurred at VINs198222and528977.
Distributed SRS
In the event of a frontal impact, when the airbag
diagnostic control unit and one of the airbag crash
sensors senses the impact, the diagnostic control unit
fires igniters. This in turn ignites tablets of sodium
azide which generate a large amount of Nitrogen gas
leading to airbag inflation in approximately 30
milli-seconds.SPS SRS
In the event of a frontal impact, when the airbag
diagnostic control unit senses the impact, the
diagnostic control unit fires igniters. This in turn ignites
tablets of sodium azide which generate a large
amount of Nitrogen gas leading to airbag inflation in
approximately 30 milli-seconds.
All Models
When fully deployed the airbag offers additional
protection to the front seat occupant. As an occupant
moves into the airbag it immediately discharges the
gas to provide progressive occupant deceleration and
reduce risk of injuries. The whole process is
completed in approximately 0.3 seconds.
WARNING: All the airbag system
components, including the wiring harness,
MUST be renewed after the airbags have
deployed.

SUPPLEMENTARY RESTRAINT SYSTEM
3
DESCRIPTION AND OPERATION SRS warning light (airbag)
Distributed SRS
The warning light in the instrument pack illuminates
after the electrical circuits are switched on whilst a
system check is carried out. After about 8 seconds the
warning light will go out. The system checks airbag
diagnostic control unit, airbag crash sensors, airbag
harness, driver and passenger modules.
SPS SRS
The warning light in the instrument pack illuminates
after the electrical circuits are switched on whilst a
system check is carried out. After about 5 seconds the
warning light will go out. The system checks airbag
diagnostic control unit, airbag harness, driver and
passenger modules.
All Models
In the event of a fault in the system the warning light
will illuminate. The airbag diagnostic control unit logs
the fault which can only be accessed using TestBook.

75SUPPLEMENTARY RESTRAINT SYSTEM
4
DESCRIPTION AND OPERATION GENERAL PRECAUTIONS
Impacts which do not deploy airbags
CAUTION: Check for structural damage in
the area of the impact, paying particular
attention to bumper armatures,
longitudinals, crash cans and bracketry.
1.Carefully inspect any airbag part before
installing. Do not install any part that shows
signs of being dropped or improperly handled,
such as dents, cracks or deformation.
2.Always remove the key from the starter switch
before beginning work.
3.Always disconnect both the negative '-' cable
and positive '+' cable at the battery before
removal of driver or passenger airbag modules.
Disconnect the negative cable first.
CAUTION: The airbag system has
sufficient stored energy to deploy airbags
for up to 20 minutes.
4.To continue work immediately, disconnect the
driver's airbag and passenger's airbag (where
fitted).
5.Do not try to dismantle the airbag module. There
are NO separately serviceable parts. Once an
airbag has been deployed, it cannot be repaired
or reused.
6.Do not install used airbag parts from another
vehicle. When repairing, use only new airbag
parts.