LAND ROVER DEFENDER 1996 Workshop Manual

33CLUTCH
2
DESCRIPTION AND OPERATION
When the clutch pedal is depressed, hydraulic fluid
transmits the movement via the slave cylinder, release
lever (10), bearing (9), to the inner fingers of the
diaphragm spring (4).
The diaphragm spring (4) pivots on the bearing rings
(7) and fulcrum posts (6) causing the pressure plate
(5) to release the clamping force on the friction plate
and linings (2).As the the clamping force is removed from the friction
plate (2), the plate slides on the splines of the primary
shaft (15) and takes up a neutral position between the
flywheel (1) and the pressure plate (5), thus
disconnecting the drive between the engine and the
gearbox.

CLUTCH
1
FAULT DIAGNOSIS CLUTCH ASSEMBLY CONDITIONS
For the clutch to operate correctly it is important the
following conditions are satisfied:-
·The primary shaft (15) must be free in the
crankshaft spigot bush (17).
·The friction plate (2) must be able to slide easily on
the splines on the primary shaft (15), to a position
where it does not contact either the flywheel or the
pressure plate.
·The friction plate must not be distorted or the
linings contaminated with oil, which may cause it to
stick or continue to run in contact with the flywheel
or pressure plate.
A number of faults can develop in the operation of the
clutch for a variety of reasons and most faults are due
to normal wear at high mileage. Problems can also
occur if the unit has been renewed by an unskilled
operator.
Recognising and diagnosing a particular clutch fault is
therefore of paramount importance in ensuring that
the problem is rectified at the first attempt.
Problems which develop in the clutch are as follows:-
·Clutch spin/drag
·Clutch slip
·Clutch judder/fierceCLUTCH SPIN - DRAG
Symptoms
Clutch spin is that, with engine running and clutch
pedal depressed, the gears cannot be immediately
engaged without making a grinding noise. This
indicates the clutch is not making a clean break.
However, if the clutch pedal is held depressed for
several seconds the friction plate will eventually break
free from the engine and the gear will engage silently.
Clutch spin as it becomes more severe develops into
clutch drag, making the silent engagement of a gear
impossible, regardless of how long the pedal is held
depressed.
CLUTCH SLIP
Symptoms
Clutch slip is most evident climbing a hill or when the
vehicle is moving off from stationary with a heavy
load. As the clutch is released, slip occurs between
the engine and the transmission, allowing the engine
speed to increase without a corresponding increase in
vehicle speed.
Clutch slip can develop to the stage where no power
is transmitted through the clutch as the pedal is
released.
CLUTCH JUDDER - FIERCE
Symptoms
Clutch judder or fierce engagement, like slip, is most
likely to occur when the vehicle is moving off from
stationary. As the clutch pedal is released the vehicle
will move rapidly or in a series of jerks, which cannot
be controlled even by careful operation of the clutch
by the driver.
It should be noted that a vehicle may display all the
symptoms or any combination of the symptoms
described, depending on the driving conditions vehicle
load and operating temperatures.

33CLUTCH
2
FAULT DIAGNOSIS FAULT/SYMPTOM CHART
Symptoms
Slip Spin/Drag Judder/Fierce Fault Item
* * * Worn or oil on clutch linings 2
* * * Mechanical damage45678
* * Distorted clutch plate 2
* Failed or air in hydraulic system 12 13
* * Primary shaft tight fit in crankshaft bush 15 17
* Clutch splines sticking 2 15
* Weak clutch plate springs or insecure/worn
engine/gearbox mountings6
* Insecure/worn propeller shafts
* Insecure/worn suspension components/rubber
bushes
The items refered to in this chart relate to the clutch components shown in J6270 and J6271.See Description
and operation, Description
CLUTCH NOISE - MECHANICAL FAULTS
Noise from clutch or gearbox in neutral, which
disappears when clutch is depressed.
Suspect gearbox input/primary shaft bearings
See MANUAL GEARBOX, Fault diagnosis,
R380 gearbox
.
Noise from clutch or gearbox in neutral, which
changes tone or becomes worse when the clutch
is depressed.
Suspect worn release bearing.
Knocking/rattling from clutch or gearbox in
neutral, which is reduced or disappears when the
clutch is depressed.
Suspect worn/weak release lever retainer or
clutch unit.
Noise from clutch or gearbox in neutral, which
disappears when clutch is depressed.
Suspect gearbox fault
See MANUAL
GEARBOX, Fault diagnosis, R380 gearbox
.HYDRAULIC FAULTS
Unable to dis-engage clutch, little or no pedal
resistance.
1.Check condition, specification and level of fluid.
2.Check pipes and cylinders for leaks.
3.Check that air vent in reservoir lid is clear.
Suspect faulty master cylinder if no fluid leaks
present
See Repair, Master cylinder.
Spongy pedal operation
1.Check condition, specification and level of fluid.
2.Check that air vent in reservoir lid is clear.
Suspect air in fluid
See Repair, Bleed
hydraulic system
.
Clutch is difficult to dis-engage and/or does not
immediately re-engage when pedal is released.
1.Check condition, specification and level of fluid.
2.Check that air vent in reservoir lid is clear.
Suspect pedal pivot, master cylinder or slave
cylinder seizure
See Repair, Master cylinder.

CLUTCH
1
ADJUSTMENT CLUTCH PEDAL AND MASTER CYLINDER
SETTING
1.Remove 6 screws and detach pedal box top
cover and gasket.
2.Slacken both locknuts on master cylinder
push-rod.
3.Check distance from lower edge of clutch pedal
to floor. Correct measurement is 140 mm (5.50
in) without floor mat.
4.Adjust pedal stop as necessary to obtain correct
setting.
5.Adjust master cylinder push rod to obtain
approximately 1,5 mm (1/16 in) free play
between push-rod and master cylinder piston.
6.Tighten push-rod locknuts.7.Check operation of clutch pedal and ensure that
there is a minimum of 6 mm (0.25 in) of free play
before pressure is felt. If necessary, readust
master cylinder push-rod.
8.Fit pedal box gasket and top cover.

CLUTCH
1
REPAIR CLUTCH ASSEMBLY
Service repair no - 33.10.01
Clutch pressure plate
Renew pressure plate if diaphragm spring fingers are
worn or if pressure plate shows signs of wear, cracks
or burning.
Clutch driven plate
Renew driven plate if centre hub splines are worn or if
lining is contaminated, burned or unevenly worn.
Remove
1.Remove gearbox
See MANUAL GEARBOX,
Repair, R380 Gearbox
.
2.Mark position of clutch pressure plate to flywheel
for reassembly.
3.Remove pressure plate securing bolts, working
evenly and diagonally.
4.Remove clutch assembly.
5.Withdraw clutch driven plate.
Refit
NOTE: To prevent driven plate sticking,
lubricate splines using Rocol MV 3 or
Rocol MTS 1000 grease.
6.Using centralising toolLRT-12-040to support
clutch driven plate locate pressure plate on
flywheel dowels. If fitting original pressure plate,
align assembly marks.
7.Secure pressure plate cover fixings evenly,
working in a diagonal sequence. Tighten to
34Nm (25 lbf/ft).
8.Fit gearbox to engineSee MANUAL
GEARBOX, Repair, R380 Gearbox
.BLEED HYDRAULIC SYSTEM
Service repair no - 33.15.01
Procedure
NOTE: During bleed procedure, keep fluid
reservoir topped up to avoid introducing
air to system. For hydraulic fluid
recommendations
See LUBRICANTS, FLUIDS
AND CAPACITIES, Information, Recommended
lubricants and fluids
.
1.Attach suitable tubing to slave cylinder bleed
screw.
2.Place free end of tube in a glass jar containing
clutch fluid.
3.Loosen bleed screw.
4.Pump clutch pedal, pausing at end of each
stroke, until fluid from tubing is free of air.
NOTE: Keep free end of tube below
surface of fluid.
5.Hold clutch pedal down, tighten bleed screw.
6.Top up fluid reservoir.

33CLUTCH
2
REPAIR MASTER CYLINDER
Service repair no - 33.20.01/03
NOTE: All hose and pipe connections and
joints should be tightened to
15 Nm (11
lbf/ft).
Remove
1.Drain hydraulic fluid from system.
2.Disconnect fluid pipe at master cylinder. Plug
master cylinder fluid port and seal end of
hydraulic pipe to prevent ingress of dirt.
3.On RH drive vehicles, unclip air cleaner retaining
straps, disconnect bottom hose, and move
assembly aside.
4.From inside vehicle, remove fibre board closing
panel above pedals.
5.Remove 6 bolts securing pedal bracket to
bulkhead.
6.Remove screw securing speedometer cable
retaining bracket to top of pedal bracket.
7.Move pipework and cables aside and lift out
pedal bracket, complete with master cylinder,
turn through 90°to ensure pedal clears aperture
in bulkhead.8.Remove 6 screws and detach pedal box top
cover and gasket.
9.Remove nut and washer securing master
cylinder push rod to clutch pedal trunnion.
10.Remove 2 nuts and bolts and withdraw master
cylinder from pedal bracket.
Refit
11.Fit master cylinder to pedal bracket, engaging
cylinder push rod through pedal trunnion.
12.Secure push rod to pedal trunnion.
13.Apply sealant to mating surfaces and fit pedal
bracket to engine bulkhead.
14.Connect fluid pipe to master cylinder.
15.Bleed clutch hydraulic system
See Bleed
hydraulic system
.
16.Check and adjust clutch pedal and master
cylinder setting
See Adjustment, Clutch pedal
and master cylinder setting
.
17.Fit top cover and gasket to pedal bracket.
18.On RH drive vehicles, refit air cleaner.

CLUTCH
3
REPAIR CLUTCH PEDAL
Service repair no - 33.33.02
Remove
1.Remove pedal bracket assembly and master
cylinder
See Master cylinder.
2.Release return spring from clutch pedal.
3.Using a suitable punch, drift out securing pin and
withdraw pedal pivot shaft.
4.Withdraw clutch pedal, complete with trunnion
and bush.
5.If necessary remove pivot bushes.
6.Examine components for wear and damage,
renew as necessary.
NOTE: If new pedal pivot bushes are
required they must be reamed to 16 mm
(0.625 in).
Refit
7.If removed, fit trunnion bush and trunnion to
clutch pedal. Lubricate components with general
purpose grease on assembly.
8.Fit pedal to bracket, insert pivot shaft and secure
with new pin.
9.Fit pedal return spring.
10.Fit master cylinder and pedal bracket assembly
See Master cylinder.
11.Adjust clutch pedal and master cylinder setting
See Adjustment, Clutch pedal and master
cylinder setting
.

33CLUTCH
4
REPAIR RELEASE BEARING ASSEMBLY
Service repair no - 33.10.07
Remove
1.Remove gearbox
See MANUAL GEARBOX,
Repair, R380 Gearbox
.
2.Remove clutch slave cylinder
See Slave
cylinder
.
3.Remove release bearing sleeve retainer staple.
4.Withdraw bearing and sleeve.
5.Remove clutch release lever from bearing guide,
complete with sliper pads.
6.If necessary, unscrew 2 bolts and remove
bearing guide from bell housing.
Refit
7.If removed, fit bearing guide to bell housing.
Tighten bolts to
25 Nm (18 lbf/ft).
8.Prior to reassembly, grease pivot post, socket,
slipper pads, pins, and ball end of slave cylinder
push-rod.
9.Fit slipper pads onto release lever pins and
locate lever on pivot post.
10.Smear release bearing sleeve inner diameter
with molybdenum disulphide grease and fit to
bearing guide, locating slipper pads to sleeve
flats.
11.Fit new bearing sleeve retainer staple.
12.Fit clutch slave cylinder
See Slave cylinder.
13.Fit gearbox
See MANUAL GEARBOX, Repair,
R380 Gearbox
.SLAVE CYLINDER
Service repair no - 33.35.01
NOTE: All hose and pipe connections and
joints should be tightened to
15 Nm (11
lbf/ft).
Remove
1.Drain hydraulic fluid from system at slave
cylinder bleed valve.
2.Disconnect fluid pipe.
3.Remove 2 bolts and withdraw slave cylinder and
backing plate.
4.If dust cover is not withdrawn with slave cylinder,
withdraw it from bell housing.
CAUTION: If removing slave cylinder with
gearbox in situ, DO NOT detach push-rod
and clip from clutch release lever in bell
housing.
Refit
5.Coat both sides of backing plate with Hylomar
P232M waterproof jointing compound.
6.Locate backing plate and dust cover in position
on slave cylinder.
7.Fit slave cylinder, engaging push-rod through
centre of dust cover and with bleed screw
uppermost.
8.Reconnect fluid pipe.
9.Replenish and bleed clutch hydraulic system
See Bleed hydraulic system.
10.Check for fluid leaks with pedal depressed and
also with system at rest.

CLUTCH
1
OVERHAUL MASTER CYLINDER - OVERHAUL
Service repair no - 33.20.07
Dismantle
1.Remove master cylinder from vehicle
See
Repair, Master cylinder
.
2.Remove circlip.
3.Withdraw push-rod and retaining washer.
4.Withdraw the piston assembly. If necessary,
apply a low air pressure to outlet port to expel
piston.
5.Prise locking prong of spring retainer clear of
piston shoulder and withdraw piston.
6.Withdraw piston seal.
7.Compress spring and position valve stem to
align with larger hole in spring retainer.
8.Withdraw spring and retainer.
9.Withdraw valve spacer and spring washer from
valve stem.
10.Remove valve seal.
Inspection
11.Clean all components in new hydraulic fluid and
allow to dry.
12.Examine cylinder bore and piston, ensure that
they are smooth to touch with no corrosion,
score marks or ridges. If there is any doubt, fit
new components.
13.The seals should be renewed with seals from
master cylinder overhaul kit.
Assemble
14.Smear seals with suitable rubber grease and
remaining internal items with new hydraulic fluid.
15.Fit valve seal, flat side first, on end of valve
stem.
16.Place bowed washer, domed side first, over
small end of valve stem, see J6281.
17.Fit spacer to valve, legs first.

33CLUTCH
2
OVERHAUL
18.Place coil spring over valve stem.
19.Insert retainer into spring.
20.Compress spring and engage valve stem in
keyhole slot in retainer.
21.Fit seal, large diameter last, to piston.
22.Insert piston into spring retainer and engage
locking prong.
23.Smear piston with suitable rubber grease and
insert assembly, valve end first, into cylinder.
24.Fit push-rod, retaining washer and circlip.
25.Fit clutch master cylinder to vehicle
See Repair,
Master cylinder
.SLAVE CYLINDER - OVERHAUL
Service repair no - 33.35.07
Dismantle
1.Remove slave cylinder
See Repair, Slave
cylinder
.
2.Withdraw dust cover.
3.Expel piston assembly, applying low pressure air
to fluid inlet.
4.Withdraw spring.
5.Remove seal from piston.
6.Remove bleed valve.
Inspection
7.Clean all components with new hydraulic fluid
fluid and allow to dry.
8.Examine cylinder bore and piston, ensure that
they are smooth to touch with no corrosion,
score marks or ridges. If there is any doubt, fit
new components.
9.Renew seal and dust cover from slave cylinder
overhaul kit.