1999 LAND ROVER DEFENDER ECU

33CLUTCH
6
DESCRIPTION AND OPERATION DESCRIPTION
General
The clutch system is a diaphragm type clutch operated by a hydraulic cylinder. The drive plate is of the rigid centre
type with no integral damping springs. The flywheel is of the dual mass type with damping springs integral with the
flywheel. The clutch requires no adjustment to compensate for wear.
Hydraulic Clutch
The hydraulic clutch comprises a master cylinder, slave cylinder and a hydraulic reservoir. The master and slave
cylinders are connected to each other hydraulically by plastic and metal pipes. The plastic section of the pipe
allows ease of pipe routing and also absorbs engine movements and vibrations.
The master cylinder comprises a body with a central bore. Two ports in the body connect the bore to the hydraulic
feed pipe to the slave cylinder and the fluid reservoir. The bore is also connected to a damper which prevents
engine pulses being transferred hydraulically to the clutch pedal. A piston is fitted in the bore and has an external
rod which is attached to the clutch pedal with a pin. Two coil springs on the clutch pedal reduce the effort required
to depress the pedal.
The master cylinder is mounted on the bulkhead and secured with two bolts. The cylinder is connected to the
shared brake/clutch reservoir on the brake servo by a braided connecting hose.
The slave cylinder is located on the left hand side of the gearbox housing and secured with two bolts. A heat
shield is fitted to protect the underside of the slave cylinder from heat generated from the exhaust system. The
slave cylinder comprises a cylinder with a piston and a rod. A port in the cylinder body provides the attachment for
the hydraulic feed pipe from the master cylinder. A second port is fitted witha bleed nipple used for removing air
from the hydraulic system after servicing. The piston rod locates on a clutch release lever located in the gearbox
housing. The rod is positively retained on the release lever with a clip.
Clutch Mechanism
The clutch mechanism comprises a flywheel, drive plate, pressure plate, release lever and a release bearing. The
clutch mechanism is fully enclosed at the rear of the engine by the gearbox housing.
A clutch release bearing sleeve is attached in the gearbox housing with two bolts and located on two dowels. A
spigot with a ball end is formed on the release bearing sleeve and provides a mounting and pivot point for the
clutch release lever. A dished pivot washer is located on the ball of the spigot. When the release lever is located
on the ball, the pivot washer seats against the rear face of the release lever. A spring clip is located on the lever
and the pivot washer and secures the lever on the spigot. A small bolt retains the spring clip in position.
The release lever is forked at its inner end and locates on the clutch release bearing carrier. The outer end of the
release lever has a nylon seat which locates the slave cylinder piston rod. A second nylon seat, positioned
centrally on the release lever, locates on the ball spigot of the release bearing sleeve and allows the release lever
to pivot freely around the ball.
The clutch release bearing locates on the clutch release lever and release bearing sleeve. The bearing is retained
on a carrier which has two flats to prevent the carrier rotating on the release lever. A clip retains the release lever
on the carrier. The bearing and carrier are not serviceable individually.
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33CLUTCH
8
DESCRIPTION AND OPERATION The dual mass flywheel is bolted on the rear of the crankshaft with eight bolts. A dowel on the crankshaft flange
ensures that the flywheel is correctly located. A ring gear is fitted on the outer diameter of the flywheel. The ring
gear is not serviceable. Thirty blind holes are drilled in the outer diameter of the flywheel adjacent to the ring gear.
The holes are positioned at 10°intervals with four 20°spaces. The holes are used by the crankshaft position
sensor for engine management.
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.
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CLUTCH
11
DESCRIPTION AND OPERATION Drive plate
1.Friction material
2.Inner plate3.Hub
4.Spring steel plate
The drive plate is of the rigid centre type and is sandwiched between the flywheel and the pressure plate. The
drive plate has a splined hub which engages with the splines on the primary drive shaft from the gearbox. The hub
is attached to an inner plate which is pressed onto the hub. A spring steel plate is riveted to the inner plate with
eight rivets and provides the attachment surface for the drive plate friction material. The spring steel plate allows
some axial compliance and contributes to smooth clutch operation. The friction material comprises two 267 mm
(10.5 in.) discs which are secured with rivets to each side of the spring steel plate. The rivets are installed through
recessed holes in the disc and emerge in recessed holes in the opposite disc.
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CLUTCH
1
REPAIR CLUTCH ASSEMBLY
Service repair no - 33.10.01.01
Remove
1.Remove gearbox assembly.See MANUAL
GEARBOX, Repair.
2.Restrain flywheel.
3.Working in sequence, loosen 6 nuts securing
clutch cover to flywheel.
4.Remove clutch cover and clutch plate.
Refit
5.Clean clutch cover and flywheel mating faces
and spigot bush in end of crankshaft.
6.Position clutch drive plate to flywheel with
’gearbox side’ facing towards gearbox.
7.PositionLRT-12-152alignment tool through
drive plate into spigot bearing in crankshaft.8.Fit clutch cover and locate on dowels.
9.Position clutch cover nuts and tighten in diagonal
sequence to25 Nm (18 lbf.ft).
10.Fit gearbox assembly.See MANUAL
GEARBOX, Repair.
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33CLUTCH
2
REPAIR BEARING - CLUTCH RELEASE
Service repair no - 33.25.12
Remove
1.Remove gearbox assembly.See MANUAL
GEARBOX, Repair.
2.Remove retaining peg and remove release
bearing.
3.Remove bolt securing clutch release fork,
remove retaining clip and remove clutch release
fork.
Refit
4.Clean release fork.
5.Examine clutch release fork pivot points for
wear.
6.Apply a smear of Molybdenum disulphide grease
to release fork pivot points.
7.Fit retaining clip ensuring it locates over pivot
point washer.
8.Fit bolt and tighten to10 Nm (7 lbf.ft).
9.Clean release bearing and bearing sleeve
mating faces.
10.Apply smear of Molybdenum disulphide grease
to release bearing sleeve.
11.Fit release bearing and secure with retaining
peg.
12.Fit gearbox assembly.See MANUAL
GEARBOX, Repair.CLUTCH - MASTER CYLINDER LH DRIVE
Service repair no - 33.20.01
Remove
1.Remove 3 screws securing closing panel to
lower’A’post.
2.Release closing panel sufficient to gain access
to clutch and brake pedal bracket bolts.
3.Remove clutch pedal rubber.
4.Remove 12 bolts securing clutch and brake
pedal brackets to body.
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CLUTCH
3
REPAIR
5.Disconnect multiplug from clutch pedal sensor.
6.Disconnect muliplug and harness clip from pedal
bracket.
7.Position cloth to collect fluid spillage.
8.Loosen pipe union, release pipe and plug pipe
and master cylinder.
9.Move brake master cylinder assembly aside and
lift out clutch master cylinder assembly.
10.Remove 6 screws, remove pedal box top cover
and discard gasket.
11.Remove nut securing push rod to clutch pedal
trunnion.
12.Remove 2 bolts and remove clutch master
cylinder from pedal bracket.
13.Remove clutch pedal sensor and pipe union
from master cylinder and discard sealing
washers.Refit
14.Clean sensor and pipe union.
15.Fit clutch pedal sensor and pipe to master
cylinder using new sealing washers.
16.Position master cylinder to pedal bracket and
align push rod to pedal trunnion.
17.Fit bolts and nuts and secure master cylinder to
pedal bracket.
18.Fit nut securing push rod to clutch pedal trunnion
but do not tighten nut at this stage.
19.Move brake master cylinder aside and position
clutch master cylinder assembly.
20.Clean clutch pipe union.
21.Align pipe and tighten union.
22.Connect multiplug to clutch pedal sensor.
23.Tighten bolts securing clutch pedal and brake
pedal brackets to body.
24.Fit clutch pedal rubber.
25.Position closing panel and tighten screws to
lower’A’post.
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33CLUTCH
4
REPAIR Clutch pedal setting
1.Loosen both locknuts on master cylinder push
rod.
2.Check distance from lower edge of clutch pedal
to floor. Correct measurement is 140 mm (5.50
in) without floor mat.
3.Adjust pedal stop to obtain correct setting.
4.Adjust master cylinder push rod to obtain
approximately 1.5 mm (0.06 in) free play
between push rod and master cylinder piston.
5.Tighten push rod locknuts.
6.Check operation of clutch pedal and ensure that
there is minimum of 6 mm (0.25in) of free play
before pressure is felt.
7.Fit pedal box top cover and multiplug bracket
using a new gasket and secure with screws.
8.Connect multiplug and harness clip to pedal
bracket.
9.Bleed clutch hydraulic system.See
Adjustment.CYLINDER - CLUTCH SLAVE
Service repair no - 33.35.01
Remove
1.Disconnect pipe from slave cylinder.
CAUTION: Plug the connections.
2.Position container to catch spillage.
3.Remove 2 bolts securing slave cylinder to bell
housing.
4.Withdraw slave cylinder from bell housing and
push rod.
Refit
5.Clean ends of pipes, bell housing and slave
cylinder mating faces.
6.Lubricate end of push rod with Molybdenum
disulphide gease.
7.Locate slave cylinder to push rod and bell
housing.
8.Fit bolts and tighten to25 Nm (18 lbf.ft).
9.Connect clutch pipe to slave clyinder.
10.Bleed clutch system.See Adjustment.
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MANUAL GEARBOX
1
REPAIR COVER - FRONT - RESEAL AND FIT NEW INPUT
SHAFT OIL SEAL
Service repair no - 37.12.33.01
Remove
1.Remove gearbox.See this Section.
2.Remove retaining peg and remove release
bearing.
3.Remove bolt securing clutch release fork,
remove retaining clip and remove clutch release
fork.
4.Remove 2 bolts securing release bearing sleeve,
remove bearing sleeve.
5.Remove 6 bolts securing clutch housing, remove
housing.
6.Remove and discard 6 bolts securing front
cover, remove cover.
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