Discovery 2. Manual — part 530

CLUTCH - TD5

DESCRIPTION AND OPERATION

33-1-5

1 Brake/clutch reservoir
2 Fluid supply pipe
3 Hydraulic feed pipe
4 Damper
5 Master cylinder
6 Piston
7 Clutch pedal
8 Primary driveshaft
9 Engine crankshaft

10 Drive plate
11 Dual mass flywheel
12 Ring gear
13 Leaf spring
14 Cover - pressure plate
15 Diaphragm
16 Release bearing
17 Ball spigot
18 Release bearing sleeve
19 Release lever
20 Slave cylinder
21 Piston
22 Bleed nipple

CLUTCH - TD5

33-1-6

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 amounting 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.

CLUTCH - TD5

DESCRIPTION AND OPERATION

33-1-7

Dual mass flywheel

1 Ring gear
2 Primary flywheel
3 Inner drive plate
4 Spring housing
5 Secondary flywheel
6 Rivet
7 Ball bearing

8 Dowel location hole
9 Mounting hole

10 Inner spring
11 Outer spring
12 Crankshaft position sensing holes
13 Pressure plate locating dowel

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.

+

ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.

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

1 Leaf spring
2 Drive plate
3 Pressure plate
4 Cover
5 Diaphragm
6 Rivet