Discovery 2. Manual — part 534

CLUTCH - V8

DESCRIPTION AND OPERATION

33-2-5

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

10 Flywheel
11 Ring gear
12 Cover - Pressure plate
13 Leaf spring
14 Retractor clip
15 Diaphragm
16 Release bearing
17 Ball spigot
18 Release bearing sleeve
19 Release lever
20 Slave cylinder
21 Piston
22 Bleed nipple

CLUTCH - V8

33-2-6

DESCRIPTION AND OPERATION

Description

General
The clutch system is a conventional diaphragm type clutch operated by a hydraulic cylinder. The clutch requires no
adjustment to compensate for wear.

Hydraulic clutch
The hydraulic clutch comprises a master cylinder, slave cylinder and a hydraulic reservoir, which is also shared with
the braking system. 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 brake/clutch fluid reservoir. A piston is fitted in the bore and has an external
rod which is attached to the clutch pedal with a pin. Two coiled springs on the clutch pedal reduce the effort required
to depress the pedal.

The master cylinder is mounted on the bulkhead in the engine compartment 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
protects the underside of the 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 with a bleed nipple 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 the 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 - V8

DESCRIPTION AND OPERATION

33-2-7

Flywheel
The flywheel is bolted to a flange on the rear of the crankshaft with six bolts. A dowel on the crankshaft flange ensures
that the flywheel is correctly located. A ring gear is fitted on the outside diameter of the flywheel and seats against a
flange. The ring gear is an interference fit on the flywheel and is installed by heating the ring and cooling the flywheel.
The ring gear is a serviceable item and can be replaced if damaged or worn.

The operating face of the flywheel is machined to provide a smooth surface for the drive plate to engage on. Three
dowels and six threaded holes provide for the location and attachment of the pressure plate. The flywheel is balanced
to ensure that it does not produce vibration when rotating. A machined slot, with a series of holes within the slot, is
located on the engine side of the flywheel. The slot accommodates the tip of the crankshaft position sensor which is
used by the Engine Control Module (ECM) for engine management.

+

ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine

management.

Pressure plate

1 Leaf spring
2 Fulcrum ring
3 Fulcrum ring
4 Drive plate
5 Pressure plate

6 Diaphragm
7 Cover
8 Rivet
9 Retractor clip

The pressure plate assembly comprises a pressure plate, cover and diaphragm and is mounted on and rotates with
the flywheel.

CLUTCH - V8

33-2-8

DESCRIPTION AND OPERATION

The pressure plate is forged from cast iron and machined to provide a smooth surface for the drive plate to engage
on. Three lugs on the outer diameter of the pressure plate connect it via three leaf springs to the cover. The leaf
springs have two tempered steel leaves which assist in pulling the pressure plate away from the drive plate when the
clutch pedal is depressed.

The cover is made from pressed steel and houses and locates all pressure plate components. Shouldered rivets
support the diaphragm and fulcrum rings inside the cover. The cover also provides attachment for balance weights
when the pressure plate assembly is balanced. Three holes in the cover locate on the dowels on the flywheel and six
further holes provide for the attachment of the cover to the flywheel with six bolts and spring washers. Larger holes
in the cover provide ventilation for the drive plate and pressure plate and flywheel contact surfaces.

The diaphragm comprises a cast ring with eighteen fingers. The diaphragm is attached to the cover with nine
shouldered rivets. Two circular steel fulcrum rings are also secured by the shouldered rivets on each side of the
diaphragm. The fulcrum rings allow the diaphragm to pivot between them when the clutch is depressed or released.
When pressure is applied to the diaphragm fingers by the release bearing, the diaphragm pivots between the fulcrum
rings and moves away from the pressure plate. Retractor clips are secured to the pressure plate and are located on
the outer diameter of the diaphragm. The retractor clips ensure that the diaphragm remains in contact with the
pressure plate.

Drive plate

1 Friction material
2 Hub
3 Damper spring
4 Retainer plate
5 Disc adaptor
6 Stop pin