Discovery 2. Manual - part 535

CLUTCH - V8

DESCRIPTION AND OPERATION

33-2-9

The drive plate is of the spring centred type and is sandwiched between the pressure plate and the flywheel. The drive 
plate has a splined hub which engages with the splines on the primary drive shaft from the gearbox. The hub is located 
in an inner plate which contains six compression damper springs. A spring retainer plate and a disc adaptor are 
secured together with stop pins which limit the angular deflection of the disc adaptor. Engine power is transmitted from 
the disc adaptor to the damper springs. The damper springs then transfer the power to the retainer plate and the hub. 
Friction washers are located between the hub, retainer plate and disc adaptor and provide further damping.

A spring steel plate is riveted to the disc adaptor and provides the attachment surface for the drive plate friction 
material. The friction material comprises discs which are secured with rivets to each side of the plate. The rivets are 
installed through recessed holes in the disc and emerge in recessed holes in the opposite disc. The drive plate is 267 
mm (10.5 in) diameter and has a friction material manufactured from APTEC T385.

CLUTCH - V8

33-2-10 DESCRIPTION AND OPERATION

Operation

Hydraulic operation
Refer to illustration. 
 

 + 

 CLUTCH - V8, DESCRIPTION AND OPERATION, Hydraulic operation.

When the clutch pedal is depressed, the master cylinder piston is pushed into the master cylinder. The movement of 
the piston pressurises the fluid in the master cylinder, forcing the pressurised fluid into the hydraulic feed pipe to the 
slave cylinder. The hydraulic pressure is felt at the slave cylinder piston which moves under the hydraulic force 
applied, pushing the clutch release lever via the piston rod.

When the clutch pedal is released, the force applied to the release lever by the fingers of the diaphragm, moves the 
release lever, which pushes the slave cylinder piston into the cylinder. The displaced hydraulic fluid is pushed up the 
hydraulic feed pipe and returned to the master cylinder.

Mechanism operation
When the clutch pedal is depressed, hydraulic pressure extends the piston and rod in the slave cylinder. The 
extension of the piston pushes the rod against the outer end of the release lever which pivots around the ball spigot.

The inner end of the release lever pivots towards the engine applying pressure to the release bearing. The release 
bearing slides along the release bearing sleeve and pushes on the fingers of the diaphragm. The diaphragm pivots 
about the fulcrum rings in the cover. As the diaphragm is deflected, it removes pressure from the pressure plate. The 
pressure plate moves away from the drive plate assisted by the three leaf springs and retractor clips.

The removal of force from the pressure plate on the drive plate reduces the friction between the flywheel, drive plate 
and pressure plate. The drive plate slips between the flywheel and the pressure plate preventing rotary movement 
being transferred from the flywheel and pressure plate to the primary driveshaft.

When the clutch pedal is released, hydraulic force is removed from the piston in the slave cylinder. This allows the 
fingers of the diaphragm to push the release bearing along the release bearing sleeve. The movement of the release 
bearing moves the release lever which pivots on the ball spigot, pushing the piston and rod back into the slave 
cylinder.

The removal of pressure from the release bearing on the diaphragm, causes the diaphragm to pivot around the 
fulcrum rings in the cover. The force applied to the pressure plate from the diaphragm overcomes the force of the leaf 
springs and the pressure plate moves towards the drive plate and flywheel.

The pressure plate applies pressure to the drive plate which is pushed against the flywheel. As the clutch pedal is 
progressively released, the friction between the drive plate, flywheel and pressure plate increases. The increase in 
friction transfers the rotary movement of the flywheel and pressure plate to the drive plate which in turn starts to rotate 
the primary driveshaft. When the clutch pedal is released fully, the force applied by the diaphragm to the pressure 
plate forces the drive plate onto the flywheel with no slippage.

CLUTCH - V8

ADJUSTMENTS 33-2-11

ADJUSTMENTS

Clutch hydraulic system - bleed

$% 33.15.01 

CAUTION: Ensure the fluid in the reservoir is 
maintained between the minimum and maximum 
levels throughout the bleed procedure using new 
brake fluid.

CAUTION: Brake fluid will damage paint finished 
surfaces. If spilled, immediately remove fluid and 
clean area with water.

Bleeding

1. Top up reservoir. 
2. Raise the front of the vehicle.

WARNING: Do not work on or under a 
vehicle supported only by a jack. Always 
support the vehicle on safety stands.

3. Connect tube to bleed screw on clutch slave 

cylinder and submerge free end in a clear 
container containing brake fluid. 

4. Loosen bleed screw, then apply steady 

pressure to the clutch pedal, depressing it 
through its full stroke. Allow the pedal to return 
unassisted.

5. Repeat the procedure until a flow of clean, air-

free fluid is purged into the container.

6. Hold the pedal to the floor and tighten the  

clutch bleed screw to 9 Nm (7 lbf.ft).

7. Check  and  top up reservoir. 

CAUTION: Never re-use fluid that has been 
bled from the system.

8. Remove stands and lower the vehicle.

CLUTCH - V8

33-2-12 ADJUSTMENTS