1700_2.pdf

Chapter 3. Power train

Clutch

The design of the clutch is shown on fig. 3-1. The clutch release fork 11 (fig. 3-1) can be of two types: with a leaf or wire spring.

Fig. 3-1. Clutch assembly:

1 - bleeder; 2 - central diaphragm spring; 3 - diaphragm spring rivet; 4 - pressure plate; 5 - clutch disc; 6 - flywheel; 7 - clutch bellhousing; 8 - bellhousing-to-flywheel bolt;

9 - gearbox input shaft; 10 - clutch release bearing assembly; 11 - clutch release fork; 12 - release fork ball socket; 13 - clutch release bearing; 14 - pressure plate thrust

flange; 15 - clutch release fork boot; 16 - clutch release fork spring; 17 - pressure plate fulcrum ring; 18 - clutch cover; 19 - clutch release fork pushrod; 20 - adjusting nut;

21 - locknut; 22 - protective cap; 23 - clutch release cylinder (slave cylinder); 24 - fork return spring; 25 - return spring bracket

Fault diagnosis

Diagnosis

Remedy

Incomplete clutch release (clutch spin)

1. Excessive gaps in clutch release drive

2. Buckling of clutch disc (camming action more than 0.5 mm)

3. Roughness on clutch disc friction linings

4. Jammed rivets or broken clutch disc friction linings

5. Jammed clutch disc hub on primary shaft splines

1. Adjust clutch release drive

2. Straighten or replace disc

3. Renew linings or clutch disc assembly

4. Renew linings, check disc runout

5. Clean splines, apply grease -15 or èîë-1, èîë-2. In case of badly

worn splines causing seizure, renew input shaft or clutch disc

6. Renew clutch cover/pressure plate assembly

7. Bleed system

8. Tighten connections, renew damaged components, bleed system

6. Broken thrust flange-to-clutch cover connecting plates

7. Air in clutch hydraulic drive system

8. Liquid leak from hydraulic drive system through connections or dam-

aged pipelines

9. Leaking master cylinder or clutch release cylinder

10. Plugged opening in reservoir cover, causing underpressure and vac-

uum leak in cylinder through sealings

11. Vacuum leak due to fouling or wear of front sealing ring in master

cylinder

12. Skew or buckling of pressure plate

9. Renew sealing rings, bleed system

10. Clean opening in tank cover, bleed system

11. Clean sealing ring, replace in case of wear

12. Renew clutch cover/pressure plate assembly

Incomplete clutch engagement (clutch slips)

1. No gaps in clutch release drive

2. Badly worn or burnt clutch disc friction linings

3. Excessive oil on clutch disc friction linings, surfaces of flywheel and

pressure plate

4. Plugged compensation port in master cylinder

5. Damaged or jammed clutch release drive

1. Adjust clutch release drive

2. Renew linings or clutch disc assembly

3. Clean oily surfaces with white-spirit, remedy the situation

4. Wash cylinder and clean port

5. Rectify malfunctions causing jamming

Clutch judder

1. Jammed clutch disc hub on primary shaft splines

1. Clean splines, apply grease -15 or èîë-1, èîë-2. In case of badly

worn splines causing seizure, renew input shaft or clutch disc

2. Clean oily surfaces with white-spirit, remedy the situation

2. Excessive oil on clutch disc friction linings, surfaces of flywheel and

pressure plate

3. Jammed clutch release drive mechanism

4. Badly worn clutch disc friction linings

5. Loose rivets on clutch disc friction linings

6. Damaged surface or buckling of pressure plate

3. Replace damaged parts, rectify malfunctions causing jamming

4. Renew linings, check for damages on disc surfaces

5. Renew damaged rivets and linings, if necessary

6. Renew clutch cover/pressure plate assembly

Excessive noise at clutch release

1. Worn, damaged or dry clutch release bearing

2. Worn front bearing on gearbox primary shaft

1. Renew bearing

2. Renew bearing

Excessive noise at clutch engagement

1. Broken or weak damper spring

2. Broken, weak or detached clutch release fork return spring

3. Broken pressure plate-to-clutch cover connecting plates

1. Renew clutch disc assembly

2. Renew spring or secure

3. Renew clutch cover/pressure plate assembly

Clutch release drive adjustment

The following adjustments are carried out in the clutch

release drive:

- the 0.1-0.5 mm gap between the pushrod and the piston of the

master cylinder (see fig. 3-2) is set. This gap, necessary for comp-

lete clutch release, is adjusted by the clutch pedal limiter bolt 5. The

clearance is determined by the pedal free travel equal to 0.4-2 mm;

- the free travel of the clutch release fork pushrod, equal to 4-

5 mm, is adjusted by bolt 5 (fig. 3-3) and fixed by locknut 6. The dis-

tance of the pushrod free travel is controlled by a special pattern.

After carrying out the above described adjustments the clutch

pedal free travel should make 25-35 mm.

Fig. 3-2. Clutch pedal and master cylinder:

1 - pedal cluster mounting bracket; 2 - clip; 3 - clutch pedal servo spring; 4 - clutch pedal return spring; 5 - clutch pedal limiter bolt; 6 - clutch pedal; 7 - pushrod;

8 - protective cap; 9 - circlip; 10 - pushrod piston; 11 - sealing ring; 12 - master cylinder piston; 13 - inlet port; 14 - sealing ring (ring valve); 15 - piston bypass orifice;

16 - cylinder cavity; 17 - piston return spring; 18 - gasket; 19 - plug; 20 - master cylinder body; 21 - bypass (compensation) port; 22 - gasket; 23 - union; 24 - washer

Bleeding the clutch hydraulic system

- depress the pedal and fully tighten the bleeder. Remove the

hose and refit the bleeder cap.

If, despite a continuos bleeding, there are still air bubbles in

the hose, check the tightness of connections, find out if there are

cracks on tubes or leaks in places of connections. Air inleak is

possible through damaged sealing rings of the master or slave

cylinders.

During bleeding:

Air in the clutch hydraulic system is indicated by incomplete

clutch release, and also by "sponginess" and "failure" of clutch

pedal.

To expel air from the hydraulic drive:

- clean the tank and the bleeder from dust and dirt;

- check the liquid level in the hydraulic system tank and top

up if necessary;

- put a hose on bleeder 9 (see fig. 3-3) of the slave cylinder

and place its lower end into a container with hydrodrive liquid (30-

50 gr);

- undo bleeder 9 by 1/2-3/4 turn, several times rapidly

depress and smoothly release the pedal until there will be no air

bubbles coming out from the hose;

- the liquid level in the reservoir should be higher than the

opening of the tube connecting the reservoir with the master

cylinder;

- the end of the bleeding hose should be always dipped in liquid;

- after bleeding, top-up liquid in the reservoir to the lower

edge of the filler neck.

Fig. 3-3. Slave cylinder and clutch release fork:

1 - release bearing; 2 - ball pivot; 3 - clutch release fork; 4 - pushrod; 5 - adjusting bolt; 6 - locknut; 7 - return spring; 8 - plug; 9 - bleeder; 10 - cylinder body; 11 - sealing

ring; 12 - protective cap; 13 - piston; 14 - sealing; 15 - sleeve; 16 - spring; 17 - spring disc; 18 -lock ring

Clutch assembly - removal and refitting

- inspect the splines on the clutch disc hub and the gearbox

input shaft, clean the splines and grease with a thin layer of

greasing -15 or -1, -2;

Removal. First remove the gearbox (see "Gearbox"). Undo the

bolts and remove the clutch cover in assembly with the pressure

plate. Do not lift this unit by holding the pressure plate thrust flange.

Refitting is a reversal of removal, providing the following:

- inspect the bearing on the crankshaft end face, if necessary

replace the bearing;

- refit the clutch disc with the hub protruding part facing the gear-

box and centralise the plate against the bearing using tool A.70081,

simulating the gearbox input shaft splined end (fig. 3-4).

Fig. 3-5. Clutch check:

1 - pressure plate thrust flange; 2 - central diaphragm spring; 3 - clutch disc;

4 - ring

Master and slave cylinders - removal and refitting

Fig. 3-4. Centering the clutch disc with tool A.70081:

1 - flywheel; 2 - clutch assembly; 3 - tool A.70081

First, drain working liquid. To do this, attach one end of the

hose to bleeder 9 (see fig. 3-3) on the slave cylinder, and the

other end place in a clean reservoir; unscrew bleeder 9 by 1/2-3/4

turn and depress the pedal several times until all liquid will be

removed from the hydrosystem, then disconnect the tubes

between the master and the slave cylinders, disconnect the

return spring 7, remove the pin from the pushrod end, and the

slave cylinder, having prior undone two fastening bolts.

To remove the master cylinder undo two nuts, with which it is

pinned to the pedal bracket, and disconnect the flexible hose

from the reservoir.

To refit the master and slave cylinders the above described

operations are executed in reverse order.

After filling with working liquid, bleed the system.

Clutch inspection

The inspection of the clutch is carried out on a bench, which

simulates the engine flywheel and has a metal intermediate ring

4 (fig. 3-5) with thickness of 8.2 mm simulating the clutch disc.

Having fixed the clutch cover, make four release strokes equal to

8-9 mm. The release stroke of 8 mm should correspond to the

travel of the pressure plate within 1.6-1.7 mm (permitted mini-

mum - 1.4 mm).

The distance from the rig base to the working surface of the

thrust flange friction washer should be 40-43 mm. During engine

operation due to wear of the clutch disc surfaces this size

increases. If it will reach 48 mm or the travel of the pressure plate

will be less than 1.4 mm, renew the clutch cover in assembly with

the pressure plate.

The clutch disc friction linings should be replaced at any signs

of cracks, reduction of distance between the rivet and the work-

ing surface up to 0.2 mm, and also at one-side scuffings. To

repair the clutch disc and replace the friction linings use tool

67.7822.9529 (fig. 3-6).

Flared rivets should have no breaks. The runout of the friction

lining working surface should not exceed 0.5 mm. If this value is

exceeded, straighten the disc (fig. 3-7) or replace with a new one.

Also replace the clutch disc assembly in case of cracks on the

clutch disc or the damper springs.

Fig. 3-6.Replacing the clutch disc friction linings:

1 - tool 67.7851.9500; 2 - clutch disc; 3 - fixture 67.7822.9517

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