However, common troubles experienced in automobile clutch along with their causes, are explained below briefly. The remedies have also been suggested. It is not within the scope of this article to deal with very exhaustively the trouble shooting of the automobile clutch.
It is sometimes experienced that the clutch slips while in engagement. In this condition it fails to transmit completely the engine torque. Moreover, because of slipping, a large amount of heat is generated due to which clutch facings wear out rapidly and even burn out. The flywheel face also wears out, there is rapid wear of pressure plate and the stiffness of the springs is also decreased. This may be caused by any or more of the following reasons:
- Incorrect linkage adjustment which causes insufficient ‘free pedal play’. Adjustment of the linkage will remedy this defect.
- Oil or grease on friction facings due to leakage from the engine crankcase or the gear box or to excessive lubrication of the clutch shaft and its support bearing. This causes glazing of the friction surfaces leading to slipping. The remedy in this case is simply to clean the components and replace the clutch facing.
- Weak or broken clutch springs. The springs may be overheated, which will be revealed by their blue colour. Overheating reduces the spring stiffness and makes them weak. In this case the only alternative is to replace the springs.
- Worn out facings, which should be replaced.
Clutch drag or spin
Sometimes when the clutch is to be disengaged, it is not disengaged completely and it causes difficulty in changing the gears. This defect is called clutch drag. Reasons for the presence of this defect may be:
- Excessive “free pedal play”. This may have been caused by the driver “riding the clutch pedal, i.e., when he is in the habit of keeping his foot on the clutch pedal while driving. When the clutch drags, the first thing to be done is to check the ‘free pedal play’. If found incorrect, it should be adjusted. If this play is already correct, then the trouble may be due to other reasons and to locate them the clutch has to be opened.
- Oil or grease on friction facings. The remedy is to clean the facings or if excessively damaged, to replace them.
- Pressure plate warped or damaged. This needs replacement.
- Clutch plate cracked or buckled. The only alternative to remedy this is the replacement of the complete plate.
- Clutch plate may be seized on clutch shaft splines. This may be remedied by cleaning up the splines on the shaft and lubricating them.
Sometimes as the clutch is engaged, a vibration or judder is produced instead of smooth gradual engagement and the vehicle suddenly jumps forward. The possible causes are:
- Loose or worn out clutch facings, which must be replaced.
- Loose rivets. The whole facing should be replaced.
- Distorted clutch plate may also be one of the reasons to cause clutch judder. The same has to be replaced.
- Misalignment of the pressure plate with the flywheel. This has to be corrected. This requires, however, special equipment.
- Flywheel may be loose on the crankshaft flange, which may be tightened to remove the defect.
- Bent splined clutch shaft. If the defect is not much, it may be possible to straighten the shaft, otherwise this has to be replaced.
- Oil, grease or dirt on the friction surfaces causing uneven engagement. The friction surfaces on the flywheel and the pressure plate should be cleaned and the clutch facing replaced.
Apart from the defects explained earlier in the engagement of clutches, some peculiar noises may be noticeable when the engine is idling. Clutch rattle is the prominent noise observed.
To locate the cause, press the clutch pedal to take up only the free movement. If the rattle disappears, it may be due to worn out or loose throw-out bearing or it may be that pedal return spring is disconnected and is loose. In the former case, the bearing has to be replaced, while in the latter case, the spring is simply to be replaced.
If, however, the rattle continues, it may be due to damaged clutch plate in which case it has to be replaced. The bent splined shaft may also be a source of rattle.
This is observed clearly when the engine is idling and the clutch is engaged. This may be due to worn out splines of the clutch plate hub or the clutch shaft. Such a situation would require replacement of the defective part i.e. either the clutch plate or the clutch shaft or both. The wearing out of the spigot bearing in the flywheel may also be a cause of knock in the clutch. The bearing will have to be replaced in this case.
Pulsation of the clutch pedal
This may be caused by the misalignment of the engine and the transmission. Due to misalignment, the clutch disc moves to and fro on the clutch shaft in each revolution and this movement is transmitted back to the pedal. This results in rapid wear of all clutch parts. To remedy this, the proper realignment has to be done. The pedal pulsations may also be caused by a wobbling flywheel, mostly due to its improper mounting on the engine crank shaft, which may be redone properly, if the flywheel is otherwise unbalanced, the same may be either balanced or replaced.