There are four main clutch faults; theses are:
2..Drag or Spin
1) Engine accelerates without giving a corresponding increase in vehicle speed.
2) Smell of burning asbestos ( or Kevlar )
3) In very bad cases, vehicle will not drive up steep hills.
Any defect that leads to insufficient:
A) pressure on clutch plate
such decects include:
1 No free pedal movement.
2 Partial seizure of linkage ( including slave cylinder ) or fouling of the pedalso as to prevent the full return of the linkage.
3 Worn clutch facings
4 Oil-contaminated facings. (N.B. Source of oil leakage must be identified. )
5 defective pressure plate: broken springs(s),partially seized mechanism.
SPIN or DRAG:-
( In the past SPIN was a design fault associated with the weight of the driven plate and DRAG was due to a deceft that could develop during the clutch life. Since the symptoms are similar, both faults are often grouped together.
1) Difficulty in engaging first gear from neutral without making a noise
2) Jolt when changing gear with the vehicle in motion.
3) In very bad cases, vehicle will continue to move even when the pedal is fully depressed.
Any defect that prevents the clean seperation of the driven plate from both driving surfaces. Such defects include:
1 Excessive free pedal movement caused by the need for adjustment or lack of fluid in the hydraulic system.
2 Fouling or wear of the linkage such that the pedal cannot be fully depressed
3 Oil-contaminated facings causing one face to stick to a driving face.
4 Defective driven plate, buckled plate or seizure on splines. (Sometimes a modification is recommended which involves the drilling of a hole in each rivet to avoid a "Vacuum pocket".)
5 Misalignment of friction faces.
6 Partially seized spigot bearing.
A severelow frequency vibration which normally occurs when the clutch is released and the vehicle is moved from the stationary position.
Any defect that prevents the smooth engagement of the clutch. Such defects include:
1 Jerky pedal operation: sticking cable or slip/grip movement of the pivot.
2 Engine movement during the take-up of the drive. Often this is caused by a defective tie rod: this is fitted to resist engine or transmission movement. Wear in the drive line or suspension points can also cause this fault.
3 Oil-contaminated facings such that the slip/grip take-up action is amplified.
4 Defective pressure plate. Often this is due to the high friction in reigions where the plate should move smoothly through the cover.
5 Misalignment of the friction faces.
6 Defective driven plate: broken springs in the hub or a partially sheared plate.
A sudden move-off of the vehicle even though the pedal is gradually released.
Any defect that allows the clutch take-up to be faster than the movement of the pedal. Such defects include:
1 Partial seizure of the pedal linkage or contamination of fluid in the hydraulic operating system. These defects produce an erratic movement of the pressure plate.
2 Oil-contaminated driven plate.
3 Misalignment of friction faces.