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Discussion Starter · #1 · (Edited)
There are four main clutch faults; theses are:
1..Slip
2..Drag or Spin
3..Judder
4..Fierceness

SLIP:-

Symptons:
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.

POSSIBLE CAUSES:

Any defect that leads to insufficient:
A) pressure on clutch plate
B) friction

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.

Symptoms:
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.

POSSIBLE CAUSES:

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.


JUDDER:-
Symptom:
A severelow frequency vibration which normally occurs when the clutch is released and the vehicle is moved from the stationary position.

POSSIBLE CAUSES:

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.

FIERCENESS:-
Symptom:
A sudden move-off of the vehicle even though the pedal is gradually released.

POSSIBLE CAUSES:

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.
 
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