Clutch Troubleshooting - Samclutch - WE ARE SOUTH AFRICA'S #1 CLUTCH MANUFACTURER

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Clutch Fails To Disengage
Clutch Grabbing
Clutch Judder
Clutch Noise
Clutch Slipping

Causes

If the clutch does no longer disengage, the problem is not necessarily damage to the clutch. Frequent causes why the clutch doesn’t disengage correctly include faults in the release system (clutch release bearing, slave cylinder, clutch lever), a jammed pilot bearing, or non-compliance with important installation requirements

Check:

- Were all check points observed during installation? See : Installing a new clutch
- Worn components in the release system?
- Cables, hydraulics, pivot points.
- Correct setting?

Twin Plate coil spring clutches.

Possible Causes:
Incorrect Fitting
Slide not brought up to the stop on fitment.

Consequence:
Insufficient pressure plate lift.
Lop-sided pressure plate lift.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate.

Pressure plate lugs broken.

Possible Causes:
Lack of release bearing clearance.
Engine vibration damper defective.
Fuel-injection system incorrectly adjusted.

Consequence:
Insufficient pressure plate lift.
Lop-sided pressure plate lift.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate

Release-lever mount broken.

Possible Causes:
Lack of release bearing free play.
Engine vibration damper defective.
Fuel-injection system incorrectly adjusted.

Consequence:
Insufficient pressure plate lift.
Lop-sided pressure plate lift.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate

Release-lever pivot pin has drifted out.

Possible Causes:
Engine vibration damper defective.
Engine torsional vibrations have caused the circlip securing the pivot pin to pop off.
Fuel-injection system incorrectly adjusted.

Consequence:
Insufficient pressure plate lift.
Lop-sided pressure plate lift.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate

Pressure plate broken : Extreme overheating.

Possible Causes:
Clutch overheated by excessive slipping due to prolonged hill starting, or an overloaded vehicle.
Release system adjusted incorrectly, seized or damaged.
Too much or incorrect grease on the gearbox input shaft, leaking engine oil or gearbox oil, causing prolonged slipping.
Faulty slave cylinder.
Insufficient downforce of the clutch pressure plate.
Excessive flywheel thickness.

Consequence:
Insufficient pressure plate lift. The clutch doesn’t fully disengage.

Solution:
Eliminate the cause of the fault and replace the clutch kit.

Centering ridge on flywheel broken off.

Possible Causes:
Incorrect fitting.
Pressure Plate not aligned to the flywheel ridge.
Bolts not torqued down evenly.

Consequence:
Insufficient pressure plate lift. The clutch doesn’t fully disengage.

Solution:
Eliminate the cause of the fault.

Clutch cover housing / pressure plate distorted.

Possible Causes:
Incorrect installation practice: bolts were not tightened sequentially and evenly.
Not aligned to flywheel correctly.
Transport / handling damage.

Consequence:
Housing deformed such that pressure plate has insufficient lift.

Solution:
Replace the clutch pressure plate.

Tangential leaf spring on pressure plate broken.

Possible Causes:
Incorrect installation practice: bolts were not tightened sequentially and evenly.
Play in the drive train e.g. worn flexible disc, worn gearbox bearing.
Incorrect driving practice: harsh gear changing.
Incorrect gear selection.
Improper towing maneuvers.
Tow-starting in 1st or 2nd gear.
Dropping the clutch prior to fitting.
Transport damage.
Incorrect clutch fitted.

Consequence:
Insufficient pressure plate lift. The clutch doesn’t fully disengage.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate.

Tangential leaf spring on pressure plate bent / distorted.

Possible Causes:
Incorrect installation practice: bolts were not tightened sequentially and evenly.
Play in the drive train e.g. worn flexible disc, worn gearbox bearing.
Incorrect driving practice: harsh gear changing.
Incorrect gear selection.
Improper towing maneuvers.
Tow-starting in 1st or 2nd gear.
Dropping the clutch prior to fitting.
Transport damage.
Incorrect clutch fitted.

Consequence:
Insufficient pressure plate lift. The clutch doesn’t fully disengage.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate.

Broken pressure plate levers.

Possible Causes:
Damaged throw out release bearing.
Release bearing running off-center.
Incorrectly adjusted release bearing.
Release fork pivot bushes worn.

Consequence:
Continuous off-center clutch releaser contact with the release levers exceeding the self-centering capacity. These relative motions increase wear on all mechanical operating elements. Clutch does not disengage properly.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Worn pressure plate levers.

Possible Causes:
Incorrectly adjusted release bearing.
Faulty release mechanism.

Consequence:
Clutch release bearing runs continuously on pressure plate levers causing excessive wear. Clutch does not disengage properly.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Worn diaphragm spring fingers.

Possible Causes:
Incorrectly adjusted clutch release system.
Incorrect driving practice: resting foot on the clutch pedal or prolonged operation of the clutch e.g. at red lights.
Incorrectly adjusted clutch release system.
Clutch release system stiff / seized.
Clutch release bearing obstructed / faulty.
Clutch releaser preload too low.
Guide tube worn or bent.
Engine and transmission not precisely centered.

Consequence:
Continuous off-center clutch releaser contact with the diaphragm spring tips exceeding the self-centering capacity. These relative motions increase wear on all mechanical operating elements. Clutch does not disengage properly. This also applies to the release levers.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Diaphragm spring contacts torsional damper during release.

Possible Causes:
Incorrect clutch disc installed.
Clutch disc installed wrong way round.
Permissible release travel exceeded.
Flywheel depth or step incorrect
Clutch disc too thick.

Consequence:
Diaphragm spring drives clutch disc.

Solution:
Make sure the clutch disc is installed the correct way round.
Make sure correct clutch disc is installed.
Check for wear on release bearing quill shaft/gear box nose cone slide.
Check clutch disc thickness.

Burst facing / facing torn off.

Possible Causes:
Selecting the wrong (too low) gear when downshifting.
Drive plate speed exceeded the burst speed of the facing material. The clutch has been disengaged while travelling at a speed above the maximum speed for the gear selected.

Consequence:
Facing debris gets stuck in the flywheel or in the clutch pressure plate housing.

Solution:
Select the correct gear when downshifting.
Replace clutch disc.

Facing burnt.

Possible Causes:
Oil-contaminated facings.
Faulty oil seals.
Release system seized or faulty.
If the flywheel has been refaced, the pot depth was not considered or the bolting surface not machined by the same amount.

Consequence:
Facing debris gets stuck in the flywheel or in the clutch pressure plate housing.

Solution:
Replace oil seal.
Check release system.
Machine flywheel to the correct specifications.

Clutch facing glazed.

Possible Causes:
Overheating.
Oil on linings.
Leaking shaft seals.
Release system seized or faulty.
If the flywheel has been refaced, the pot depth was not considered or the bolting surface not machined by the same amount.

Consequence:
Clutch fails to disengage due to lower friction values of the facings.

Solution:
Replace oil seal.
Check release system.
Machine flywheel to the correct specifications.

Damaged spline profile.

Possible Causes:
Incorrect fitting (Gearbox input shaft and hub splines not correctly aligned prior to fitting or driven plate not centered).
Transmission shaft and clutch hub forced together during installation.
Incorrect clutch disc.

Consequence:
The clutch disengages badly because the clutch disc jams instead of sliding on the input shaft.

Solution:
Center the clutch disc - using the right tools - during installation.
Do not move the transmission too far up and down or laterally during mounting.

Hub spline worn / burr formation.

Possible Causes:
Clutch bell housing and crankcase flange not centered, wobble motion due to angular or parallel offset.
Spigot (Pilot) bearing missing.
Transmission input shaft has excessive play or is not guided.

Consequence:
Hub jammed or tilted on transmission input shaft.
Hub spline heavily worn.

Solution:
Replace transmission input shaft.
Make sure spigot (Pilot) bearing is fitted or correctly fitted.
Replace clutch disc.

Splines damaged on one side and worn to a taper, torsion damper damaged.

Possible Causes:
Spigot (pilot) bearing defective.
Misalignment between engine and gearbox.

Consequence:
The clutch disengages badly because the clutch disk jams instead of sliding on the input shaft.

Solution:
Center the clutch disc - using the right tools - during installation.
Do not move the transmission too far up and down or laterally during mounting.
Replace spigot(pilot) bearing.
Replace clutch disc.

Rust on hub / stiff clutch disc on the gearbox input shaft.

Possible Causes:
Corrosion in the hub profile.
Dirty gearbox shaft.
Hub profile damaged due to rough handling / installation.
Input shaft not or not correctly greased during installation.

Consequence:
Clutch disc fails to slide freely on transmission shaft, jams. Clutch facing still contacts friction surface on flywheel.

Solution:
Check the hub profile, then clean and lubricate the profile with the correct grease.
Replace clutch disc.

Driven plate segments sheared.

Possible Causes:
Worn or missing spigot (pilot) bearing.
Misalignment condition between engine and gearbox.
Defective or missing dowel pins between engine and gearbox.
Defective dowel pins on the flywheel.
Gearbox hung while fitting the clutch.

Solution:
Eliminate the cause of the fault and replace the defective clutch parts.

Torsional damper destroyed by overloading.

Possible Causes:
Low-revving driving style, driving at low speeds in high gear and full throttle.
Extreme irregular engine operation.
Worn joints in the driveline.

Consequence:
Fragments are thrown outwards and get stuck in the facings.

Solution:
Select the correct gears according to recv ratio/speeds.
Check all mechanical parts.
Check Joints in the drivline.
Replace clutch disc.

Cushion springs or driving plate fractured.

Possible Causes:
Engine or transmission dropped with the input shaft still in the clutch disc hub, fracture due to lever effect.
Parallel or angular offset.

Consequence:
Clutch disc lateral run-out too large.

Solution:
Do not move the transmission too far up and down or laterally during mounting.
Only lower transmission during disassembly and assembly when the input shaft is not inside the clutch disc.
Replace clutch disc.

Damaged idle damper.

Possible Causes:
Incorrect installation.
Incorrect clutch disc.

Consequence:
Serious damage leading to component failure.

Solution:
Multi-step torsional damping mechanisms have a complex, almost delicate structure. Handle with the utmost care during installation.
Fit the correct clutch disc for the correct application.

Excessive driven plate run-out.

Possible Causes:
Clutch disc not checked before fitting.
Clutch disc bent during transport or installation.
Lateral run-out of approx. 0.5 mm significantly exceeded.

Consequence:
The specified lift on the pressure plate is no longer sufficient to ensure full disengagement.

Solution:
Always check clutch discs for lateral runout before installation.

Backing plate distorted.

Possible Causes:
Incorrect installation.
Gearbox input shaft and hub splines were not correctly aligned.

Consequence:
The clutch does no longer disengage because the prescribed lift on the pressure plate is no longer sufficient.

Solution:
Center the clutch disc - using the right tools - during installation.
Do not move the transmission too far up and down or laterally during mounting.
Replace clutch disc.

Clutch disc “dished”.

Possible Causes:
Input shaft jammed against clutch disc hub during installation.
Deformation due to severe overheating (blue discoloration of metal components).

Consequence:
The clutch does no longer disengage because the prescribed lift on the pressure plate is no longer sufficient.

Solution:
Center the clutch disc - using the right tools - during installation.
Do not move the transmission too far up and down or laterally during mounting.
Replace clutch disc.

Damaged inner bore on release bearing.

Possible Causes:
Damaged gearbox snout.
Incorrect grade of grease or no grease used.

Consequence:
The clutch disengages badly because the release bearing jams instead of sliding freely on the input shaft.

Solution:
Replace release bearing.
Use the correct grade of grease.

Gearbox snout worn.

Possible Causes:
Damaged release bearing.
Incorrect grade of grease or no grease used.

Consequence:
The clutch disengages badly because the release bearing jams instead of sliding freely on the input shaft.

Solution:
Replace release bearing.
Use the correct grade of grease.

Damaged release bearing lugs.

Possible Causes:
Damaged release system.

Solution:
Eliminate the cause of the fault and replace the release bearing.

Bearing and casing damaged.

Possible Causes:
Overheating of the release bearing due to incorrect clearance, causing loss of grease and resulting in the bearing breaking up.

Solution:
Eliminate the cause of the fault and replace the release bearing.

Bearing carrier damaged.

Possible Causes:
Worn or damaged release arm bushes.
Release bearing seized on gearbox snout.
Damaged gearbox snout.

Solution:
Eliminate the cause of the fault and replace the release bearing.

Release bearing worn and damaged.

Possible Causes:
Incorrect adjustment of release arm.
Insufficient preload on bearing.

Solution:
Eliminate the cause of the fault and replace the release bearing.

Release bearing surface mating.

Possible Causes:
Worn release fork.
Worn guide tube.
Worn release shaft bearings.

Solution:
Check release system.
Replace release fork.
Eliminate the cause of the fault and replace the release bearing.

Retractor plate clamping ring worn.

Possible Causes:
Defective release system.

Consequence:
Insufficient preload.

Solution:
Check release system.
Replace retractor plate.
Eliminate the cause of the fault and replace the retractor plate.

Release bearing clamping ring worn.

Possible Causes:
Defective release system.

Consequence:
Insufficient preload.

Solution:
Check release system.
Eliminate the cause of the fault and replace the retractor plate.

Clutch grabbing - what is it?

When alternating torques occur in the slip phase (e.g., due to friction value fluctuations) and causes vibration of the driveline, this is called clutch grab. Instead of slipping evenly, the clutch grips suddenly, then loses contact. The driver experiences these oscillations as vibrations, rolling or bucking. A grabbing or juddering clutch produces a severe vibration motion and can have various causes.

Why does a clutch grab?

In order to know how to stop the clutch grabbing, it is necessary to find out what causes the juddering problem. Apart from the clutch itself, poor engine setting or worn engine or transmission mounts can prevent smooth clutch engagement. Other possible causes for grabbing clutches are installation of the wrong clutch disk or incorrect installation.

Tangential leaf spring on pressure plate bent / distorted.

Possible Causes:
Incorrect installation practice: bolts were not tightened sequentially and evenly.
Play in the drive train e.g. worn flexible disc, worn gearbox bearing.
Incorrect driving practice: harsh gear changing.
Incorrect gear selection.
Improper towing maneuvers.
Tow-starting in 1st or 2nd gear.
Dropping the clutch prior to fitting.
Transport damage.
Incorrect clutch fitted.

Consequence:
Insufficient pressure plate lift.
Lop-sided pressure plate lift.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate.

Clutch facing slightly contaminated with oil or grease.

Possible Causes:
Engine or gearbox oil seals defective.
Excessive grease on the transmission input shaft or pilot bearing.
Leakage in hydraulic actuation system.
Contamination of the friction surfaces due to incorrect handling.

Consequence:
Clutch grabs due to lower friction values of the facings.
Even minor traces of oil or grease have a significant adverse effect on friction values, and thus start-up performance when the clutch is engaged.

Solution:
Eliminate the cause of the leak.
Replace the clutch disc and clean the remaining parts.

Damaged spline profile.

Possible Causes:
Incorrect fitting (Gearbox input shaft and hub splines not correctly aligned prior to fitting or driven plate not centered).
Transmission shaft and clutch hub forced together during installation.
Incorrect clutch disc.

Consequence:
The clutch grabs because the clutch disc jams instead of sliding on the input shaft.

Solution:
Center the clutch disc - using the right tools - during installation.
Do not move the transmission too far up and down or laterally during mounting.

Worn engine / transmission mounts.

Possible Causes:
Worn parts.

Consequence:
Leads to pseudo grab (bonanza effect) in driveline during setting off and gear changing or load changing.

Solution:
Always check these components for signs of wear (e.g., cracks in the rubber-metal joints or damaged joints).
Eliminate the cause of the fault and replace the worn parts.

Causes

A clutch that vibrates uncontrollably, sometimes known as “clutch judder”, when the clutch is initially engaged can be a clear sign that your clutch is failing. In a lot of cases, it could simply be that fluid has leaked into the gears, usually oil, causing them to lose grip.

Check:

- Inspect all the components for damage.
- Have the flywheel check for warp and re-machine or replace if needed.
- If oil or grease is present, find the source and fix the leak.
- If a clutch disc has been covered in oil, it should be replaced?

Section of the flywheel’s rim has broken off.

Possible Causes:
Incorrect Fitting
→ Pressure Plate not aligned to flywheel step.
→ Pressure Plate not torqued down correctly.

Consequence:
Pressure Plate not torqued down correctly.

Solution:
Eliminate the cause of the fault.

Tangential leaf spring on pressure plate bet / distorted.

Possible Causes:
Incorrect installation practice: bolts were not tightened sequentially and evenly.
Play in the drive train e.g. worn flexible disc, worn gearbox bearing.
Incorrect driving practice: harsh gear changing.
Incorrect gear selection.
Improper towing maneuvers.
Tow-starting in 1st or 2nd gear.
Dropping the clutch prior to fitting.
Transport damage.
Incorrect clutch fitted.

Consequence:
Insufficient pressure plate lift. The clutch doesn’t fully disengage.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate.

Bent diaphragm fingers.

Possible Causes:
Incorrect installation.
Diaphragm fingers bent during installation.

Consequence:
Uneven pressure plate lift.
Release bearing does not run evenly on diaphragm fingers.

Solution:
Eliminate the cause of the fault and replace the clutch pressure plate.

Scored flywheel.

Possible Causes:
Mating surface of the flywheel badly worn.
Incorrect flywheel, wrong or excessively re-machined.

Solution:
Replace or re-machine the flywheel to correct specifications.

Clutch facing contaminated with oil.

Possible Causes:
Engine or gearbox oil seals defective.
Leakage in hydraulic actuation system.

Consequence:
Clutch shudders due to lower friction values of the facings.

Solution:
Eliminate the cause of the leak.
Replace the clutch disc and clean the remaining parts.

Clutch facing contaminated with grease.

Possible Causes:
Excessive grease on the transmission input shaft or pilot bearing.
Surplus grease was not removed.
Grease has been thrown out onto the facing material.
Contamination of the friction surfaces due to incorrect handling.

Consequence:
Clutch shudders due to lower friction values of the facings.

Solution:
Eliminate the cause of the leak.
Replace the clutch disc and clean the remaining parts.

Facing does not contact entire surface / facing scored on flywheel side.

Possible Causes:
Friction surface severely scored (flywheel was not re-machined).
Friction surface of flywheel or pressure plate warped due to overheating.

Consequence:
Lower friction values.
Altered friction radius (effective force lever).

Solution:
Replace or re-machine the flywheel to correct specifications.

Damaged spline profile.

Possible Causes:
Incorrect fitting (Gearbox input shaft and hub splines not correctly aligned prior to fitting or driven plate not centered).
Transmission shaft and clutch hub forced together during installation.
Incorrect clutch disc.

Consequence:
The clutch judders badly because the clutch disc jams instead of sliding on the input shaft.

Solution:
Center the clutch disc - using the right tools - during installation.
Do not move the transmission too far up and down or laterally during mounting.

Stiff clutch disc on the gearbox input shaft.

Possible Causes:
Corrosion in the hub profile.
Dirty gearbox shaft.
Hub profile damaged due to rough handling / installation.
Input shaft not or not correctly greased during installation.

Consequence:
Clutch disc fails to slide freely on transmission shaft, jams. Clutch facing still contacts friction surface on flywheel.

Solution:
Check the hub profile, then clean and lubricate the profile with the correct grease.
Replace the clutch disc.

Damaged inner bore on release bearing.

Possible Causes:
Damaged gearbox snout.
Incorrect grade of grease or no grease used.

Consequence:
The clutch judders because the release bearings jams instead of sliding freely on the input shaft.

Solution:
Replace release bearing.
Use the correct grade of grease.

Release bearing worn.

Possible Causes:
Release clutch fork worn.
Release system damaged.

Consequence:
The clutch judders because the release bearing engages un-evenly.

Solution:
Replace release bearing.
Replace release clutch fork.
Check release system.

Gearbox snout worn.

Possible Causes:
Damaged release bearing.
Incorrect grade of grease or no grease used.

Consequence:
The clutch judders because the release bearings jams instead of sliding freely on the input shaft.

Solution:
Replace release bearing.
Use the correct grade of grease.

Release bearing incorrectly lubricated.

Possible Causes:
Use of a solids-based lubricant.

Solution:
Use the correct grade of grease.

Retractor plate clamping ring worn.

Possible Causes:
Defective release system.

Consequence:
Insufficient preload.

Solution:
Check release system.
Replace retractor plate.
Eliminate the cause of the fault and replace the retractor plate.

Release bearing clamping ring worn.

Possible Causes:
Defective release system.

Consequence:
Insufficient preload.

Solution:
Check release system.
Eliminate the cause of the fault and replace the retractor plate.

Causes

What can you do when the clutch is making noises or the clutch whistles? There are many different kinds of clutch noises. Whistling or whining from the clutch can be caused e.g. by the release bearing running off-center, an off-center input shaft, or a defective pilot bearing.

On the other hand, rattling noises may be due to load alterations if clutch disks are furnished with preliminary dampers. These noises do not impair the function or service life of the clutch.

Additional possible causes of the clutch making noises include installation of the wrong parts, or installation of the clutch disk in the wrong position. Clutch noises can also indicate a defect. The following questions are important for workshops: do the clutch noises occur during setting off or during disengaging? Do they occur when the clutch pedal is pressed, while pedaling, or in neutral position? Do noises occur when the clutch is engaged, while declutching, or at idle speed?

Check:

- Correct part installed?
- Correct installation position?
- Pilot bearing installed and not worn or defective?
- Condition (wear) of actuating system checked?

Diaphragm spring fingers worn.

Possible Causes:
Incorrectly adjusted clutch release system.
Incorrect driving practice: resting foot on the clutch pedal or prolonged operation of the clutch e.g. at red lights.
Clutch release system stiff / seized.
Clutch release bearing obstructed / faulty.
Clutch releaser preload too low.
Guide tube worn or bent.
Engine and transmission not precisely centered.

Consequence:
Continuous off-center clutch releaser contact with the diaphragm spring tips exceeding the self-centering capacity. These relative motions increase wear on all mechanical operating elements. Clutch does not disengage properly. This also applies to the release levers.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Clutch disc centre retaining rivet worn.

Possible Causes:
Incorrect clutch disc.
Incorrect driving practice: driving in a too high gear at low revs.
Extreme irregular engine operation.
Worn joints in the driveline.
Judder vibrations.

Consequence:
Overloading of components.

Solution:
Eliminate the cause of the fault and replace the clutch disc.

Torsion damper retainer plate broken.

Possible Causes:
Incorrect driving practice.
Driving too long at excessively low engine speeds has caused the damper's efficiency limits to be exceeded.
Clutch bell housing and crankshaft housing flange not centered.
Wobbling motion due to angular or parallel offset.
Pilot bearing missing, transmission input shaft not guided.
Excessive angular movement during transmission installation.
Wrong clutch disc installed.

Consequence:
Loose components brush adjacent parts.

Solution:
Eliminate the cause of the fault and replace the clutch disc.

Torsion spring broken.

Possible Causes:
Incorrect clutch disc fitted.
Engine tuning.
Incorrect driving practice: driving in a too high gear at low revs.
Oil or grease on the clutch facing.
Defective release system.
Judder vibrations.

Solution:
Eliminate the cause of the fault and replace the clutch disc.

Hub profile splines worn / damaged.

Possible Causes:
Incorrect fitting (Gearbox input shaft and hub splines not correctly aligned prior to fitting or driven plate not centered).
Transmission shaft and clutch hub forced together during installation.
Pilot bearing damaged / Dowel pins damaged.

Solution:
Check the pilot or gearbox input shaft bearing and replace if necessary.
Check the dowel pins between engine and gearbox, and the flywheel dowel pins and replace if necessary.

Hub spline no longer present.

Possible Causes:
Clutch bell housing and crankshaft housing flange not centered.
Wobbling motion due to angular or parallel offset.
Pilot bearing missing, transmission input shaft not guided.

Consequence:
Causes drag problems and noise in early stages.

Solution:
Eliminate the cause of the fault and replace the clutch disc.

Release fork bearing surface worn.

Possible Causes:
Defective release system (cable or hydraulics).
Worn release-shaft bearings.
Worn guide tube.

Solution:
Check release system.
Replace release fork.
Eliminate the cause of the fault and replace the release bearing.

Clutch release fork worn.

Possible Causes:
Defective release system (cable or hydraulics).
Worn release-shaft bearings.
Worn guide tube.

Solution:
Check release system.
Replace release fork.
Eliminate the cause of the fault and replace the release bearing.

Wear induced grooves on inner ring of clutch release bearing.

Possible Causes:
Off-center clutch releaser contact due to parallel offset.
Worn guide tube.
Insufficient clutch releaser preload.

Consequence:
Relative movements cause various types of noise.
Relative movements cause excessive temperature.

Solution:
Check release system.
Replace the clutch release bearing.

Retractor plate clamping ring worn.

Possible Causes:
Defective release system.

Consequence:
Insufficient preload.

Solution:
Check release system.
Replace retractor plate.
Eliminate the cause of the fault and replace the retractor plate.

Release bearing clamping ring worn.

Possible Causes:
Defective release system.

Consequence:
Insufficient preload.

Solution:
Check release system.
Eliminate the cause of the fault and replace the retractor plate.

Causes

The problem of slipping clutches is very wide-ranging. For example, the clutch of a vehicle may slip only at high speeds. Other drivers complain that their clutch slips when the engine is cold, during starting, when setting off, or in first speed position. Another notices the clutch slipping through much of the period of acceleration, and yet another says his clutch slips after chip tuning. Clutch slipping symptoms and causes are just as varied as the symptoms. Even a brand new clutch can be slipping for a variety of reasons. Besides the clutch pressure plate and the clutch disk, clutch slipping causes can often be found in the release system. Additional causes include an incorrectly reworked flywheel or installation of the wrong clutch.

Check in case of clutch slipping:

- Release system wear, freedom of movement, adjustment?
- Correct parts for the vehicle?
- Flywheel correctly reworked?
- Contamination of the friction surfaces with lubricant?
- Deformation and warping of the friction surfaces on the flywheel and pressure plate?

Severe scoring and glazing on the pressure plate.

Possible Causes:
Oil on the facings (reduced coefficient of friction).
Faulty oil seals.
Insufficient release bearing clearance.
Damaged release system (cable or hydraulic).
Incorrect driving.
Allowing the clutch to slip for too long.
Flywheel too thick (re-machining not done correctly).

Consequence:
The clutch slips because the downforce is too low. In all cases, the constant clutch slip will generate more heat than can be absorbed. This results in overheating.

Solution:
Eliminate the cause of the fault and replace the clutch kit.

Overheating of pressure plate.

Possible Causes:
Oil on the facings (reduced coefficient of friction).
Faulty oil seals.
Insufficient release bearing clearance.
Damaged release system (cable or hydraulic).
Incorrect driving.
Allowing the clutch to slip for too long.
Flywheel too thick (re-machining not done correctly).

Consequence:
The clutch slips because the downforce is too low. In all cases, the constant clutch slip will generate more heat than can be absorbed. This results in overheating.

Solution:
Eliminate the cause of the fault and replace the clutch kit.

Deep grooves and traces of overheating on the pressure plate.

Possible Causes:
Facings badly worn.
Incorrect release bearing clearance.
Faulty release system.
Clutch operating in a partially disengaged condition.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Diaphragm spring fractured.

Possible Causes:
Excessive pressure / release travel greatly exceeded.

Consequence:
Diaphragm spring downforce no longer conforms to application design values.

Solution:
Replace the clutch pressure plate.

Damaged diaphragm spring fingers.

Possible Causes:
Incorrectly adjusted clutch release system.
Incorrect driving practice: resting foot on the clutch pedal or prolonged operation of the clutch e.g. at red lights.
Clutch release system stiff / seized.
Clutch release bearing obstructed / faulty.
Clutch releaser preload too low.
Guide tube worn or bent.
Engine and transmission not precisely centered.

Consequence:
Continuous off-center clutch releaser contact with the diaphragm spring tips exceeding the self-centering capacity. These relative motions increase wear on all mechanical operating elements. Clutch does not disengage properly. This also applies to the release levers.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Worn pressure plate levers.

Possible Causes:
Incorrectly adjusted release bearing.
Faulty release mechanism.

Consequence:
Clutch release bearing runs continuously on pressure plate levers causing excessive wear. Clutch does not disengage properly.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Replace the clutch pressure plate.

Flywheel depth too big / heavy scoring marks.

Possible Causes:
Mating surface of the flywheel badly worn.
Incorrect flywheel, wrong or excessively re-machined.

Solution:
Replace or re-machine the flywheel to correct specifications.

Facing material worn down to rivet's.

Possible Causes:
Facing worn.
Normal wear for the specific conditions of use.
Vehicle being driven despite slipping clutch.
Frequent start-up operation / incorrect driving style.
Allowing the clutch to slip for too long.
Incorrect clutch assembly.
Clutch actuation mechanism stiff.
Actuation system not correctly set or reset.
Faulty release mechanism.

Consequence:
Full downforce not available for clutch pressure plate.

Solution:
Check the clutch release bearing mechanism and adjust / replace if necessary.
Eliminate the cause of the fault and replace the clutch disc.

Clutch facing contaminated with oil.

Possible Causes:
Engine or gearbox oil seals defective.
Leakage in hydraulic actuation system.

Consequence:
Clutch slipping due to lower friction values of the facings.

Solution:
Eliminate the cause of the leak.
Replace the clutch disc and clean the remaining parts.

Clutch facing contaminated by grease.

Possible Causes:
Excessive grease on the transmission input shaft or pilot bearing.
Surplus grease was not removed.
Grease has been thrown out onto the facing material.
Contamination of the friction surfaces due to incorrect handling.

Consequence:
Clutch slipping due to lower friction values of the facings.

Solution:
Eliminate the cause of the leak.
Replace the clutch disc and clean the remaining parts.

Clutch facing burnt or disintegrated.

Possible Causes:
Clutch permitted to slip constantly.
Vehicle started up in too high a gear.
Insufficient downforce.
Problems in the release system - no clutch play and consequent stiffness.
Contamination with oil or grease.
Excessive flywheel thickness.

Consequence:
Bonding agent on facing severely deteriorated due to overheating.

Solution:
Eliminate the cause of the fault and replace the clutch disc.

Clutch facing carbonized.

Possible Causes:
Facing oil contaminated.
Defective oil seal.
Clutch allowed to slip for too long (overheating).

Consequence:
Bonding agent on facing severely deteriorated due to overheating.

Solution:
Eliminate the cause of the fault and replace the clutch disc.

Facing does not contact entire surface / facing scored on flywheel side.

Possible Causes:
Friction surface severely scored (flywheel was not re-machined).
Friction surface of flywheel or pressure plate warped due to overheating.

Consequence:
Lower friction values.
Altered friction radius (effective force lever).

Solution:
Replace or re-machine the flywheel to correct specifications.

Damaged idle damper.

Possible Causes:
Incorrect installation.
Incorrect clutch disc.

Consequence:
Serious damage leading to component failure.

Solution:
Multi-step torsional damping mechanisms have a complex, almost delicate structure. Handle with the utmost care during installation.
Fit the correct clutch disc for the correct application.

Damaged inner bore on release bearing.

Possible Causes:
Damaged gearbox snout.
Incorrect grade of grease or no grease used.

Consequence:
The clutch slips because the release bearings jams instead of sliding freely on the input shaft.

Solution:
Replace release bearing.
Use the correct grade of grease.

Gearbox snout worn.

Possible Causes:
Damaged release bearing.
Incorrect grade of grease or no grease used.

Consequence:
The clutch slips because the release bearings jams instead of sliding freely on the input shaft.

Solution:
Replace release bearing.
Use the correct grade of grease.

Samclutch Chat

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