Clutch Failures

 

Heat Damaged Pressure Plate

Pressure Plate Heat Damaged

Excessive heat is the predominant cause of clutch failure. When the heat between the flywheel, discs, intermediate plate (floater plate) and pressure plate increases above operating specifications, the friction material may be worn away and the metal components of the clutch can distort. This may result in catastrophic failure of the clutch which could be detrimental to life, limb and property.

With excessive heat being the leading cause of clutch failure, improper vehicle operation is the main cause of excessive heat. Actions that cause clutch slippage generate heat faster than can be dissipated. Below is a list of common operational errors than can initiate clutch failure.

  • Riding the clutch pedal while in motion. This duplicates the effect of a slipping clutch, keeping continuous pressure on the release bearing, often causing it to fail
  • Attempting to hold a vehicle stationary on an incline with a slipping clutch
  • Exceeding load specifications of a vehicle
  • Initial movement in the wrong gear
  • Insufficient acceleration prior to up shifting. This and skip shifting (below) can create a situation where the vehicle speed and engine speed differ to a degree that causes the clutch to overheat while attempting to equalize the differing speeds
  • Skipping a gear while upshifting
  • Riding the clutch pedal while in motion. This duplicates the effect of a slipping clutch, keeping continuous pressure on the release bearing, often causing it to fail

14" Pot Style Clutch - Grooved Drive Pin Slots

  • Incorrectly Angled drive pins
  • Reuse of old drive pins
  • Failure to replace set screws

14" Pot Style Clutch - Worn or Fractured Drive Pins/Drive Slots

  • Improper or non-installation of anti-rattle springs
  • Improper application
  • Improper maintenance (filing the drive slots in order to accommodate angled drive pins)

14" Pot Style Clutch - Insufficient Clutch Release

  • Incorrectly Angled drive pins
  • Damaged drive pins
  • Improper or non-installation of anti-rattle springs
  • Damaged drive slots

Over Adjusted Self-Adjusting Clutch

  • Incorrect distance between the clutch brake and the release bearing

Damaged Self Adjusting Cam Tab

  • Improper maintenance

Excessive Bushing Wear/Failure

  • Insufficient lubrication
  • Improper lubrication type
  • Bushing contamination
  • Damage to the transmission input shaft

Non Adjusting Self-Adjusting Clutch

  • Contaminates within the clutch housing

Worn Release Bearing Wear Pad

  • Operating the vehicle without free play

Excessive Free Play

  • Free play may increase during the breaking in period
  • Clutch brake not installed
  • Over adjusted self-adjusting clutch
  • Improperly set linkage system

Insufficient Clutch Release

  • Oil contaminated disc
  • Incorrectly facing discs
  • Wrong disc installed
  • Warped disc
  • Clutch cover contamination
  • Missing clutch cover mounting bolts
  • Improperly tightened clutch cover mounting bolts
  • Release yoke bridge to cover contact upon full clutch release
  • Flywheel interfering with the disc
  • Improper clutch cover to flywheel fit (Cover pinch)
  • Partial pressure plate retraction
  • Lever to pressure plate contact
  • Damaged pressure plate
  • Intermediate plate catching on improperly angled drive pins
  • Damaged intermediate plate
  • Absent clutch brake squeeze
  • Damaged clutch brake
  • Improper clutch brake use
  • Worn transmission drive gear spline
  • Transmission input drive gear contamination
  • Wrong throw out bearing installed
  • Throw out bearing catching on the transmission stem
  • Damaged pilot bearing
  • Incorrectly fitting pilot bearing
  • Bushing damage inside the release bearing sleeve
  • Release sleeve bushing to input shaft contact
  • Improper or non-installation of anti-rattle springs
  • Damaged or non-set positive separator pin
  • Improper clutch pedal height
  • Excessive free pedal
  • (15” flywheel) Step is greater than 0.002”
  • (Self-adjusting and SAS only) Incorrectly facing intermediate plate and spacer ring

Clutch Noise

  • Flywheel interfering with the disc
  • Excessive flywheel run-out
  • Flywheel interference from the dampener spring cover
  • Clutch is not firmly attached to the flywheel.
  • Failing linkage system
  • Improperly installed linkage system
  • Improperly adjusting the clutch by the linkage
  • Yoke bridge to cover contact
  • Release yoke fingers to cover contact
  • Failure of the input shaft to move freely through the disc hubs (contamination, corrosion)
  • Excessive RPM engine idle
  • Failure to cover the transmission inspection hole
  • Damaged pilot bearing
  • Damaged release bearing
  • Insufficient release bearing lubrication
  • Worn release sleeve bushing
  • Damaged throw out bearing
  • Retainer interference from the rivets of the rear disc
  • Wrong disc installed
  • Worn or fractured drive pins/drive slots
  • Incorrect rotation of the ring
  • Failure to install anti-rattle springs when required

Clutch Chatter

  • Disc grease/oil contamination
  • Excessive disc wear
  • Input shaft spline wear
  • Bound or worn linkage system
  • Excessive release yoke finger wear
  • Worn release bearing wear pads
  • Improperly set clutch engagement torque (electronic engine)

Slipping Clutch

  • Operator error that results in excessive heat.
  • Lack of free pedal
  • Prolonged operation without free-play
  • Improper application
  • Vehicle overload
  • Disc grease/oil contamination
  • Improperly adjusting the clutch by the linkage
  • Damaged retainer assembly

Clutch Vibration

  • Improperly tightened clutch cover mounting bolts
  • Retainer assembly interference from the rivets of the rear disc
  • Improperly set free travel
  • Linkage system wear
  • Cross shaft wear
  • Disc wear down to the rivets
  • Free play changes caused by excessive crankshaft end play
  • Loose flywheel
  • Unbalanced flywheel
  • Clutch is not properly seated against the flywheel
  • Excessive flywheel run-out

Clutch Cover to Yoke Fingers Contact

  • Incorrect rotation of the ring
  • Fractured release bearing housing
  • Yoke finger breakage or excessive wear
  • Clutch cover damage
  • Incorrect clutch adjustment
  • Improperly installed linkage system
  • Linkage system breakage

Yoke Bridge to Cover Contact

  • Overstroking the yoke in order to acquire the correct clutch brake squeeze. This can be due to:
  • Damaged or wrong transmission bearing retainer cap
  • Wearing of the yoke fingers and/or the release bearing pads
  • Fractured or missing clutch brake
  • Wrong yoke installation
  • Incorrect linkage system setup
  • Worn clutch brake

Fractured Clutch Cover

  • Straightened release yoke fingers
  • Incorrect torque to the flywheel mounting bolts

Release Lever to Pressure Plate Contact

  • Incorrect release bearing travel
  • Worn cross shaft bushings
  • Worn cross shafts
Worn Release Levers

Worn Release Lever

  • Damaged throw out bearing
  • Improperly fitted throw out bearing
  • Worn or bound linkage

Clutch cover/flywheel detachment

  • Incorrect torque to the flywheel mounting bolts.
Spring Damaged Pressure Plate

Pressure Plate/Intermediate Plate Damage

  • Improper application
  • Operator error that results in excessive heat
  • Prolonged operation without free-play
  • Improperly adjusting the clutch by the linkage
  • Damaged retainer assembly
  • Vehicle overload
  • Damaged disc or disc hub

Grooved Pressure Plate/Intermediate Plate/Flywheel

  • Rivet contact from a worn disc

Damaged Intermediate Plate Aluminum Spacing Ring

  • Improper installation

Partial Pressure Plate Retraction

  • Damaged pressure plate return springs
  • Incorrect release bearing travel
  • Incorrect release lever nose installation

Intermediate Plate Interference

  • Incorrectly angled drive pins

Disc Grease/Oil Contamination

  • Transmission leakage
  • Rear main engine seal leakage
  • Failure to remove rust preventative from the flywheel
  • Greasing the input shaft splines
  • Greasing the disc hub splines

Abnormal Disc Wear

  • Unevenly worn or unsurfaced flywheel

Warped Disc

  • Improper transmission installation

Flywheel Interfering With the Disc

  • Disc rivets contacting the flywheel mounting bolts. (link to reasons)
  • Disc installed facing the incorrect direction
  • Damaged pilot bearing
  • Inappropriate clutch installed

Burnt Disc

  • Slippage
  • Riding the clutch pedal
  • Attempting to hold a vehicle stationary on an incline with a slipping clutch
  • Prolonged operation without free-play
  • Inappropriate clutch installed
  • Excessive disc facing wear
  • Partial clutch unloading due to another component failure
  • Retainer assembly interference

Damaged Damper Cover

  • Transmission shaft forced into the disc hub
  • Improper transmission installation
Damaged Clutch Disc Hub

Damaged Disc Hub

  • Torsional vibrations
  • Shock load
  • Improper transmission installation
  • Improper disc installed
  • Excessive flywheel run-out
Absent Clutch Disc Dampener Springs

Absent or Damaged Dampener Springs

  • Shock load
  • Torsional vibrations
  • Improper application
  • Excessive RPM engine idle
Damaged Clutch Disc

Damaged Disc

  • Coasting with the clutch pedal depressed while the vehicle is in gear
Worn Clutch Disc Facings

Loss of Disc Friction Material

  • Coasting with the clutch pedal depressed while the vehicle is in gear with high RPMs

Damaged Sleeve Bushing

  • Input shaft not centered with the release bearing assembly sleeve during transmission installation
  • Unsupported transmission in the sleeve bushing

Release Shaft Wear

  • Damaged linkage system
  • Variance in free play
  • Improper engagement of the clutch
  • Excessive side loading on the release bearing

Damaged Input Shaft Spline

  • Torsional vibrations
  • Misaligned input shaft

Damaged Input Shaft

  • Undue release sleeve pressure on the input shaft
  • Damaged linkage system
  • Worn release bearing
  • Worn release yoke fingers
  • Push starting the truck
  • High speed down shift

Release Sleeve Bushing to Transmission Input Shaft Contact

  • Protruding cross shafts through the release yoke
  • Damaged release yoke fingers
  • Improper clutch cover installation
  • Improper cover fit into the flywheel pilot
  • Transmission bell housing not aligned with the engine housing
  • Loose transmission mounting bolts
  • Improper linkage system adjustment

Worn Release Yoke Fingers

  • Riding the clutch pedal while in motion
  • Operating the vehicle without free play

Damaged Retainer Assembly

  • Improper transmission installation
  • Rivet contact from a worn disc
  • Improperly adjusting the clutch by the linkage

Damaged Positive Separator Pin

  • Improper installation

Damaged Kwik-Adjust® System

  • Failure to fully depress the adjuster while rotating the gear
  • Rotating the gear while the clutch is engaged

Damaged Throw Out Bearing

  • Prolonged partial clutch release while in motion
  • Prolonged operation without free-play
  • Continuous contact with the release levers

Damaged Pilot Bearing

  • Insufficient lubrication
  • Improper outer bearing race fit in the flywheel
  • Improper inner bearing race fit on the input shaft

Release Bearing Failure

  • Inadequate lubrication
  • Improper lubricant
  • Prolonged partial clutch release while in motion
  • Excessive wear pad and yoke fingers wear
Excessive Clutch Brake Wear

Excessive Clutch Brake Wear

  • Insufficient clutch release
  • Engaging the clutch brake while the vehicle is moving and transmission is in gear
  • Improper installation
  • Damaged transmission bearing cap
  • The clutch brake has exceeded its normal life expectancy