Clutch Service

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CLUTCH SERVICE
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Clutch Service
Diagnosing Clutch Problems

• Gather all possible information
• Obtain the customers explanation of the concern
• Look up service history
• Road test the vehicle to verify customer concern
• Pay close attention to the clutch during all
  phases of operation
• Go to Strategy Based Diagnostics for more
  information

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Clutch Problems

• Clutch slippage - with the clutch engaged, engine
  speed increases but vehicle speed does not
• Before disassembly
• Check linkage
• Check for worn or binding parts

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Clutch Slippage

• Before disassembly
• Check engine mounts

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Clutch Slippage

• Before disassembly
• Check free-play adjustment

If these check fine - a worn clutch disc or
pressure plate is the most probable cause
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Clutch Problems (contd)

• Clutch chatter - Shaking or shuddering when the
  clutch is engaged
• Before disassembly
• Check engine mounts
• Check for leaks from rear main seal, transmission
  input shaft seal, and clutch slave cylinder

If these check fine - a warped or scored flywheel
or pressure plate is probable
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Clutch Problems (contd)

• Clutch noises
• These noises are usually caused by bad bearings
  or bushings
• To diagnose, determine whether the noise changes
  with the clutch engaged or disengaged

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Clutch Problems (contd)
Clutch noises

• Clutch disengaged ONLY
• These noises are usually caused by a bad
  throw-out bearing or pressure plate release lever
  problem
• Pilot bearing
• Clutch engaged ONLY
• Input shaft bearing
• Internal transmission component (other)

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Clutch Problems (contd)

• Clutch vibrations
• Are usually caused by worn engine mounts, loose
  bolts, excessive flywheel runout, or flywheel
  and/or pressure plate assembly imbalance
• Dragging clutch
• Is usually caused by linkage problems, incorrect
  adjustments, improper lubrication or defective
  clutch assembly

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Clutch Problems (contd)

• Pulsating clutch pedal
• Is usually caused by broken or bent release
  levers, misaligned bell housing, or warped
  pressure plate, flywheel or clutch disc
• Binding clutch
• Is usually caused by binding linkage or cables,
  defective clutch assembly, a worn bearing
  retainer or improper installation

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Clutch Problems (contd)
A WORN BEARING RETAINER
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Mechanical Linkage Service

• Free-play adjustment
• Misadjustment causes premature wear and clutch
  slippage
• Wear on clutch linkage components can cause
  inaccurate adjustment
• Pedal travel
• One of the most frequent causes of clutch failure

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Free-Play Adjustment

• Insufficient free-play can cause premature
  throw-out bearing failure
• Excessive free-play can prevent full
  disengagement when clutch pedal is depressed

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Free-Play Adjustment

• Adjustment should be made when free-play falls
  below 1/2 inch (13mm)

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Free-Play Adjustment
Generic mechanical clutch adjustment
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Free-Play Adjustment
Typical hydraulic clutch adjustment
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Free-Play Adjustment

• Some mechanical clutch linkages are self
  adjusting.
• Refer to the shop manual (alldata) first!

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Hydraulic Clutch Diagnosis

• Inspect the fluid
• Check for dirt or other contaminants
• Check the pedal feel and travel
• Some causes of a soft pedal are
• Low fluid level
• Internal leaks in master or slave cylinder
• External leaks

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Hydraulic Clutch Diagnosis

• Excessive pedal travel or a spongy pedal can be
  caused by low fluid level
• Low fluid is often caused by leaks in the system

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Hydraulic Clutch Service

• Hydraulic clutch systems are serviced like
  hydraulic brakes

• Some common problems are
• Fluid leaks
• Worn out piston seals
• Air in the system
• Corrosion buildup

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Hydraulic Clutch Service

• Hydraulic clutch systems need to be bled just
  like brake systems
• The slave cylinder will have a bleeder screw
• All air must be removed for proper operation
• Use of a pressure or vacuum bleeder can greatly
  reduce time

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Hydraulic Clutch Service
Brake fluid is widely used as hydraulic clutch
fluid but CHECK WITH THE SERVICE MANUAL
(alldata) FIRST
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Pressure Plate Service

• Pressure plate is usually replaced when replacing
  a worn clutch disc
• It should be checked for hot spots, scoring,
  finger wear, and bent or broken fingers

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Pressure Plate Service

• Attaching bolts must be loosened in a staggered
  sequence

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Clutch Disc Service

• Improper driving technique is the usual cause of
  premature failure
• Inspect the clutch for indication of cause of
  failure
• If the clutch is removed from a vehicle with more
  than 50,000 miles, it should be replaced

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Flywheel Service

• The flywheel should be checked for excessive
  runout
• In many cases, the flywheel can be resurfaced

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Flywheel Service

• Check the condition of the ring-gear teeth
• Mark the alignment of the flywheel to crankshaft
  prior to removal

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Clutch Service

• If the system uses a pilot bearing it should be
  replaced with the disc/pressure plate
• A removal tool is usually necessary

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Clutch Service

• Pilot bearing installation

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Clutch Service

• All clutch disc mating surfaces must be free of
  dirt and grease

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Clutch Service

• Use of a clutch alignment tool is essential

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Clutch Service

• The alignment tool centers the clutch disc before
  the pressure plate is tightened.

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Clutch Service

• The splines on the input shaft must be lightly
  greased
• Always test-fit a new clutch disc on the input
  shaft prior to installation

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Clutch Service

• All metal to metal friction points must be
  lightly greased including
• Bearing retainer
• Throw-out bearing
• Fork pivots
• Linkage pivots
• Input shaft

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Clutch Service

• Torque the pressure plate and flywheel to
  manufacturers specifications in a staggered
  sequence

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Hints for Removing Clutch

• Always refer to the correct service information
• Clean the area around the clutch housing and
  transmission
• Suspend any components that are disconnected so
  that they dont hang free
• Be aware that the clutch disc contains harmful
  asbestos fibers