CLUTCH SERVICE Clutch Service Diagnosing Clutch Problems l

CLUTCH SERVICE

Clutch Service Diagnosing Clutch Problems l l Gather all possible information • Obtain the customer’s 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

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

Clutch Slippage • Before disassembly: • Check engine mounts

Clutch Slippage • Before disassembly: • Check free-play adjustment If these check fine - a worn clutch disc or pressure plate is the most probable cause

Clutch Problems (cont’d) l 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

Clutch Problems (cont’d) l 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

Clutch Problems (cont’d) Clutch noises l Clutch disengaged ONLY • These noises are usually caused by a bad throwout bearing or pressure plate release lever problem • Pilot bearing l Clutch engaged ONLY • Input shaft bearing • Internal transmission component (other)

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

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

Clutch Problems (cont’d) A WORN BEARING RETAINER

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

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

Free-Play Adjustment l. Adjustment should be made when free-play falls below 1/2 inch (13 mm)

Free-Play Adjustment Generic mechanical clutch adjustment

Free-Play Adjustment Typical hydraulic clutch adjustment

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

Hydraulic Clutch Diagnosis l Inspect the fluid • Check for dirt or other contaminants l 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

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

Hydraulic Clutch Service l. Hydraulic clutch systems are serviced like hydraulic brakes l Some common problems are: • Fluid leaks • Worn out piston seals • Air in the system • Corrosion buildup

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 properation • Use of a pressure or vacuum bleeder can greatly reduce time

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

Pressure Plate Service l l 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

Pressure Plate Service l Attaching bolts must be loosened in a staggered sequence

Clutch Disc Service l l l 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

Flywheel Service l l The flywheel should be checked for excessive runout In many cases, the flywheel can be resurfaced

Flywheel Service l l Check the condition of the ring-gear teeth Mark the alignment of the flywheel to crankshaft prior to removal

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

Clutch Service • Pilot bearing installation

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

Clutch Service • Use of a clutch alignment tool is essential

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

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

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

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

Hints for Removing Clutch l l 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 don’t hang free Be aware that the clutch disc contains harmful asbestos fibers