Clutch: Testing and Inspection

CLUTCH

ROAD TEST

Road test the vehicle and inspect components to determine the clutch problem.

During a road test, drive the vehicle at normal speeds. Shift the transmission through all gear ranges and observe clutch action. If the clutch chatters, grabs, slips or does not release properly, remove and inspect the clutch components. If the problem is noise or hard shifting further diagnosis may be needed as the transmission or another driveline component may be at fault.

CLUTCH CONTAMINATION

Clutch contamination can be caused by oil, water or clutch fluid on the clutch discs and pressure plate surfaces. This will cause chatter, slip and grab. Inspect the clutch components and verify the contaminate.

Oil contamination indicates a leak at either the rear main seal or transmission input shaft causing an oil residue on the housing interior and clutch cover and flywheel. Heat buildup caused by slippage between the pressure plate, discs and flywheel can bake the oil residue onto the components. A glaze-like residue ranges in color from amber to black will be noticed.

Road splash contamination, dirt/water can enter the clutch housing due to loose bolts, housing cracks or through hydraulic line openings. Driving through deep water puddles can force water/road splash into the housing through such openings.

IMPROPER RELEASE OR CLUTCH ENGAGEMENT

Clutch release or engagement problems are caused by wear or damage to one or more clutch components.

Release problems can result in hard shifting and noise. Inspect the clutch cylinders/interconnecting line, slave cylinder, release bearing, clutch discs and pressure plate. Inspect these components for loose, worn and damaged mounting bolts or components.

Normal condensation in vehicles that are stored or out of service for long periods of time can generate enough corrosion to make the discs stick to the flywheel, or pressure plate. If this condition is experienced loosen the disc manually through the inspection plate opening if equipped.

Engagement problems can result in slip, chatter/shudder and noisy operation. Inspect the clutch discs and pressure plate for contamination, wear, misalignment and distortion.

CLUTCH MISALIGNMENT

Clutch components must be in proper alignment with the crankshaft and transmission input shaft. Misalignment caused by excessive runout or warpage of any clutch component will cause grab, chatter and improper clutch release.

PRESSURE PLATE

Check pressure plate for flatness with a straightedge. Pressure plate friction area must be flat within 0.50 mm (0.020 in.). Attaching bolt holes should be in contact with surface plate within 0.38 mm (0.015 in.). Inspect friction faces of the flywheel and pressure plate for:

- Flywheel Dowel Pin Fit
- Excessive Discoloration
- Burned Areas
- Small Cracks
- Deep Grooves
- Ridges

CLUTCH DISC

Replace clutch discs and pressure plate if discs are worn within 0.38 mm (0.015 in.) of the rivet heads. Inspect clutch discs for:

- Discoloration
- Burned Areas
- Cracks
- Worn Disc Hub Splines
- Broken Springs
- Lose Rivets
- Oil Soaked

DIAGNOSIS CHART

The diagnosis charts Diagnosis Chart describe common clutch problems, possible causes and correction.

Diagnosis Chart