Clutch: Testing and Inspection

CLUTCH





During road test, drive the vehicle at normal speeds. Shift the transmission through all gear ranges and observe clutch action. If clutch chatters, grabs, slips or does not release properly inspect clutch components. If problem is noise or hard shifting, check transmission and driveline component.

Inspection is recommended to determine a clutch problem.

CLUTCH CONTAMINATION

Oil leakage from either the rear main seal or transmission input shaft will produce a residue on the housing interior, clutch disc, plate and flywheel. Heat buildup caused by slippage between the plate, disc and flywheel, can bake the oil onto the components. The glaze-like residue ranges in color from amber to black.

Road splash contamination means dirt/water is entering the clutch housing. Driving through deep water puddles can force water/road splash into the housing through loose bolts, housing cracks or through hydraulic line openings.

Oil, water or clutch fluid on the clutch disc and pressure plate surfaces will cause chatter, slip and grab.

NOTE: Clutch fluid leaks are usually from damaged slave cylinder push rod seals.

IMPROPER CLUTCH RELEASE OR 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. Items to look for are:

- Leak at clutch cylinder
- Leaks at connecting lines
- Loose slave cylinder bolts
- Worn/loose release fork
- Worn/loose pivot stud
- Damaged release bearing
- Worn clutch disc
- Worn/damaged pressure plate

Normal condensation in vehicles that are stored for long periods of time can generate enough corrosion to make the disc stick to the flywheel or pressure plate. If this condition is experienced, correction only requires that the disc be loosened manually through the inspection plate opening.

Engagement problems usually result in slip, chatter, shudder and noisy operation. The primary causes are:

- Clutch disc contamination
- Worn clutch disc
- Flywheel damage
- Clutch misalignment
- Warped disc/pressure plate

CLUTCH MISALIGNMENT

Clutch components must be in alignment with the crankshaft and transmission input shaft. Misalignment of any clutch component will cause grab, chatter and improper clutch release.

CLUTCH PRESSURE PLATE AND DISC RUNOUT

Check the clutch disc before installation. Axial (face) runout of a new disc should not exceed 0.50 mm (0.020 in.). Measure runout 6 mm (0.24 in.) from outer edge of disc facing.

A warped pressure plate or diaphragm spring will cause grab and incomplete release or engagement. Be careful when handling the plate and disc. Impact can distort the plate, diaphragm spring, release fingers and hub of the clutch disc.

CAUTION: Use alignment tool when positioning the disc on the flywheel. This will prevent accidental misalignment which could result in plate distortion and disc damage.

NOTE: Clutch plate distortion (and consequent misalignment) can result from improper bolt tightening.

DIAGNOSIS CHART









The clutch inspection chart outlines items to be checked before and during clutch installation.

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