Clutch: Testing and Inspection

SERVICE DIAGNOSIS-CLUTCH GRAB/CHATTER





SERVICE DIAGNOSIS-CLUTCH SLIPS








SERVICE DIAGNOSIS-IMPROPER CLUTCH RELEASE





SERVICE DIAGNOSIS-CLUTCH PEDAL NOISE

DRIVE PLATE MISALIGNMENT
Common causes of misalignment are:
- Heat warping
- Mounting drive plate on a dirty crankshaft flange
- Incorrect bolt tightening
- Improper seating on the crankshaft shoulder
- Loose crankshaft bolts
Clean the crankshaft flange before mounting the drive plate. Dirt and grease on the flange surface may misalign the flywheel, causing excessive runout. Use new bolts when mounting drive plate to crankshaft. Tighten drive plate bolts to specified torque only. Over-tightening can distort the drive plate hub causing excessive runout.

CLUTCH COVER AND DISC RUNOUT
Check condition of the clutch cover before installation. A warped cover or diaphragm spring will cause grab and/or incomplete release or engagement. Use care when handling the clutch assembly. Impact can distort the cover, diaphragm spring, and release fingers.

CLUTCH CHATTER COMPLAINTS
For all clutch chatter complaints, do the following:
1. Check for loose, misaligned, or broken engine and transmission mounts. If present, they should be corrected at this time. Test vehicle for chatter. If chatter is gone, there is no need to go any further. If chatter persists:
2. Check to see if clutch cable routing is correct and operates smoothly.
3. Check for loose connections in drive train. Correct any problems and determine if clutch chatter complaints have been satisfied. If not:
4. Remove transaxle.
5. Check to see if the release bearing is sticky or binding. Replace bearing, if needed.
6. Check linkage for excessive wear on the pivot stud and fork fingers. Replace all worn parts.
7. Check clutch assembly for contamination (dirt, oil). Replace clutch assembly, if required.
8. Check to see if the clutch disc hub splines are damaged. Replace with new clutch assembly, if necessary.
9. Check input shaft splines for damage. Replace, if necessary.
10. Check for uneven wear on clutch fingers.
11. Check for broken clutch cover diaphragm spring fingers. Replace with new clutch assembly, if necessary.

CLASH-INTO-REVERSE COMPLAINTS
Certain NV T350 (A-578) manual transaxles are equipped with a reverse brake. It prevents clash when shifting into reverse, but only if the vehicle is not moving. See Manual Transmission/Transaxle for further diagnosis. Testing and Inspection
1. Depress clutch pedal to floor and hold. After three seconds, shift to reverse. If clash is present, clutch has excessive spin time, and the reverse brake may not be functioning.
2. Remove transaxle.
3. Check the input shaft spline, clutch disc splines, and release bearing for dry rust. If present, clean rust off and apply a light coat of bearing grease to the input shaft splines. Apply grease on the input shaft splines only where the clutch disc slides. Verify that the clutch disc slides freely along the input shaft spline.
4. Check to see if the clutch disc hub splines are damaged, and replace with new clutch assembly if required.
5. Check the input shaft for damaged splines. Replace as necessary.
6. Check for broken clutch cover diaphragm spring fingers.
7. Install clutch assembly and transaxle.