DIAGNOSIS AND TESTING
CLUTCH SYSTEM
Clutch problem diagnosis will generally require a road test to determine the type of fault. Component inspection will then determine the problem after road testing.
Drive the vehicle at normal speeds during road test. Shift the transaxle through all gear ranges and observe clutch action. If chatter, grab, slip, or improper release is experienced, remove and inspect the clutch components. If the problem is noise or hard shifting, further diagnosis may be needed. The transaxle or other driveline components may actually be at fault.
| CONDITION |
POSSIBLE CAUSES |
CORRECTION |
| CLUTCH DISC FACING COVERED WITH OIL OR GREASE |
Oil leak at engine rear main or transaxle input shaft seal. |
T355 equipped- Correct leak and replace modular clutch assembly. |
| BG6 equipped - Clean pressure plate, flywheel, and replace clutch disc. |
||
| Too much grease applied to splines of disc and input shaft. |
Apply lighter coating of grease to splines. |
|
| NO FAULT FOUND WITH CLUTCH COMPONENTS |
Problem actually related to suspension or driveline component. |
Further diagnosis required. Check engine/transmission mounts, suspension attaching parts and other driveline components as needed. |
| Engine related problems. |
Check EFI and ignition systems. |
|
| PARTIAL ENGAGEMENT OF CLUTCH DISC |
Clutch cover, spring, or release fingers bent, distorted (rough handling, improper assembly). |
Replace clutch assembly. |
| Clutch disc damaged or distorted. |
Replace clutch assembly. |
|
| Clutch misalignment. |
T355 equipped - Verify modular clutch pilot plate alignment to crankshaft. Replace the modular clutch assembly if the pilot plate is loose or bent. |
|
| BG6 equipped - Check alignment and runout of flywheel, disc, or cover. Check clutch housing to engine dowels and dowel holes for damage. Correct as necessary. |
| CONDITION |
POSSIBLE CAUSES |
CORRECTION |
| DISC FACING WORN OUT |
Normal wear. |
Replace clutch assembly. |
| Driver frequently rides (slips) clutch, results in rapid wear, overheating. |
Replace clutch assembly. |
|
| Insufficient clutch cover diaphragm spring tension |
Replace clutch assembly. |
|
| CLUTCH DISC FACING CONTAMINATED WITH OIL OR GREASE |
Leak at rear main oil seal or transaxle input shaft seal |
T355 equipped - Replace leaking seals. Replace clutch assembly. |
| BG6 equipped - Replace leaking seals. Clean the pressure plate and flywheel surface and replace clutch disc. |
||
| Excessive amount of grease applied to input shaft splines |
T355 equipped - Apply less grease to input shaft. Replace clutch assembly. |
|
| BG6 equipped - Apply less grease to input shaft. Clean the pressure plate and flywheel surface and replace clutch disc. |
||
| Road splash, water entering housing |
Seal housing. Inspect clutch assembly. |
|
| Concentric Slave Cylinder leaking hydraulic fluid |
Replace Concentric Slave Cylinder (CSC) |
|
| CLUTCH IS RUNNING PARTIALLY DISENGAGED |
Release bearing sticking or binding, does not return to normal running position. |
Verify that bearing is actually binding. Then, replace bearing and transmission front bearing retainer if sleeve surface is damaged. |
| Slave cylinder binding |
Replace slave cylinder |
|
| CLUTCH DISC FACINGS HAVE FRACTURED INTO SMALL PIECES |
Driver performs a 5-1 downshift at vehicle speed in excess of 60 miles per hour |
Alert driver to problem cause. Replace clutch assembly. Inspect slave cylinder and bearing for damage. |
| Leak at rear main or transaxle input shaft seal |
T355 equipped - Replace seal. Replace clutch assembly. |
|
| BG6 equipped - Replace seal. Clean the pressure plate and flywheel surface and replace clutch disc. |
||
| Excessive heat from slippage |
Replace Clutch Assembly |
| CONDITION |
POSSIBLE CAUSES |
CORRECTION |
| CLUTCH DISC BINDS ON INPUT SHAFT SPLINES |
Clutch disc hub splines damaged during installation |
Clean, smooth, and lubricate disc and shaft splines. Replace modular clutch assembly, or clutch disc, and/or input shaft if splines are severely damaged. |
| Input shaft splines rough, damaged. |
Clean input shaft splines. Then lube. |
|
| Corrosion or rust formations on splines of input shaft and disc |
Clean input shaft splines and disc splines, then lube |
|
| CLUTCH DISC RUSTED TO FLYWHEEL AND/OR PRESSURE PLATE |
Occurs in vehicles stored or not driven for extended period of time. Also occurs after steam cleaning if vehicle is not used for extended period. |
Replace clutch assembly. |
| CLUTCH WILL NOT DISENGAGE PROPERLY |
Disc bent, distorted during transaxle installation |
Replace clutch assembly. |
| Clutch cover diaphragm spring damaged during transaxle installation |
Replace clutch assembly. |
|
| Air in clutch hydraulic system. |
Bleed clutch hydraulic system to purge air. |
|
| Clutch master cylinder or slave cylinder leaking |
Check and replace master and/or slave cylinder |
| CONDITION |
POSSIBLE CAUSES |
CORRECTION |
| CLUTCH PEDAL SQUEAKS WHEN DEPRESSED TO FLOOR |
Pedal bushings worn out or inadequate lubrication |
Replace or lubricate bushings |
| Clutch pedal return spring worn out |
Lubricate or replace return spring |
CLUTCH CHATTER COMPLAINTS
For all clutch chatter complaints, perform 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.
2. If chatter persists, check hydraulic clutch release system is functioning properly.
3. Check for loose connections in drivetrain. Correct any problems and determine if clutch chatter complaints have been satisfied. If not:
a. Remove transaxle.
b. Check to see if the release bearing is sticky or binding. Replace bearing, if needed.
c. Check clutch assembly for contamination (dirt, oil). Replace clutch assembly, if required.
d. Check to see if the clutch disc hub splines are damaged. Replace with new clutch assembly, if necessary.
e. Check input shaft splines for damage. Replace, if necessary.
f. Check for uneven wear on clutch fingers.
g. Check for broken clutch cover diaphragm spring fingers. Replace with new clutch assembly, if necessary.
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 misalignment 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.
CLASH-INTO-REVERSE COMPLAINTS
All T355 manual transaxles are equipped with a reverse brake. It prevents clash when shifting into reverse, but only if the vehicle is not moving.
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.