128 Manual Drive Trains and Axles
Figure 7-2. Clutch diagnosis chart. (General Motors)
Condition
Fails to Release (Pedal pressed
to floor. Shift lever does not move
freely in and out of reverse gear.
Slipping
Grabbing or Chattering
Rattling-Transmission Click
Throwout Bearing Noise with
Clutch Fully Engaged
Noisy
Pedal Stays on Floor When
Released
Hard Pedal Effort
Probable Cause
a. Improper linkage adjustment.
b. Improper pedal travel.
c. Loose linkage.
d. Faulty pilot bearing.
e. Faulty driven disc.
f. Fork off ball stud.
g. Clutch disc hub binding on clutch gear
spline.
h. Clutch disc warped or bent.
i. Loose pivot rings in cover assembly.
a. Improve adjustment (no lash).
b. Oil soaked driven disc.
c. Worn facing or facing torn from disc.
d. Warped pressure plate or flywheel.
e. Weak diaphragm spring.
f. Driven plate not seated in.
g. Driven plate overheated.
a. Oil on facing. Burned or glazed facings.
b. Worn splines on clutch gear.
c. Loose engine mountings.
d. Warped pressure plate or flywheel.
e. Burned or smeared resin on flywheel
or pressure plate.
a. Weak retracting springs.
b. Release fork loose on ball stud or in
bearing groove.
c. Oil in driven plate damper.
d. Driven plate damper spring failure.
a. Improper adjustment. No lash.
b. Release bearing binding on trans-
mission bearing retainer.
c. Insufficient tension between clutch
fork spring and ball stud.
d. Fork improperly installed.
e. Weak linkage return spring.
a. Worn release bearing.
b. Fork off ball stud (heavy clicking).
c. Pilot bearing loose in crankshaft.
a. Bind in linkage or release bearing.
b. Springs weak in pressure plate.
c. Springs being over traveled.
a. Bind in linkage.
b. Driven plate worn.
Correction
a. Adjust linkage.
b. Trim bumper stop and adjust linkage.
c. Replace as necessary.
d. Replace bearing.
e. Replace disc.
f. Install fork onto stud. Lightly lubricate
fingers at release bearing. Also lube
bearing I.D. groove.
g. Repair or replace clutch gear
and/or disc.
h. Replace disc (runout should not
exceed 0.020″).
i. Replace plate and cover assembly.
a. Adjust linkage to spec.
b. Install new disc and correct leak at its
source.
c. Replace disc.
d. Replace pressure plate or flywheel.
e. Replace pressure plate. (Be sure lash
is checked before replacing plate.)
f. Make 30 to 40 normal starts.
CAUTION: Do Not Overheat.
g. Allow to cool–check lash.
a. Install new disc and correct leak.
b. Replace transmission clutch gear.
c. Tighten or replace mountings.
d. Replace pressure plate or flywheel.
e. Sand off if superficial, replace burned
or heat checked parts.
a. Replace pressure plate.
b. Check ball stud and retainer.
c. Replace driven disc.
d. Replace driven disc.
a. Adjust linkage.
b. Clean, relubricate, check for burrs,
nicks, etc.
c. Replace fork.
d. Install properly.
e. Replace spring.
a. Replace bearing.
b. Install properly and lubricate fork
fingers at bearing.
c. See Section 6 for bearing fits.
a. Lubricate and free up linkage and
release bearing.
b. Replace pressure plate.
c. Adjust linkage to get proper lash, be
sure proper pedal stop (bumper) is
installed.
a. Lubricate and free linkage.
b. Replace driven plate.
Clutch Trouble Diagnosis