(overslipping clutch upon acceleration), resting your
foot on the clutch pedal while driving, and other
driving errors can cause early clutch failure.
When a vehicle enters the shop for clutch troubles,
you should test-drive the vehicle. While the vehicle is
being test-driven, you should
check the action of the clutch pedal,
listen for unusual noises, and
feel for clutch pedal vibrations.
Gather as much information as you can on the
operation of the clutch. Use this information, your
knowledge of clutch principles, and a service manual-
troubleshooting chart to determine which components
There are five types of clutch problemsslipping,
grabbing, dragging, abnormal noises, and vibration. It
is important to know the symptoms produced by these
problems and the parts that might be the cause.
Slipping occurs when the driven disc fails to rotate
at the same speed as the driving members when the
clutch is fully engaged. This condition results
whenever the clutch pressure plate fails to hold the disc
tight against the face of the flywheel. If clutch slippage
is severe, the engine speed will rise rapidly on
acceleration, while the vehicle gradually increases in
speed. Slight but continuous slippage may go
unnoticed until the clutch facings are ruined by
excessive temperature caused by friction.
Normal wear of the clutch lining causes the free
travel of the clutch linkage to decrease, creating the
need for adjustment. Improper clutch adjustment can
cause slippage by keeping the release bearing in
contact with the pressure plate in the released position.
Even with your foot off the pedal, the release
mechanism will act on the clutch fork and release
Some clutch linkages are designed to allow only
enough adjustment to compensate for the lining to
wear close to the rivet heads. This prevents damage to
the flywheel and pressure plate by the rivets wearing
grooves in their smooth surfaces.
Other linkages will allow for adjustment after the
disc is worn out. When in doubt whether the disc is
worn excessively, remove the inspection cover on the
clutch housing and visually inspect the disc.
Binding linkage prevents the pressure plate from
exerting its full pressure against the disc, allowing it to
slip. Inspect the release mechanism for rusted, bent,
misaligned, sticking, or damaged components. Wiggle
the release fork to check for free play. These problems
result in slippage.
A broken motor mount (engine mount) can cause
clutch slippage by allowing the engine to move,
binding the clutch linkage. Under load, the engine can
lift up in the engine compartment, shifting the clutch
linkage and pushing on the release fork.
Grease and oil on the disc will also cause slippage.
When this occurs, locate and stop any leakage,
thoroughly clean the clutch components, and replace
the clutch disc. This is the only remedy.
If clutch slippage is NOT caused by a problem
with the clutch release mechanism, then the trouble is
normally inside the clutch. You have to remove the
transmission and clutch components for further
inspection. Internal clutch problems, such as weak
springs and bent or improperly adjusted release levers,
will prevent the pressure plate from applying even
pressure. This condition allows the disc to slip.
To test the clutch for slippage, set the emergency
brake and start the engine. Place the transmission or
transaxle in high gear. Then try to drive the vehicle
forward by slowly releasing the clutch pedal. A clutch
in good condition should lock up and immediately kill
the engine. A badly slipping clutch may allow the
engine to run, even with the clutch pedal fully released.
Partial clutch slippage could let the engine run
momentarily before stalling.
Never let a clutch slip for more than a
second or two. The extreme heat generated by
slippage will damage the flywheel and pressure
A grabbing or chattering clutch will produce a very
severe vibration or jerking motion when the vehicle is
accelerated from a standstill. Even when the operator
slowly releases the clutch pedal, it will seem like the
clutch pedal is being pumped rapidly up and down. A
loud bang or chattering may be heard, as the vehicle
Clutch grabbing and chatter is caused by problems
with components inside the clutch housing (friction