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Clutch University
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OEM
Technical notes
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SELF ALIGNING RELEASE BEARINGS
Most late model applications are supplied with self-aligning (SA) release
bearings. The main purpose of the self-aligning release bearing is to help
eliminate premature bearing wear and failure due to slight misalignments between
the engine and the transmission. A slight gap between the inner race and collar
allow the bearing to move slightly about on the collar. This movement will allow
the bearing to find its own center on the clutch fingers, resulting in better
alignment and reduced wear. SELF-ALIGNING BEARINGS MAY APPEAR OFF CENTER IF
VIEWED FROM THE BEARING SIDE. IF YOU CAN MANUALLY MOVE THE BEARING ABOUT ON THE
COLLAR, YOU HAVE A SELF-ALIGNING BEARING.
HONDA APPLICATIONS
FLYWHEEL RESURFACING
Always have the flywheel machined to the proper factory specification. Due to
the recessed flywheels used in many Honda applications, material must be removed
from the clutch mounting surface in the same amount as is removed from the
friction surface. This is known as the 'step'. Failure to do this will result in
erratic or non-release situations.
CLUTCH CHATTER, HARD PEDAL
Cross shaft release fork equipped Hondas tend to develop problems over time.
Wear on the bosses machined into the transmission case where the cross shaft
rides can cause the shaft to stick or bind. The cross shaft may also become out
of alignment and cause the release bearing to ride unevenly on the clutch
fingers causing clutch chatter, uneven release, and binding. All release
components must be carefully inspected and replaced if worn.
OUT OF BALANCE VIBRATION
If the clutch exhibits an out of balance condition, check for worn inner CV
joints.
INPUT SHAFT PLAY
Some Honda models do not come equipped with pilot bushings. This situation may
cause excessive pressure to the bearings in the transmission. Over time, the
input shaft will run out, causing stress to the clutch disc and hub assembly.
THIS IS A MAJOR CAUSE OF DISC FAILURES IN HONDA APPLICATIONS.
CLUTCH CABLE PROBLEMS
Extremely hard pedal effort on some 84-87 Honda cars may be caused by a problem
with the accelerator pedal bracket. A welded bracket located on the accelerator
pedal utilizes a tube through which the clutch cable is routed. These brackets
are known to break off, leaving no support for the clutch cable. This will cause
binding and hard pedal feel. Visually inspect these components if a hard or
binding pedal is encountered.
FORD/FORD TRUCK
1752SAR RELEASE BEARING - TAURUS SHO, TEMPO, TOPAZ, ESCORT
This release bearing contains a steel repair sleeve that fits over the original
aluminum quill. The factory quill is prone to galling which will cause the pedal
to fluctuate in stiffness and cause erratic release.
SELF-ADJUSTING CLUTCH CABLES
Many Ford vehicles use a self-adjusting ratchet mechanism that is attached to
the clutch pedal under the dash. When installing a new clutch, this mechanism
must be reset so that proper pedal height and release will be attained. Pull the
pedal all the way up, then release the pawl from the gear quadrant to the pedal
swings free. Let the pedal return and let go of the pawl. Cycle the pedal
several time to allow the ratchet mechanism to set itself.
BRONCO II AND RANGER HYDRAULIC
RELEASE BEARING
1784-87 trucks using the 1738SA release bearing contain a new style bearing that
may be different from the original. When replacing this bearing, the steel
sleeve located in the original slave assembly MUST BE REMOVED or the bearing
will not sit flat on the slave cylinder, causing the bearing to ride the clutch
fingers and the clutch to slip.
PREMATURE FAILURE OF SLAVE CYLINDER ON 93-95 F SERIES TRUCKS
Ford trucks equipped with 7.3L IDI, IDI turbo, DI turbo diesel, or 7.5 gas
engines may experience premature failure of the slave cylinder due to extreme
exhaust heat. Ford offers replacement parts for this problem including a slave
cylinder heat shield.
GM
RELEASE BEARING INSTALLATION - 1716SA
The most common installation error on GM vehicles with stamped clutch forks is
installing the release bearing improperly. The front of the stamped fork AND the
spring clips must both sit between the flanges of the release bearing. Failure
to do so can cause non-release, erratic release, bearing failure, and broken
release bearings.
HYUNDAI
EXCEL - when replacing the clutch in these vehicles it is imperative to inspect
the roll pins that hold the release bearing fork to the cross shaft. These pins
often break or bend, causing release problems. Change these pins on any clutch
replacement for this application.
JEEP
HYDRAULIC RELEASE MECHANISM PROBLEMS
When troubleshooting release problems on Jeeps using an external slave cylinder,
check the plastic pivot at the end of the slave cylinder rod for cracks. This
part is prone to cracking or complete breakage resulting in non-release of the
clutch.
NISSAN
MAXIMA - Always check the transmission quill/collar for this application for
wear or galling. This problem can cause the release bearing to bind or stick
when the pedal is released, and can cause damage to the other components such as
the clutch or transmission. Replace this collar if worn or galled.
PONTIAC
FIERO RELEASE PROBLEMS
A common cause of release problems with Fieros is due to the release shaft
lever. The original lever is made of stamped steel and is prone to flexing and
breaking. This problem will surface as the clutch will not fully release or the
transmission will drag while shifting, and may seem as though the slave cylinder
is bad or the hydraulic system will not bleed properly. GM offers a replacement
lever made of cast steel that will solve the problem.
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