Tech Article – Clutch – Inspection, Removal and Installation

 
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Tech Article – Clutch – Inspection

All vehicles that have a manual transaxle need to use a single dry-plate, coil
spring clutch (1972 and earlier models) or diaphragm spring clutch (1973 and
later models). The clutch disc has a splined hub that allows it to slide along
the splines of the transaxle input shaft. The clutch and pressure plate are held
in contact by spring pressure exerted by the coil springs or the diaphragm spring
in the pressure plate.

The clutch release system is cable operated. The clutch pedal, the clutch
cable, the clutch release lever, the clutch release shaft and the clutch release
bearing, are all included in the release system.

When the clutch pedal is depressed, its movement is transmitted by the cable
to the clutch release lever. The forks on the release shaft push against the
release bearing, as the lever pivots, which slides along the input shaft toward
the flywheel. The release bearing pushed against the release ring, on earlier
clutches, which pushes on the inner ends of the three release levers, which
releases the pressure plate from the clutch disc, which allows the clutch disc
to disengage from the flywheel. The release bearing pushes against the fingers
of the diaphragm spring of the pressure plate assembly, on later clutches,
lifting the pressure plate off the clutch disc and allowing it to disengage
from the flywheel.

When discussing the clutch components, terminology can be a problem because
common names are in some cases different from those used by the manufacturer.
For example, the driven plate is also called the clutch plate or disc, the
clutch release bearing is sometimes called a throwout bearing, etc.

Always perform the flowing preliminary checks to pinpoint the source of clutch
problems, unless you re planning to replace obviously damaged components.

a) Check clutch inchspin down time inch. Run the engine at normal idle speed
with the transaxle in Neutral and the clutch pedal up. Disengage the clutch
(depress the clutch pedal), wait several seconds and shift the transaxle into
Reverse. You shouldn t hear any gears grinding. A grinding noise indicates
a problem in the pressure plate or the clutch disc.

b) Verify that the clutch releases completely. Run the engine (with the parking
brake applied to prevent the vehicle from moving) and hold the clutch pedal
about ?-inch from the floor. Now shift the transaxle between 1st gear and Reverse
several times. Something in the clutch release mechanism is broken if the shift
is hard or the transaxle grinds.

c) Look over the pivot bushing between the clutch pedal and the pedal shaft
for binding or for too much play.

d) The most likely cause if the clutch pedal is difficult to operate, is a
faulty clutch cable. Remove the cable and check it for kinks, frayed wires,
rust and other signs of corrosion. Replace it if it s in bad shape. Lubricate
it with penetrating oil and try it again if it looks like it s in good condition.

Clutch Removal

Note: Any time the engine is removed for major overhaul, check the clutch
for wear and replace worn components as needed. The relatively low cost of
the clutch components compared to the time spent gaining access to them warrants
their replacement – unless they are new or in near perfect condition – anytime
the engine is removed.

Take out the engine.

Scribe or paint alignment marks on the pressure plate and the flywheel to
make sure of proper realignment of the pressure plate during reassembly, if
the old pressure plate is to be reused.

Loosen the pressure plate-to-flywheel bolts by turning each bolt only a little
at a time. Work in a criss-cross pattern until all spring pressure is relieved.
Now hold the pressure plate securely and completely remove the bolts then by
the pressure plate and clutch disc. Caution: Remember that the pressure plate
is under tremendous spring pressure. If you work your way around the cover,
removing each bolt one at a time, it will warp.

Inspection

Normally, clutch problems are caused by a worn out clutch driven plate (clutch
disc). It s a really good idea to look over eh other components too, just
in case any of them are worn or damaged.

Look over the flywheel for cracks, heat checking, grooves and other obvious
defects. A machine shop can machine the surface flat and smooth (highly recommended,
regardless of the surface appearance), if the imperfections are slight. If
you need to, replace the flywheel.

Clean the needle bearings inside the flywheel gland nut (the large nut in
the center of the flywheel). Inspect the needle bearings using a small flashlight.
Replace the gland nut if they re flattened from too much wear or otherwise
damaged. If you are going to re-use the old gland nut, be sure to repack the
bearings with multi-purpose grease (just enough to coat all needles lightly).
Now put a little oil onto the felt ring just in from of the needle bearings.
Note: In view of the low replacement cost for a new gland nut, it s a good
idea to replace it anytime the clutch is removed, even if the needle bearings
look okay.

Look over the lining on the clutch disc. There should be at least 1/16-inch
lining above the rivet heads. Check over for loose rivets, cracks, distortion,
broken springs and other obvious damage. As mentioned, normally the clutch
disc is routinely replaced, so if you re not about the condition, replace it
with a new one. If you re planning to re-use the old clutch disc, it s a good
idea to check it for runout.

Carefully look over the splines inside the hub of the clutch disc and the
splines on the input shaft. They can t be broken or distorted. Lubricate the
splines in the disc hub and the splines on the input shaft with graphite, then
make sure that the clutch disc slides freely on the drive shaft splines without
too much radial play. You re probably going to replace the clutch disc anyway,
but if the splines on the input shaft are damaged, you ll have to replace the
input shaft as well.

Look over the friction surface of the pressure plate for wear, grooves and
cracks. Alternating dull and bright areas indicate a warped plate. You can
remove light glazing with a medium grit emery cloth. Inspect the friction surfaces
of the release ring and the release levers for too much wear on earlier (coil
spring type) plates. Inspect the diaphragm spring fingers for too much wear
and make sure they re not distorted on later (diaphragm spring type). Shake
the pressure plate assembly and verify that the diaphragm spring doesn t rattle.
Replace the pressure plate with a new or rebuilt unit if it is damaged or worn
in any way.

Look over the release bearing. If it is noisy or rough, replace it. Also look
over the bushings for the clutch release shaft and replace if needed. Note:
Like the gland nut, the release bearing should normally be replace anytime
the clutch is replaced.

Installation

If removed, install the flywheel.

Clean the flywheel and pressure plate friction surfaces with lacquer thinner
or acetone. Caution: Don t use oil or grease on these surfaces or on the clutch
disc lining. Make sure to clean your hands before handling the parts.

With the clutch held in place with an alignment tool, position the clutch
disc and pressure plate against the flywheel. The best alignment tool is an
old input shaft. Make sure the clutch disc is installed properly (most replacement
clutch plates will be marked “flywheel side” or something like that.
If it s not marked, install the clutch disc with the damper springs toward
the transaxle). Make sure the marks you made on the pressure plate and the
flywheel are matched up (if you re using the old pressure plate). Tighten the
pressure plate-to-flywheel bolts finger tight, working around the pressure
plate.

Center the clutch disc by ensuring the alignment tool extends through the
splined hub and into the needle bearing in the gland nut. Wiggle the tool up,
down or side-to-side as you need to, to bottom the tool into the gland nut.
Working in a criss-cross pattern, tighten the pressure plate-to-flywheel bolts
a little at a time. This will prevent distorting the cover. Tighten them to
the torque after all of the bolts are snug.

Remove the alignment tool.

If removed, install the release bearing. Make sure to lubricate the bore of
the release bearing and (on 1971 and later models) the outer surface of the
central guide sleeve with high-temperature grease, and apply multi-purpose
grease to the contact areas of the forks on the release shaft.

Now install the engine.

Adjust the clutch pedal freeplay