1994 JEEP CHEROKEE Service Repair Manual

²input shaft pilot hub
²transmission front bearing retainer slide surface
Never apply grease to any part of the clutch
cover, or disc.
RECOMMENDED LUBRICANTS
Use Mopar multi-purpose grease for the clutch
pedal bushings and pivot shaft. Use Mopar high tem-
perature grease (or equivalent) for all other lubrica-
tion requirements. Apply recommended amounts and
do not overlubricate.
CLUTCH OPERATION
Leverage, spring force and friction are what make
the clutch work. The disc serves as the friction ele-
ment. The diaphragm spring acting on the pressure
plate provides the apply (or clamping) force. And the
pedal, hydraulic linkage, release lever and bearing
provide the leverage.
The clutch cover, which is bolted to the flywheel, is
the component that clamps the disc against the fly-
wheel. The cover is actually an assembly consisting
of the cover, diaphragm spring, pressure plate, and
fulcrum components.
It is the clutch cover pressure plate that actually
clamps the clutch disc against the flywheel. Pressure
plate force is supplied by the diaphragm spring.
The disc has a splined hub for installation on the
transmission input shaft splines. The splined hub is
what connects the disc to the transmission.The clutch linkage uses hydraulic pressure to oper-
ate the clutch. The clutch master cylinder is con-
nected to the clutch pedal and the slave cylinder is
connected to the release lever. In operation, pressing
the clutch pedal develops fluid pressure in the clutch
master cylinder. This pressure is then transmitted
directly to the slave cylinder via the connecting line.
In turn, the slave cylinder operates the clutch release
lever.
The clutch release bearing is mounted on the
transmission front bearing retainer. The bearing is
attached to the release lever which moves the bear-
ing in and out of contact with the diaphragm spring.
In operation, slave cylinder force causes the release
lever to pivot toward the clutch. This action moves
the release bearing into direct contact with the dia-
phragm spring fingers. As additional force is applied,
the release bearing pushes the spring fingers inward
relieving spring force on the pressure plate. At this
point, the clutch disc is disengaged and freewheeling.
The process of clutch re-engagement, is simply the
reverse of what occurs during disengagement. Re-
leasing pedal pressure removes linkage pressure. The
release bearing moves away from the spring which
again applies clamping force on the disc through the
pressure plate.
6 - 2 CLUTCHJ

CLUTCH DIAGNOSIS
INDEX
page page
Clutch Problem Causes..................... 3
General Diagnosis Information................ 3Inspection and Diagnosis Charts.............. 4
GENERAL DIAGNOSIS INFORMATION
Unless the cause of a clutch problem is obvious, ac-
curate problem diagnosis will usually require a road
test to confirm a problem. Component inspection will
then be required to determine the actual problem
cause.
During a road test, drive the vehicle at normal
speeds. Shift the transmission through all gear
ranges and observe clutch action. If chatter, grab,
slip, or improper release is experienced, remove and
inspect the clutch components. However, if the prob-
lem is noise or hard shifting, further diagnosis may
be needed as the transmission or another driveline
component may be at fault. Careful observation dur-
ing the test will help narrow the problem area.
CLUTCH PROBLEM CAUSES
CONTAMINATION
Fluid contamination is a frequent cause of clutch
malfunctions. Oil, water, or clutch fluid on the clutch
contact surfaces will cause faulty operation. The
usual result is chatter, slip and grab.
During inspection, note if any components are con-
taminated with oil, hydraulic fluid, or water/road
splash.
Oil contamination indicates a leak at either the
rear main seal or transmission input shaft. Oil leak-
age produces a residue of oil on the housing interior
and on the clutch cover and flywheel. Heat buildup
caused by slippage between the cover, disc and fly-
wheel, can sometimes bake the oil residue onto the
components. The glaze-like residue ranges in color
from amber to black.
Road splash contamination means dirt/water is en-
tering the clutch housing due to loose bolts, housing
cracks, or through hydraulic line openings. Driving
through deep water puddles can force water/road
splash into the housing through such openings.
Clutch fluid leaks are from loose or damaged slave
cylinder fluid lines and connecting fittings. However,
clutch fluid leaks will usually be noted and corrected
before severe contamination occurs.
CLUTCH MISALIGNMENT
Clutch components must be in proper alignment
with the crankshaft and transmission input shaft.Misalignment caused by excessive runout or warpage
of any clutch component will cause grab, chatter and
improper clutch release.
Flywheel Runout
Check flywheel runout whenever misalignment is
suspected. Flywheel runout should not exceed 0.08
mm (0.003 in.). Measure runout at the outer edge of
the flywheel face with a dial indicator. Mount the in-
dicator on a stud installed in place of one of the fly-
wheel bolts.
Common causes of runout are:
²heat warpage
²improper machining
²incorrect bolt tightening
²improper seating on crankshaft flange shoulder
²foreign material on crankshaft flange
Flywheel machining is not recommended. The fly-
wheel clutch surface is machined to a unique contour
and machining will negate this feature. However,
minor flywheel scoring can be cleaned up by hand
with 180 grit emery, or with surface grinding equip-
ment. Remove only enough material to reduce scor-
ing (approximately 0.001 - 0.003 in.). Heavy stock
removal isnot recommended.Replace the flywheel
if scoring is severe and deeper than 0.076 mm (0.003
in.). Excessive stock removal can result in flywheel
cracking or warpage after installation; it can also
weaken the flywheel and interfere with proper clutch
release.
Clean the crankshaft flange before mounting the
flywheel. Dirt and grease on the flange surface may
cock the flywheel causing excessive runout. Use new
bolts when remounting a flywheel and secure the
bolts with Mopar Lock And Seal. Tighten flywheel
bolts to specified torque only. Overtightening can dis-
tort the flywheel hub causing runout.
Clutch Cover And Disc Runout
Check the clutch disc before installation. Axial
(face) runout of anewdisc should not exceed 0.50
mm (0.020 in.). Measure runout about 6 mm (1/4 in.)
from the outer edge of the disc facing. Obtain an-
other disc if runout is excessive.
Check condition of the clutch before installation. A
warped cover or diaphragm spring will cause grab
and incomplete release or engagement. Be careful
JCLUTCH DIAGNOSIS 6 - 3

when handling the cover and disc. Impact can distort
the cover, diaphragm spring, release fingers and the
hub of the clutch disc.
Use an alignment tool when positioning the disc on
the flywheel. The tool prevents accidental misalign-
ment which could result in cover distortion and disc
damage.
A frequent cause of clutch cover distortion (and
consequent misalignment) is improper bolt tighten-
ing. To avoid warping the cover, the bolts must tight-
ened alternately (diagonal pattern) and evenly (2-3
threads at a time) to specified torque.
Clutch Housing Misalignment
Clutch housing alignment is important to proper
clutch operation. The housing maintains alignment
between the crankshaft and transmission input shaft.
Misalignment can cause clutch noise, hard shifting,
incomplete release and chatter. It can also result in
premature wear of the pilot bearing, cover release
fingers and clutch disc. In severe cases, misalign-
ment can also cause premature wear of the transmis-
sion input shaft and shaft bearing.
Housing misalignment is generally caused by in-
correct seating on the engine or transmission, loose
housing bolts, missing alignment dowels or housing
damage. Infrequently, misalignment may also be
caused by housing mounting surfaces that are not
completely parallel. Misalignment can be corrected
with shims.INSTALLATION METHODS AND PARTS
USAGE
Distortion of clutch components during installation
and the use of non-standard components are addi-
tional causes of clutch malfunction.
Improper clutch cover bolt tightening can distort
the cover. The usual result is clutch grab, chatter
and rapid wear. Tighten the cover bolts as described
in Clutch Service section.
An improperly seated flywheel and/or clutch hous-
ing are additional causes of clutch failure. Improper
seating will produce misalignment and additional
clutch problems.
The use of non-standard or low quality parts will
also lead to problems and wear. Use recommended
factory quality parts to avoid comebacks.
INSPECTION AND DIAGNOSIS CHARTS
The clutch inspection chart (Fig. 1) outlines items
to be checked before and during clutch installation.
Use the chart as a check list to help avoid overlook-
ing potential problem sources during service opera-
tions.
The diagnosis charts describe common clutch prob-
lems, causes and correction. Fault conditions are
listed at the top of each chart. Conditions, causes and
corrective action are outlined in the indicated col-
umns.
The charts are provided as a convenient reference
when diagnosing faulty clutch operation.
6 - 4 CLUTCH DIAGNOSISJ

Fig. 1 Clutch Inspection Points
JCLUTCH DIAGNOSIS 6 - 5

6 - 6 CLUTCH DIAGNOSISJ

JCLUTCH DIAGNOSIS 6 - 7

6 - 8 CLUTCH DIAGNOSISJ

JCLUTCH DIAGNOSIS 6 - 9