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J
CLUTCH
6-1
CLUTCH
CONTENTS
page
page
CLUTCH DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . 3
CLUTCH SERVICE . . . . . . . . . . . . . . . . . . . . . . . 10
GENERAL INFORMATION
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GENERAL INFORMATION
INDEX
page
Clutch Components . . . . . . . . . . . . . . . . . . . . . . . . 1
Clutch Linkage Fluid . . . . . . . . . . . . . . . . . . . . . . . . 1
page
Clutch Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Hydraulic Linkage Components . . . . . . . . . . . . . . . . 1
The clutch master cylinder push rod is connected to
the clutch pedal. The slave cylinder push rod is con-
nected to the clutch release fork. The master cylinder
is mounted on the driver side of the dash panel ad-
jacent to the brake master cylinder and booster as-
sembly. This positioning is similar for both left and
right hand drive models.
CLUTCH COMPONENTS
The clutch mechanism in XJ/YJ models consists of
a single, dry-type disc and a diaphragm style clutch
cover. A hydraulic linkage is used to operate the
clutch release bearing and fork.
A needle-type pilot bearing supports the transmis-
sion input shaft in the crankshaft. A sleeve type re-
lease bearing is used to engage and disengage the
clutch cover pressure plate.
The release bearing is operated by a release fork in
the clutch housing. The fork pivots on a ball stud
mounted in the housing. The release fork is actuated
by a hydraulic slave cylinder mounted in the hous-
ing. The slave cylinder is operated by a clutch master
cylinder mounted on the dash panel. The cylinder
push rod is connected to the clutch pedal.
The clutch disc has cushion springs in the disc hub.
The clutch disc facing is riveted to the hub. The fac-
ing is made from a non-asbestos material. The clutch
cover pressure plate is a diaphragm type with a one-
piece spring and multiple release fingers. The pres-
sure plate release fingers are preset during
manufacture and are not adjustable.
CLUTCH LINKAGE FLUID
The integral clutch master cylinder reservoir, slave
cylinder and fluid lines are prefilled with fluid prior
to assembly operations.
The hydraulic system should not require additional
fluid under normal circumstances. In fact,
the reser-
voir fluid level will actually increase as normal
clutch wear occurs. For this reason, it is impor-
tant to avoid overfilling, or removing fluid from
the reservoir. This will cause clutch release
problems.
If inspection or diagnosis indicates additional fluid
may be needed, use Mopar brake fluid, or an equiv-
alent meeting standards SAE J1703 and DOT 3. Do
not use any other type of fluid.
HYDRAULIC LINKAGE COMPONENTS
The hydraulic linkage consists of a clutch master
cylinder with integral reservoir, a clutch slave cylin-
der and an interconnecting fluid line.
6-2
CLUTCH
J
mitted to the slave cylinder through a 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 into contact with the clutch cover diaphragm
spring.
Slave cylinder force causes the release lever to
move the release bearing into contact with the dia-
phragm spring. As additional force is applied, the
bearing presses the diaphragm spring fingers inward
on the fulcrums. This action moves the pressure
plate rearward relieving clamp force on the disc. The
clutch disc is disengaged and freewheeling at this
point.
The process of clutch re-engagement, is simply the
reverse of what occurs during disengagement. Releas-
ing pedal pressure removes clutch linkage pressure.
The release bearing moves away from the diaphragm
spring which allows the pressure plate to exert
clamping force on the clutch disc.
CLUTCH OPERATION
Leverage, clamping force, and friction are what
make the clutch work. The disc serves as the friction
element and a diaphragm spring and pressure plate
provide the clamping force. The clutch pedal, hydrau-
lic linkage, release lever and bearing provide the le-
verage.
The clutch cover assembly clamps the disc against
the flywheel. The assembly consists of the cover, dia-
phragm spring, pressure plate, and fulcrum compo-
nents. The pressure plate clamps the clutch disc
against the flywheel and the spring provides the
clamping force.
The clutch disc friction material is riveted to the
disc hub. The hub bore is splined for installation on
the transmission input shaft. The hub splines con-
nect the disc to the transmission.
The clutch linkage uses hydraulic pressure to oper-
ate the clutch. The clutch master cylinder push rod is
connected to the clutch pedal and the slave cylinder
push rod is connected to the release lever in the
clutch housing.
Depressing the clutch pedal develops fluid pressure
in the clutch master cylinder. This pressure is trans-
J
CLUTCH DIAGNOSIS
INDEX
page
Clutch
Clutch
Clutch
Clutch
Contamination . . . . . .
Cover and Disc Runout
Housing Misalignment
Misalignment . . . . . . .
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4
3
CLUTCH DIAGNOSIS
6-3
page
Flywheel Runout . . . . . . . . . . . . . . .
General Diagnosis Information . . . .
Inspection and Diagnosis Charts . . .
Installation Methods and Parts Usage
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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.
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:
•
heat warpage
•
improper machining
•
incorrect bolt tightening
•
improper seating on crankshaft flange shoulder
•
foreign 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, mi-
nor flywheel scoring can be cleaned up by hand with
180 grit emery, or with surface grinding equipment.
Remove only enough material to reduce scoring (ap-
proximately 0.001 - 0.003 in.). Heavy stock removal
is
not recommended.
Replace the flywheel if scor-
ing is severe and deeper than 0.076 mm (0.003 in.).
Excessive stock removal can result in flywheel crack-
ing 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 CONTAMINATION
Fluid contamination is a frequent cause of clutch
malfunctions. Oil, water, or clutch fluid on the clutch
disc and pressure plate surfaces will cause 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 usually from damaged slave
cylinder push rod seals. This type of leak can only be
confirmed by visual inspection.
CLUTCH COVER AND DISC RUNOUT
Check the clutch disc before installation. Axial
(face) runout of a
new
disc 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
CLUTCH MISALIGNMENT
Clutch components must be in proper alignment
with the crankshaft and transmission input shaft.
6-4
CLUTCH DIAGNOSIS
J
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.
A cocked pilot bearing is another cause of clutch
noise, drag, and hard shifting, and rapid bearing
wear. Always use an alignment tool to install a new
bearing. This practice helps avoid cocking the bear-
ing during installation.
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, mis-
alignment can also cause premature wear of the
transmission input shaft and front bearing.
Housing misalignment is generally caused by incor-
rect 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.
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.
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.
J
CLUTCH DIAGNOSIS
6-5
Fig. 1 Clutch Inspection Points

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