Jeep XJ. Manual — part 57
(4) Install combination valve/bracket and retaining
nuts.
(5) Install brake lines on cylinder and valve.
Torque brake lines to 19 N·m (170 in. lbs.).
(6) Connect differential pressure switch wire on
the combination valve.
(7) Fill and bleed the brake system. Refer to the
procedure in this group.
(8) Connect the negative battery cable.
(9) Adjust the brake lamp switch. Refer to the pro-
cedure in this group.
WARNING: Be
certain
a
firm
brake
pedal
is
achieved prior to attempting to operate the vehicle.
SPECIFICATIONS
TORQUE SPECIFICATIONS
DESCRIPTION
TORQUE
Brake Booster to Cowl Panel
Nuts . . . . . . . . . . . . . . . . . . . . . 39 N·m (29 ft. lbs.)
Brake Lines at Master Cylinder and
Combination Valve
Tube Nuts . . . . . . . . . . . . . . . . 19 N·m (170 in. lbs.)
Master Cylinder to Vacuum Booster
Nuts . . . . . . . . . . . . . . . . . . . 17.5 N·m (155 in. lbs.)
5 - 4
BRAKES
XJ
REMOVAL AND INSTALLATION (Continued)
2000 JEEP CHEROKEE
CLUTCH
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
CLUTCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
FLYWHEEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
CLUTCH DISC. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
CLUTCH PRESSURE PLATE . . . . . . . . . . . . . . . . . 2
CLUTCH RELEASE BEARING . . . . . . . . . . . . . . . . 3
HYDRAULIC CLUTCH LINKAGE . . . . . . . . . . . . . . 4
DIAGNOSIS AND TESTING
SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . 4
INSTALLATION METHODS AND PARTS
USAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
CLUTCH DIAGNOSTIC INFORMATION . . . . . . . . . 4
CLUTCH CONTAMINATION . . . . . . . . . . . . . . . . . . 6
IMPROPER CLUTCH RELEASE OR
ENGAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 6
CLUTCH FLYWHEEL RUNOUT . . . . . . . . . . . . . . . 6
CLUTCH COVER AND DISC RUNOUT . . . . . . . . . 7
CLUTCH DIAGNOSIS CHARTS . . . . . . . . . . . . . . . 7
SERVICE PROCEDURES
CLUTCH COMPONENT LUBRICATION . . . . . . . . . 9
CLUTCH LINKAGE FLUID . . . . . . . . . . . . . . . . . . . 9
CLUTCH FLUID LEVEL . . . . . . . . . . . . . . . . . . . . 10
FLYWHEEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
REMOVAL AND INSTALLATION
CLUTCH COVER AND DISC . . . . . . . . . . . . . . . . 11
RELEASE BEARING . . . . . . . . . . . . . . . . . . . . . . 12
PILOT BEARING . . . . . . . . . . . . . . . . . . . . . . . . . 12
CLUTCH HOUSING . . . . . . . . . . . . . . . . . . . . . . . 13
CLUTCH HYDRAULIC LINKAGE . . . . . . . . . . . . . 13
SPECIFICATIONS
TORQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
DESCRIPTION AND OPERATION
CLUTCH
DESCRIPTION
The clutch mechanism consists of a flywheel, a sin-
gle, dry-type disc, and a diaphragm style clutch cover
(Fig. 1). A hydraulic linkage is used to operate the
clutch release bearing and fork. The flywheel is
bolted to the rear flange of the crankshaft. The
clutch pressure plate is bolted to the flywheel with
the clutch disc located between these two compo-
nents. The clutch system provides the mechanical,
but still easily detachable, link between the engine
and the transmission. The system is designed to
ensure that the full torque output of the engine is
transfered to the transmission while isolating the
transmission from the engine firing pulses to mini-
mize concerns such as gear rattle.
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
leverage.
Fig. 1 Engine Powerflow
XJ
CLUTCH
6 - 1
The clutch master cylinder push rod is connected
to the clutch pedal. When the clutch pedal is
depressed, the slave cylinder is operated by the
clutch master cylinder mounted on the dash panel.
The release fork is actuated by the hydraulic slave
cylinder mounted on the transmission housing. The
release bearing is operated by a release fork pivoting
on a ball stud mounted in the transmission housing.
The release bearing then depresses the pressure
plate spring fingers, thereby releasing pressure on
the clutch disc and allowing the engine crankshaft to
spin independently of the transmission input shaft
(Fig. 2).
FLYWHEEL
DESCRIPTION
The flywheel (Fig. 3) is a heavy plate bolted to the
rear of the crankshaft. The flywheel incorporates the
ring gear around the outer circumference to mesh
with the starter to permit engine cranking. The rear
face of the flywheel serves as the driving member to
the clutch disc.
OPERATION
The flywheel serves to dampen the engine firing
pulses. The heavy weight of the flywheel relative to
the rotating mass of the engine components serves to
stabilize the flow of power to the remainder of the
drivetrain. The crankshaft has the tendency to
attempt to speed up and slow down in response to
the cylinder firing pulses. The flywheel dampens
these impulses by absorbing energy when the crank-
shaft speeds and releasing the energy back into the
system when the crankshaft slows down.
CLUTCH DISC
DESCRIPTION
The clutch disc friction material is riveted to the
disc hub (Fig. 4). The hub bore is splined for installa-
tion on the transmission input shaft. The clutch disc
has cushion springs in the disc hub to dampen disc
vibrations during application and release of the clutch.
OPERATION
The clutch disc is held onto the surface of the fly-
wheel by the force exerted by the pressure plate’s dia-
phragm spring. The friction material of the clutch disc
then transfers the engine torque from the flywheel and
pressure plate to the input shaft of the transmission.
CLUTCH PRESSURE PLATE
DESCRIPTION
The clutch pressure plate assembly is a diaphragm
type with a one-piece spring and multiple release fin-
gers (Fig. 5). The pressure plate release fingers are
preset during manufacture and are not adjustable.
The assembly also contains the cover, pressure plate,
and fulcrum components.
Fig. 2 Clutch Operation
1 – FLYWHEEL
2 – PRESSURE PLATE FINGERS
3 – PIVOT POINT
4 – RELEASE BEARING PUSHED IN
5 – CLUTCH DISC ENGAGED
6 – CLUTCH DISC ENGAGED
7 – RELEASE BEARING
Fig. 3 Flywheel
1 – CRANKSHAFT
2 – RING GEAR
3 – FLYWHEEL
6 - 2
CLUTCH
XJ
DESCRIPTION AND OPERATION (Continued)
OPERATION
The clutch pressure plate assembly clamps the
clutch disc against the flywheel. When the release
bearing is depressed by the shift fork, the pressure
exerted on the clutch disc by the pressure plate
spring is decreased. As additional force is applied,
the bearing presses the diaphragm spring fingers
inward on the fulcrums. This action moves the pres-
sure plate rearward relieving clamp force on the disc.
The clutch disc is disengaged and freewheeling at
this point.
CLUTCH RELEASE BEARING
DESCRIPTION
A conventional release bearing (Fig. 6) is used to
engage and disengage the clutch pressure plate
assembly. The clutch release bearing is mounted on
the transmission front bearing retainer. The bearing
is attached to the release fork, which moves the bear-
ing into contact with the clutch cover diaphragm
spring.
OPERATION
The release bearing is operated by a release fork in
the clutch housing. Slave cylinder force causes the
release lever to move the release bearing into contact
with the diaphragm 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. Releasing pedal pressure removes clutch
hydraulic pressure. The release bearing then moves
away from the diaphragm spring which allows the
pressure plate to exert clamping force on the clutch
disc.
Fig. 4 Clutch Disc-Typical
1 – FACING MATERIAL
2 – DAMPER SPRINGS
3 – HUB
Fig. 5 Clutch Pressure Plate-Typical
1 – COVER
2 – RELEASE FINGERS
3 – PRESSURE PLATE
Fig. 6 Clutch Release Bearing
1 – RELEASE BEARING
2 – RELEASE FORK
XJ
CLUTCH
6 - 3
DESCRIPTION AND OPERATION (Continued)
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