pack JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

VARI-LOKTDIFFERENTIAL
In a standard differential if one wheel spins, the
opposite wheel will generate only as much torque as
the spinning wheel.
A gerotor pump and clutch pack are used to pro-
vide the torque transfer capability. One axle shaft is
splined to the gerotor pump and one of the differen-
tial side gears, which provides the input to the pump.
As a wheel begins to lose traction, the speed differ-
ential is transmitted from one side of the differential
to the other through the side gears. The motion of
one side gear relative to the other turns the inner
rotor of the pump. Since the outer rotor of the pump
is grounded to the differential case, the inner and
outer rotors are now moving relative to each other
and therefore creates pressure in the pump. The tun-ing of the front and rear axle orifices and valves
inside the gerotor pump is unique and each system
includes a torque-limiting pressure relief valve to
protect the clutch pack, which also facilitates vehicle
control under extreme side-to-side traction varia-
tions. The resulting pressure is applied to the clutch
pack and the transfer of torque is completed.
Under conditions in which opposite wheels are on
surfaces with widely different friction characteristics,
Vari-loktdelivers far more torque to the wheel on
the higher traction surface than do conventional
Trac-loktsystems. Because conventional Trac-lokt
differentials are initially pre-loaded to assure torque
transfer, normal driving (where inner and outer
wheel speeds differ during cornering, etc.) produces
torque transfer during even slight side-to-side speed
variations. Since these devices rely on friction from
this preload to transfer torque, normal use tends to
cause wear that reduces the ability of the differential
to transfer torque over time. By design, the Vari-lokt
system is less subject to wear, remaining more con-
sistent over time in its ability to transfer torque. The
coupling assembly is serviced as a unit. From a ser-
vice standpoint the coupling also benefits from using
the same lubricant supply as the ring and pinion
gears.
DIAGNOSIS AND TESTING
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, tooth contact, worn/damaged
gears or the carrier housing not having the proper
offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak-noise range. If the noise stops or changes
greatly:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehi-
cle turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise.
Fig. 1 DIFFERENTIAL-STRAIGHT AHEAD DRIVING
1 - IN STRAIGHT AHEAD DRIVING EACH WHEEL ROTATES AT
100% OF CASE SPEED
2 - PINION GEAR
3 - SIDE GEAR
4 - PINION GEARS ROTATE WITH CASE
Fig. 2 DIFFERENTIAL-ON TURNS
1 - PINION GEARS ROTATE ON PINION SHAFT
3 - 16 FRONT AXLE - 186FBIWJ
FRONT AXLE - 186FBI (Continued)

AXLE SHAFT SEALS
REMOVAL
(1) Raise and support vehicle.
(2) Remove axle shafts.
(3) Remove differential assembly.
(4) Remove inner axle shaft seals with a pry bay.
INSTALLATION
(1) Remove any sealer remaining from original
seals.
(2) Install oil seals with Discs 8110 and Turn-
buckle 6797 (Fig. 24). Tighten tool until disc bottoms
in housing.
(3) Install differential and axle shafts.
(4) Fill differential with lubricant.
(5) Remove support and lower vehicle.
AXLE - C/V JOINT
REMOVAL
NOTE: The only service procedure to be performed
on the axle C/V joint, is the replacement of the joint
seal boot. If any failure of internal axle shaft com-
ponents is diagnosed during a vehicle road test, the
axle shaft must be replaced as an assembly.
(1) Remove axle shaft.
(2) Remove large and small C/V boot clamps (Fig.
25) and discard.
(3) Slid boot off the C/V joint housing and slide it
down the axle shaft.
(4) Remove C/V joint from axle then slid boot off
the axle.
(5) Thoroughly clean and inspect axle C/V joint
assembly and axle shaft for any signs of excessive
wear.
INSTALLATION
(1) Slidenewboot over axle shaft.
(2) Install C/V joint onto the axle shaft.
(3) Distribute 1/2 the amount of grease provided in
seal boot service package(DO NOT USE ANY
OTHER TYPE OF GREASE)into axle C/V joint
assembly housing. Put the remaining amount into
the sealing boot.
(4) Position boot on the axle locating grove and on
the C/V joint.
Fig. 24 AXLE SEAL TOOLS
1 - TURNBUCKLE
2 - DISCS
Fig. 25 OUTER C/V BOOT CLAMPS
1 - C/V JOINT HOUSING
2 - LARGE CLAMP
3 - AXLE SHAFT
4 - SMALL CLAMP
5 - SEALING BOOT
WJFRONT AXLE - 186FBI 3 - 35

INSTALLATION
(1) Pack the bearing caps 1/3 full of wheel bearing
lubricant. Apply extreme pressure (EP), lithium-base
lubricant to aid in installation.
(2) Position the spider in the yoke. Insert the seals
and bearings, then tap bearing caps into the yoke
bores far enough to hold the spider in position.
(3) Place the socket (driver) against one bearing
cap. Position the yoke with the socket in a vise.
(4) Tighten the vise to force the bearing caps into
the yoke. Force the caps enough to install the retain-
ing clips.
(5) Install the bearing cap retaining clips.
(6) Install axle shaft.
PINION SEAL
REMOVAL
(1) Raise and support the vehicle.
(2) Remove wheel and tire assemblies.
(3) Remove brake rotors and calipers, refer to 5
Brakes for procedures.
(4) Mark propeller shaft and pinion companion
flange for installation reference.
(5) Remove the propeller shaft from the pinion
companion flange.
(6) Rotate the pinion gear a minimum of ten times
and verify the pinion rotates smoothly.
(7) Record torque necessary to rotate the pinion
gear with a inch pound torque wrench.
(8) Using a short piece of pipe and Spanner
Wrench 6958 to hold the pinion companion flange
and remove the pinion nut and washer.
(9) Remove pinion companion flange with Remover
C-452 and Flange Wrench C-3281.
(10) Remove pinion seal with Remover 7794-A and
a slide hammer (Fig. 31).
INSTALLATION
(1) Apply a light coating of gear lubricant on the
lip of pinion seal. Install seal with an appropriate
installer (Fig. 32).
(2) Install pinion companion flange on the pinion
gear with Installer W-162-D, Cup 8109 and Wrench
6958.
CAUTION: Never exceed the minimum tightening
torque 298 N´m (220 ft. lbs.) while installing pinion
nut at this point. Damage to collapsible spacer or
bearings may result.
(3) Install the pinion washer and anewnut on
the pinion gear.Tighten the nut only enough to
remove the shaft end play.
Fig. 29 AXLE SHAFT OUTER U-JOINT
1 - SHAFT YOKE
2 - BEARING CAP
3 - SNAP RINGS
4 - BEARING CAP
5 - SPINDLE YOKE
6 - BEARING
7 - BEARING CAP
8 - SNAP RINGS
9 - BEARING CAP
Fig. 30 YOKE BEARING CAP
1 - LARGE-DIAMETER SOCKET
2 - VISE
3 - SMALL-DIAMETER SOCKET
WJFRONT AXLE - 186FBI 3 - 37
AXLE - U-JOINT (Continued)

REAR AXLE - 198RBI
TABLE OF CONTENTS
page page
REAR AXLE - 198RBI
DESCRIPTION.........................50
OPERATION...........................50
DIAGNOSIS AND TESTING................51
REMOVAL.............................55
INSTALLATION.........................56
ADJUSTMENTS........................56
SPECIFICATIONS.......................65
SPECIAL TOOLS.......................66
AXLE SHAFTS
REMOVAL.............................69
INSTALLATION.........................69
AXLE BEARINGS/SEALS
REMOVAL.............................69
INSTALLATION.........................70
PINION SEAL
REMOVAL.............................71
INSTALLATION.........................71
COLLAPSIBLE SPACER
REMOVAL.............................73INSTALLATION.........................73
DIFFERENTIAL
REMOVAL.............................75
DISASSEMBLY.........................77
ASSEMBLY............................77
INSTALLATION.........................77
DIFFERENTIAL-TRAC-LOC
DIAGNOSIS AND TESTING................79
DISASSEMBLY.........................79
CLEANING............................82
INSPECTION..........................82
ASSEMBLY............................82
DIFFERENTIAL CASE BEARINGS
REMOVAL.............................83
INSTALLATION.........................84
PINION GEAR/RING GEAR
REMOVAL.............................84
INSTALLATION.........................86
REAR AXLE - 198RBI
DESCRIPTION
The Rear Beam-design Iron (RBI) axle housing has
an iron center casting with axle shaft tubes extend-
ing from either side. The tubes are pressed into and
welded to the differential housing to form a one-piece
axle housing. The axles has semi-floating axle shafts,
meaning that loads are supported by the axle shaft
and bearings. The axle shafts are retained by bearing
retainer plates on the axles which are bolted to
flanges at the outboard end of the axle tubes.
The differential case is a one-piece design. Differ-
ential bearing preload and ring gear backlash is
adjusted by the use of selective spacer shims. Pinion
bearing preload is set and maintained by the use of a
collapsible spacer. A differential cover provides a
means for inspection and service.
Axles with optional Trac-Loktdifferential have a
one-piece differential case, and the same internal
components as a standard differential, plus two
clutch disc packs.
OPERATION
The axle receives power from the transmission/
transfer case through the rear propeller shaft. Therear propeller shaft is connected to the pinion gear
which rotates the differential through the gear mesh
with the ring gear bolted to the differential case. The
engine power is transmitted to the axle shafts
through the pinion mate and side gears. The side
gears are splined to the axle shafts.
STANDARD DIFFERENTIAL
During straight-ahead driving, the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to the gears is
divided and distributed equally between the two side
gears. As a result, the pinion gears revolve with the
pinion mate shaft but do not rotate around it (Fig. 1).
When turning corners, the outside wheel must
travel a greater distance than the inside wheel to
complete a turn. The difference must be compensated
for to prevent the tires from scuffing and skidding
through turns. To accomplish this, the differential
allows the axle shafts to turn at unequal speeds (Fig.
2). In this instance, the input torque applied to the
pinion gears is not divided equally. The pinion gears
now rotate around the pinion mate shaft in opposite
directions. This allows the side gear and axle shaft
attached to the outside wheel to rotate at a faster
speed.
3 - 50 REAR AXLE - 198RBIWJ

TRAC-LOKTDIFFERENTIAL
This differentials clutches are engaged by two con-
current forces. The first being the preload force
exerted through Belleville spring washers within the
clutch packs. The second is the separating forces gen-
erated by the side gears as torque is applied through
the ring gear (Fig. 3).
This design provides the differential action needed
for turning corners and for driving straight ahead
during periods of unequal traction. When one wheel
looses traction, the clutch packs transfer additional
torque to the wheel having the most traction. This
differential resist wheel spin on bumpy roads and
provide more pulling power when one wheel looses
traction. Pulling power is provided continuously until
both wheels loose traction. If both wheels slip due to
unequal traction, Trac-lokŸ operation is normal. Inextreme cases of differences of traction, the wheel
with the least traction may spin.DIAGNOSIS AND TESTING
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, tooth contact, worn/damaged
gears, or the carrier housing not having the proper
offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
Fig. 1 STRAIGHT AHEAD DRIVING
1 - WHEELS ROTATE AT CASE SPEED
2 - PINION GEAR
3 - SIDE GEAR
4 - PINION GEARS ROTATE WITH CASE
Fig. 2 DIFFERENTIAL ON TURNS
1 - PINION GEARS ROTATE ON PINION SHAFT
Fig. 3 TRAC-LOK LIMITED SLIP DIFFERENTIAL
1 - CASE
2 - RING GEAR
3 - DRIVE PINION
4 - PINION GEAR
5 - MATE SHAFT
6 - CLUTCH PACK
7 - SIDE GEAR
8 - CLUTCH PACK
WJREAR AXLE - 198RBI 3 - 51
REAR AXLE - 198RBI (Continued)

(2) Remove ring gear if the ring gear is to be
replaced. The Trac-loktdifferential can be serviced
with the ring gear installed.
(3) Remove the pinion gear mate shaft lock screw
(Fig. 58).
(4) Remove pinion gear mate shaft with a drift and
hammer (Fig. 59).(5) Install and lubricate Step Plate C-6960-3 (Fig.
60).
(6) Assemble Threaded Adapter C-6960-1 into top
side gear. Thread Forcing Screw C-6960-4 into
adapter until it becomes centered in adapter plate.
(7) Position a small screw driver in slot of
Threaded Adapter Disc C-6960-1 (Fig. 61) to prevent
adapter from turning.
(8) Install Forcing Screw C-6960-4 and tighten
screw to 122 N´m (90 ft. lbs.) maximum to compress
Belleville springs in clutch packs (Fig. 62).
(9) With a feeler gauge remove thrust washers
from behind the pinion gears (Fig. 63).
(10) Insert Turning Bar C-6960-2 into the pinion
mate shaft hole in the case (Fig. 64).
(11) Loosen the Forcing Screw in small increments
until the clutch pack tension is relieved and the dif-
ferential case can be turned using Turning Bar.
(12) Rotate differential case until the pinion gears
can be removed.
(13) Remove pinion gears from differential case.
(14) Remove Forcing Screw, Step Plate and
Threaded Adapter.
Fig. 58 MATE SHAFT LOCK SCREW
1 - LOCK SCREW
2 - PINION GEAR MATE SHAFT
Fig. 59 PINION MATE SHAFT
1 - PINION MATE SHAFT
2 - SIDE GEAR
3 - DRIFT
4 - PINION MATE GEAR
Fig. 60 Step Plate
1 - LOWER SIDE GEAR
2 - DIFFERENTIAL CASE
3 - STEP PLATE
3 - 80 REAR AXLE - 198RBIWJ
DIFFERENTIAL-TRAC-LOC (Continued)

(15) Remove top side gear, clutch pack retainer
and clutch pack. Keep plates in correct order during
removal (Fig. 65).
(16)
Remove differential case from the Holding Fix-
ture. Remove side gear, clutch pack retainer and clutch
pack. Keep plates in correct order during removal.
CLEANING
Clean all components in cleaning solvent and dry
components with compressed air.
INSPECTION
Inspect clutch pack plates for wear, scoring or dam-
age. Replace both clutch packs if any one component
in either pack is damaged. Inspect side and pinion
gears for cracks chips or damage and replace as nec-
essary. Inspect differential case and pinion shaft and
replace if worn or damaged.
ASSEMBLY
NOTE: New Plates and discs with fiber coating (no
grooves or lines) must be presoaked in Friction
Modifier before assembly. Soak plates and discs for
a minimum of 20 minutes.
(1) Lubricate components with gear lubricant.
(2) Assemble clutch discs into packs and secure
disc packs with retaining clips (Fig. 66).NOTE: Dished plate is position with the convex side
against the side gear.
(3) Position assembled clutch disc packs on the
side gear hubs.
(4) Install clutch pack and side gear in the ring
gear side of the differential case (Fig. 67).Verify
clutch pack retaining clips are in position and
seated in the case pockets.
Fig. 65 SIDE GEARS AND CLUTCH DISCS
1 - DIFFERENTIAL CASE
2 - RETAINER
3 - SIDE GEAR AND CLUTCH DISC PACK
Fig. 66 CLUTCH PACK
1 - DISCS
2 - DISHED PLATE
3 - RETAINER
4 - SIDE GEAR
5 - RETAINER
6 - PLATES
Fig. 67 CLUTCH PACK AND LOWER SIDE GEAR
1 - DIFFERENTIAL CASE
2 - SIDE GEAR AND CLUTCH PACK
3 - 82 REAR AXLE - 198RBIWJ
DIFFERENTIAL-TRAC-LOC (Continued)

(5) Position the differential case on the Holding
Fixture 6965.
(6) Install lubricated Step Plate C-6960-3 in lower
side gear (Fig. 68).
(7) Install the upper side gear and clutch disc pack
(Fig. 68).
(8) Hold assembly in position. Insert Threaded
Adapter C-6960-1 into top side gear.
(9) Install Forcing Screw C-6960-4 and tighten
screw to slightly compress clutch disc.
(10) Place pinion gears in position in side gears
and verify that the pinion mate shaft hole is aligned.
(11) Rotate case with Turning Bar C-6960-2 until
the pinion mate shaft holes in pinion gears align
with holes in case. It may be necessary to slightly
tighten the forcing screw in order to install the pin-
ion gears.
(12) Tighten forcing screw to 122 N´m (90 ft. lbs.)
maximum to compress the Belleville springs.
(13) Lubricate and install thrust washers behind
pinion gears and align washers with a small screw
driver. Insert mate shaft into each pinion gear to ver-
ify alignment.
(14) Remove Forcing Screw, Step Plate and
Threaded Adapter.(15) Install pinion gear mate shaft and align holes
in shaft and case.
(16) Install pinion mate shaft lock screw finger
tight to hold shaft during differential installation.
(17) Lubricate all differential components with
hypoid gear lubricant.
DIFFERENTIAL CASE
BEARINGS
REMOVAL
(1) Raise and support vehicle.
(2) Remove differential case from axle housing.
(3) Remove bearings from the differential case
with Puller/Press C-293-PA, Adapter 8352 and Plug
SP-3289 (Fig. 69).
Fig. 68 CLUTCH PACK AND UPPER SIDE GEAR
1 - SIDE GEAR AND CLUTCH PACK
2 - DIFFERENTIAL CASE
3 - STEP PLATE
Fig. 69 Differential Bearing
1 - ADAPTERS
2 - BEARING
3 - DIFFERENTIAL
4 - PLUG
5 - PULLER
WJREAR AXLE - 198RBI 3 - 83
DIFFERENTIAL-TRAC-LOC (Continued)

REAR AXLE - 226RBA
TABLE OF CONTENTS
page page
REAR AXLE - 226RBA
DESCRIPTION.........................90
OPERATION...........................90
DIAGNOSIS AND TESTING................92
REMOVAL.............................95
INSTALLATION.........................96
ADJUSTMENTS........................97
SPECIFICATIONS......................105
SPECIAL TOOLS.......................106
AXLE SHAFTS
REMOVAL............................109
INSTALLATION........................109
AXLE BEARINGS/SEALS
REMOVAL............................109
INSTALLATION........................110
PINION SEAL
REMOVAL............................111
INSTALLATION........................112
COLLAPSIBLE SPACER
REMOVAL............................113INSTALLATION........................114
DIFFERENTIAL
REMOVAL............................115
DISASSEMBLY........................117
ASSEMBLY...........................117
INSTALLATION........................117
DIFFERENTIAL - TRAC-LOK
DIAGNOSIS AND TESTING...............119
DISASSEMBLY........................119
CLEANING...........................121
INSPECTION.........................121
ASSEMBLY...........................121
DIFFERENTIAL CASE BEARINGS
REMOVAL............................123
INSTALLATION........................123
PINION GEAR/RING GEAR
REMOVAL............................124
INSTALLATION........................126
REAR AXLE - 226RBA
DESCRIPTION
The Rear Beam-design Aluminum (RBA) axle hous-
ing has an aluminum center casting (differential
housing) with axle shaft tubes extending from either
side. The tubes are pressed into the differential hous-
ing to form a one-piece axle housing. The axle has
semi-floating axle shafts, meaning that vehicle load
is supported by the axle shaft and bearings.
The differential case is a one-piece design. Differen-
tial bearing preload and ring gear backlash is adjusted
with selective shims. Pinion bearing preload is set and
maintained by the use of a collapsible spacer. The cover
provides a means for inspection and service.
Optional Trac-Loktdifferential differential has a
one-piece differential case, and the same internal
components as a standard differential, plus two
clutch disc packs.
Optional Vari-Loktdifferential has a one-piece dif-
ferential case which contains the gerotor pump
assembly and the clutch mechinism. The unit is ser-
viced only as an assembly.
OPERATION
The axle receives power from the transfer case
through the front propeller shaft. The front propellershaft is connected to the pinion gear which rotates
the differential through the gear mesh with the ring
gear bolted to the differential case. The engine power
is transmitted to the axle shafts through the pinion
mate and side gears. The side gears are splined to
the axle shafts.
STANDARD DIFFERENTIAL
During straight-ahead driving the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to the gears is
divided and distributed equally between the two side
gears. As a result, the pinion gears revolve with the
pinion mate shaft but do not rotate around it (Fig. 1).
When turning corners, the outside wheel must travel
a greater distance than the inside wheel to complete a
turn. The difference must be compensated for to prevent
the tires from scuffing and skidding through turns. To
accomplish this, the differential allows the axle shafts
to turn at unequal speeds (Fig. 2). In this instance, the
input torque applied to the pinion gears is not divided
equally. The pinion gears now rotate around the pinion
mate shaft in opposite directions. This allows the side
gear and axle shaft attached to the outside wheel to
rotate at a faster speed.
3 - 90 REAR AXLE - 226RBAWJ

TRAC-LOKTDIFFERENTIAL
The differential clutches are engaged by two con-
current forces. The first being the preload force
exerted through Belleville spring washers within the
clutch packs. The second is the separating forces gen-
erated by the side gears as torque is applied through
the ring gear (Fig. 3).
This design provides the differential action needed
for turning corners and for driving straight ahead
during periods of unequal traction. When one wheel
looses traction, the clutch packs transfer additional
torque to the wheel having the most traction. The
differential resist wheel spin on bumpy roads and
provide more pulling power when one wheel looses
traction. Pulling power is provided continuously until
both wheels loose traction. If both wheels slip due tounequal traction, the operation is normal. In extreme
cases of differences of traction, the wheel with the
least traction may spin.VARI-LOKTDIFFERENTIAL
In a standard differential, if one wheel spins, the
opposite wheel will generate only as much torque as
the spinning wheel.
A gerotor pump and clutch pack are used to pro-
vide the torque transfer capability. One axle shaft is
splined to the gerotor pump and one of the differen-
tial side gears, which provides the input to the pump.
As a wheel begins to lose traction, the speed differ-
ential is transmitted from one side of the differential
to the other through the side gears. The motion of
one side gear relative to the other turns the inner
rotor of the pump. Since the outer rotor of the pump
is grounded to the differential case, the inner and
outer rotors are now moving relative to each other
Fig. 1 OPERATION-STRAIGHT AHEAD DRIVING
1 - IN STRAIGHT AHEAD DRIVING EACH WHEEL ROTATES AT
100% OF CASE SPEED
2 - PINION GEAR
3 - SIDE GEAR
4 - PINION GEARS ROTATE WITH CASE
Fig. 2 OPERATION-ON TURNS
1 - PINION GEARS ROTATE ON PINION SHAFT
Fig. 3 TRAC-LOK LIMITED SLIP DIFFERENTIAL
1 - CASE
2 - RING GEAR
3 - DRIVE PINION
4 - PINION GEAR
5 - MATE SHAFT
6 - CLUTCH PACK
7 - SIDE GEAR
8 - CLUTCH PACK
WJREAR AXLE - 226RBA 3 - 91
REAR AXLE - 226RBA (Continued)