1994 JEEP CHEROKEE Service Repair Manual

Wash bearings with solvent and towel dry, do not
dry with compressed air.Cup and bearing must be
replaced as a matched sets only.
Clean the axle shaft tubes with a clean cloth.
Inspect for;
²Smooth appearance with no broken/dented surfaces
on the bearing rollers or the roller contact surfaces.
²Bearing cups must not be distorted or cracked.
²Machined surfaces should be smooth and without
any raised edges.
²Raised metal on shoulders of cup bores should be
removed with a hand stone.²Wear or damage to pinion gear mate shaft, pinion
gears, side gears and thrust washers. Replace as a
matched set only.
²Worn or chipped teeth to ring and pinion gears.
²Damaged bolt threads to ring gear. Replaced as a
matched set only.
²Pinion yoke for cracks, worn splines, pitted areas,
and a rough/corroded seal contact surface. Repair or
replace the as necessary.
DIFFERENTIAL ASSEMBLY
ASSEMBLY
(1) Install the following components in the differ-
ential case (Fig. 38).
²Differential side gears and thrust washers
²Pinion gears and thrust washers
²Pinion gear mate shaft (align holes in shaft and
case)
(2) Install and seat the locking roll pin in the dif-
ferential case and mate shaft with a punch and ham-
mer (Fig. 38). Peen metal part of case over pin in two
places 180 degrees apart.
If replacement gears and thrust washers were
installed, it is not necessary to measure the gear
backlash. Correct fit is due to close machining
tolerances during manufacture.
(3) Invert the differential case and start two ring
gear bolts. This will provide case-to-ring gear bolt
hole alignment.
(4) Install new ring gear bolts and alternately
tighten to 95-122 Nzm (70-90 ft. lbs.) torque (Fig. 39).
(5) Lubricate all differential components with hy-
poid gear lubricant.
Fig. 35 Front Bearing Cup Removal
Fig. 36 Rear Bearing Cup Removal
Fig. 37 Inner Bearing Removal
2 - 36 FRONT SUSPENSION AND AXLEJ

PINION GEAR DEPTH INFORMATION
Ring and pinion gears are supplied as matched sets
only. The identifying numbers for the ring and pin-
ion gear are etched into the face of each gear (Fig.
40). A plus (+) number, minus (-) number or zero (0)
is etched into the face of the pinion gear. This num-
ber is the amount (in thousandths of an inch) the
depth varies from the standard depth setting of a
pinion etched with a (0). The standard setting from
the centerline of the ring gear to the back face of thepinion is 92.1 mm (3.625 inches) for Model 30 axles
(Fig. 41). The standard depth provides the best teeth
contact pattern.
THE BUTTON END ON THE PINION GEAR
HEAD IS NO LONGER A MACHINED-TO-SPECI-
FICATIONS SURFACE. DO NOT USE THIS SUR-
FACE FOR PINION DEPTH SET-UP OR
CHECKING (Fig. 41).
Compensation for depth variance is achieved by a
selected thickness oil slinger (production) or shims
(service). The slinger is placed between the inner
pinion bearing cone and gear head (Fig. 42). The
shim pack is placed under the inner (rear) bearing
cup for service. To change the pinion adjustment,
shims are available in thicknesses of 0.003, 0.005,
and 0.010 inch.The oil slinger or baffle must be
measured and the thickness included with the
total shim pack.
New gear set: note the depth variance etched
into both the original and the replacement pin-
ion gear. Add or subtract the thickness of the
Fig. 38 Mate Shaft Pin Installation
Fig. 39 Ring Gear Bolt Installation
Fig. 40 Pinion Gear ID Numbers
Fig. 41 Pinion Gear Head
JFRONT SUSPENSION AND AXLE 2 - 37

original depth shims to compensate for the dif-
ference in the depth variances. Refer to the
Depth Variance charts.
Note where Old and New Pinion Marking columns
intersect. Intersecting figure represents plus or mi-
nus amount needed.
For example, if old pinion is plus (+) 1 and the
new pinion is minus (-) 3, intersecting figure is
(+)0.004 inch (0.10mm). Add this amount to the
original shim. Or if the old pinion is (-) 3 and thenew pinion is (-) 2, intersecting figure is (-)0.001 inch
(0.025mm). Subtract this amount from original shim.
Refer to the Pinion Gear Depth Variance Chart.
DIFFERENTIAL AND PINION MEASUREMENT
DIFFERENTIAL ZERO END PLAY
MEASUREMENT
(1) Place Master Differential Bearing D-134
(D-348) on the case hubs (Fig. 43) and install differ-
ential case into housing.
(2) Install a pilot stud at the right side of housing.
Attach Dial Indicator to the pilot stud. Load indica-
tor plunger against the back of the ring gear (Fig.
44).
(3) Insert a small pry bar between the bearing cap
and left side of differential case. Pry the case as far
as possible to right side (Fig. 44). Zero the dial indi-
cator pointer.
(4) Pry the case to left side andrecordthe travel
distance.
The measurement above is the shim thickness
necessary for case zero end-play. The total
thickness will be determined during the ring
gear backlash adjustment.
(5) Remove indicator, pilot stud and differential
case from housing.
PINION GEAR DEPTH MEASUREMENT
Pinion gear depth measurement is necessary
when axle housing is replaced or pinion select
shim pack is unknown. It is also recommended
when ring and pinion gears are replaced.
PINION GEAR DEPTH VARIANCE
Fig. 42 Shim Locations
2 - 38 FRONT SUSPENSION AND AXLEJ

Measurements are done with pinion cups and pin-
ion bearings installed in housing. Take measure-
ments with Pinion Gauge Set 6774, Pinion Block
6733 and Dial Indicator C-3339 (Fig. 45).
(1) Assemble Pinion Gauge Set, Pinion Block and
pinion bearings. Install assembly into differential
pinion gear bore and hand tighten cone (Fig. 46).
(2) Place Arbor Disc 6732 on Arbor D-115-3 and
position in the bearing cradles (Fig. 47). Install dif-
ferential bearing caps on Arbor Discs and tighten
caps snug only.
Fig. 45 Pinion Gear Depth Gauge Tools
Fig. 46 Pinion Height Block
Fig. 47 Gauge Tools In Housing
Fig. 43 Master Bearing Tools On Hubs
Fig. 44 Differential Case End Play Measurement
JFRONT SUSPENSION AND AXLE 2 - 39

Arbor Discs have different steps to fit other
axle sizes. Pick correct size step for axle being
serviced.
(3) Firmly place Scooter Block and Dial Indicator
on pinion height block tool and zero the dial indica-
tor pointer.
(4) Slide the Scooter Block across the arbor while
observing indicator (Fig. 48). Record the longest
travel distance, whether inward (-) or outward (+),
indicated by the pointer.
The plunger travel distance indicated, plus or
minus the variance etched in the gear is the re-
quired thickness for the depth shims.
(5) Measure the thickness of each depth shim with
a micrometer and combine the shims necessary fortotal required shim pack thickness.Include oil
slinger or baffle thickness with the total shim
pack thickness.
(6) Remove the measurement tools from the differ-
ential housing.
PINION GEAR ASSEMBLY/INSTALLATION
(1) Place the shims (and baffle if equipped) in the
pinion gear rear bearing bore. Install the bearing cup
with Installer D-146 and Driver Handle C-4171 (Fig.
49). Ensure cup is correctly seated.
(2) Install the pinion front bearing cup with In-
staller D-144 and Handle C-4171 (Fig. 50).
(3) Install the rear bearing and oil slinger on the
pinion gear with Installer W-262 until completely
seated (Fig. 51).
Fig. 48 Pinion Depth Measurement
Fig. 49 Pinion Rear Bearing Cup Installation
Fig. 50 Pinion Front Bearing Cup Installation
Fig. 51 Pinion Rear Bearing Installation
2 - 40 FRONT SUSPENSION AND AXLEJ

(4) Assemble collapsible spacer onto pinion shaft
(Fig. 52).
(5) Install pinion front bearing cone into cup and
end yoke thrust washer.
(6) Apply a light coat of gear lubricant on lip of
new pinion seal. Install seal with Installer W-147-E
and Handle C-4171 (Fig. 53).
(7) Install pinion gear into differential housing.
(8) Install yoke with Installer W-162-D and
Wrench C-3281 (Fig. 54).(9) Install the yoke washer and a new nut on the
pinion gear. Use Flange Wrench C-3281 to retain the
yoke (Fig. 55). Tighten nut to 216 Nzm (160 ft.lbs.)
torque or enough to remove play.Do not over-
tighten.
CAUTION: Never loosen the pinion gear nut to de-
crease the pinion gear bearing preload torque. If the
specified preload torque is exceeded, a new col-
lapsible spacer must be installed. The torque se-
quence will have to be repeated.
Fig. 52 Collapsible Preload Spacer
Fig. 53 Pinion Seal Installation
Fig. 54 Pinion Yoke Installation
Fig. 55 Tightening Pinion Nut
JFRONT SUSPENSION AND AXLE 2 - 41

(10) Use Flange Wrench C-3281 to retain the yoke
(Fig. 55). Slowly tighten the nut in small increments
until the rotating torque is achieved. Measure the ro-
tating torque frequently to avoid over-tightening the
nut.
(11) Check bearing rotating torque with an inch
pound torque wrench (Fig. 56). The torque necessary
to rotate the pinion gear should be;
²Original Bearings Ð 1 to 3 Nzm (10 to 20 in. lbs.).
²New BearingsÐ2to5Nzm (15 to 35 in. lbs.).
DIFFERENTIAL SHIM PACK MEASUREMENT AND
ADJUSTMENT
(1) Place Master Differential Bearing D-134
(D-348) on the case hubs.
(2) Install a pilot stud at the left side of housing.
Attach Dial Indicator to housing. Load the indicator
plunger against the back of the ring gear (Fig. 57).
Ensure ring and pinion gear teeth are tightly
meshed. Zero the indicator.
(3) Insert a small pry bar between the bearing cap
and left side of differential case. Pry the case as far
as possible to right side (Fig. 57). Zero the dial indi-
cator pointer.
(4) Repeat the measurement several times to check
consistency. Record the travel distance.
The measurement above shows shim thickness
necessary to eliminate ring gear backlash. Sub-
tract this thickness from case zero end-play
shim thickness (Fig. 58). The shims must be
placed at the ring gear side between the case
and bearing.
(5) Remove indicator and pilot stud.
(6) Remove the differential case from housing.(7) Remove the master bearing tools from the dif-
ferential case hubs.
(8) Position the backlash shims (with determined
thickness) on case hub (ring gear side). Install bear-
ing on the hub with Bearing Installer C-3716-A and
Driver Handle C-4171 (Fig. 59).
(9) Position the remaining zero end-play shims on
hub at opposite side of case. Include an additional
Fig. 56 Check Pinion Gear Torque
Fig. 57 Shim Pack Measurement
Fig. 58 Shim Pack Calculations
2 - 42 FRONT SUSPENSION AND AXLEJ

0.015 in. (0.38 mm) thick shim on this hub. This will
provide the required differential bearing preload
torque.
(10) Install bearings on hubs with Installer
C-3716-A and Handle C-4171 (Fig. 59).
(11) Match each bearing cup with bearing (origi-
nal). Install the cups on the bearings.
DIFFERENTIAL INSTALLATION
(1) Position Spreader W-129-B with the tool dowel
pins seated in the locating holes (Fig. 60). Install the
holddown clamps and tighten the tool turnbuckle fin-
ger-tight.
(2) Install a pilot stud at the left side of the differ-
ential housing. Attach Dial Indicator to housing pilotstud. Load the indicator plunger against the opposite
side of the housing (Fig. 60) and zero the indicator.
CAUTION: Do not spread over 0.38 mm (0.015 in). If
the housing is over-separated, it could be distorted
or damaged.
(3) Spread the housing enough to install the case
in the housing. Measure the distance with the dial
indicator (Fig. 60).
(4) Remove the dial indicator.
(5) Install case in the housing. Tap the differential
case to ensure the bearings are fully seated (Fig. 61).
Remove the spreader.
(6) Install the bearing caps at their original loca-
tions (Fig. 62). Tighten the bearing cap bolts to 61
Nzm (45 ft. lbs.) torque.
Fig. 59 Differential Bearing Installation
Fig. 60 Spread Differential Housing
Fig. 61 Differential Installation
Fig. 62 Differential Bearing Cap Reference Letters
JFRONT SUSPENSION AND AXLE 2 - 43