hose unless the caliper must also be removed
for maintenance.Support the caliper with a
hanger to prevent brake fluid hose damage.
(2) Remove the dust cap, the cotter pin, the nut re-
tainer, the adjustment nut, and the thrust washer
from the spindle (Fig. 3). Discard the cotter pin.
(3) Remove the wheel outer bearing from the hub.
(4) Remove the wheel hub/disc brake rotor from
the spindle.
(5) Remove the seal and the inner wheel bearing
from the hub cavity.
(6) After removal, inspect both front wheel bearing
races for indications of pitting, brinelling and exces-
sive heat.
(7) Wipe the spindle clean and apply a small
amount of chassis/wheel bearing lubricant (NLGI
GC-LB lubricant) to prevent rust. Wipe the wheel
hub cavity clean.
CAUTION: Do not over-fill the wheel hub cavity with
lubricant. Excessive lubricant can cause overheat-
ing and bearing damage. Also, excessive lubricant
can be forced out of the wheel hub cavity and con-
taminate the brake rotor/pads.
(8) Partially fill the wheel hub cavity with chassis/
wheel bearing lubricant (NLGI GC-LB lubricant).
(9) Pack the wheel bearings with chassis/wheel
bearing lubricant (NLGI GC-LB lubricant). Ensure
that sufficient lubricant is forced between the bear-
ing rollers.
(10) Install the wheel inner bearing in the wheel
hub and install a replacement seal.
(11) Clean the disc brake rotor contact surfaces, if
necessary.
(12) Install the wheel hub/disc brake rotor on the
spindle.
(13) Install the wheel outer bearing, the thrust
washer, and the spindle nut.(14) Tighten the spindle nut with 28 Nzm (21 ft.
lbs.) torque while rotating the disc brake rotor to
seat the bearings.
(15) Loosen the spindle nut 1/2 turn. While rotat-
ing the disc brake rotor, tighten the spindle nut with
2Nzm (19 in. lbs.) torque.
(16) Install the nut retainer and a replacement cot-
ter pin.
(17) Clean the dust cap and apply wheel bearing
lubricant to the inside surface.Do not fill the dust
cap with lubricant.
(18) Install the dust cap.
(19) Install the disc brake caliper.
POWER STEERING SYSTEM
The power steering fluid level should be inspected
when other under hood service is performed. For
proper service procedures, refer to Group 19, Steer-
ing.
Inspect the power steering system (Fig. 4, and 5)
for the sources of fluid leaks, steering gear housing
cracks and ensure that the steering gear is securely
attached to the vehicle frame rail. Inspect the steer-
ing damper for leaks and loose connections.
FLUID SPECIFICATION
Use MOPAR Power Steering Fluid, or an equiva-
lent product.
POWER STEERING FLUID INSPECTION
WARNING: ENGINE MUST NOT BE RUNNING WHEN
INSPECTING POWER STEERING FLUID LEVEL,
PERSONAL INJURY CAN RESULT.
Fig. 3 2WD Front Wheel BearingsÐXJ Vehicles
Fig. 4 Power Steering SystemÐXJ Vehicles
JLUBRICATION AND MAINTENANCE 0 - 29
the opposite wheel. Wheels are attached to a hub/
bearings which bolts to the knuckles. The hub/bear-
ing is not serviceable and is replaced as a unit.
Steering knuckles pivot on replaceable ball studs at-
tached to the axle tube yokes.
The upper and lower suspension arms are different
lengths, with bushings at both ends. They bolt the
axle assembly to the body. The lower arms uses
shims at the body mount to allow for adjustment of
caster and drive shaft pinion angle. The suspension
arm travel is limited through the use of jounce
bumpers in compression and shocks absorbers in re-
bound.
Suspension components which use rubber bushings
should be tightened at vehicle ride height. This will
prevent premature failure of the bushing and main-
tain ride comfort. Bushings must never be lubricated.
The coil springs control ride quality and maintain
proper ride height. The coil springs mount up in the
fender shield which is part of the unitized body
bracket. A rubber isolator is located between the top
of the spring and the frame. The bottom of the spring
seats on a axle pad and is retained with a clip.
The shock absorbers dampen jounce and rebound of
the vehicle over various road conditions. The top of
the shock absorbers are bolted to the body. The bot-
tom of the shocks are bolted to the axle spring
bracket.
The stabilizer bar is used to minimize vehicle body
roll during turns. The spring steel bar helps to con-
trol the vehicle body in relationship to the suspen-
sion. The bar extends across the front underside of
the chassis and connects to the body rails. Links are
connected from the bar to the axle brackets. Stabi-
lizer bar mounts are isolated by rubber bushings.
The track bar is used to minimize front axle side-
to-side movement. The bar is attached to a frame rail
bracket with a ball stud and isolated with a bushing
at the axle bracket.
TUBE AXLE (2WD VEHICLES)
The front axle used on two-wheel drive vehicles is
a one-piece, tubular axle (Fig. 2). The tubular axle
mounts in the same bracketry as the four-wheel
drive axle.
The steering knuckles and hub bearing assemblies
are the same as used on the Model 30 drive axle.
YJ VEHICLES
The Wrangler (YJ) front suspension is leaf spring
design comprised of (Fig. 3);
²Drive axle
²Track bar
²Stabilizer bar
²Leaf springs
²Dual-action shock absorbers
²Jounce bumpers (used to limit the travel of the
suspension)The front suspension has semi-elliptic multi-leaf
springs mounted to the axle assembly. The rearward
end of the springs are mounted to the frame rail
hangers. The forward end of the springs are attached
to the frame with shackles. The springs and shackles
use rubber bushings to isolate road noise. The shack-
les allow the springs to change their length as the
vehicle moves over various road conditions. The
Fig. 2 Front AxleÐ2WD Vehicles
Fig. 3 YJ Front Suspension
2 - 2 FRONT SUSPENSION AND AXLEJ
FRONT WHEEL ALIGNMENT
INDEX
page page
Alignment Measurements and Adjustments....... 8
General Information........................ 5Pre-Alignment Inspection.................... 6
GENERAL INFORMATION
Front wheel alignment involves the correct posi-
tioning of the wheels in relation to the vehicle. The
positioning is accomplished through suspension and
steering linkage adjustments. An alignment is con-
sidered essential for efficient steering, good direc-
tional stability and to maximize tire wear. The most
important measurements of front end alignment are
caster, camber and toe position.
Routine inspection of the front suspension
and steering components is a good preventative
maintenance practice. Inspection also helps to
ensure safe operation of the vehicle.
²CASTER is the forward or rearward tilt of the
steering knuckle from vertical. Tilting the top of the
knuckle rearward provides positive caster. Tilting thetop of the knuckle forward provides negative caster.
Caster is a directional stability angle. This angle en-
ables the front wheels to return to a straight ahead
position after turns (Fig. 1).
²CAMBER is the inward or outward tilt of the
wheel relative to the center of the vehicle. Tilting the
top of the wheel inward provides negative camber.
Tilting the top of the wheel outward provides positive
camber. Incorrect camber will cause wear on the in-
side or outside edge of the tire (Fig. 1). The angle is
not adjustable, the damaged component(s) must be
replaced to correct mis-alignment.
²WHEEL TOE POSITION is the difference between
the leading inside edges and trailing inside edges of
the front tires (Fig. 1). Incorrect wheel toe position is
the most common cause of unstable steering and un-
Fig. 1 Wheel Alignment Measurements
JFRONT SUSPENSION AND AXLE 2 - 5
even tire wear. The wheel toe position is thefinal
front wheel alignment adjustment.
²STEERING AXIS INCLINATION ANGLE is mea-
sured in degrees and is the angle that the steering
knuckles are tilted (Fig. 1). The inclination angle has
a fixed relationship with the camber angle. It will not
change except when a spindle or ball stud is dam-
aged or bent. The angle is not adjustable, the dam-
aged component(s) must be replaced to correct mis-
alignment.
WARNING: DO NOT ATTEMPT TO MODIFY ANY
SUSPENSION OR STEERING COMPONENT BY
HEATING AND BENDING.
PRE-ALIGNMENT INSPECTION
Before starting a front wheel alignment, the follow-
ing inspection and necessary corrections must be
completed.(1) Tires with the same recommended air pressure,
size, and thread wear. Refer to Group 22, Tires And
Wheels for diagnosis information.
(2) Front wheel bearings for wear and looseness.
(3) Ball studs, steering linkage pivot points and
steering gear for looseness, roughness, binding or
wear. Refer to Group 19, Steering for additional in-
formation.
(4) Front wheels for excessive radial or lateral
runout and unbalance. Refer to Group 22, Tires And
Wheels for diagnosis information.
(5) Suspension components for wear. Check compo-
nents for correct torque. Refer to Groups 2 and 3,
Suspension and Axle for additional information.
2 - 6 FRONT SUSPENSION AND AXLEJ
ALIGNMENT MEASUREMENTS AND ADJUSTMENTS
Before each alignment reading, the vehicle should
be jounced (rear first, then front). Grasp each
bumper at the center and jounce the vehicle up and
down several times. Always release the bumper in
the down position.Set the front end alignment to
specifications with the vehicle at its NOR-
MALLY RIDE HEIGHT.
CAMBER
The wheel camber angle is preset. This angle is not
adjustable and cannot be altered.
CASTER
Before checking the caster of the front axle for cor-
rect angle, be sure the axle is not bent or twisted.
Road test the vehicle, make left and right turns. If
the steering wheel returns to the center position un-
assisted, the caster angle is correct. If steering wheeldoes not return toward the center position unas-
sisted, an incorrect caster angle is probable.
Caster can be adjusted by installing the appropri-
ate size shims (Fig. 2, 3).Changing caster angle
will also change the front propeller shaft angle.
The propeller shaft angle has priority over
caster. Refer to Group 16, Propeller Shafts for
additional information.
TOE POSITIONÐXJ VEHICLES
The wheel toe position adjustment should be the fi-
nal adjustment.
(1) Start the engine if equipped with power steer-
ing. Turn wheels both ways before straightening the
Fig. 2 AdjustmentÐYJ Vehicles
Fig. 3 AdjustmentÐXJ Vehicles
Fig. 4 Steering LinkageÐXJ (LHD)
2 - 8 FRONT SUSPENSION AND AXLEJ
wheels. Secure the steering wheel with the front
wheels in the straight-ahead position. Turn off the
engine.
(2) Loosen the adjustment sleeve clamp bolts (Fig.
4, 5).
(3) Adjust the right wheel toe position with the
drag link. Turn the sleeve until the right wheel is at
specifications. Position the clamp bolts as shown (Fig.
6) and tighten to 49 Nzm (36 ft. lbs.) torque.Make
sure the toe setting does not change during
clamp tightening.(4) Adjust the left wheel toe position with the tie
rod. Turn the sleeve until the left wheel is at specifi-
cations. Position the clamp bolts as shown (Fig. 6)
and tighten to 27 Nzm (20 ft. lbs.) torque.Make sure
the toe setting does not change during clamp
tightening.
(5) Verify the right toe setting.
Fig. 5 Steering LinkageÐXJ (RHD)
Fig. 6 Drag Link and Tie Rod Clamp Location (LHD)
JFRONT SUSPENSION AND AXLE 2 - 9
TOE POSITIONÐYJ VEHICLES
The wheel toe position should be the final front
wheel alignment adjustment. In all instances follow
the equipment manufacturer's recommended proce-
dure.
(1) Start the engine if equipped with power steer-
ing. Turn wheels both ways before straightening the
wheels. Secure the steering wheel with the front
wheels in the straight-ahead position. Turn off the
engine.
(2) Loosen the adjustment sleeve clamp bolts on
the tie rod (Fig. 7).The tie rod and adjustment sleeve have both
right and left hand threads to provide equal ad-
justment for each wheel.
(3) After the adjustment is completed, position the
tie rod adjustment sleeve clamp bolts as shown.
(4) Tighten the adjustment sleeve clamp bolts to
27 Nzm (20 ft. lbs.) torque.
(5) Complete the adjustment. Position the drag
link clamp bolts as shown. Tighten the bolts to 49
Nzm (36 ft. lbs.) torque.
Fig. 7 Steering Linkage
YJ Vehicles
ALIGNMENT SPECIFICATIONSÐXJ VEHICLESALIGNMENT SPECIFICATIONSÐYJ VEHICLES
2 - 10 FRONT SUSPENSION AND AXLEJ
MODEL 30 AXLE AND TUBE AXLE (2WD)
INDEX
page page
Axle Bushing Replacement.................. 34
Axle ShaftÐCardan U-Joint.................. 26
Backlash and Contact Pattern Analysis......... 45
Cleaning/Inspection........................ 37
Differential and Pinion Measurement........... 40
Differential Assembly....................... 38
Differential Disassembly.................... 35
Differential Installation...................... 44
Differential Removal....................... 34
Differential Shim Pack Measurement and
Adjustment............................ 43
Drive Axle Assembly ReplacementÐXJ Vehicles . . 23
Drive Axle Assembly ReplacementÐYJ Vehicles . . 24Final Assembly........................... 46
Hub Bearing and Axle Shaft................. 25
Information.............................. 22
Inner Axle Shaft Oil Seal Replacement......... 35
Lubricant Change......................... 23
Lubricant Specifications..................... 22
Pinion Gear Assembly/Installation............. 42
Pinion Gear Depth Information............... 39
Pinion Removal/Disassembly................. 36
Pinion Seal Replacement................... 25
Steering Knuckle and Ball Studs.............. 32
Vacuum Disconnect AxleÐYJ Vehicles......... 27
INFORMATION
The Model 30 front axles consists of a cast iron dif-
ferential housing with axle shaft tubes extending
from either side. The tubes are pressed into the dif-
ferential housing and welded.
The integral type housing, hypoid gear design has
the centerline of the pinion set above the centerline
of the ring gear.
The axle has a fitting for a vent hose used to re-
lieve internal pressure caused by lubricant vaporiza-
tion and internal expansion.
The axles are equipped with semi-floating axle
shafts, meaning that loads are supported by the hub
bearings. The axle shafts are retained by nuts at the
hub bearings. The hub bearings are bolted to the
steering knuckle at the outboard end of the axle tube
yoke. The hub bearings are serviced as an assembly.
The axles are equipped with ABS brake sensors.
The sensors are attached to the knuckle assemblies
and tone rings are pressed on the axle shaft.Use
care when removing axle shafts as NOT to dam-
age the tone wheel or the sensor.
The stamped steel cover provides a means for in-
spection and servicing the differential.
The Model 30 axle has the assembly part number
and gear ratio listed on a tag. The tag is attached to
the housing cover. Build date identification codes are
stamped on the axle shaft tube cover side.
The differential case is a one-piece design. The dif-
ferential pinion mate shaft is retained with a roll
pin. Differential bearing preload and ring gear back-
lash is adjusted by the use of shims (select thick-
ness). The shims are located between the differential
bearing cones and case. Pinion bearing preload is set
and maintained by the use of collapsible spacer.
COMMAND-TRACÐYJ VEHICLES
The Command-Trac system is a vacuum disconnect
axle. The system has a two-piece axle shaft coupled
together by a shift collar. For two-wheel drive opera-
tion, the vacuum motor and shift fork disengages the
axle shaft splines. For four-wheel drive operation, the
vacuum motor and shift fork engages the axle
splines.
SELEC-TRACÐXJ VEHICLES
The Selec-Trac system is a non-disconnect axle.
Shifting from two-wheel to four-wheel drive is done
at the transfer case.
For XJ vehicles equipped withSelec-Tracand
ABS brake system, refer to Group 5ÐBrakes for ad-
ditional service information.
LUBRICANT SPECIFICATIONS
Multi-purpose, hypoid gear lubricant should be
used for Model 30 axles. The lubricant should have
MIL-L-2105C and API GL 5 quality specifications.
MOPARtHypoid Gear Lubricant conforms to both of
these specifications.
²The factory fill for the Model 30 axle is SAE Ther-
mally Stable 80W-90 gear lubricant.Do not use
heavier weight lubricant, this will cause axle
engagement difficulties.
²The factory installed lubricant quantity for the
NON-DISCONNECT TYPE AXLE is 1.48 L (3.13
pts.).
²The factory installed lubricant quantity for the
VACUUM-DISCONNECT TYPE AXLE is 1.65 L (3.76
pts.).
Refer to Group 0, Lubrication and Maintenance for
additional information regarding temperature range,
viscosity and fluid level.
2 - 22 FRONT SUSPENSION AND AXLEJ