1994 JEEP CHEROKEE suspension

Above that temperature range the viscosity will de-
crease, and below that range the viscosity will in-
crease.
An engine oil with an SAE 5W-30 viscosity grade
provides good flow capability for fast cold weather
engine starts. The viscosity will then increase with
engine temperature to provide good high-tempera-
ture engine lubrication.
API SERVICE GRADE
The API Service Grade specifies the type of engine/
operating conditions for which the oil is intended.
The API Service Grade specifications also apply to
energy conserving engine oils (Fig. 3). The API cer-
tification mark is also used indicating that the oil is
certified to meet the most critical requirements es-
tablished by the manufacturer (Fig. 4).
For maximum protection, use API Service Grade
SG, SG/CD or SG/CE engine oil in Jeeptengines.
GEAR LUBRICANTS
A dual SAE viscosity grade is also used to specify
the viscosity of multipurpose gear lubricants.
The API lubrication quality grade designation
identifies gear lubricants in terms of recommended
usage.
CHASSIS COMPONENT AND WHEEL BEARING
LUBRICANTS
The chassis component and wheel bearing lubri-
cants are identified by the NLGI Certification Sym-
bol (Fig. 5).
The letterGindicates wheel bearing lubricant and
the letterLindicates chassis lubricant. When the
letters are combined the lubricant can be used for
dual applications. The suffix lettersCandBindi-
cates quality level of the lubricant. Use only lubri-
cants that display the NLGI Certification Symbol.
RECOMMENDED LUBRICANT AND REPLACEMENT
PARTS
Jeeptvehicles are engineered to provide many
years of dependable operation. When necessary,MO-
PAR brand lubricants and genuine replacement
partsare highly recommended.
COMPONENTS REQUIRING NO LUBRICATION
There are many components that should not be lu-
bricated. The components that shouldnotbe lubri-
cated are:
²air pumps;
²generator bearings;
²drive belts;
²drive belt idler pulleys;
²rubber bushings;
²starter motor bearings;
²suspension strut bearings;
²throttle control cables;
²throttle linkage ball joints; and
²water pump bearings.
Fig. 4 The API Engine Oil Certification Mark
Fig. 5 NLGI Lubricant Certification/Identification
Symbol
JLUBRICATION AND MAINTENANCE 0 - 3

PORTABLE STARTING UNIT
There are many types of portable starting units
available for starting engines. Follow the manufac-
turer's instructions when involved in any engine
starting procedure.
HOISTING RECOMMENDATIONS
FLOOR JACK
When properly positioned, a floor jack can be used
to lift a Jeeptvehicle. Support the vehicle in the
raised position with jack stands at the front and rear
ends as applicable (Fig. 7).
CAUTION: Do not attempt to lift a JeepTvehicle
with a floor jack positioned under:
²an axle tube,
²a body side sill,
²a steering linkage component,
²a drive shaft,
²the engine or transmission oil pan,
²the fuel tank, or
²a front suspension arm.
Use the correct sub-frame rail or frame rail
lifting locations only (Fig. 7).
HOIST
A Jeeptvehicle can be lifted with a swiveling-arm
type hoist; with a wheel-lift, twin-post hoist; or with
a ramp-type, drive-on hoist.
When a swiveling-arm, frame-contact type
hoist is used, ensure that the lifting pads are po-
sitioned at the correct sub frame rail (Fig. 7).
TOWING RECOMMENDATIONS
TOWING EQUIPMENT
A vehicle equipped with SAE approved sling-type
towing equipment can be used to tow all Jeeptvehi-
cles (Fig. 8). When it is necessary to rear-tow a vehi-
cle, use the wheel-lift towing method with a tow
dolly located under the front wheels. A vehicle with
flat-bed towing equipment can also be used to trans-
port a disabled vehicle.
A wooden crossbeam with spacer blocks could pos-
sibly be required for proper connection when using
the sling-type, front-end towing method (Fig. 9).
SAFETY PRECAUTIONS
The following safety precautions must be consid-
ered when preparing for and during a vehicle towing
operation:
Fig. 7 Correct Vehicle Lifting LocationsÐTypical
Fig. 8 Tow Vehicles With Approved Equipment
Fig. 9 Crossbeam & Spacer Block Construction
0 - 8 LUBRICATION AND MAINTENANCEJ

FRONT SUSPENSION AND AXLE
CONTENTS
page page
AXLE NOISE/VIBRATION DIAGNOSIS....... 16
FRONT WHEEL ALIGNMENT............... 5
GENERAL INFORMATION.................. 1
MODEL 30 AXLE AND TUBE AXLE (2WD) . . 20TORQUE SPECIFICATIONS................ 47
XJ FRONT SUSPENSION................. 10
YJ FRONT SUSPENSION................. 13
GENERAL INFORMATION
FRONT SUSPENSION
XJ VEHICLES
The Cherokee front suspension is a link/coil design
comprised of (Fig. 1);
²Drive axle (4WD), tube axle (2WD)
²Track bar
²Stabilizer bar
²Upper and lower suspension arms
²Coil springs
²Dual-action shock absorbers²Jounce bumpers (used to limit the travel of the
suspension)
The link/coil suspension allows each wheel to adapt
to different road surfaces without greatly affecting
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
Fig. 1 XJ Front Suspension
JFRONT SUSPENSION AND AXLE 2 - 1

axle assembly to the frame. The lower arms uses
shims at the frame mount to allow for adjustment of
caster and pinion angle. The suspension arm travel
(jounce or rebound) is limited through the use of rub-
ber bumpers.
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 frame. The bot-
tom of the shocks are bolted to the axle spring
bracket.
The stabilizer bar is used to minimize vehicle front
sway 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 frame 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 does the four-wheel
drive front axle. The steering knuckles and hub bear-
ing 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 uses semi-elliptic multi-leaf
springs mounted on the drive axle. The rearward end
of the springs are mounted to the frame rail hangers
through rubber bushings. The bushings isolate road
noise as the springs move. The forward end of the
springs are attached to the frame with shackles. The
spring and shackles use rubber bushings to isolate
road noise. The shackles allow the springs to changetheir length as the vehicle moves over various road
conditions. The spring and axle travel (jounce or re-
bound) is limited through use of rubber bumpers
mounted on the frame.
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. The bushings should never be lu-
bricated.
Fig. 2 Front AxleÐ 2WD Vehicles
Fig. 3 YJ Front Suspension
2 - 2 FRONT SUSPENSION AND AXLEJ

The shocks absorbers dampen jounce and rebound
of the vehicle over various road conditions. The top of
the shock absorbers are bolted to the frame. The bot-
tom of the shocks are bolted to the axle bracket.
The stabilizer bar is used to minimize vehicle front
sway 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 frame 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 track bar is attached to a
frame rail bracket and the axle bracket.
The bar uses bushings at both ends.
FRONT DRIVE AXLE
It is not necessary to remove the complete axle
from the vehicle for routine differential service. If
the differential housing or axle shaft tubes are dam-
aged, the complete axle assembly can be removed
and serviced.
For complete drive axle assembly removal and in-
stallation refer to Drive Axle Assembly Replacement
in this Group.
The removable cover provides for servicing without
removing axle from vehicle.
The integral type housing, hypoid gear design has
the centerline of the pinion set above the centerline
of the ring gear.
The Model 30 axle has the assembly part number
and gear ratio listed on a tag. The tag is attached to
the housing cover (Fig. 4). Build date identification
codes are stamped on the axle shaft tube cover side.XJ and YJ axles are equipped with an optional
A.B.S. brake system. The A.B.S. tone rings are
pressed onto the axle shaft near the hub and
knuckle. For additional information on the A.B.S.
system refer to Group 5, Brakes.
²XJ vehicles use a non-disconnect axle.
²YJ vehicles use a vacuum disconnect axle (Fig. 5).
STANDARD DIFFERENTIAL OPERATION
The differential gear system divides the torque be-
tween the axle shafts. It allows the axle shafts to ro-
tate at different speeds when turning corners.
Each differential side gear is splined to an axle
shaft. The pinion gears are mounted on a pinion
mate shaft and are free to rotate on the shaft. The
pinion gear is fitted in a bore in the differential case
and is positioned at a right angle to the axle shafts.
In operation, power flow occurs as follows:
²Pinion gear rotates the ring gear
²Ring gear (bolted to the differential case) rotates
the case
²Differential pinion gears (mounted on the pinion
mate shaft in the case) rotate the side gears
²Side gears (splined to the axle shafts) rotate the
shafts
During straight-ahead driving, the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to gears is di-
vided 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. 6).
When turning corners, the outside wheel must travel
a greater distance than the inside wheel. This difference
must be compensated for in order to prevent the wheels
from scuffing and skidding through the turn. To accom-
plish this, the differential allows the axle shafts to turn
at unequal speeds (Fig. 7). 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 ro-
tate at a faster speed.
Fig. 4 Model 30 Differential Cover
Fig. 5 Disconnect Feature
JFRONT SUSPENSION AND AXLE 2 - 3

Fig. 6 Differential OperationÐStraight-Ahead
DrivingFig. 7 Differential OperationÐOn Turns
2 - 4 FRONT SUSPENSION AND AXLEJ

FRONT WHEEL ALIGNMENT
INDEX
page page
Alignment Measurements and Adjustments...... 6
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 the
top of the knuckle forward provides negative caster.
Caster is a directional stability angle whichenables 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).
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-
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
Fig. 1 Wheel Alignment Measurements
JFRONT SUSPENSION AND AXLE 2 - 5

not change except when a spindle or ball stud is
damaged or bent. The angle is not adjustable and the
damaged component(s) must be replaced to correct
mis-alignment.
CAUTION: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.
(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 and noise.
Check components for correct torque. Refer to Groups
2 and 3, Suspension and Axle for additional informa-
tion.
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 (Fig. 1) is preset at ZERO
DEGREES (0É). The angle is not adjustable and can-
not be altered.
CASTER
The caster angle (Fig. 1) is set at:
²XJ manual transmission, POSITIVE 6.5 DE-
GREES (+6.5É).
²XJ automatic transmission, POSITIVE 8.0 DE-
GREES (+8.0É).
²YJ all transmissions, POSITIVE 6.0 DEGREES
(+6.0É).
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, and make left and right
turns. If the steering wheel returns to the center po-
sition unassisted, the caster angle is correct. How-ever, if steering wheel does not return toward the
center position unassisted, 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.
Fig. 2 AdjustmentÐYJ Vehicles
Fig. 3 AdjustmentÐXJ Vehicles
2 - 6 FRONT SUSPENSION AND AXLEJ