Jeep Cherokee (XJ): Alignment

Description and operation

WHEEL ALIGNMENT

DESCRIPTION

Wheel alignment involves the correct positioning of the wheels in relation to the vehicle. The positioning is accomplished through suspension and steering linkage adjustments. An alignment is considered essential for efficient steering, good directional stability and to minimize tire wear. The most important measurements of an alignment are caster, camber and toe position (Fig. 1).

CAUTION: Never attempt to modify suspension or steering components by heating or bending.

CAUTION: Components attached with a nut and cotter pin must be torqued to specification. Then if the slot in the nut does not line up with the cotter pin hole, tighten nut until it is aligned. Never loosen the nut to align the cotter pin hole.

NOTE: Periodic lubrication of the front suspension/ steering system components may be required. Rubber bushings must never be lubricated. Refer to Group 0, Lubrication And Maintenance for the recommended maintenance schedule.

OPERATION

•  CASTER 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. This angle enables the front wheels to return to a straight ahead position after turns.
•  CAMBER 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 inside or outside edge of the tire. The angle is not adjustable, damaged component(s) must be replaced to correct the camber angle.
•  WHEEL TOE POSITION is the difference between the leading inside edges and trailing inside edges of the front tires. Incorrect wheel toe position is the most common cause of unstable steering and uneven tire wear. The wheel toe position is the final front wheel alignment adjustment.
•  STEERING AXIS INCLINATION ANGLE is measured in degrees and is the angle that the steering knuckles are tilted. The inclination angle has a fixed relationship with the camber angle. It will not change except when a spindle or ball stud is damaged or bent. The angle is not adjustable, damaged component(s) must be replaced to correct the steering axis inclination angle.
• THRUST ANGLE is the angle of the rear axle relative to the centerline of the vehicle. Incorrect thrust angle can cause off-center steering and excessive tire wear. This angle is not adjustable, damaged component(s) must be replaced to correct the thrust angle.

Fig. 1 Wheel Alignment Measurements

1 - WHEEL CENTERLINE
2 - NEGATIVE CAMBER ANGLE
3 - PIVOT CENTERLINE
4 - SCRUB RADIUS
5 - TRUE VERTICAL
6 - KING PIN
7 - VERTICAL
8 - POSITIVE CASTER

Diagnosis and testing

SUSPENSION AND STEERING SYSTEM

Service procedures

PRE-ALIGNMENT

Before starting wheel alignment, the following inspection and necessary corrections must be completed.

Refer to Suspension and Steering System Diagnosis Chart for additional information.

1.  Inspect tires for size and tread wear.
2.  Set tire air pressure.
3.  Inspect front wheel bearings for wear.
4.  Inspect front wheels for excessive radial or lateral runout and balance.
5.  Inspect ball studs, linkage pivot points and steering gear for looseness, roughness or binding.
6.  Inspect suspension components for wear and noise.

WHEEL ALIGNMENT

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 NORMAL 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 correct 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 unassisted, the caster angle is correct. If steering wheel does not return toward the center position unassisted, an incorrect caster angle is probable.

Caster can be adjusted by installing the appropriate size shims (Fig. 2).

NOTE: Changing caster angle will also change the front propeller shaft angle. The propeller shaft angle has priority over caster. Refer to Group 3 Differential & Driveline for additional information.

Fig. 2 Caster Adjustment

1 - SHIM
2 - SUSPENSION ARM

TOE POSITION (LHD)

NOTE: The wheel toe position adjustment is the final adjustment. The engine must remain running during the entire toe position adjustment.

1.  Start the engine and turn wheels both ways before straightening the wheels. Secure the steering wheel with the front wheels in the straight-ahead position.
2.  Loosen the adjustment sleeve clamp bolts (Fig. 3).
3.  Adjust the right wheel toe position with the drag link. Turn the sleeve until the right wheel is at correct TOE-IN specifications. Position the clamp bolts as shown (Fig. 4) and tighten to 49 N·m (36 ft. lbs.). NOTE: 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 specifications. Position the clamp bolts as shown (Fig. 4) and tighten to 27 N·m (20 ft. lbs.). NOTE: Make sure the toe setting does not change during clamp tightening.
5.  Verify the right toe setting and turn off engine.
6.  Road test the vehicle on a flat level road to verify the steering wheel is centered.

NOTE: Once the toe setting is correct, the steering wheel can be re-centered by adjusting only the drag link.

TOE POSITION (RHD)

NOTE: The wheel toe position adjustment is the final adjustment. The engine must remain running during the entire toe position adjustment.

1.  Start the engine and turn wheels both ways before straightening the wheels. Secure the steering wheel with the front wheels in the straight-ahead position.

Fig. 4 Drag Link and Tie Rod Clamp (LHD)

2. Loosen the adjustment sleeve clamp bolts (Fig. 5).
3.  Adjust the left wheel toe position with the drag link. Turn the sleeve until the left wheel is at the correct TOE-IN specifications. Position the clamp bolts to their original position and tighten to 49 N·m (36 ft. lbs.).

Fig. 3 Steering Linkage (LHD)

1 - PITMAN ARM
2 - ADJUSTMENT SLEEVE
3 - DRAG LINK
4 - TIE ROD
5 - STEERING DAMPENER

Fig. 5 Steering Linkage (RHD)

1 - PITMAN ARM
2 - DRAG LINK
3 - STEERING DAMPNER
4 - TIE ROD
5 - ADJUSTMENT SLEEVE

NOTE: Make sure the toe setting does not change during clamp tightening.

4.  Adjust the right wheel toe position with the tie rod. Turn the sleeve until the right wheel is at correct TOE-IN specifications. Position the clamp bolts to their original position and tighten to 27 N·m (20 ft. lbs.).

NOTE: Make sure the toe setting does not change during clamp tightening.

5.  Verify the right toe setting and turn off engine.
6.  Road test the vehicle on a flat level road to verify the steering wheel is centered.

NOTE: Once the toe setting is correct, the steering wheel can be re-centered by adjusting only the drag link.

Specifications

ALIGNMENT

NOTE: All alignment specifications are in degrees.