Jeep Wrangler 1999 Electronic Service Manual page 27

TJ
ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
FRONT SUSPENSION . . . . . . . . . . . . . . . . . . . . . . 6
DESCRIPTION AND OPERATION
WHEEL ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . 1
DIAGNOSIS AND TESTING
SUSPENSION AND STEERING SYSTEM . . . . . . . 3
SERVICE PROCEDURES
PRE-ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . 4
DESCRIPTION AND OPERATION
WHEEL ALIGNMENT
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 stabil-
ity and to minimize tire wear. The most important
measurements of an alignment are caster, camber
and toe position (Fig. 1).
• 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
SUSPENSION
CONTENTS
page
REAR SUSPENSION . . . . . . . . . . . . . . . . . . . . . . 13
ALIGNMENT
INDEX
page
WHEEL ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . 4
SPECIFICATIONS
ALIGNMENT SPECIFICATIONS . . . . . . . . . . . . . . 5
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 steer-
ing 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 dam-
aged 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 exces-
sive tire wear. This angle is not adjustable, damaged
component(s) must be replaced to correct the thrust
angle.
CAUTION: Never attempt to modify suspension or
steering components by heating or bending.
NOTE: Periodic lubrication of the front suspension/
steering system components may be required. Rub-
ber bushings must never be lubricated. Refer to
Group 0, Lubrication And Maintenance for the rec-
ommended maintenance schedule.
SUSPENSION 2 - 1
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