Chrysler Town, Dodge Caravan. Manual — part 23
WHEEL ALIGNMENT
TABLE OF CONTENTS
page
page
WHEEL ALIGNMENT
DIAGNOSIS AND TESTING - SUSPENSION
. . . . . . . . . . . . . . . . . . . . . . 49
ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . 51
STANDARD PROCEDURE - CURB HEIGHT
MEASUREMENT . . . . . . . . . . . . . . . . . . . . . . 54
. . . . . . . . . . . . . . . . . . . 55
WHEEL ALIGNMENT
DESCRIPTION - WHEEL ALIGNMENT
Vehicle wheel alignment is the positioning of all
interrelated front and rear suspension angles. These
angles affect the handling and steering of the vehicle
when it is in motion. Proper wheel alignment is
essential for efficient steering, good directional stabil-
ity, and proper tire wear.
The method of checking a vehicle’s front and rear
wheel alignment varies depending on the manufac-
turer and type of equipment used. The manufactur-
er’s instructions should always be followed to ensure
accuracy
of
the
alignment,
except
when
DaimlerChrysler Corporation’s wheel alignment spec-
ifications differ.
On this vehicle, the suspension angles that can be
adjusted are as follows:
• Front Camber (with camber bolt package and
standard procedure)
• Front Toe
Check the wheel alignment and make all wheel
alignment adjustments with the vehicle standing at
its proper curb height specification. Curb height is
the normal riding height of the vehicle. It is mea-
sured from a certain point on the vehicle to the
ground or a designated area while the vehicle is sit-
ting on a flat, level surface. Refer to Curb Height
Measurement in this section for additional informa-
tion.
Typical wheel alignment angles and measurements
are described in the following paragraphs.
CAMBER
Camber is the inward or outward tilt of the top of
the tire and wheel assembly (Fig. 1). Camber is mea-
sured in degrees of angle relative to a true vertical
line. Camber is a tire wearing angle.
• Excessive negative camber will cause tread wear
at the inside of the tire.
• Excessive positive camber will cause tread wear
on the outside of the tire.
CROSS CAMBER
Cross camber is the difference between left and
right camber. To achieve the cross camber reading,
subtract the right side camber reading from the left.
Fig. 1 Camber
1 - WHEELS TILTED OUT AT TOP
2 - WHEELS TILTED IN AT TOP
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WHEEL ALIGNMENT
RS
For example, if the left camber is +0.3° and the right
camber is 0.0°, the cross camber would be +0.3°.
CASTER
Caster is the forward or rearward tilt of the steer-
ing knuckle in reference to the position of the upper
and lower ball joints. Caster is measured in degrees
of angle relative to a true vertical center line. This
line is viewed from the side of the tire and wheel
assembly (Fig. 2).
• Forward tilt (upper ball joint ahead of lower)
results in a negative caster angle.
• Rearward tilt (upper ball joint trailing lower)
results in a positive caster angle.
Although caster does not affect tire wear, a caster
imbalance between the two front wheels may cause
the vehicle to lead to the side with the least positive
caster.
CROSS CASTER
Cross caster is the difference between left and
right caster.
TOE
Toe is the inward or outward angle of the wheels
as viewed from above the vehicle (Fig. 3).
• Toe-in is produced when the front edges of the
wheels on the same axle are closer together than the
rear edges.
• Toe-out is produced when the front edges of the
wheels on the same axle are farther apart than the
rear edges.
Toe-in and toe-out can occur at the front wheels
and the rear wheels.
Toe is measured in degrees or inches. The mea-
surement identifies the amount that the front of the
wheels point inward (toe-in) or outward (toe-out). Toe
is measured at the spindle height. Zero toe means
the front and rear edges of the wheels on the same
axle are equally distant.
Fig. 2 Caster
Fig. 3 Toe
1 - TOE-IN
2 - TOE-OUT
RS
WHEEL ALIGNMENT
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WHEEL ALIGNMENT (Continued)
TOE-OUT ON TURNS
Toe-out on turns is the relative positioning of the
front wheels while steering through a turn (Fig. 4).
This compensates for each front wheel’s turning
radius. As the vehicle encounters a turn, the out-
board wheel must travel in a larger radius circle
than the inboard wheel. The steering system is
designed to make each wheel follow its particular
radius circle. To accomplish this, the front wheels
must progressively toe outward as the steering is
turned from center. This eliminates tire scrubbing
and undue tire wear when steering a vehicle through
a turn.
DYNAMIC TOE PATTERN
Dynamic toe pattern is the inward and outward toe
movement of the front and rear tires through the
suspension’s jounce and rebound travel. As the vehi-
cle’s suspension moves up and down, the toe pattern
varies. Toe pattern is critical in controlling the direc-
tional stability of the vehicle while in motion. Front
and rear dynamic toe pattern is preset by the factory
at the time the vehicle is assembled.
It is not necessary to check or adjust front or rear
dynamic toe pattern when doing a normal wheel
alignment. The only time dynamic toe pattern needs
to be checked or adjusted is if the frame of the vehi-
cle has been damaged.
STEERING AXIS INCLINATION (S. A. I.)
Steering axis inclination is the angle between a
true vertical line starting at the center of the tire at
the road contact point and a line drawn through the
center of the upper ball joint (or strut) and the lower
ball joint (Fig. 5). S.A.I. is built into the vehicle and
is not an adjustable angle. If S.A.I. is not within
specifications, a bent or damaged suspension compo-
nent may be the cause.
INCLUDED ANGLE (I. A.)
Included angle is the sum of the S.A.I. angle plus
or minus the camber angle, depending on whether or
not the wheel has positive or negative camber (Fig.
5). If camber is positive, add the camber angle to the
S.A.I. angle. If camber is negative, subtract the cam-
ber angle from the S.A.I. angle. Included angle is not
adjustable, but can be used to diagnose a frame mis-
alignment or bent suspension component (spindle,
strut).
Fig. 4 Toe-Out On Turns
1 - TOE-OUT ON TURNS
Fig. 5 S.A.I. and I.A.
1 - S.A.I.
2 - CAMBER
3 - I.A.
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WHEEL ALIGNMENT
RS
WHEEL ALIGNMENT (Continued)
THRUST ANGLE
Thrust angle is the averaged direction the rear
wheels are pointing in relation to the vehicle’s center
line (Fig. 6). The presence of negative or positive
thrust angle causes the rear tires to track improperly
to the left or right of the front tires (dog tracking).
• Negative thrust angle means the rear tires are
tracking to the left of the front tires.
• Positive thrust angle means the rear tires are
tracking to the right of the front tires.
Improper tracking can cause undue tire wear, a
lead or pull and a crooked steering wheel. Excessive
thrust angle can usually be corrected by adjusting
the rear wheel toe so that each wheel has one-half of
the total toe measurement.
DIAGNOSIS AND TESTING - SUSPENSION AND STEERING
CONDITION
POSSIBLE CAUSES
CORRECTION
Front End Whine On Turns
1. Defective wheel bearing
1. Replace wheel bearing
2. Incorrect wheel alignment
2. Check and reset wheel alignment
3. Worn tires
3. Replace tires
Front End Growl Or
Grinding On Turns
1. Defective wheel bearing
1. Replace wheel bearing
2. Engine mount grounding
2. Check for motor mount hitting frame rail
and reposition engine as required
3. Worn or broken C/V joint
3. Replace C/V joint
4. Loose wheel lug nuts
4. Verify wheel lug nut torque
5. Incorrect wheel alignment
5. Check and reset wheel alignment
6. Worn tires
6. Replace tires
7. Front strut pin in upper strut mount
7. Replace the front strut upper mount and
bearing
Front End Clunk Or Snap
On Turns
1. Loose lug nuts
1. Verify wheel lug nut torque
2. Worn or broken C/V joint
2. Replace C/V joint
3. Worn or loose tie rod
3. Tighten or replace tie rod end
4. Worn or loose ball joint
4. Tighten or replace ball joint
5. Worn/loose control arm bushing
5. Replace control arm bushing
6. Loose stabilizer bar.
6. Tighten stabilizer bar to specified torque
7. Loose strut mount to body
attachment
7. Tighten strut attachment to specified
torque
8. Loose crossmember bolts
8. Tighten crossmember bolts to specified
torque
Fig. 6 Thrust Angle
RS
WHEEL ALIGNMENT
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WHEEL ALIGNMENT (Continued)
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