Chrysler RAM TRUCK 2500 1994 Service Manual page 61

2 - 4 FRONT SUSPENSION AND AXLE
•
FRONT W H E E L ALIGNMENT
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 en^ 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.
• 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 which enables
the front wheels to return to a straight ahead posi­
tion after turns (Fig. 1,2).
• 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 in­
side or outside edge of the tire (Fig. 1,2).
POSITIVE
CASTER
NEGATIVE
CASTER
POSITIVE NEGATIVE
C A M B E R ^ j CAMBER,
FRONT OF VEHICLE
PIVOT
POINT*4J^;j
J9402-56
Fig. 1 Alignment Angles IFS
• WHEEL TOE POSITION is the difference between
the leading inside edges and trailing inside edges of
the front tires (Fig. 1,2). 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 mea­
sured i n degrees. I t is the angle that the steering
CAMBER
WHEEL
TRUE
,|
I -
j
— CfcNTERLINE
VERTICAL _ j
, NEGATIVE
CAMBER
«
| / ANGLE
_ PIVOT
1
u
CENTERLINE
\
LL
/ SCRUB
— RADIUS
POSITIVE CAMBER (NOT S H O W N )
TOP OF WHEEL OUTBOARD
CASTER
POSITIVE CASTER-
K I N G PIN
OF VEHICLE
VERTICAL
FRONT OF VEHICLE
tS
— 1 -
NEGATIVE TOE (TOE OUT) B > A
POSITIVE TOE (TOE IN) B < A
THRUST ANGLE
4*
ANGLE OF REAR AXLE
RELATIVE TO VEHICLE CENTERLINE
( + ) AXLE POINTS LEFT ( - ) AXLE POINTS RIGHT
J9402-57
Fig. 2 Alignment Angles Link/Coil