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2 - 4
FRONT SUSPENSION
•
The c a s t e r angle i s the n u m b e r o f degrees of for-
w a r d or r e a r w a r d t i l t of t h e steering k n u c k l e (wheel
spindle support a r m ) f r o m t h e v e r t i c a l (i.e., from 0
degrees). F o r w a r d t i l t f r o m t h e v e r t i c a l i s negative
caster. Rearward t i l t f r o m t h e v e r t i c a l i s positive
caster (Fig. 1, F i g . 2).
RN1030
Fig. 2 Caster & Camber Adjustment Location—2WD
Vehicles
The c a m b e r angle is t h e n u m b e r of degrees t h e
top of the wheel is t i l t e d i n w a r d or o u t w a r d from the
vertical plane (i.e., f r o m 0 degrees). I n w a r d t i l t of the
top of t h e wheel f r o m the v e r t i c a l plane i s a negative
camber angle. O u t w a r d t i l t o f the t o p of the wheel
from t h e v e r t i c a l plane is a positive camber angle.
A n excessive camber angle w i l l cause abnormal t i r e
tread wear. A n excessive negative camber angle w i l l
cause t h r e a d wear a t the inside of the t i r e , w h i l e a n
excessive positive camber angle w i l l cause thread
wear a t t h e outside o f the t i r e (Fig. 1, F i g . 2).
The w h e e l " t o e " p o s i t i o n is t h e l i n e a r distance
differential between t h e l e a d i n g inside edges of the
front tires and t h e t r a i l i n g inside edges o f the front
tires. Incorrect wheel "toe" position i s the most seri-
ous cause for excessive t i r e t h r e a d wear. The wheel
"toe" position is t h e f i n a l f r o n t wheel a l i g n m e n t ad-
j u s t m e n t .
The s t e e r i n g a x i s i n c l i n a t i o n is measured i n de-
grees a n d is t h e angle t h a t t h e steering k n u c k l e
(wheel spindle support) is t i l t e d f r o m t h e vertical
plane (i.e., f r o m 0 degrees). I t has a fixed r e l a t i o n -
ship w i t h the camber angle a n d w i l l not change ex-
cept w h e n t h e spindle or b a l l stud is damaged or
bent. T h e angle i s not adjustable and the damaged
components
m u s t
be replaced
to correct
m i s -
alignment.
The w h e e l " t o e - o u t " o n t u r n s ( t u r n i n g radius) is
measured i n degrees and i s t h e difference between
the t w o front w h e e l t u r n i n g angles. T h i s t u r n i n g a n -
gle difference i s provided b y t h e design o f the steer-
i n g l i n k a g e a n d i s based o n t h e wheelbase o f t h e
vehicle. I t is n o t adjustable. W h e n t h e wheel "toe-
out" o n t u r n s ( t u r n i n g radius) i s not w i t h i n t h e rec-
ommended specification, inspect for possible bent or
damaged components.
PRE-ALIGNMENT INSPECTION
Before i n i t i a t i n g front wheel alignment, the follow-
i n g inspection a n d the necessary corrections m u s t be
completed for those components t h a t interact w i t h
the steering o f t h e vehicle.
(1) Check a n d i n f l a t e a l l t h e tires w i t h t h e same
recommended pressure. A l l t h e tires should be t h e
same size, i n good condition a n d have approximately
the same t h r e a d wear. I f abnormal, note the type o f
t i r e t r e a d wear, w h i c h w i l l a i d i n the diagnosis (refer
to Group 2 2 - T i r e s A n d Wheels).
(2) Inspect a n d adjust ( i f necessary) the front wheel
bearings.
(3) Inspect t h e f r o n t wheels/tires for evidence o f ex-
cessive r a d i a l a n d l a t e r a l " r u n o u t " (refer to Group
22—Tires A n d Wheels for measurement procedures).
(4) Inspect t h e wheels/tires for evidence of " u n b a l -
ance". B o t h static and dynamic unbalance can affect
the vehicle steering.
(5) Inspect t h e b a l l studs and a l l the steering l i n k -
age p i v o t locations for excessive looseness.
(6) Inspect t h e shock absorbers for leaks and jounce
the vehicle to determine i f the shock absorbers prop-
erly dampen vehicle body movement.
(7) Inspect t h e steering gear operation for r o u g h -
ness, b i n d i n g or a " s t i c k i n g " condition. Adjust/repair
as necessary.
(8) Inspect t h e rear springs for cracked or b r o k e n
leaves,
a n d t h e U-bolt n u t s for correct tightness
(torque).
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