Chevrolet 1977 light duty truck Service Manual page 191

G eneral D e sc rip tio n ...................
M aintenan ce and Adjustments
Specifications.................................
F R O N T A L IG N M E N T
The term " f ro n t alig nm en t" refers to the angular
relationships between the
suspension attaching parts and the ground.
The pointing in or "toe-in " of the front wheels, the
tilt of the front wheels from vertical (when viewed from
the front of the vehicle) and the tilt o f the suspension
m em bers from vertical (when viewed from the side of
the vehicle), all these are involved in front alignment.
The various factors that enter into front alignment are
covered here each one under its own heading.
CASTER
Caster is the tilting o f the front steering axis either
forward or backward from the vertical (when viewed
from the side o f the vehicle). A backward tilt is said to
be positive ( + ) and a forward tilt is said to be negative
( - ) .
O n the short and long arm type suspension you
cannot see a caster angle without a special instrument,
but you can understand that if you look straight down
from the top o f the upper control arm to the ground you
would lind that the ball joints do not line up (fore and
aft) when a caster angle other than 0° is present. If you
had a positive caster angle the lower ball joint would be
slightly ahead (toward the front o f the vehicle) o f the
upper ball jo in t center line. In short then, caster is the
forward or backward tilt o f the steering axis as viewed
SECTION 3A
FRONT ALIGNMENT
C O N T E N T S
GENERAL DESCRIPTION
front wheels, the front
3 A- 1
3A-2
3A-6
from a side elevation. Caster is designed into the front
axle assembly on all K series vehicles (l'our-wheel drive),
an d is no n-adjustab le.
A D JU ST M EN TS.
CAMBER
Cam ber is the tilting of the front wheels from the
vertical when viewed from the front o f the vehicle.
W hen the wheels tilt outward at the top, the cam ber is
said to be positive ( + ) . W hen the wheels tilt inward at
the top, the cam ber is said to be negative (—). The
am ount of tilt is measured in degrees from the vertical
and this m easurem ent is called
C am ber is designed into the front axle assembly o f all K
series vehicles and is non-adjustable. See cam ber copy
under A D JU ST M E N T S.
TOE-IN
Toe-in is the turning in o f the front wheels. The
actual am ount o f toe-in is normally only a fraction of an
inch. The purpose o f a toe specification is to ensure
parallel rolling o f the front wheels. (Excessive toe-in or
toe-out will cause tire wear). Toe-in also serves to offset
the small deflections o f the wheel support system which
occurs when the vehicle is rolling forward. In other
words, even when the wheels are set to toe-in slightly
when the vehicle is standing still, they tend to roll
parallel on the road when the vehicle is moving. See toe-
in copy under A D JU STM E N T S.
See caster copy un d e r
the c am ber angle.