GENERAL DESCRIPTION
“Front End Alignment” refers to the angular relationship between the front wheels, the front suspension
attaching parts and the ground.
Proper front end alignment must be maintained in order to insure efficient steering, good directional
stability and to prevent abnormal tire wear.
The most important factors of front end alignment are wheel toe-in, wheel camber and axle caster.
DEFINITION OF TERMS
CAMBER
Camber is the inward or outward tilting of the front wheels
from the vertical. When the wheels tilt outward at the top,
the camber is positive (+). When the wheels tilt inward at
the top, the camber is negative (–). The amount of tilt
measured in degrees from the vertical is called the camber
angle.
If camber is extreme or unequal between the wheels,
improper steering and excessive tire wear will result.
Negative camber causes wear on the inside tire, while
positive camber causes wear to the outside.
CASTER
Caster is the tilting of the wheel axis either forward or
backward from the vertical (when viewed from the side of
the vehicle). A backward tilt is positive(+) and a forward tilt
is negative(–).
On the short and long arm type suspension you cannot
see a caster angle without a special instrument, but if you
look straight down from the top of the upper control arm
to the ground, the ball joints do not line up (fore and aft)
when a caster angle other than 0 degree is present. With a
positive angle, the lower ball joint would be slightly ahead
(toward the front of the vehicle) of the upper ball joint
center line.
TOE-IN
Toe-in is the turning of the front wheels. The actual
amount of toe-in is normally a fraction of a degree. Toe-in
is measured from the center of the tire treads or from the
inside of the tires. The purpose of toe-in is to insure
parallel rolling of the front wheels and to offset any small
deflections of the wheel support system which occurs
when the vehicle is rolling forward. Incorrect toe-in results
in excessive toe-in and unstable steering. Toe-in is the last
alignment to be set in the front end alignment procedure.