Introduction to different terms used in steering wheel alignment camber, caster and toe alignment.

1. INTRODUCTION TO WHEEL ALIGNMENT
Alignment refers to an adjustment of a vehicle’s
suspension – the system that connects a vehicle to its
wheels. It is not an adjustment of the tires or wheels
themselves. The key to proper alignment is adjusting
the angles of the tires which affects how they make
contact with the road.
If uneven effects are examined in the vehicles such
as,
1. tread wear
2. Vehicle pulling to the left or right
3. Your steering wheel is off center when driving
straight
4. Steering wheel vibration
Then you should check your alignments at technician

2. WHEN A TECHNICIAN CHECKS YOUR TIRE
ALIGNMENT, HE OR SHE IS MAINLY CONCERNED
WITH THREE THINGS:
1) Caster
2) Camber
3) Toe

3. WHAT IS CAMBER ANGLE AND ITS
SIGNIFICANCE?
Camber angle is the
angle made by the
wheels of a vehicle;
specifically, it is the
angle between the
vertical axis of the
wheels used for steering
and the vertical axis of
the vehicle when viewed
from the front or rear.
 It is used in the design
of steering and
suspension

4. TWO TYPES OF CAMBER ALIGNMENT
If the top of the wheel is
farther out than the bottom
(that is, away from the axle),
it is called positive camber.
If the top of the tire is
leaned in closer to the center
of the car, that particular
wheel and tire exhibit what is
called negative camber.

5. EFFECT ON HANDLING OF CAMBER ANGLE
 Camber angle alters the handling qualities of a particular
suspension design; in particular, negative camber
improves grip when cornering especially with a short
long arm suspensions. This is because it places the tire
at a better angle to the road, transmitting the centrifugal
forces through the vertical plane of the tire rather than
through a shear force across it.
 This effect is compensated for by applying negative
camber, maximizing the contact patch area. Note that
this is only true for the outside tire during the turn; the
inside tire would benefit most from positive camber again
only with short long arm system. Caster angle will
compensate this to a degree, as the top of the outside
tire will tilt slightly inward and the inner tire will

6. INTRODUCTION TO CASTERIN WHEEL
ALIGNMENT.
It is the angle between
the pivot line (in a car an
imaginary line that runs
through the center of the
upper ball joint to the
center of the lower ball
joint) and vertical. In
automobile racing, the
caster angle may be
adjusted to optimize
handling characteristics
for a particular venue.
The caster angle or castor angle is the angular displacement
of the steering axis from the vertical axis of a steered wheel in
a car, motorcycle, bicycle, other vehicle or a vessel, measured
in the longitudinal direction.

7. THERE ARE TWO BASIC TYPES OF
CASTER.
 Positive caster
 Negative caster

8. WHAT IS POSITIVE CASTER?
 Positive caster is when the steering axis is in
front of the verticle .
 In a road car, this would mean that the top of
the coilover would be pushed towards the
rear of the car.
 Positive caster angles run between 3 - 5° on
modern vehicles.
 This gives a good mix of highway stability
and steering feel.

9. WHAT DOES NEGATIVE CASTER DO?
 Negative caster is when the steering axis is behind
the vertical.
 Modern vehicles do not use negative caster. It will
lighten the steering effort but also increases the
tendency for the car to wander down the road .
 The steering axis (the red dotted line in the diagram
above) does not have to pass through the center of
the wheel, so the caster can be set independently
of the trail, which is the distance between where the
steering axis intersects the ground, in side view,
and the point directly below the axle.

10. WHAT IS THE MAJOR DIFFERANCE BETWEEN
CASTER AND CAMBER?
 Caster is the steering angle with respect to
wheels’ centre. In a chopper motorcycle, notice
the handlebar and forks angle. That is the
Caster angle.
 Camber is a wheel’s angle with respect to its
centre. In this case, when negative camber is
mentioned, take it that the front wheels (the
ones used for steering) will be tilted to have less
contact patch on outside portion than inside of a
tire .

11. Introduction to toe in wheel
alignment.
When a pair of wheels is set so that their leading
edges are pointed slightly towards each other, the
wheel pair is said to have toe-in. If the leading
edges point away from each other, the pair is said
to have toe-out.
What
does it
means ?

12. The amount of toe can be expressed in degrees as the
angle to which the wheels are out of parallel, or more
commonly, as the difference between the track widths as
measured at the leading and trailing edges of the tires
or wheels.
 Toe-in means that the fronts of the tires are closer to
each other than the rears. Toe-out is just the opposite. An
incorrect toe-in will cause rapid tire wear to both tires
equally.
This type of tire wear is called a saw-tooth wear pattern
.

13. TOE SETTINGS AFFECT THREE MAJOR
AREAS OF PERFORMANCE.
Tire wear.
straight-line stability.
 corner entry handling
characteristics.

14. TIRE WEAR
•For minimum tire wear and power
loss, the wheels on a given axle of
a car should point directly ahead
when the car is running in a
straight line.
• Excessive toe-in or toe-out
causes the tires to scrub, since
they are always turned relative to
the direction of travel.• Too much toe-in causes
accelerated wear at the outboard
edges of the tires, while too much
toe-out causes wear at the inboard
edges.
• So if minimum tire wear and
power loss are achieved with zero
toe.

15. STRAIGHT LINE STABILITY
•When the wheel on one
side of the car encounters
a disturbance, that wheel
is pulled rearward about
its steering axis. This
action also pulls the other
wheel in the same
steering direction.
•If it's a minor disturbance, the disturbed wheel will steer only
a small amount, perhaps so that it's rolling straight ahead
instead of toed-in slightly. But note that with this slight steering
input, the rolling paths of the wheels still don't describe a turn.
•The wheels have absorbed the irregularity without
significantly changing the direction of the vehicle. In this way,
toe-in enhances straight-line stability.

16. corner entry handling
characteristics •It should be noted that in
recent years, designers have
been using bushing
compliance in street cars to
their advantage.
• To maximize transient
response, it is desirable to use
a little toe-in at the rear to
hasten the generation of slip
angles and thus cornering
forces in the rear tires.
• By allowing a bit of compliance in the front lateral links of an A-arm
type suspension, the rear axle will toe-in when the car enters a hard
corner; on a straightaway where no cornering loads are present, the
bushings remain undistorted and allow the toe to be set to an angle that
enhances tire wear and stability characteristics.
• Such a design is a type of passive four-wheel steering system.