CamberCasterToe

Steering axis inclinationTurning radius

CAMBER Inward or outward

tilt of the wheel at the top when viewed from the front of the car.

It is measured in degrees of a circle.

#2 Pull rule #2 Tire wear

Positive Camber

When camber is positive the tire leans out away from the vehicle at the top.

On both front and rear wheels camber is important.

Negative Camber

When camber is negative the tire leans in toward the car at the top.

Camber Tire Wear

Camber Pull When the camber

is more than ½ degree different from one side to the other, the car will pull or drift.

CASTER Forward or rearward

tilt of the steering knuckle at the top

Measured in degrees of a circle

Provides straight line driving and steering wheel return

#1 Pull rule. Does NOT effect tire

wear

Measuring Caster

Caster is measured in degrees of a circle from true vertical. If the steering knuckle leans toward the rear of the car at the top that is positive caster. If the steering knuckle leans toward the front of the car at the top that is negative caster.

How Caster Works

There are two points of importance:

The point of contact.

The point of lead. The vehicle will

always follow the point of lead.

Effects of Caster If the difference in the caster angle

is more than ½ degree from side to side, the car will pull to the side of the most negative caster.

Caster has no effect on tire wear.

TOE-IN TOE-OUT Toe is the difference

in distance between the front and rear of the front wheels.

Measured in inches, millimeters or degrees.

#1 Tire wearing angle.

Does not effect handling.

Measuring Toe Toe is typically

measured in inches. (fractions of inches)

If it is off, the tires will wear feather edged. Also the steering wheel spoke is usually crooked.

STEERING AXIS INCLINATION

Gives directional stability much like caster

Non-adjustable Only changes

when parts are bent

Very important to check in collision work

TURNING RADIUSor TOE-OUT ON TURNS

Changes radius for inboard and outboard wheel while turning

Non-adjustable Important to check if doing collision work

Vehicle Thrust Line The rear wheels

determine the path of the vehicle. Not the front wheels as commonly thought.

Setting Up the Car Car suspension & steering must be

checked out prior to alignment and repaired.

Pull car on the rack correctly. Set rack on alignment stands. Connect alignment wheel reflectors. Punch in alignment specifications.

Rolling Compensation This runs out the

wheel clamp and measures camber, toe, thrust line and set back.

Checking Caster and S.A.I.

The wheel must be turned to reveal caster and SAI.

Interpreting the results. On the rear, adjust

camber the then toe.

On the front adjust camber, caster and then toe.