Camber Caster Toe Steering axis inclination Turning 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 ď Ž
When camber is negative the tire leans in toward the car at the top.
Camber Tire Wear
Camber Pull ď Ž
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 ď Ž
ď Ž
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 RADIUS or 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 ď Ž
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 ď Ž
This runs out the wheel clamp and measures camber, toe, thrust line and set back.
Checking Caster and S.A.I. ď Ž
The wheel must be turned to reveal caster and SAI.
Interpreting the results. ď Ž
ď Ž
On the rear, adjust camber the then toe. On the front adjust camber, caster and then toe.