Automotive Alignment Angles Camber Caster Front toe Rear toe

Primary Alignment Angles Front Camber Rear Camber Caster Front Toe Rear Toe 2 lines meet to form an Angle

0 º ± 1 º -.5 º ± 1 º Camber Definition: Typical Range: The inward or outward tilt of the top of the wheel as viewed from the front. Typical Range: Front camber - Rear camber - 0 º ± 1 º -.5 º ± 1 º

Zero Camber Wheel is vertical when viewed from the front Measured as Zero degrees Applicable to front and rear tires

Reasons to use at or near Zero Camber Extremely wide tires Positive offset rims Extended Tire life

Positive Camber Top of tire leans outboard at the top when viewed from the front Measured in degrees Primarily used on front wheels

Reasons to use Positive Camber Places load inboard on spindle Increases road isolation Increases directional stability

Negative Camber Top of tire leans inboard at the top when viewed from the front Measured in degrees Primarily used on rear wheels

Reasons to use Negative Camber Places load outboard on spindle Increased cornering ability Increases road shock & component wear

Outside Shoulder Wear due to Excessive Positive Camber Angle

Camber may cause a Pull Cross camber is the side-to-side difference in camber measurements More than 1/2º difference side-to side may cause the vehicle to pull to the wheel with the most positive camber.

Excessive Cross Camber Vehicle may pull to side of most positive camber

Camber Specifications Preferred Specs Front = 0º Rear = -.40º Tolerance Front = 1º Rear = .75º Cross camber .70º

Exception to the rule

Caster Front The Forward or Rearward Tilt of the Steering Axis as viewed from the side Typical Range Typical tolerance ± 1º 1º to 6 º positive

Steering Axis Line drawn between the two pivot points of the steering knuckle

Zero Caster Steering Axis is vertical as viewed from the side and measured as 0º

Negative Caster Forward tilt of the Steering Axis as viewed from the side and measured in degrees Front

Positive Caster Rearward tilt of the Steering Axis as viewed from the side and measured in degrees Front

Benefits of Positive Caster Helps to return wheels to straight ahead after being steered Helps to maintain directional stability Weight must be picked up as spindle turns downward ….

Negative effects of Excessive Positive Caster Excessive steering effort & road shock Shimmy due to excessive speed of wheels returning to center Steering damper used to control speed of steered wheels returning to center Dampner

Caster Measurement The amount of camber change during a 10° steer to the left & right spindle arc

Tire wear factor of Caster Tires may show wear on both outer edges due to camber roll. Camber roll - the change in camber during a turn due to caster The amount of camber change is relative to the amount of positive caster

Camber Roll Left spindle down - right spindle up Left spindle up - right spindle down

Caster may cause a Pull Cross caster is the side-to-side difference in caster measurements More than 1/2º difference side-to side may cause the vehicle to pull to the wheel with the least positive caster.

Cross Caster Vehicle may pull to side of least positive caster Cross Caster = Left caster minus right caster 2º caster 1º caster Vehicle may pull to side of least positive caster

Caster Specification Preferred Spec Front 3.80º Rear n/a Tolerance Front 1º Cross caster .85º

Review Purpose of Alignment Angles Camber Definitions Measurement method Specification Tire wear factor Pull factor

Review Caster Definitions Measurement method Specification Tire wear factor Pull factor

Front Toe Angles Incorrect front toe angles may cause: outside shoulder wear inside shoulder wear wandering darting Total toe changes as the speed of the vehicle increases

Total Toe The difference in the distance measured between lines drawn through the center of tires on the same axle. Measurements are taken at the front and rear of the tires.

Zero Total Toe 80” Equal distance when measured across the front and the rear of tires on the same axle.

Toe-In Measured distance is shorter between the front of the tires. front = 79 in. rear = 80 in. 79” 80” Total toe-in = 1 in.

Excessive Toe-In Tire Wear Outside shoulder wear Center of car

Toe-Out Measured distance is shorter between the front of the tires. front = 80 in. rear = 79 in. 80” 79” Total toe-out = 1 in.

Excessive Toe-Out Tire Wear Inside shoulder wear Center of car

Total Toe Angle The Total toe may also be displayed as an angle and expressed in degrees. Total toe angle

Total Toe Specification Negative number indicates Toe-Out Positive number indicates Toe-In

Individual Toe Front individual toe is responsible for steering wheel position

Front Individual Toe Left Front Individual toe angle Centerline toe angle Angle formed by the intersection of the geometric centerline and a line drawn through the center of the wheel

Rear Individual Toe Rear individual toe is responsible for: tire wear thrust angle vehicle tracking

Rear Tire Wear Patterns Toe-In Outside shoulder Toe-Out Inside shoulder Diagonal Wipe a condition that may result on rear tires with excessive toe Diagonal Wipe

Geometric Centerline A line drawn between the midpoint of both the front and rear axles.

Thrust Line The bisector of rear total toe. Also described as the direction the rear wheels are pushing the vehicle.

Thrust Angle - formed by the intersection of the geometric centerline and the thrustline ( a line bisecting rear total toe ) Thrustline Thrust angle Geometric Centerline

Positive & Negative Thrust Angle + Positive Thrust Angle is to the Right Negative Thrust Angle is to the Left -

Dog Tracking A visible dog track condition will be present, if the thrust angle is excessive.

Review Front total toe is responsible for tire wear factors: excessive toe-in = outside shoulder wear darting excessive toe-out = inside shoulder wear wandering Front individual toe is responsible for steering wheel position

Thrustline: the direction the rear wheels are pointing the vehicle bisector of the total toe angle Thrust Angle: the angle formed by the intersection of the geometric centerline and the thrustline Rear tire wear patterns: outside or inside shoulder wear diagonal wipe if the toe angle is extreme Main Menu