Alignment Fundamentals Part One

Suspension Systems• Designed to:

– provide satisfactory vehicle control– acceptable driver effort

• Maintains directional stability:– on various road surfaces– all types of weather– loaded and unloaded– towing

Road Variables• Road Crown• Bumps & Pot Holes• Crosswinds & Cross winds created by

other vehicles• Road surfaces• Side forces• Drive axle forces• Suspension part movement

Rear Wheel Alignment & Vehicle Tracking

• Thrust Line – Imaginary line @ 90 degree angle to the centerline of the rear wheels

• Rear Wheel Offset – axle asm out of position, not parallel to centerline

Improper Thrust Angle

Wheel Base

• The distance between the center of the front & rear wheels

Tracking

• Position of the rear wheels in relationship to the front

Ride Height • The distance between the frame &

the ground. If distance varied over ¼” between sides, handling can be affected.

Camber Fundamentals• Inward/outward tilt of wheel from true vertical. • Vehicle will pull to side most positive. • Affects tire wear.

Camber FundamentalsNegative Camber Positive Camber

Jounce & Rebound• Jounce - Upward wheel movement• Rebound – Downward wheel movement

Caster Fundamentals• Tilt of a line that intersects the

lower and upper ball joints (strut mount) in relation to true vertical

Caster Fundamentals

Positive Caster

• Helps return to straight ahead position• Increases steering effort, the wheels

try to stay straight• Pos caster helps maintain directional

stability• Too much affects steering, rapid

wheel return• Pulls to side with the most pos caster.

Negative Caster

• Decreases directional stability• Reduces steering effort

Tire Wear

• Caster has effect on tire wear