Wheel Alignment Specifications & Procedures: Adjustments: Caster

1. Caster is the tilting of front steering axis either forward or backward from vertical, as viewed from the side of vehicle. See Fig 1 .
2. When axis is tilted backward from vertical, caster is positive. This creates a trailing action on front wheels. When axis is tilted forward, caster is negative, causing a leading action on front wheels.

Fig 1: Determining Caster Angle