Specifications & Procedures: Description: Caster

Caster is forward or rearward tilt of steering knuckle in reference to position of upper and lower ball joints. Caster is measured in degrees of angle relative to a true vertical center line. This line is viewed from side of tire and wheel assembly. See Figure .

1. Forward tilt (upper ball joint ahead of lower) results in a negative caster angle.
2. Rearward tilt (upper ball joint trailing lower) results in a positive caster angle.

Although caster does not affect tire wear, a caster imbalance between 2 front wheels may cause vehicle to lead to side with least positive caster.