A critical wheel alignment angle that measures the displacement of the steering axis from the vertical center of the wheel. Positive caster tilts the upper pivot point backward, which creates a self-centering force that improves high-speed straight-line stability and steering feel. Negative caster tilts it forward and is rarely used on production cars because it makes steering twitchy.
Heard on the job
The steering feels a bit vague on the highway, so let's dial in a little more positive caster.
Insider tip
If a car pulls to one side but the camber and toe are perfect, check for a caster split between the left and right wheels.
Also heard as
- caster angle
Do not mix it up with
- Camber: Caster is the forward or backward tilt of the steering axis, while camber is the inward or outward tilt of the wheel itself.