Explanation:

• Castor is the angle between the steering axis and the vertical in the plane of the wheel.
• If your upper ball joint or strut mount is located more toward your vehicle’s rear than the lower ball joint, your vehicle has a positive caster.
  
• Positive castor improves the straight-line stability of the car
• When the upper ball joint or strut mount is more towards the vehicle’s front than the lower ball joint, the vehicle has a negative caster.
• While a positive caster has several advantages, there are no advantages to a negative caster in modern vehicles.
  
• Caster angle refers to the location of your vehicle’s upper ball joint or strut mount compared to the lower ball joint
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