[quote=jockbolter50Yes,caster shims are to change caster angles,it's all to do with KPI (king pin inclination)
My understanding is positive caster will produce lighter steering but will also affect the steerings ability to self center.
Negative caster will ultimately make the steering slightly heavier but it will track much straighter. [/quote]Other way around. Positive caster produces heavier steering and better self centering, negative caster makes for easier steering, but less self centering and stability. Most vehicles use positive caster, but there are a few exceptions, mostly '60s Ford products.
The KPI doesn't really have much to do with caster, it's related to camber, steering axis inclination, included angle, and scrub radius.
