Steering Axis Inclination
The angle that an imaginary line makes with respect to the groundplain, thru the upper and lower balljoints, as viewed from the front.
When you turn the steering wheel the geometry of the front end actually lifts the front of the car. That weight now wants to come back down, you know, gravity and all that. The raised weight can only return to rest by turning the wheels back, which it can do if you allow it to. But every pivot point in the system must be free as well, and the steering box,very important, must also allow it.
Some guys make the mistake of trying to remove "perceived slop" by over-tightening the sector-shaft end-play, which makes the auto return system very difficult or impossible. That's why RRR mentioned the FSM procedure.
The A-body auto-return system is weak because the factory caster/camber settings are almost miniscule, as is the SAI, and radial tires just don't push as hard as the original type tires.
So if you want to improve things, the best you can do is install the problem-solver UCA bushings, which can improve your caster to perhaps 5 degrees at O camber. By the time you dial in .5 degree negative camber, you might be down to 3.5 caster. That's about as good as it gets without spending a lot of money. For a citycar I would set both sides the same.
