Suspension geometry terminology

[Jeremy]

I was wondering if someone can tell me what the proper term for an alignment term is? What I am wanting to know is what is it called when the top of the tire tilts into the direction of the steering input. I was in a parking lot today and happened to watch a new Superbee pull into its spot. The top of the inside tire tilted into the turn pretty agressively.

I checked my TA to see if it did the same and it did not. I did not put a level on it to see what it exactly did, but the calibrated eye ball said it stayed perpendicular or tilted towards the outside of the turn slightly.

I would assume the tilt into the turn would be desireable to keep the tire flat when the body rolled. Second, how can you change this?

[83hurstguy]

I believe you are referring to caster. Caster is defined as the inclination of the steering axis from a side view...
I suppose a simple way to describe caster is "camber gain resulting from a change in toe". Camber is the vertical orientation of the tire from a front view of a car, toe is tire angle from the top view of the car.

Positive caster allows the wheels to lean into the turn.
In order to adjust your caster, you need to change the steering axis inclination... you are limited in range of what you can do by shimming factory upper control arms, and aftermarket set of adjustable uppers should be able to help you out.

Hopefully this made sense... for a little more information on alignment terminology, I googled and found this: http://www.ozebiz.com.au/racetech/theory/align.html

[Jeremy]

Thanks, that's what I thought, but couldn't find anything to confirm.

[High Plains Mopars]

Caster is static part of it, but isn't the only part of the change you described as the wheel is turned.

What you are describing is a combination of several things; steering axis inclination, which is built into the spindle. Spindle bearing offset, which is the distance from the steering axis incline to the bearings, also built into the spindle. Finally is scrub radius, which is the distance from centerline of the wheel to the intersection of the axis inclination on the road surface.

The axis inclination and the bearing offset can only be changed with a change in spindles. Later model cars tend to have more of these two characteristics than older muscle era cars do. The scrub radius can be altered with differing offsets of wheels.

These settings not only incline the wheel as the steering input is added, but they also reduce the wheelbase on the inside while lengthening wheelbase on the ouside of the turn which creates a stablizing effect in corners.