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Old 11-08-2012, 04:45 PM
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We will assume you have a early GM B Body here for the sake of clarification. The have an upper and lower control arm ( or A Arm) if you will.

Caster is first. The caster is adjusted by moving the upper A Arm forward or back ,accomplished by adding or removing shims at the front or rear mounting stud of the upper A Arm shaft.The lower A arm, or control arm is fixed and not adjustable. No adjustment is made on the lower.
Each time you add or remove shims, you need to perform a caster sweep to measure it. Measuring it is dependant on the type of machine you are using.
Once you get the caster within specs, then you need to get camber pulled in or out, to around zero, or a tad on the + side.
This entails going back to adding or removing shims at the same place you did to adjust the caster. You add or remove shims ,however to keep the caster adjustment that you just adjusted, you need to add or subtract the same thickness of shim front and back. That way the location of the upper ball joint stays the same front to rear, caster does not change, but by adding and subtracting equal amounts, the camber changes as the balljoint is moves in or out, perpendicualer to the suspension and lower ball joint, which leans the wheel and tire in or out at the top.
Last but not least would be toe in.
That is usually set near zero or at just a small amount toed in as suspension loads against the bushings as the car rockets down the freeway, which can negate a small amount of toe in as the bushings will collapse a small amount(even brand new ones), so a small amount of toe in is recommended.
Toe is adjusted by turning the tie rod adjusting collars , either lengthening or shortening them. Also, at the same time keeping the steering wheel straight ahead, so the wheel is level when the car is going straight down the road.
many of the new alignment racks have a steer ahead and total toe reading, left and right, which makes it real sweet and simple to get the toe correct and the steering wheel level.
Fact is stranger than Fiction
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