Performance Tuning Front End Alignment
An Article by Larry Paulick
There are also very expensive turntables, that allow the front wheels to move with the weight in the car, ie you, and when you turn the front wheels left and right to measure the caster. You can get very accurate measurements by using plastic garbage bags under the 2 front wheels. This surface allows the wheels a relatively slippery surface to move on, and while is not as good as the $400-$1,200 turntables, works very well.
When setting up the car, bounce the front up and down to settle the alignment, after making changes with shims. Then take the car for a short ride, come back, and check the specs again.
Set your tire pressure to specs, gas in tank at least 1/2 full, and the normal stuff you would have in the car if you were racing/autocrossing, but not all the junk found in a lot of cars. The extra weigh will change the alignment of you car.
Doing your own alignment allows you to do this.
ALWAYS TORQUE THE BOLTS TO SPEC, WITHOUT FAIL. KEEP IT SAFE, AND DO NOT FORGET.
3. Setting up the caster can be accomplished in 2 ways. If the car is really out of spec, and factory spec is 3 degrees and 50 seconds positive caster, just about 4 degrees, such as mine was you can add shims under the cross member, between the alum wedge spacer and the frame rails. My caster was 1.5 degrees pos. caster on the left, and 1.5 degrees neg. caster on the right.
a. I found an alum ruler from Home Depo for $7, yes ruler, that was 1/8" thick and 2" wide, the same width as the alum spacer that goes between the crossmember and the frame rails. I used the original aluminum wedge space as a templet to find the location of the hole where the 5/8" diameter bolt goes through the crossmember, and bolts to the frame rail. I cut the ruler in 2" long strips for the spacer. Bonus is that you have the measurement right on the ruler.
I used 2 spacers for a total of 1/4" at the rear of the alum spacer. This added approximately 2 degrees pos caster to the car. It has been suggested that you not add more than 1/4", and after looking at this spacer, I thing that should be the limit.
BTW, I tried adding 1/4" spacer on the left, and a 3/8" spacer on the right to correct the difference in the caster noted above. It did not work, as I only got 2 degrees with either the 1/4" or 3/8' spacer. It also shows that the crossmember is really stiff. As pointed out to me, it may over time do something funny to the frame rail on the right.
b. The additional caster, or if your car is not that far out of spec, is set up at the rear bolt on the upper a arm, by adding single shims at this point.