After taking our measurements, we can adjust the camber to the desired setting.If you have a slanted top hat like I do, then keep in mind that using it for camber adjustment will throw your caster off.
After you’re happy with your caster and camber settings, it’s time to string up the car and set the final toe.
For the alignment bars, I use two pieces of 1” aluminum square tube that I picked up from Home Depot. However, anything that is long enough and straight will work, as long as it’s rigid and doesn’t flex.You can even use 2×4’s if you want. Just make sure that whatever you’re using is longer than your track width.
Setting up the strings is probably the most tedious part. You have to make sure you set the strings perfectly square to the car, or your toe measurements will be off. This involves a lot of tedious back and forth measurements as you lightly nudge the bars to adjust them.
The first step is to ensure that the strings are mounted at the same distance from each other on the bars. You do this by making equidistant string guides that will hold the string in place on the bar. However, you need to know that distance first. Measure your track width (from lip to lip, so not actual track width) on the widest end of the car (usually this is the back on race cars, but my car with Wisefab has a wider front end), then add about 12 inches, so that you get 6 inches of clearance between the lip and the string on each side.I actually 3D printed my own adjustable string guides. It’s basically a screw clamp that has a slot for the string to sit in. I like to zip tie the two tubes together to make sure that the guides are in perfect alignment before I clamp them down. If you don’t have a 3D printer, there is a much simpler way to do this, of course. You can simply use an angle grinder with a cut off disk to make a notch on the edge of the tube for the string to sit in.Now grab four identical jack stands and prop your bars across them. Adjust the jack stands so that the top of the bars (where the string sits) are roughly in the middle of the wheel. This is to ensure that you can measure to the front and back edge of the lip.
ATAN in excel returns the result in radians by default. Convert it to degrees by changing your formula to =DEGREES(ATAN((SIN(RADIANS(B64))-SIN(RADIANS(C64)))/(2*SIN(RADIANS(B65))))
Great article and a very clear explanation of the string method for alignment but one query. You stress the importance of the bars being parallel to each other but presumably they don’t actually have to be square to the car – making a parallelogram out of the string and the bars is sufficient and they don’t have to make a rectangle. Would you agree?
This is correct, a perfect rectangle isn’t necessary. An isosceles trapezoid or parallelogram is okay. In either case, the string is spaced evenly from the hub cap on each side.
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Thanks for the guide but I have a problem.
I entered your shortened caster formula in Microsoft Excel, and got a totally different value.
=ATAN((SIN(RADIANS(B64))-SIN(RADIANS(C64)))/(2*SIN(RADIANS(B65)))
=0.05481679
Instead of 4.2
ATAN in excel returns the result in radians by default. Convert it to degrees by changing your formula to =DEGREES(ATAN((SIN(RADIANS(B64))-SIN(RADIANS(C64)))/(2*SIN(RADIANS(B65))))
This worked, thank you.
Great article and a very clear explanation of the string method for alignment but one query. You stress the importance of the bars being parallel to each other but presumably they don’t actually have to be square to the car – making a parallelogram out of the string and the bars is sufficient and they don’t have to make a rectangle. Would you agree?
This is correct, a perfect rectangle isn’t necessary. An isosceles trapezoid or parallelogram is okay. In either case, the string is spaced evenly from the hub cap on each side.
Thanks!
Thank you for the great article and explanation, you’ve inspired me to give it a try!
Is this an empirical formula? If not, could you provide the source? I’d like to know how it was derived.
You do know the average driver don’t want to change tires every 25 miles
Do you know the tires won’t wear out in anything close to 25 miles even with the most extreme racing settings?