Race car setup is a crucial aspect of success on the track. But some of the tools, such as scales and laser alignment equipment, are very expensive. One solution is to get a group of racers together to share equipment, or borrow equipment when you can. But the reality is that you can get 99 percent of the work done with some basic equipment. For less than $100, you can get your car set up, then all you really need is a tire pyrometer (as low as $99) and a stopwatch. Here's what you need:
* Machinist's Rule
* Plumb Bob
* Angle Finder
* Tape Measure
* Angle Iron Or Plate (Steel Or Aluminum)
1 Check Toe With String
A roll of survey string--available at any hardware store--is all you need to quickly check front toe. The string must be held so that it passes around the outside of the rear tire and touches both the front and rear sidewall bulges at axle height. Unroll the string and, with the string taut, slowly move the string until it just touches either the front or rear sidewall bulge, again at axle height. Measure the gap with a machinist's rule at the end not touching the sidewall. The measurement is the toe-out if the gap is at the rear and toe-in if the gap is at the front. If the string does not contact both the front and rear bulge of the rear-tire sidewall, either the rear axle is offset or it is out of alignment. Keep in mind that this method will not work on race cars in which the rear track width varies more than 1 inch from the front track width.
2 Check Front And Rear Toe With Plumb Bobs
Refer to the illustrations. First, put a true scribe mark around the tire. Then place a piece of 1-inch masking tape on the floor where the plumb bobs will touch. Next, lay string with plumb bobs accurately over the scribe line so the tips of the plumb bobs just clear the floor. Let the plumb bobs stabilize, and carefully mark the floor where the plumb bobs come to rest. Do this on both sides, and use a tape measure to measure between the marks. This is a very accurate way to measure toe if the scribe lines are accurate.
An even more accurate way to do this is to use 24-inch-long aluminum- or steel-angle iron. Carefully notch each end for the plumb bob string so the notch is in exactly the same location at each end. Mount the angle iron to the brake rotor with either reversed lug nuts or clamps, and level the angle iron. Mark the floor where the plumb bobs come to rest as above and repeat on the opposite side. Take measurements on the floor between the marks. You can also use this method to check rear-axle-housing toe.
3 Square The Box
The box formed by the steering arm, idler arm, and drag link must be square to avoid unwanted bumpsteer. The distance between pivot points of the steering must be measured accurately. Center the steering by rolling the car forward at least one full tire revolution. Measure between the steering arm and idler arm pivots at the end at the drag link. They should be identical. Adjust if needed. Then measure the diagonals. They should also be equal. If the distance between pivots is equal, but the diagonals are unequal, something is bent. Take a closer look.
Bumpsteer is toe change during vertical wheel travel. You can use the same setup as in No. 2 to measure bumpsteer. Just disconnect the spring and shock (with the chassis on stands) and use a jack to raise and lower the suspension. Start with the suspension at ride height and mark your piece of tape. This is your baseline. As you raise and lower the suspension, the marks will usually move inward with zero bumpsteer. If one end moves farther from the baseline than the other end, bumpsteer is present. The difference in measurements is the amount of bumpsteer. If the front measurement is bigger, you have toe-out; if the rear is bigger, you have toe-in. Plot the change at 1-inch increments for 3 inches of bump and 3 inches of rebound travel at each front wheel.