After centering the steering, it must be locked in place. Use of a 26 board and clamp is c
Here we lay a steel tube on the jackstands parallel to the frame and touching the front of
The materials for a set of toe gauges. Use 3/8-inch steel rod and cut as follows: two piec
A pair of toe gauges welded up. Calibrate by standing gauges together with the long end do
Here the wheels are turned 15 degrees to the right. Toe is set at 3/8-inch out to compensa
The toe gauges in place to set toe with wheels in the straight ahead position. With wheels
Detail of how gauges are set up and aligned with the steel tapes.
This shows how to use the toe gauges without the wheel. Cut a block to fit under the suspe
Keith Frisse after the first heat with new toe setting.
Toe setting is often an overlooked item on entry level dirt track race cars. Many of those who do bother to set the toe will either set it by the factory specs or, as one fellow told me, "I look down both sides of the car and make sure the tires point kinda straight." Honest!
This time, we will concern ourselves with dirt track cars. Paved track racing requires different settings, sometimes to the reverse of dirt, and the front end alignment needs to be more precise to its purpose.
Each make and model of car has its own steering geometry. This determines the direction the wheels point at any given amount of steering input. You have to ask a number of questions to get the best results. Is the car front steer or rear steer? Does it have Ackermann effect built in? What about the bump steer? Simply put, different cars need different toe settings.
I’m going to approach this in a practical way. My best ever chassis teacher, Duke Southard at Southard’s School of Racing, suggested first to center the steering box. Do this by turning the wheels lock to lock both ways. Count the steering wheel turns and find the halfway point.
This is very necessary because toe adjustments may have been done all on one side in the past, as we found on our subject car. It turned 4 degrees further to the left, reducing the wheel’s turn angle to the right side, leaving less to correct a drift, and increased it on the other. After establishing center, we used tape to mark the centered location on the steering wheel and locked it in place.
Next, our observation tells us a dirt track car spends much of its time in a corner with the wheels turned right to about 15 degrees, depending on the weight and power and other handling factors of the car. Here, the right front is carrying considerable load and the left very little. The toe setting should be as efficient as possible at the moment of the highest load.
Since the right front is heavier than the left front, the right will have a higher slip angle. Slip angle is the difference between the direction the wheel rotates and the direction the tire patch points. Remember, this is a rubber tire and it flexes in all directions. On a DOT steel radial, the right front tire, when loaded in a turn, will carry about one degree more angle than the left. This translates to about 3/8-inch of toe as measured at the outside diameter of a 28-inch diameter tire. Real race tires are more flexible than DOT tires and will have higher slip angles. The reason the slip angle is important to our toe setting is that we should align the slip angles rather than the wheels.
At the point in a turn where the right front is turned right in a drift, the wheel is dragging the tire, inducing a slip angle. With the wheels toed out, the tire patch is running truer to the direction of travel than the wheel. With this in mind, we need to set the toe out to 3/8-inch, which compensates for the one degree slip angle difference.
The next problem is how to know when the right wheel is turned 15 degrees. We laid a bar across two jack stands, parallel to the frame. Measure to this at the outer diameter of the tire to locate 15 degrees. Assuming you have a 28-inch diameter (88-inch circumference) tire on the right front, 15 degrees of turn would measure 71/4-inch difference front to rear on the bar. If your tire is not the same size, plus or minus 11/2 inch of circumference will make a difference of about 1/16 of an inch.
I built a simple set of toe gauges which I find very useful. The photo explains their construction. I used 3/8-inch steel rod and some 1/2-inch nuts.Weld together and straighten as necessary. The small end should be 12 inches and the long end 28 inches. Cut the single centerbar to 20 inches. Cut off these bars and deburr only; you don’t want to round off the ends since this is what you will be measuring to. I keep two steel tapes dedicated for use with these gauges.
These toe gauges are the simplest I’ve found. Stringing the car is a good idea, but if you work by yourself or have limited time such as between heat races, this will work. They are best used on smooth, hard surfaces but can be used with reasonable accuracy in the dirt at the track.
The procedure for finding toe begins with having a true wheel. On our subject car, a Chevelle owned by Keith Frisse, the rims showed some competition adjustments, but the centers checked true on both wheels.
The right front wheel is now turned to 15 degrees. Set the strings and jackstands on each side of the car. The strings must be parallel to the wheels. Measure carefully. On the right side, use a small piece of tape to mark a starting spot on the string. Measure out 28 inches and place another piece of tape at that spot. Using a carpenter’s square to sight from one string to the other, make another tape mark on the left string, then measure out 28 inches for the last tape mark. The tape marks should represent the corners of a rectangle. Measuring at the tape marks will reveal the toe setting with the wheels turned 15 degrees.
Keith set the toe at 3/8-inch out with the right front wheel turned right 15 degrees. That’s just what we thought we needed until we straightened the steering back to center. Re-checking the toe setting now revealed a slight (1/16-inch) toe-in condition. Duke says, "Toe in will make a car squirrelly in the straight. Use at least 1/8-inch toe out and let the left front drag a little in the corner."
Keith set the toe to 1/8-inch out, which is 9/16-inch at the 15 degree turn angle. Your car may very well be different, though. Dragging too much toe out around the track is a waste of horsepower and too little makes the car uncomfortable to drive.
Some cars will have more than 1/8-inch toe out when the wheels are straightened. If this is the case, leave the toe setting where it is. Don’t reduce it because the car has shown you how much it needs in the corners.
Don’t blindly take our findings to be correct for your car. Each model has different front end geometry. Once you have established the toe setting your car needs, it will not be necessary to go through all the aforementioned steps every time. Don’t be fooled, though. It is very difficult to visually align proper toe angles. Use the toe gauges and check the toe setting any time you think someone may have helped you make a competition adjustment to your toe setting.
Our street-driven brethren usually need small amounts of toe-in to behave on the way to the grocery. This is fine for them, but dirt track race cars need toe out for that all important corner balance.
As an end result, Keith reported the car felt better and corner consistency was improved after resetting the toe. Mission accomplished.