Turn the wheel past 0 degrees on the turn plates and go past that to 20 degrees left turn. Again, level the gauge and read the amount of caster in the display. Repeat for the left-front wheel, only in reverse order, turning left first.
Camber Defined
Camber is when a wheel is tilted so that the top of the tire is either closer to or farther from the centerline of the car. Negative camber is when the top of the tire is closer to the center of the car than the bottom of the tire. Positive camber is when the top of the tire is farther away from the center of the car than the bottom of the tire.
Circle Track Camber
In circle track racing, we use positive camber on the left-front wheel of the car and negative camber on the right-front wheel. We can easily check the amount of camber by using a caster/camber gauge and reading the amount directly on the camber bubble vial.
We have learned some interesting and important aspects of tire camber for short-track racing. We have always known that a racing tire will flex under the stress of cornering and the tread will move and roll under the wheel when the extreme forces associated with cornering are present. Different brands of tires have different stiffnesses of sidewall construction and therefore roll over more or less.
To measure on the floor to get exactly 20 degrees of steering, cut a 30-inch piece of 1x6-inch wood, or a similar straight, flat piece, and lay it against the tire. Mark midway on the wood (15 inches) and line that up with the center of the hub. Mark the outside corner of each end of the wood. Turn the steering wheel until the ends have moved 5 3/16 inches and you will have turned the wheel 20 degrees.
Tire temperatures tell us more about how much static camber we need than anything else. The overall goal is that we need the tire contact patch to be relatively flat on the racing surface at midturn in order for the tire to be able to provide the maximum amount of traction. This is often referred to as the maximum "footprint."
Tire temperatures can alert us to improperly set static cambers. A front tire that is hotter on the inside edge (side toward the inside of the racetrack) usually has too much positive camber in the case of a left-front wheel, or too much negative camber if it is the right-front wheel.
Camber Change
The cambers will change as the car dives and rolls when it enters and negotiates a turn. True camber change is a product of both chassis dive and chassis roll. Gone are the days when we would jack up the wheel and measure how many degrees the camber changed in each inch of bump. Those numbers really don't tell us anything. They are only part of the answer. Chassis roll has an effect that adds or subtracts from what dive does. So what we really need to know is what the dynamic camber is after the car dives and rolls, just like it does in the turns.
The left front always loses a lot of camber, so we need to allow for that in setting the amount of static camber. Generally, if we end up with between 1/2 and 1 degree of positive camber at the left-front wheel after the car dives and rolls, then that tire will have the dynamic camber that it needs.
From a driver's view, positive left-front camber is when the top of the tire leans out, away from the centerline of the car. The opposite is true of the RF tire, which has negative camber where the top of the tire leans toward the centerline.
The right-front camber change is a little different. We can design our car so that the right-front camber does not change after dive and roll. This is actually exactly what that tire wants for most short-track applications. The reason for this is that as we enter the turn, the right-front tire takes a set fairly quickly. If the camber continues to change after that initial set, then the tire will give up traction and the car will usually push.
The right upper control arm angle mostly controls the right-front camber change, so we try to work with that control arm angle. Once we have the proper camber change (zero), we leave that angle alone as we further design our front end for moment center location.
Spindle Height
Spindle height affects the amount of camber change at each wheel. The taller the spindle, the less camber change will occur. Trends that have taken place in the past 10 years or so have resulted in excess camber change due to the use of shorter spindles. That trend is in the reverse mode now as the car builders move toward using taller spindles.
Measuring Camber Change
We can measure camber change by several different methods. In the shop, we can set the chassis ride heights just as they would be at midturn on the racetrack and then directly measure the camber at each wheel. To do this, we will need to know the shock travel at midturn, which is very hard to estimate.
Move camber adjustment shims back and forth from each mounting bolt, or slide the control arm shaft if it is slotted, to adjust the amount of caster in each wheel. This will move the upper ball joint forward (to reduce caster) or to the rear (to add caster).
If we look at the shock travel indicators on the shaft of the shock, it always tells us total shock travel, which includes braking, going over bumps, banking changes such as exiting the racetrack and driving down onto the apron (this could be quite a lot of left-front shock travel at some high-banked racetracks), or something as simple as steering the car back and forth to warm the tires before running hot laps.
Conclusion
Remember that caster settings are mostly adjusted for driver preference and comfort, and camber settings are important so that the front end will have the maximum amount of footprint and traction to use to turn the car at midturn. Many of our problems related to a car that won't turn well come from incorrect camber settings and camber change problems.
Often, a car that has a serious push can be helped by analyzing and adjusting the static camber as well as knowing the camber change amounts. For dirt cars, taking tire temperatures may not be feasible, but measuring tire wear can tell us a similar story as temperatures. The more wear, probably the more temperature that part of the tire experiences. Even wear across the tread translates to more even tire temperatures and the best camber settings.
For measuring camber, level the gauge and just read the amount on the vial, for a manual gauge, or the display on a digital gauge.
In our test of Intercomp's caster and camber gauges, the camber readings came out the same for both gauges. Make sure the car is at ride height with all of the weight in the car, including the driver. Air the tires up to operating pressures. These settings may change once the car is raced and the tire temperatures have been evaluated. | 
As the chassis dives, the upper ball joints are pulled in toward the centerline of the car. This causes a movement toward negative camber in both front wheels. The greater the angle of the upper control arms, the more change in camber from chassis dive. But this is not all that is happening. | 
Besides chassis dive, when we turn the car left, the chassis also rolls. As the chassis pickup points move in roll, the upper ball joints move to the right. This causes the LF wheel to further lose camber toward the negative and the RF wheel to move toward positive camber.
If we combine the effects of dive and roll, we see where the LF wheel will lose in both dive and roll where the RF dynamic camber will be a product of combining two movements that are in opposite directions. That is why we can achieve a net zero change in camber at the RF wheel. |