Sprint Car setup technology...
Sprint Car setup technology has become more or less standardized. Even so, there is still much to learn about the finer points of adjusting our cars for optimum performance. Bob Armbruster
Sprint Car racing is one of, if not the, most exciting motorsports forms we have. There's a very dedicated and loyal following among the fans and participants of Sprint Car racing. One of our former owners owned and published Open Wheel magazine until it was decided, wisely or not, that it was no longer economically feasible to continue to offer that title. We would like to continue where OW left off and provide tech content in Circle Track. This article is the beginning of many Sprint Car related offerings in the years to come.
Technology for Sprint Cars has not evolved very much over the years. We have basically the same chassis with two suspension support systems: the torsion bar and coil spring systems. The straight axle front suspension is standard, as is the steering. Designs become "standardized" through trial and error and Sprint Car design is what it is because of the need for simplicity and durability. Is this the only system that will work? We don't know, but it would be fun to experiment. And we might do that in the coming issues. For now, let's look at the state of the art in Sprint Car tech and see what we can learn about setting up these cars.
Dirt Sprint Cars have large...
Dirt Sprint Cars have large and wide right rear tires and the resulting large amount of stagger helps make the car turn and provides more bite when exiting the corners. Stagger changes are used to tune the car for changing track conditions. Bob Bolles
Sprint Cars are all constructed in a similar fashion. The suspension has a straight axle for both the front and rear, the driver sits in the center of the car, the rear axle is supported inside birdcages, the rear tires are much larger and wider than the fronts, especially the right rear, and the cars are sprung with either a coilover spring/shock combination, torsion bars, or a combination of both.
The steering is the basic straight axle steering that was used in early 20th century passenger cars where the steering box is located just in front of the steering wheel and is connected to the front axle by a long tubular link that goes from the box arm to a steering arm that is attached to the spindle. A tie rod then connects both front spindles. The cars may have wings or not, depending on the particular rules. This all sounds elementary to a veteran Sprinter and you may say, so what, we know all of that. We are pointing out these various design features so we can evaluate them individually later on.
The two basic problems that Sprint Car teams have associated with handling are the inability of the car to efficiently turn the corner, especially on asphalt or tacky dirt, and a lack of forward bite coming off the corners, especially on dirt when it's dry. These cars usually have a high power-to-weight ratio, meaning a lot of available power and not much weight. The wide RR tire helps provide much of the forward bite but can also make the car tight on entry and in the middle of the turn. If we loosen the car to make it turn, we lose forward bite.
This unique Sprint Car defied...
This unique Sprint Car defied tradition. It was custom built by Bill Montagne in 1978 with an independent suspension at the front and rear with torsion bar springs. Do we need for someone to come along now and redefine the Sprint Car, or is the design maxed out? Photo courtesy Bill Montagne
If we use the standard manufacturer's suggested settings for setup, we might not find the true potential for our cars. That is because car builders must publish information that would fit a wide range of tracks and track conditions. If your team runs one particular track every weekend, then you should try to tailor your setup to work for your racetrack.
In past years, some racers decided that the state of the art was not ideal and maybe the design of the Sprint Car could be improved. We never learn anything if we don't try, so in and around 1978, Bill Montagne of California, designed and built his own unique double A-arm front and rear Sprint Car. It had several interesting features.
Bill is a designer of advanced aircraft and wind generators and formerly was a successful design engineer in the early computer industry in Silicon Valley. He had never raced on four wheels before designing and running this car. Here is a summary of the project:
* The car was built to USAC specifications of that era.