Sprint Car Chassis have evolved over nearly a century, from humble beginnings of two seater cars utilising components from Model T Fords to today’s light-weight, purpose built racing cars. In all this time the basic size and configuration has changed little, look at classic shots dating back to the 1930’s and you can see the similarities to the sprint cars on the track today.
Constructed from aircraft quality steel tubing, sprint cars are unlike Champ Cars and Formula One, which utilize expensive, high tech composite materials. While simple, the engineering principles used in sprint car construction ensure they are extremely strong and can withstand high speed impacts.
The most common type of chassis design currently in use is known as the “High-Bar” chassis, this type of chassis gets its name from the two down tubes that run from the top of the roll cage to front of the chassis. These down tubes assist in keeping the chassis rigid, without these the chassis can flex too much, making setup difficult. The down tubes also add to the safety of the chassis. The “Low-Bar” chassis does not have the two down tubes of the “High-Bar” chassis, this type of chassis is rarely used in competition today.
Sprint Cars have a relatively short wheelbase of between 83 and 90 inches, this compares to a Champ Car with a wheelbase of around 120 inches. USAC Silver Crown cars have a larger minimum wheelbase of 102 inches. The most common chassis dimensions are 87 or 88 inches. You may see sprint car chassis described as 88/40 or 87/40 etc. 88/40 means the wheelbase (center of the front axle to the center of the rear axle) is 88 inches and the front of the motorplate is 40 inches from the center of the rear axle, this is known as engine setback. "Raised rail" is also another common term used, this relates to the fact that the left lower chassis rail is raised around an inch compared to the right side.
A new bare Sprint Car chassis will set you back around US $3,000, pretty cheap when you compare it to a Champ Car which cost hundreds of thousands of dollars!
The chassis in use today are all very similar in design, this is a bonus for competitors as most components are interchangeable between chassis makes.
While the top teams don’t usually bother repairing damaged cars, most accident damage to a sprint car can be repaired, in fact the entire front end of a sprint car chassis can be cut off and replaced, this is known as putting a new “front clip” onto a car.
Most teams have more than one chassis at their disposal, teams that compete on gruelling series such as the World of Outlaws Sprint Series will have numerous chassis stored in their haulers. If a chassis is wrecked in an accident it is possible to build a new car in a matter of hours.
The big 3 chassis constructors in the world today are Maxim, Eagle and J&J, all constructed in the US.