The days of converting production cars to race cars are gone. Stock car racing teams build their own cars with the track in mind. In fact, many teams build different cars for different tracks. One area of the car that they often experiment with is the chassis. The chassis is the steel frame of the car that holds the body and the motor.
The chassis is almost always rectangular, but teams often tweak its minute geometry, moving suspension mounting points depending on the track and the needs of the driver. Offset chassis are not permitted, so they have to build parallel frame rails. Chassis rails are built to strict guidelines of weight, length and thickness [source: Burt].
The chassis includes a main frame (frame and side rails) and front and rear subframes, which are connected by cross members. Every connection that holds the frame together is welded.
Suspension fittings are added to the frame in varying positions, which the builders determine for specific tracks. After everything else, small flanges are added to strengthen all connections [source: Burt]. It's crucial that the chassis be strong enough to handle the weight of the car on top of the intense racing conditions. So they have to add every piece of support that adds security without weighing down the car and decreasing speed.
The roll cage is part of the chassis and adds strength and security to the car. Side bars are installed to protect the driver during side impacts, and all roll bars that are accessible to the driver are padded. Before the chassis travels down the assembly line, the roll bar framework is completed, passing through the floor boards and firewall, and connected to the frame rails [source: Burt].
A stock car team constantly tweaks and adjusts a car's suspension, from the chassis to the steering column. It takes more than just a gifted driver to win a stock car race; it takes the dedication and creativity of the whole team.
Learn more about how stock car suspension works by checking out the resources on the following page.