Keep this handy guide by your side when watching your next NASCAR race to stay in the know with stock-car racing terminology:
Camber: The amount a tire is tilted in or out from vertical. Described in degrees, either positive or negative.
Dirty air: Aerodynamic term for the turbulent air currents caused by fast-moving cars that can cause a particular car to lose control or find difficulty in passing.
Downforce: A combination of aerodynamic and centrifugal forces that help “plant” a race car to the ground. The more downforce, the more grip a car has. But more downforce also means more drag, which can rob a race car of speed.
Drafting: The practice of two or more cars, while racing, to run nose-to-tail, almost touching. The lead car, by displacing the air in front of it, creates a vacuum between its rear end and the nose of the following car, actually pulling the second car along with it.
Drag: The resistance a car experiences when passing through air at high speeds. A resisting force exerted on a car parallel to its air stream and opposite in direction to its motion.
Groove: Slang term for the best route around the race track; the most efficient or quickest way around the track for a particular driver. The “high groove” takes a car closer to the outside wall for most of a lap, while the “low groove” takes a car closer to the apron than the outside wall. Road racers use the term “line.” Drivers search for a fast groove, and that has been known to change depending on track and weather conditions.
Loose: Also known as “oversteer.” When the rear tires of the car have trouble sticking in the corners. This causes the car to “fishtail” as the rear end swings outward during turns. A minor amount of this effect can be desirable on certain tracks.
Quarter-panel: The sheet metal on both sides of the car from the C-post to the rear bumper below the deck lid and above the wheel well.
Round (of wedge): Slang term for a way of making chassis adjustments utilizing the race car’s springs. A wrench is inserted in a jack bolt attached to the springs, and is used to tighten or loosen the amount of play in the spring. This in turn can loosen or tighten up the handling of a race car.
SAFER barrier: The Steel and Foam Energy Reduction barrier system — SAFER, for short — is an impact-absorbing wall of welded steel tubing backed by foam. The majority of tracks where NASCAR national series compete have SAFER barriers lining the retaining walls as a safety measure, designed to reduce the energy of crashes.
Short pit: The strategy of pitting well before running out of fuel, getting fresh tires to make up time on the front-runners and theoretically taking the lead once those lead cars need to pit. Short pitting puts a car on an alternate pit cycle and could be beneficial or not depending in part upon how cautions fall the rest of the race.
Side drafting: When a car races alongside another car and “dumps” air flow from that car’s nose to the spoiler of the other car, causing the other car to lose momentum and allowing the side-drafting car to pull away. It’s a strategy used on larger tracks such as Talladega, Daytona and Michigan.
Slingshot: A maneuver in which a car following the leader in a draft suddenly steers around it, breaking the vacuum; this can provide an extra burst of speed that allows the second car to take the lead.
Splitter: Runs the entire width of the car at the front and sometimes appears as if it’s touching the ground. What the spoiler does for downforce in the back of the car, the splitter provides downforce to the front. Damage to the splitter can be difficult to overcome because of the important role it plays in the aerodynamics of the car.
Spoiler: A metal blade attached to the rear deck lid of the car. It helps restrict airflow over the rear of the car, providing downforce and traction.
Tapered spacer: A metal piece that limits how much air gets into the engine cylinder, which in turn limits how much fuel can go into the cylinder and reduces the amount of energy produced.
Tight: Also known as “understeer.” A car is said to be tight if the front wheels lose traction before the rear wheels do. A tight race car doesn’t seem able to steer sharply enough through the turns. Instead, the front end continues toward the wall.
Track bar: A lateral bar that keeps the rear tires centered within the body of the car. It connects the frame on one side and the rear axle on the other. Changes to the track bar settings affect the weight distribution of the car and how it moves through the corners on the track. Also called the panhard bar.
‘Tower’: Short for race control tower, it’s the term used by racing officials and teams in radio communications to address the NASCAR race director for a given event. Fans, teams and spotters listening on the race officials’ scanner channel will hear frequent references to “tower” for race control.
Wave around: Lapped cars that do not pit during a regular yellow-flag pit cycle are allowed to take a “wave around” past the pace car once the one-to-go signal is given during that caution period. This procedure ensures that lead-lap cars restart at the front of the field. Wave-around cars restart at the rear of the field, but they are placed in front of cars that have received a penalty.