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NASCAR Glossary A-D

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A

Aero Push

When following another vehicle closely, the airflow off the lead vehicle does not travel across the following one(s) in a normal manner. Therefore, downforce on the front of the trailing vehicle(s) is decreased and it does not turn in the corners as well, resulting in an "aero push." This condition is more apparent on the exit of the turns.

Aerodynamic Drag

A number that is a coefficient of several factors that indicates how well a race vehicle will travel through the air and how much resistance it offers. Crewmen work to get the best "drag horsepower" rating they can, determining how much horsepower it will take to move a vehicle through the air at a certain mile-per-hour rate. At faster speedways teams strive to get the lowest drag number possible for higher straightaway speeds.

Air Dam

A strip that hangs under the front grill, very close to the ground. It helps provide downforce at the front of the car.

Air Pressure

With the advent of radial tires with stiffer sidewalls, changing air pressure in the tires is used as another setup tool that is akin to adjusting spring rates in the vehicle's suspension. An increase in air pressure raises the "spring rate" in the tire itself and changes the vehicle's handling characteristics. If his race vehicle was "tight" coming off a corner, a driver might request a slight air pressure increase in the right rear tire to "loosen it up."

B

Back Marker

A car running off the pace near the rear of the field.

Balance

When a car doesn't tend to oversteer or understeer, but goes around the racetrack as if its on rails, it's said to be in balance.

Banking

The sloping of a racetrack, particularly at a curve or a corner, from the apron to the outside wall. Degree of banking refers to the height of a racetrack's slope at the outside edge.

C

Camber

Camber addresses the angle at which a tire makes contact with the track surface. "Positive camber" indicates the angle of the tire is tilted away from the vehicle's centerline while "negative camber" indicates the tire is tilted toward the centerline. A typical oval track setup would have positive camber in the left front and negative camber in the right front to help the vehicle make left-hand turns.

Camshaft

A rotating shaft within the engine that opens and closes the intake and exhaust valves in the engine.

Chassis

The combination of a car's floorboard, interior and roll cage.

Chassis Roll

The up-and-down movement caused when a car travels around corners at high speeds. The side of the car facing the turn becomes lighter while the extra weight goes toward the outside of the turn.

Contact Patch

The part of the tire that's actually touching the road.

D

Dirty Air

The air used and discarded by the lead car.

Downforce

The air pressure traveling over the surfaces of a race vehicle creates "downforce" or weight on that area. In order to increase corner speeds teams strive to create downforce that increases tire grip. The tradeoff for increased corner speeds derived from greater downforce is increased drag that slows straightaway speeds.

Draft

The aerodynamic effect that allows two or more cars traveling nose-to-tail to run faster than a single car. When one car follows closely, the one in front cuts through the air, providing less resistance for the car in back.

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.