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Glossary for IMSA WeatherTech SportsCar Championship

Photo by DMT Imaging

Ever overhear team members talking in their pits and wondering what language they’re speaking? Here’s a handy glossary from the IMSA WeatherTech SportsCar Championship folks to help decipher motorsport talk.  


Air Pressure – Measurement of a tire’s internal pressure.

Alternator – Device mounted on the front of an engine used to recharge a car’s battery while the engine is running.

AMB System – Timing system used to calculate a car’s speed and position on the track during a race. The timing system is run with transponders, or small, radio transmitters that trigger the system when crossing a loop in the track. 


Banking – The inclination or sloping, measured in degrees, of any or all parts of a track’s surface.

Bite – Racing tire adhesion.

Block – 1. Basic structure of internal combustion engine. 2. Intentional interruption of a competitor’s line by another competitor.


Caster – The fore/aft inclination of the kingpins in the front suspension.

Camber – The outward/inward inclination, measured in positive or negative degrees, of the wheels in relation to the track’s surface.

Change Gears – Gears located in car’s rear end, which can be easily changed to alter final drive gear ratio.

Chassis – Structure of the car.

Coil – Circular wound spring suspension device.

Combustion – The sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species.

Compound – A formula or “recipe” of rubber composing a particular tire. Different tracks require different tire compounds.

Constructor – Person and/or company responsible for the building of a chassis.

Contact patch – Functioning surface area of a racing tire, i.e., where the tire actually touches the track’s surface.

Countersteer – Correction of the steering to compensate for a car’s sliding.

Cubic inch – Displacement of internal combustion piston engine.

Cylinder – A device that converts fluid power into linear mechanical force and motion.


Dicing – Heated battling between two or more cars that involves multiple passes or pass attempts for position.

Differential – A device that usually uses gears to transmit torque and rotation through three shafts. In an automobile, the “diff” allows each of the driving wheels to rotate at different speeds.

Downforce – Aerodynamic and centrifugal forces, which keep a car glued to the ground and from air getting underneath, which causes the car to lift. While downforce keeps the car stuck to the track, it also creates drag, thus limiting speed.

Draft – Process of closing in on or keeping close to another car by allowing the lead car(s) to push through the air, thus pulling the following car(s) along. The trailing car(s) can essentially conserve fuel or let off throttle slightly and still attain the same speed as the lead car(s).

Drag – The resistance exerted on a vehicle moving through the air at high speeds.

Drive Through – Penalty in which a car is required to drive through the pits under green flag conditions at the pit lane speed limit, resulting in lost track position. Also called a “pass through.”

Drive Train – Component which connects engine to car’s rear end, producing power.


Engine – A machine, in this case a power plant, which produces mechanical force and motion from another form of energy, such as a fuel source, compressed air or electricity.

Esses – Term used for a series of acute left- and right-hand turns on a road course, one turn immediately following another.


Fabricator – Person and/or company responsible for the creation and/or assembly of a chassis or another component.

Feather the Throttle – Light, frequent engagements of the acceleration pedal to prevent tire spin or enhance fuel mileage.

Fuel Cell – Durable container holding race fuel in car that is capable of withstanding heavy impact and preventing leakage.

Fishtail – Left and/or right side slide during wheel spin or lack of traction.

Frame – Basic tubular chassis in which all components are attached.

Flat Out – Term for a car at 100 percent acceleration.


Gas Shocks – Shock absorber in which the internal chambers are pressure charged with nitrogen to reduce cavitations in the fluid.

Gear Ratio – Ratio of rotation between the powered gears in the gear train, which can assist in finding additional speed.

Grip – See traction.


Handling – The performance or reaction of a car, determined by a car’s setup and tires as well as outside forces and other factors, when on the racing surface at speed.

HANS Device – Device developed to protect a driver’s head and neck in the event of an accident.  Acronym for Head and Neck Safety Device.

Horsepower – Measurement of mechanical or engine power. Measured in the amount of power it takes to move 33,000 pounds one foot in a minute.


Ignition – A process that initiates the combustion of the compressed air/fuel mixture in the combustion chamber.

Infield – The portion of the venue inside the track surface which many times includes the paddock, garage area, transporters, and Victory Lane.


Jump – Forward progress by the leader or another car that gives that car a positional or lengthy track advantage when the green flag is displayed. This progress is legal when the car hits a certain area on the track, determined by the chief steward prior to the race, and cars may be penalized for early progress.


Lap – 1. Measured one completed circuit of race track. 2. To pass another car while leading.

Lapped traffic – Traffic that has already been or is in the process of being passed by the race leader.

Lift – 1. Opposite of downforce. Upward motion experienced by a car caused by trapped air under a car’s panel. 2. To let off the throttle.

Line – Preferred line of entry and exit in a turn, usually marked by laid down rubber.

Lineup – Rundown of cars and drivers and their positions prior to or during the race.

Loose – Term for oversteer.


Motor – Engine.


Neutral – 1. A term that drivers use when referring to how their car is handling. It is used when a car is neither oversteering (loose) nor understeering or pushing (tight). 2. The selection in a transmission when no gear is engaged.


Oversteer – A cornering condition where the rear tires lose more traction than the front tires.  Also known as loose.


Pace Car – Passenger car used to keep racing cars at lower speeds during caution periods. Also leads racing cars to the green flag at the start of the race as well as restarts.

Piston – Round aluminum object – located inside engine – which moves up and down and forms the bottom part of the combustion chamber. Object propelled by combustion.

Pit – 1. Location of one’s crew – off the actual racing surface – to make additions, changes or adjustments to one’s car. 2. The act of making the additions, changes or adjustments to one’s car.

Push – Term for understeer.


Qualifying – Session in which cars are timed to determine where they will start for the event. Both the TUDOR United SportsCar Championship and Continental Tire Sports Car Challenge hold 15-minute sessions for each of the classes.


Radials – Tire construction where the body plies are more or less perpendicular to the bead of the tire.

Restart – Period of which racing resumes following a caution period.

RPM – Acronym for Revolutions Per Minute.


SAFER Barrier – Acronym for Steel And Foam Energy Reduction. This is the retaining wall, developed by the University of Nebraska-Lincoln, designed to reduce the level of impact of cars. Also commonly known and referred to as soft wall.

Sandbag – To deceive competitors by saving car’s maximum ability in practice or another event for qualifying or the feature race.

Scaling the Car – Documentation, with scales, by weighing four corners of car individually.

Scuffs – Term for tires that have been used at least once and saved for further racing. A lap or two is enough to “scuff” them in. Most often used in qualifying.

Setup – Combination of various adjustments, determined by the crew chief and/or driver, to make a car handle better, maximize its fuel capacity, make the driver more comfortable in a seat, etc.

Shock – Compression and rebound device for designated corners of a car.

Shut the Door – Phrase for the lead car of a two-car pack to disallow an attempted pass, usually in the track’s turns.

Sidewall – The side(s) of a tire.

Slick – 1. A track condition where, for a number of reasons, it’s hard for a car’s tires to adhere to the surface. A slick racetrack is not necessarily wet or slippery because of oil, water, etc. 2. A tire that has no tread elements, just a smooth rubber contact surface.

Slingshot – Passing method in which a trailing car moves past the lead car(s) with the help of the draft.

Spin – The incidental turning of a moving car by more than 90 degrees.

Splash and Go – A quick pit stop that involves nothing more than refueling the race car with the amount of fuel necessary to finish the race.

Spotter – Team member designated to assist and inform a driver with what may be going on around the track during a practice, qualifying or a race. Spotters are expected to inform drivers of an accident as well as the driving of other competitors on the track.

Spring – A mechanical device that is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces.

Stickers – Term for new tires. The name is derived from the manufacturer’s stickers that are affixed to each new tire’s contact surface.

Stop and Go – A penalty requiring the car to be brought onto pit road at the appropriate speed and stopped for one full second in the team’s pit stall before returning to the track.

Straightaway – Straight line of track connecting the track’s turns.

Suspension – The assembly of springs, shock absorbers, torsion bars, joints, arms, etc., that cushions the shock of bumps on the road and serves to keep the wheels in constant contact with the road, thereby improving control and traction.

Sway Bar – Sometimes called an “antiroll bar.” Bar used to resist or counteract the rolling force of the car body through the turns.


Tight – Term for understeer.

Title Sponsor – Primary sponsor of a sanctioning body and/or one or more of its divisions, the sponsor of a racing event, and/or the primary sponsor of a race car or race team.

Tie Rod – Linkage that connects the front two wheels.

Track – 1. The race course.  2. The distance measured between the centerline of each front or rear tire, i.e., the mechanical width of the suspension.

Traction – The amount of adhesion between a tire’s surface and the track’s surface.

Traction Control – Device limiting the loss of traction. This is not allowed in GRAND-AM competition.

Transmission – 1. Ratio-changing device to increase/decrease momentum. 2. Conversation between team members over the radio.

Transponder – Device, temporarily attached to racing car, which transmits timing and scoring information to a computer.

Transporter – Box trailer used to carry race car and equipment.


Understeer – A cornering condition where the front tires lose more traction than the rear tires.


Valve – A device that opens and closes to allow the passage of air or liquids.


Wheelbase – The distance from the center of each axle