Racing Glossary (Racing 101)

A component of suspension, these metal or carbon fiber rods connect the tires and wheels to the chassis.  They are usually shaped like an "A", with the point of the A connected to the wheel and the bottom two points of the A connected to the chassis.  There are usually two A-arms at each wheel, one top and bottom. Also called wishbones

The science of managing airflow plays a major role in racecar design and tuning because modern day open wheeled cars are highly sophisticated aerodynamic devices. Areas of high and low pressure are carefully managed to maximize downforce (to give a car grip) while minimizing drag (to maximize speed). You can see the wings on the nose and the large wing at the rear of the car. Underneath, two large grooves (like funnels cut in half) suck the car down on the track by creating a partial vacuum under the car. This is generally referred to as "ground effects." Wind tunnels play a key role in modern day open wheeled cars design and evolution.

Mechanics can adjust a car's handling by raising or lowering air pressure in the tires. Flex in the sidewall of a tire acts like another spring in the suspension. Increasing the air pressure makes the overall spring rate higher, while lowering the pressure will make it softer. This adjustment can be made much more quickly and easily than changing a spring on a shock.

A mechanical linkage, one each for the front and rear suspensions, that helps transfer more weight to the inside tires in the corners and helps keep all four tires gripping the track. The driver adjusts the anti-roll bars with levers in the cockpit. Also called a sway bar.

The geometric inside center point of a corner. In racing, a driver will often use a "late apex," turning into the corner a little later than normal in order to straighten out the last part of the corner. This allows the driver to accelerate earlier and harder, gaining maximum speed down the next straight.

A car running near the back of the field.

The fireproof hood drivers wear under their helmets to avoid burns to the face and neck.

On oval tracks, the corners are often tilted inward to provide faster speeds. On some road courses, certain turns may actually be banked outward, a very difficult type of corner known as "off-camber."

This flag is waved by the starter to signal a driver that he or she must immediately report to the pits for consultation related to a dangerous mechanical condition or a driving infraction. Failure to heed the flag can result in exclusion from the final results of the event. This flag may also be displayed in a "furled" (rolled-up) manner as a warning. Corner workers may also display a black flag if the session has been halted by the display of a red flag by the starter.

This flag is displayed by corner workers around the track to signal to a driver that a faster car is either approaching (steady flag) or attempting a pass (waved flag). The driver being flagged has no obligation to do anything other than be alert, maintain the racing line and avoid intentionally obstructing the faster car.

The exterior of the car. The bodywork is generally made from carbon fiber. The panels lift off in sections so mechanics can get to mechanical components easily and quickly. Bodywork is carefully sculpted to maximize aerodynamic efficiency.

In most cars, including street cars, pressing on the brake pedal applies a little more force to the front brakes than the rear. This is designed to take advantage of the fact that under braking, weight transfers to the front of the car. With lots of weight on the front tires, the brakes can be applied very hard without completely stopping the wheels from rotating ("locking the wheels"). At the same time, the rear of the car tends to get lighter, so the rear brakes must be engaged less than the fronts to avoid locking the rear wheels and possibly losing control. In a racecar, brake bias is adjustable by the driver to compensate for changing conditions, such as on a wet track where there is less weight transfer to the front of the car under braking, or to adjust for a changing center of gravity as fuel is burned off.

Brakes transform motion into heat. The heat in the  rotors of a car can reach 5,000 degrees F. When the fluid in the brake system exceeds its boiling point due to hard use, bubbles can form in the brake lines and calipers. Since these bubbles can be squeezed smaller by pressure from the brake pedal, the pedal tends to "go soft" and may even go to the floorboard without the brakes working properly.

In shock absorbers, a bump adjustment is a change to the dampening of the shock on the compression stroke. As a car passes over a bump on the track, each wheel assembly rises up to pass over it. Without compression dampening, the momentum of the wheel assembly would cause it to continue to rise after the bump until the spring finally overcomes the inertia and pushes the wheel back down. Since a tire can't do any work while in the air, bump dampening stops the upward momentum and allows the tire to stay in constant contact with the pavement. Bump adjustments also affect how the weight of the car shifts around during braking, acceleration and cornering, known as "weight transfer."

Refers to changes in wheel alignment (toe, camber and caster) as the wheel moves through the suspension range. Wheel alignment is set with the car stationary, so bump steer affects must be properly considered to ensure that suspension movement does not cause adverse changes in handling or grip.

An element of chassis tuning. Each tire can be tilted inward or outward depending on the track. The usual idea is to tilt the top of the tire inward (negative camber) so that under cornering loads, the entire surface of the tread is being used to the maximum. On oval tracks, because the car only turns left, the left-side tires may be tilted outward (positive camber). Teams adjust the camber setting based on reading tire temperatures across the surface of the tread, with the goal of having equal temperatures on the inside, middle and outside edges. Equal temperatures across the surface of the tire indicate the tire is being used to its maximum capacity.

Carbon fiber is lighter than aluminum, stronger than steel, and very expensive material. It's used to construct the chassis of a modern open wheeled car. Sheets of carbon fiber cloth are "laid up" like fiberglass by an expert fabricator using a mold, and then heated and reheated for days in an autoclave, a large, high-tech oven.

Another measure of chassis tuning related to the front wheels. The front wheels are attached to the suspension at the top and bottom of the wheel assembly. The top attachment is typically set a little farther back than the lower attachment, creating caster. The more caster used, the more the wheel resists turning forces, providing stability. Too much caster makes it very difficult to steer, and causes the tire camber to change significantly as the wheel is turned. Not enough caster results in the front end "wandering," or trying to turn on its own.

When the track is unsafe because of an accident, debris or a sudden downpour, the officials may put the track under caution by waving yellow flags at the starter stand and around the track. This brings out the pace car to gather the field and lead them around at reduced speed until the track is safe for a restart.

The basic structure of a car, including the driver tub, gearbox and suspension. Engines are provided separately.

This black-and-white checked flag is the most famous in racing, signifying the end of the session or race. At the end of a race, the first car to receive the checkered flag at the finish line is the winner.

A quick succession of sharp, slow turns, usually intended to reduce straightaway speeds.

Any time cars are on the racing surface, the chief steward is in charge of the entire facility. He is stationed in race control with radio communications all around the circuit, and he also has at his disposal a full bank of television monitors that give him a view of the entire circuit.

When a car is running by itself on the track, it's in "clean air" because the air is not being disturbed by other cars. See Dirty air.

Tires are extremely important in racing. Compound refers to the chemical composition of the rubber tread, which requires a balance between the conflicting goals of traction (soft compound) and durability (hard compound).

This refers to the distribution of a car's weight among the four wheels. Management of corner weights is very important to handling. This weight is usually adjusted through raising and lowering each corner by rotating a threaded spring perch on each shock absorber or at some other point in the suspension linkage.

Acronym for "Data Acquisition Geek," a computer expert who maintains a team's Data Acquisition system and analyzes the data.

Teams use sophisticated sensors, transmitters, computers and software to provide information on what the car and the driver are doing. Everything from engine stress to the driver's heartbeat can be monitored. The information is analyzed to improve handling, performance and even driver technique. Data can be acquired by connecting a computer to the car or by wireless telemetry.

The bodywork at the rear underside of the car that controls underbody airflow as it exits the back of the car. A good diffuser generates significant downforce.

The rear wing of the car in front tends to push the air higher, creating a very turbulent low-pressure area directly behind the car. At high speeds, downforce can be disrupted by following closely behind another car. A car following closely often will suffer understeer as a result of being in this "dirty air."

Wings on a racing car are upside down compared to an airplane wing. Instead of lifting the car, they press the car harder onto the track, providing increased traction for braking, acceleration and cornering. Downforce is also provided by the ground-effects tunnels underneath the car, creating a vacuum that sucks the car to the track. A modern open wheeled car provides so much downforce that it could actually stick to the ceiling at just over 100 miles per hour. Increased downforce also results in increased drag, which slows a car down, so it's a tradeoff.

A fast-moving car creates a low-pressure area behind it, causing the air to try to move with the car. A car following behind can take advantage of this low pressure as it actually sucks the car along faster, known as "being in the slipstream." A savvy driver can either use the draft to pass, or to lift off the gas slightly and conserve fuel.

A contraction of "Dynamometer," an engine-testing device used in the shop that measures power and simulates the loads and environment of a racing engine.

Flags signal drivers of events or conditions. Green, white, white/red, black, checkered, blue, yellow, red and red/yellow flags each have a different meaning. See each individual color for an explanation of what each flag means.

If a driver locks a tire (brakes so hard that the wheel stops turning), he'll grind a flat spot on the surface of the tire. This causes vibration that can make the car almost undrivable.

Formula cars must fit within a specific set of design rules or "formula." The formulas are usually quite complex, but basic issues include minimum weight, engine displacement, vehicle dimensions, wing sizes and placement, ground-effects tunnel size and configuration, tire and wheel size, and safety considerations.

The transmission attached to the rear of the engine. Open wheeled cars have "sequential" shift patterns, which is more like a motorcycle gear change than the traditional "H" pattern on most street cars.

The green flag is used by the starter to signal drivers that the race is under way, either at the start of the event or at the conclusion of a full-course yellow flag condition. Green flags are used by corner workers on road courses to let drivers know that they have passed beyond a yellow flag area and may resume passing.

The starting order of cars, as determined by qualifying position.

see Line.

In airplanes, this refers to a cushion of air that builds up as a plane nears the ground. In racecars, this refers to artificially generated low-pressure areas underneath the car that help it adhere to the ground. This is done by "tunnels' on each side of the bottom of the car, which start off small near the front and gradually get bigger towards the rear, creating a vacuum as the car moves forward using the ground as the fourth side of the tunnel. The specifications of these ground effects tunnels are carefully monitored. Rules specify the dimensions of the tunnels and how high the outside edge of each tunnel must be from the ground. The greater the gap between the tunnel side and the ground, the more air escapes and the less downforce is generated.

 On the front and rear wings there are often small vertical strips along the trailing edges of the wings, set at 90 degrees to the plane of the wing. Because these strips greatly reduce turbulent air behind the wing, they can add significant downforce with a minimal amount of drag. On the rear wing, it can be easily exchanged for a different size during a pit stop. American racing legend Dan Gurney is generally credited with creating this device, which is also known as a "wickerbill." 

A sharp, 180-degree turn.

A tire that has been heated up through use and then cooled down has experienced one heat cycle. This often results in a slight hardening of the tire compound, which can make the tire perform at a high level for a longer period of time. See Scrubbed Tires.

A measure of an engine's maximum output in terms of torque over a period of time. open wheel car engines produce around 900hp.

The area inside the boundary of the track.

A brand name for a certain type of carbon fiber, used in everything from driver's helmets to bodywork to bulletproof vests used by police. A very strong, expensive and lightweight material.

This term describes two things: the absorbent powder used to soak up fluid spills on the track (often real kitty litter) and the gravel runoff areas on the outside of many road course turns that help slow cars that go off the track.

This is the quickest way around a race circuit, taking advantage of braking, cornering and acceleration. For example, the line for a typical right-handed corner would begin by lining up on the left side of the approaching straight, braking hard, turning in all the way across the track to the inside curb, and then unwinding the steering wheel on the exit to release the friction of the turn, which takes the car back across the track to the outside again. The idea is to use the maximum amount of arc possible to maintain the greatest speed through the corner. The line is often visible due to the rubber laid down by cars, and interestingly is not the shortest way around the track, just the fastest.

Same as Oversteer. Typically describes a cornering condition where the rear tires lose adhesion before the front tires, resulting in a car that feels like it wants to spin easily. This is one of the most unpleasant sensations for a driver  because once the car goes, it's almost impossible to catch. Solutions include adjustments to tire pressure, increasing the angle of the rear wing for more rear downforce, adjusting the rear anti-roll bar setting or spring rates in order to provide more grip, and reducing grip at the front by reducing the front wing angle or stiffening the front anti-roll bar setting or spring rates. Here is an easy way to remember whether a car is loose (oversteer) or tight (understeer): If the front end hits the wall, it was understeer. If the rear end hits the wall, it was oversteer.

Bits of rubber scrubbed off of tires while cornering. These small balls collect on the outside of the turn, and if a car goes wide (into the marbles, or "the gray", referring to the lighter appearance of an area covered with marbles), then much adhesion is lost. In addition, this rubber debris will stick to the hot tires and cause poor traction for the next few corners until they are rubbed off the tire.

A roughly 10 to 20 foot wide strip between the track and the spectators where only officials and media personnel with credentials may stand while the cars are on the track. Usually it's between fences and behind barriers, but it varies from track to track and at different sections of the track.

A fire- and heat-resistant material used to make driving suits, gloves, shoes, helmet liners, balaclavas and underwear. Divers wear four or five layers of Nomex, including long underwear for complete fire protection. When combined with fuel bladders that are resistant to breaking open in a crash, the risk of fire has been greatly reduced over the last 20 years. Much of this technology was developed for the military.

Refers to any type of racecar that does not have enclosed wheels. Formula 1 and CART are open-wheel cars. Stock cars and sports cars are typically based more closely on production cars, with the wheels enclosed within fenders.

See Loose.

Some turns on road and street courses are actually banked outward, which can make them very tricky to negotiate. This is known as an off-camber turn. 

The area where the team transporters are parked, and where the teams work on cars between on-track sessions.

The area where cars come in for fuel, tires, adjustments and repairs during on-track sessions. The name originated from early racetracks, where the mechanics actually stood in a shallow pit where they could duck if an out-of-control car came their way. Today, mechanics are protected by concrete walls, and the pit lane is segregated from the actual racing surface.

This historic term refers to the driver who starts at the front of the field on the inside of the front row by virtue of the fastest qualifying time. The term originated at horse tracks, where many of the original races were held on dirt. The finish and distance markers of a horse track are marked by poles set on the inside edge of the track.

Same as Understeer or Tight. Typically describes a cornering condition where the front tires lose adhesion before the rear tires, resulting in a car that feels like it wants to go straight. Solutions include adjustments to tire pressure; increasing the angle of the front wings to press the tires harder to the ground; softening the front anti-roll bar setting or spring rates in order to provide more grip; or by making changes to reduce grip at the rear. such as reducing the rear wing angle or stiffening the rear anti-roll bar setting or spring rates. Here is an easy way to remember whether a car is loose (oversteer) or tight (understeer): If the front end hits the wall, it was understeer. If the rear end hits the wall, it was oversteer.

Qualifying determines starting positions, based on each driver's best lap time during the qualifying session or sessions. Each car is timed, and the starting grid is determined by the order of fastest cars.

Treaded tires used on a wet track. Also referred to as "Wets."

In shock absorbers, a rebound adjustment is a change to the dampening of the shock on the expansion stroke. Without rebound dampening, the car would tend to bounce as it passes over bumps on the track. Rebound adjustments can also affect how the weight of the car shifts around during braking, acceleration and cornering.

When displayed at the start/finish line, a red flag signifies an immediate halt of the session due to a dangerous condition such as a flooded track or a car blocking the track. Corner workers around the track will display black flags when this happens, and all cars are required to stop racing and slowly return to the pits. The lap in progress is discarded, and the field reverts to the order of the previous lap when racing resumes. If the race has run more that 50 percent of the laps, the chief steward has the option to declare a complete race if track conditions are not expected to improve. If a race has run less than 50 percent, it will be concluded on another date.

This striped flag is displayed by corner workers to signify debris (oil, sand, water or some other substance) on the track.

Modern engines are controlled by electronic "mapping" software that controls things such as fuel consumption and ignition timing. Rev limiting is used for two purposes: to keep the engine from exceeding its maximum rotational speed and exploding into bits of very expensive shrapnel, and to adhere to speed limit rules in the pit lane. Maximum rev limits are set by the engine manufacturer, while the pit lane rev limiter is controlled by a pushbutton on the steering wheel.

Height of the chassis above the ground. Because of the relationship between the height of the ground-effect tunnels and their performance, maintaining optimum ride height is an important facet of car setup and design. However, it is hard to manage since the faster a car goes, the more the aerodynamic effects press it to the ground. Many very complex methods are used to maintain a consistent ride height.

Also known as Scuffed Tires, which have a few laps on them to remove the outer sheen and provide more consistent traction. See Heat Cycles.

There are a huge number of variable adjustments to the suspension, tires, gears, engine, wings, brakes and virtually every other piece of the car that can be moved or electronically altered. The idea is to improve the handling and performance by making a car conform to a particular track, temperature and even weather condition. The driver with the best setup is in a good position to win. A driver with a less-than-perfect setup can sometimes "hustle the car" and compensate for the deficiency, but most drivers perform at their utmost only when the car is comfortable.

British term for crash or accident.

A racing tire with no tread. There is a misconception that the tread pattern of a tire provides traction. This is true in dirt, snow or on wet pavement, but on dry pavement the maximum amount of "contact patch" is desirable.

See Drafting.

Teams on an oval track will usually have crew members on top of the grandstand where they can see the entire track and warn drivers of an accident or advise them where to go in traffic.

A brand new tire, with the manufacturer's sticker still on the "tread."

An acronym you may hear on the in-car audio, referring to the electronic "Shift With Out a Lift" device, which allows gear shifts without lifting off the throttle, making the shift faster.

A driver following closely behind another car may dart momentarily to the inside at the entry to a corner, pretending to attempt a pass in order to disrupt the concentration of the driver in front and hopefully cause a small mistake, setting up a subsequent passing attempt.

Data acquisition transmitted wirelessly while the car is on the track.

Braided Kevlar double strap bolted to the wheel on one end and to the chassis on the other to keep the wheel attached to the chassis in case of an accident.

See Push.

In order to provide stable tracking, all four tires are usually pointed slightly inward if viewed from overhead. More toe-in provides more stability but increased tire drag. On high-speed oval tracks, these toe settings are even more crucial. Teams usually adjust toe with the most unsophisticated methodology seen in racing, using a string around the outside of the car and a caliper to measure the difference in the distance from the string between the front outside of the tire and the rear outside of the tire.

A measure of engine power, described in foot-pounds of force. 10 foot-pounds of torque would raise 10 pounds of weight one foot in the air. Horsepower is a measurement of torque over a period of time.

Small blue electronic transmitter mounted to the chassis. When the car crosses a wire embedded in the track, it sends a signal to the timing computer for lap and lap segments timing. Each car has a specific code so the computer can keep track of the individual cars.

Ground-effect-generating venturi underneath the side pods of a Champ Car. See Aerodynamics.

As a car reaches a corner, this is the moment at which a driver actually begins to turn the wheel. The timing of this action and the car's response to it are crucial for setting fast lap times.

See Push.

An area of revolving compressed air. The most obvious examples are the vortices that are visible coming off the rear wing  in humid conditions. These vortices are always there but only visible in certain conditions.

When waved by the starter, this signifies the start of the last lap of the race. When waved by a corner worker, it signifies that a slow-moving vehicle is on the track.

Used by the starter, this white flag with a diagonal red stripe indicates that an emergency or service vehicle is on the track, and extreme caution should be used.

See Gurney Flap.

If displayed by a corner worker, this means the subsequent section of the track has a problem that requires that drivers slow down and not make any passes. Usually this is because a car has crashed and is in a dangerous position. If the starter displays two yellow flags, it signifies a full-course caution, which prompts the pace car to enter the track and lead the cars around at reduced speed.