A

• A-Post – The post extending from the roofline to the base of the windshield on either side of the car.
• Air Bump – They help protect the vehicle and suspension components from hard bottom-outs and they also play a critical role in end-stroke damping.
• Air Shock – This allows you to increase the ride height of your vehicle, helping to bring it to the level when hauling a heavy load. When air shocks are installed with heavier springs on a truck chassis, they help to increase the useful load of the vehicle. Air shocks use a large diameter shaft to act as a spring and damper.
• Apex – The point in a turn where the car is turning most sharply. By definition, the apex is usually the slowest part of the turn; the car slows down into the apex, and then accelerates out of it.
• Apron – An area on the inside of the track for cars that are going slowly. The apron is also used as the approach to the pits

B

• Balanced – The state in which a tire and wheel spin with all their weight distributed equally. Also refers to a car’s setup being correct.
• Bead Lock – A device used on some short-track racing cars to positively fasten the tire bead to the wheel rim. Particularly with low-pressure tires often used on dirt tracks, a bead lock keeps the tire on the wheel, and prevents the tire from slip rotating around the
• Binders – Another name for brakes/act of braking ie: Putting on the binders
• Bleed – A valve through the piston where oil can pass through. Bleeding is ridding the brake system of trapped air, but some of the old fluid is expelled as well.
• Balancing – The process of equalizing the weight of the combined tire and wheel assembly so that it spins smoothly at high speed.
• Ballast – Something that is added to a car to bring it up to the minimum weight.
• Brake Fade – Condition that occurs when the brakes get so hot they are ineffective and braking power is reduced.

C

• Center of Gravity – A measurement used in chassis setup to determine the overall balance of a race vehicle and adjust handling characteristics. The center of gravity is an imaginary point located in the car where if raised by that point, the car would balance perfectly.
• Circumference – The measured distance around the tread portion of a tire.
• Coil over – An automobile suspension device used to prevent the chassis from bottoming out, support each individual wheel on the vehicle, and to mitigate or reduce body roll when taking turns and cornering, particularly at higher speeds.
• Cold Inflation Pressure – The amount of air pressure in a tire, measured in pounds per square inch (psi) before a tire has built up heat from driving.
• Compound – This refers to the mixture or durability of the rubber on the tread of the tire. Compounds are usually described as “hard” or “soft”. The more abrasive the track is the harder the compound you would want to use.
• Contact Patch – The area of a tire that is in contact with the ground.
• Cord – The strands of material forming the plies or layers of the tire. Cords may be made from fiberglass, rayon, nylon, polyester, steel or other materials.
• Cornering – A measurement of the force exerted on the vehicle’s center of gravity.
• Corner Weight – The weight of one corner of the vehicle. Left and right sides may be slightly different.
• Cross Weight – The percentage of weight on the right front vs. the left rear wheel.
• Cushion – Area of the corner above the farthest outside groove on a dirt track where loose dirt builds up.

D

• Damper – A mechanical or hydraulic device designed to absorb and damp shock impulses.
• Dialed In – When a cars setup is in an ideal state
• Dialing In – The driver and crew making setup adjustments for better handling
• Dynamic – Dimensions or descriptions that apply when an object (tire, suspension or car) is in use or in motion. (As opposed to static when a car is not in motion)

F

• Footprint – The portion or amount of area of the tread that contacts the road. AKA Contact Patch
• Forward Bite – A general term used to describe the amount of force available to move the car forward. In setup, putting more forward bite in usually refers to adding more traction to the rear of the car.
• Free – The same as loose. A handling condition (known as “over-steer” to road racers) where, when the car goes through a corner, the rear end of the car wants to slide towards the outside of the turn. If the car gets loose enough, it will spin out
• Fresh Rubber – New Tires

G

• Gather/Gathering it up – Regaining control of a racecar after becoming loose or spinning.
• Green Track – A track which has not been run in. On asphalt, it is newly paved and doesn’t have the same grip.
• Grip – A term describing the total cornering envelope of a race car by the friction component of the tire, the mass of the machine and the downforce generated.
• Groove – The line or path through a corner which drivers have found to be the fastest.

H

• Handling – A general term for the racecar’s capability to go where the driver wants it to go on the track, and be fast in the process.

I

• Hitting Your Marks – The best spots on the track to either get on or off the throttle. Also may refer to the best line or spots on the track in which to run.

J

• Jounce – The upward suspension travel that compresses the spring and shock absorber.

L

• Late Apex – Turning into a corner late and missing the optimum apex point.
• Lifting – A modification to a vehicle to raise the ride height. It is done for the purpose of improving the off-road performance of SUVs or trucks and other off-road vehicles, or for cosmetic purposes.
• Line – The route taken by a driver, especially through a turn. The high line is a route close to the wall. A low line is closer to the track’s infield and shortest distance around the track.
• Locked Rear – Normal rear-end gears in a rear-wheel-drive automobile perform a “differential” function; when the car goes around a corner, they permit one wheel to turn faster than the other, to compensate for the fact that the wheel on the outside must cover a greater distance. Locked rear is a fixed rear and both wheels turn the same at the hub even if the wheels are of different diameter.
• Loose – A handling condition (known as “over-steer” to road racers) where, when the car goes through a corner, the rear end of the car wants to slide towards the outside of the turn. If the car gets loose enough, it will spin out. Loose is the opposite of a push or under-steer.
• Low Groove – The line or path on the track nearest to the infield. This is the shortest distance around the track but in some conditions, it may not be the fastest.

M

• Marbles – Loose pieces of rubber or debris above the upper groove on the racetrack.
• Motion Ratio – describes the amount of shock travel for a given amount of wheel travel. Mathematically it is the ratio of shock travel and wheel travel.

O

• Offset – Weight: The difference in weight between the left and ride sides of the car. On an oval track, handling is improved by having as much weight over to the left as possible, so car builders usually offset the weight to the left as much as the series rule
• Oversteer – A handling condition (known as “loose”) where, when the car goes through a corner, the rear end of the car wants to slide towards the outside of the turn. If the car gets loose enough, it will spin out. Oversteer is the opposite of push and under-steer.

P

• Panhard Bar – In a rear suspension, a lateral bar that prevents the axle from moving left or right. It is generally attached to the end of the axle housing on the left, and to a frame bracket on the right. Also called a track bar.
• Plowing – When the car is pushing up the track in the turns.
• Porpoising – An undesirable condition in which the racecar is bouncing up and down due to improper setup.
• Preload – A measurement of how much a spring is compressed at full extension of the shock.
• Push Rod – an inboard suspension component that functions as a portal for transferring lubricating oil though the valve lifter and up to the cylinder head.
• Percent slip – The difference between theoretically calculated forward speed based on angular speed of the rim and rolling radius, and the actual speed of the vehicle.

R

• Radius – 1/2 the diameter of a round object. The measurement from the center of an object extending to the outer surface
• Rebound – This regulates the speed at which your fork or shock recovers, or bounces back, from an impact and returns to its full travel.
• Rev Limiter – A device that limits the maximum RPM that an engine can reach, usually by momentarily cutting out the ignition when the set limit is reached.
• Ride Height – The distance between the car’s frame rails and the ground.
• Rocker – An inboard suspension component used to transfer wheel loads to the spring. This can be an entire suspension control arm or a component between the pull/push rod and spring.
• Roll Axis – A line connecting the rear suspension roll center with that of the front.
• Roll Center – The theoretical point where suspension components intersect. This defines the point of rotation for the “lean’ or “roll’ when cornering. In practice, this point changes as the suspension moves up and down. For racecar design it is used in connection with
• Rotation – The description of movement for a car and what it is doing while turning. “To get the car to rotate through the turns, we put more air in the right rear”
• Round – Making one full turn of a component. Can be an adjustment of moving a spring up down. This is also known as taking a turn in/out of the springs.

S

• Sawing on the Wheel – Expression describing when a driver turns the steering wheel back and forth in a rapid manner. Usually associated with a driver trying to overcome an ill-handling car.
• Scuffs – In general, any tire that has been used, but usually refers specifically to tires that have been run for a few laps, removed from the car, allowed to cool, and then put aside for later use.
• Section Width – the measurement of the tire’s width from its inner sidewall to its outer sidewall at the widest point.
• Setup – The configuration of the chassis in order to achieve the desired handling.
• Side Bite – A general term used to describe the amount of force available to hold the car in the apex of a corner. In car setup, putting more side bite in usually refers to reducing the sliding motion of a car in the corner.
• Sipes – Special slits within a tread that can increase traction. Most often used in dirt track applications.
• Sipping – A term used when a tool with a very narrow blade is used to alter the tread pattern of a tire. When using this tool, it will create a slice in the tread surface.
• Slip Angle – The angle between the direction in which a wheel is pointing and the direction in which it is actually traveling.
• Slick Track – Referring to a track surface that has glossed over or has no moisture left and it is difficult for the car to get traction.
• Solid Axle – A dependent suspension design, in which a set of wheels is connected laterally by a single beam or shaft.
• Spring Rate – the amount of weight that is needed to compress a spring one inch. 
• Sprung Weight – the portion of the vehicle’s total mass that is supported by the suspension, including in most applications approximately half of the weight of the suspension itself.
• Stabilizer Bar – A part of many automobile suspensions that helps reduce the body roll of a vehicle during fast cornering or over road irregularities. It connects opposite wheels together through short lever arms linked by a torsion spring.
• Squat – Vehicle pitch under acceleration.
• Squirrelly – Used to describe an ill handling race car or driver that isn’t driving correctly
• Stagger – A difference in circumference between the left-side and right-side tires on a car. In a car with a locked rear end, rear-tire stagger will make the car want to continuously turn in the direction of the side with the smaller circumference tire.
• Static – Dimensions or descriptions that apply to an object that is not in use or in motion.
• Sticker Tires – Tires that have never been run on a car, and still have the manufacturer’s sticker on them. The stickers can easily be seen on the tires when a car equipped with sticker tires leaves the pits. See also scuffs.

T

• Tacky – A track condition where the racing surface is slightly wet and sticky.
• Taking Rubber – A dirt track term describing when a racetrack loses its moisture and rubber from the tires begins to stick to the dirt surface, creating an asphalt-like condition. 
• Tight – A handling condition where the front wheels tend to slide when turning into a corner, which makes the car want to keep going straight. Also called push or understeer. Tight is the opposite of loose and oversteer.
• Toe Angle – The symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects.
• Track Bar – Lateral bar that prevents the axle from moving left or right. It is generally attached to the end of the axle housing on the left, and to a frame bracket on the right. Also called a Panhard bar.
• Turn In – Location on the track where the driver starts to turn the steering wheel to enter the turn.
• Turn Out – Location on the track where a driver turns the steering wheel back for exiting a turn.
• Tweak – Making minor set adjustments

U

• Understeer – A handling condition where the front wheels tend to slide when turning into a corner, which makes the car want to keep going straight. Also called push or tight. The opposite of loose and over-steer.
• Unsprung Weight – The weight of the wheel, tire, and suspension parts that are not supported by the springs.

W

• Weight Jacking – The art of shifting a portion of the weight of a car to certain wheels or corners to improve tire grip and the cars handling
• Weight Transfer – The dynamics of weight being transferred. Side to side during cornering, to the rear wheels during acceleration and to the front during deceleration or braking.
• Wheelbase – The horizontal distance between the centers of the front and rear wheels.
• Wheel Hop – A hopping action of the rear wheels during heavy acceleration. Traction is lost and regained in rapid cycles after power is applied to the rear wheels.
• Wheel Rate – This is the spring rate at the wheel, it takes into account the suspension motion ratio and is useful for comparing across vehicles.

Y

• Yaw – The angle between vehicle centerline and actual direction of motion around a turn.