RC Dictionary

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The world of radio-controlled vehicles uses quite a lot of specific terms and acronyms for cars, parts, racing, driving etc. This dictionary is splitted into sections between:


2-wheel drive vs. 4-wheel drive: As in full-scale cars, there are two main drive types: two-wheel drive (2WD) where power is supplied to the two rear wheels, and four-wheel drive (4WD) where power is supplied to all four wheels. The 2WD vehicles are less expensive and require less overall assembly and maintenance than 4WD vehicles. Assembly and maintenance for 4WD vehicles tends to be more involved, though not necessarily more difficult; the trade-off is that 4WD vehicles offer better steering through turns.

2.4GHz: The newest radio band available for R/C use, which operates at a higher frequency than noise. See also: FHSS and DMSS.

6061-T6 Alloy: Alloy is a mixture of two or more elements in which aluminum is the predominant metal. Aluminium alloys are used extensively due to their high strength-to-weight ratio; and 6061-T6 alloy is the most widely used grade for aluminum RC parts.

7075-T6 Alloy: Zinc is the primary alloying element in its component. It is stronger than 6061-T6 grade alloy. Parts can be made smaller or thinner due to better strength.


Arm: generally refers to the lower suspension arm of the car, although it can refer to the upper arm also. Often times resembles the letter “A”.

ABC / Non-Ringed: These letters stand for aluminum, brass and chrome or a composite such as nickel and are related to internal combustion engines. These engines have an aluminum piston and a chrome or composite coated brass cylinder sleeve which allows them to be more efficient for higher performance. They have no piston ring and rely on a very tight piston/cylinder fit to obtain a piston/cylinder seal. New ABC engines are normally hard to turn over by hand. Because of the tight fit, it is very important that the engine is broken in properly.

ABN: Engine construction that consists of an aluminum piston and a brass cylinder that has been nickel plated. Sometimes used today on higher performance engines.

ABS: A form of plastic that is easy to form but is not crash-resistant. However, some manufacturers use ABS in particular wheels which is slightly lighter than the high-impact nylon used in other wheels.

Accelerate: To make the car move faster, either from a full stop or while already moving.

Acceleration: A measure of how quickly a car can accelerate. Acceleration is affected by items like the weight of the car and its rotating mass.

Ackermann: The degree of difference in the steering angle between the inside and outside wheel when a vehicle is turning. It describes the angle of the inside tire in relation to the outside tire when the wheels are turned to full lock (the furthest the wheels can go to the left or right). Normally, when the front wheels are turned all the way left or right, the inside wheel is at a sharper angle than the outside wheel. If one extends the center line of each front tire to a point where both lines intersect and measure that angle, it is known as the Ackerman angle. Ideally, for perfect steering, the Ackerman angle will cross at the center line of the rear axle. In a wide turn, the front tires are not turned very far to the right or left, the inside wheel is not steering at a sharper angle than the outside wheel, and the Ackerman angle is not very wide. In a tight turn, the inside wheel is steering at a steeper angle than the outside wheel, and this is what is called the Ackerman effect. A bellcrank steering system approximates a way to copy the Ackerman effect, and is adequate for RC cars because of tire slip, tire sidewall folding and other factors. Adjusting the Ackerman angle can be done by changing the length of the center link, also called the Ackerman link that connects the bellcrank steering arms, or changing the mounting location on the steering arms without changing the link length. See the Ackermann article for more information.

Ackerman Link: The center link of the bell crank steering system that connects the two steering arms.

Adjustable Travel Volume (ATV): ATV allows the driver to preset the maximum travel of a servo to either side from its neutral position. Such settings helps tailor control action to suit the driver flying or driving style.

After-Run Oil: After a pilot is done running his nitro engine, it is recommended to remove the glow plug and place a couple of drops of After-Run oil in the cylinder as well as in the carb throat.

Air Dam: An extension of the front bumper that blocks, or dams, too much air from getting under the car and producing lift. Most RC bodies for Touring Cars have air dams built in.

Aluminum: In general terms, aluminum is a metal that is lighter than steel, but not as strong. It can be machined (cut on a machine) to replace many plastic parts of an RC car, but is not recommended for replacing suspension arms.

AM: Short for Amplitude Modulation, an AM radio in RC is considered a budget radio, what most newcomers to RC will start out with. Most hobbyists will be fine with an AM radio, but some racers can benefit from FM or PCM radios. An AM radio will have more glitching than other, more expensive radios.

Amp Hour: The electric charge transferred past a specified circuit point by a current of one ampere in one hour.

Angle of Attack: Refers to the angle that a surface contacts the air, usually mentioned when talking about spoilers and wings. A higher AOA helps solve over steer but increases drag and decreases top speed. A lower AOA is used to alleviate under steer and increase top speed.

Anodize: the process of adding color to a machined part.

Anti-squat: Refers to the angle of caster on the rear wheels. That particular angle prevents the squatting of the rear suspension. Anti-squat is most effective on acceleration from a stop, when much of the car’s weight is forced onto the rear suspension. Lifting the front of the hingepin of the rear arms gives a caster (anti-squat) angle, and helps to transfer more power into forward motion rather than lifting the front of the car up.

Arcing: When voltage jumps from the brush to the commutator (or from one surface to another) due to poor or corroded contact between the two components. Arcing will cause excessive heat, resulting in premature brush and commutator wear.

Armature: Is the spinning part of an electric motor. Also known as the arm.

Axle: The metal rod the wheel of a car spins or rotates on. A drive axle is an axle that is actually powered and turns the wheel (such as the rear axles on a rear wheel drive car), otherwise the wheel will spin on bushings or bearings on the axle.


Ball Cup: A hollow plastic piece that snaps onto a ball end to provides a pivot point, usually for suspension movement. Using a ball cup/ball end assembly instead of a rigid system allows the car to absorb crash damage, so the ball cup will pop off instead of breaking. Ball cups are usually paired with turnbuckles for the ultimate in ease of use and assembly.

Ball Differential (Ball Diff): A differential that uses a series of steel or carbide-steel ball bearings in a circle, pressed between two metal rings, to provide the differential action, allowing one wheel to rotate more than another in a turn. Ball diffs are easier to adjust than gear diffs but are harder to maintain, as they need checking every day of running and are not recommended for Nitro racers. Normally a screw on one side controls the tension between the metal rings, which controls how much the outside wheel in a corner can turn. The looser (to a point) a diff is, the more traction there is at that end of the car. It is recommended to start tuning a car by setting the ball diffs to the same tension at each end, and use the diffs only to fine-tune the car.

Ball Differentials or Gear Differentials: Ball differentials should be initially set to the kit specifications: the diff should be set so that the pulley is not be able to be turned with two flat head screwdrivers or Allen wrenches slid through the outdrive. A different type of differential is the One-Way Diff, which uses expensive one-way bearings to control wheelspin.

Ball End: A metal ball that has a hex (6-sided) and screw threads on one end. A ball cup will attach over the ball end to provide a pivot point.

Ballooned: Term refering to a LiPo battery that has been over charged or over loaded and has expanded in size due to the creation of gasses inside the packaging. Ballooned LiPo batterys should always be disposed of correctly and never re-used.

Barrel Carburetor: the standard model engine carburetor, carried over from airplane engines when they were adapted for car use. This type of carburetor fits most hobbyists and racers because it is simple to install and adjust. The throttle servo turns a barrel which has a hole through it, and this controls the amount of air going into the engine. A needle valve on the carburetor controls the amount of fuel going into the engine.

Batteries: A battery holds an electrical charge for future use by an electrical device. A single cell is a battery, a collection of cells is a battery pack. Batteries in use in the R/C hobby can contain alkaline materials (non-rechargeable, used for transmitter batteries), nickel-cadmium or nickel metal hydride. Each type of battery has its advantages and disadvantages. See the Batteries article for more detailed information.

Battery Eliminator Circuitry (BEC): A circuit that eliminates the need for a separate battery pack to power the receiver and servos. This circuitry can be found in speed controls as well as receivers.

Battery Pack: A collection of batteries that are joined together to combine the voltage of the batteries to power an electrical device. This term is used for electric RC cars (normally a pack to power the motor) and also for Nitro cars (to power the servos controlling steering and throttle/brake).

BB: These letters usually designate a ball-bearing supported crankshaft in an RC engine. This makes the engine run smoother and last longer. Ball-bearings are also used on wheels and other rotating parts on a car or trucks chassis, allowing the vehicle to roll more freely, which in turn, allows the Nitro engine or Electric Motor to power the vehicle to its fastest speeds.

Bearing: A hollow metal donut that uses balls inside to increase the efficiency of a rotating shaft (like an axle). Highly recommended as the first option part for any kit equipped with bushings, bearings have become a standard accessory in most R/C kits today.

Bellcrank: The type of steering mechanism most common in RC cars, trucks and buggies. It consists of two posts, one of which has a connection to the steering servo. This connection turns one of the steering arms, which is connected with an Ackerman link to a second steering arm. The left side steering arm is connected to the left steering knuckle with a turnbuckle, just as the right steering arm is connected to the right steering knuckle. Some bellcrank systems allow racers to alter the Ackerman angle, which can tune the steering effect of the steering system in different ways.

Bled: After correctly assembling a shock absorber with no excess oil and no air bubbles, that shock absorber is considered properly bled.

Bleeding: The process of removing air and excess oil from shock absorbers. A properly assembled shock absorber is considered bled

Body: In RC terms, the body is the thin, usually Lexan, clear plastic piece that covers the car and provides the shape of the car. Most bodies, especially on touring cars and some other vehicles, are easily interchangeable.

Body Clip: A pin or clip that holds the lexan shell/body of a radio-controlled vehicle to the chassis of that vehicle.

Body Reamer: The body reamer is an RC tool for creating body post holes in Lexan bodies and other semi-soft materials.

Body Roll: The changing of the chassis’ angle in relation to the ground when going through turns or corners.

Bottom End: A vehicle’s acceleration rate from a dead stop, or the amount torque available from a motor depending on type of motor and gearing.

Brake: The system used to slow a car or bring it to a stop. In an electric car, the electronic speed control performs this function. In a nitro car, braking is normally provided by a disc brake and brake pads.

Brush: A small rectangular piece of conductive metal that makes contact with the commutator inside an electric motor.

Brushless Motor: A DC motor that relies on an external ESC to operate. The ESC acts as speed control and as a "switcher" in place of a standard armature/brush assembly found in most DC motors.

Buggy: Among the more popular types of RC cars, buggies are durable cars that can run on most surfaces. The most popular are rear-motor two-wheel drive (2WD) electric buggies and four-wheel drive (4WD) nitro and electric 4WD buggies.

Bulkhead: A part of the car that is generally connected to the chassis. During assembly, other parts are connected to the bulkhead, making the bulkhead one of the primary foundation pieces of the car.

Bump-Steer: The changing of steering angles while the suspension is moved through its range of travel.

Bushing: A metal donut that supports a rotating shaft (like an axle). Most bushings are metal, with most metal bushings made out of Bronze Oilite. This is a metal that is permanently lubricated.


C-Hubs (Caster Blocks): A part shaped like the letter "C" that holds the front knuckles and placed on the front arms, connecting to the main chassis.

Camber: Seen from the front and rear of the car, the angle of the tires in relation to the ground; tires that are perfectly perpendicular to the ground (90 degrees) are said to be at ‘zero camber’. See the Camber article for detailed information.

Camber Link: Normally made up of a turnbuckle or threaded rod with a ball cup at each end. The Camber Link allows the suspension arm and upright to flex a little more than an upper arm would.

Can motor: Inexpensive DC motor, generally with a fixed end-bell, internal carbon brushes and ferrite magnets. Used in lower cost/lower performance RC applications.

Car Stand: A stand an RC car will be on while work is being done to it. It can be as simple as a block of wood, or as complicated as a padded rotating stand with parts bins. Another main function of a car stand is to keep the wheels off the ground during breakin and while work is being done.

Carburetor: The mechanism on an engine that controls the ratio of fuel and air that enters the engine.

Caster: Present in almost every RC car, Caster is the angle that the car’s front wheels pivot on when turning. Most on-road Touring Car type kits use between 5 and 10 degrees of caster. Off-road kits like buggies and trucks have about 25 to 30 degrees of ‘kick-up’ on the front axles. More caster generally gives more steering going into a turn, but less coming out while less caster give less steering going into a turn (initial steering), but more steering as the car exits. Caster also gives more stability on straightaways, but this effect is more pronounced in 2WD vehicles. See the Caster article for detailed information.

Caster Blocks: See C-Hubs.

Cell: A singular reference of batteries which generally refers to the nickel-cadmium or nickel-metal hydride batteries used in RC cars.

Center of Gravity: A point in space that represents the central point of a car’s mass. At high speed, vehicles with a high Center of Gravity might tip over more easily in tight turns than cars with lower Centers of Gravity.

Charger: Device used to recharge batteries.

Chassis: The foundation of an RC car or truck. It is the main part of a car that all other parts attach to. It can be made from woven graphite, molded plastic composites or aluminum. See the Chassis article for detailed information.

Closed Cell Foam: A type of foam that is molded, normally used in RC for molded inner foams. More expensive than open cell foam, it holds its shape better and if molded it does not move back and forth on a wheel.

Compound: The material in which a tire is made. The softness or firmness of the comound will translate to grip VS durability. The firmer (harder) the compound, the less grip the tire will have but the longer life the tire will have. The softer the compound is, the more grip the tire will have but for a shorter lifespan. Most racers use a firm compound tire as the racing surface heats up during the day. A softer compound tire is best used when the track is cool, such as in the morning or late evening. See the Tires article for detailed information.

Contact Patch: The footprint of the car’s tire, or the area of the tire that comes in contact with the ground at any given moment. Affected by camber, turning and acceleration. A wider contact patch (from wider wheels) does NOT mean you will automatically get more traction.

Coupe: In general terms, refers to a 2-door car. Some RC touring car body manufacturers offer bodies that faithfully represent full-size cars.

Crystal: The part of a vintage radio system that gives the transmitter the particular frequency on which to emit and the receiver on what particular frequency to listen.

Current Limiter: An adjustment on an ESC to limit the current that the motor can draw during acceleration. This eliminates high, inefficient current spikes and reduces wheel spin.


Dampening: The resistance caused by fluid in a shock body when the piston moves through it.

Damper Plate: See Shock Tower.

Damping: Refers to a variable based on a set of conditions for the parts of an RC car suspension and which impacts the drive. Damping affected by the strength of the shock spring (length and thickness of the wire plus the number of coils on te spring), size and number of holes in the shock piston, and the viscosity, or weight, of the oil in the shocks. The spring controls how hard the shock compresses, and both the piston and the oil control how quickly the spring pushes the shock to its full length (which can be limited by shock spacers), and so affect the quickness of the shock’s return. Stiffer springs need heavier oil and/or smaller-hole pistons to control the speed of the rebound, and bumpy tracks need lighter oil so the shocks, or dampers, can compress and rebound quickly. Softer damping gives more ‘stick’ on a particular wheel, but makes the car less responsive because the chassis takes longer to reset after a turn, and is also more forgiving to drive. Softer damping also reduces weight transfer at that wheel. Stiffer damping makes handling more responsive, but reduces traction to a particular wheel which can make the car slippery as the chassis snaps back into place after a turn. Stiffer damping also increases weight transfer at that wheel.

Dialed: A slang term used in the 1/8 scale buggy meaning that after the hard work of tuning the suspension, shock oil, diff oil, and other parts, a buggy is finally ideally tuned.

Diff Rings: The metal rings that the diff balls run against.

Differential: A system that transfers power equally from a shaft input to shaft outputs. A differential (or diff) allows the outside wheel of a car going through a corner to travel farther than the inside wheel, preserving corner speed and efficiency. See the Differential article for detailed information.

Diode: A semiconductor device used to control the flow of electric charge. High-rated schottky diodes are used in single-direction ESCs to prevent back-EMF (voltage 'spikes') generated by the motor from entering the ESC.

Discharge: The act of draining a battery of its stored energy, either by running a vehicle or connecting the battery pack to a discharge device.

DMSS (Direct Sequence Spread Spectrum): A 2.4GHz radio system which selects one (or two) of the available “free” frequencies and transmits only on the one(s) chosen. Like FHSS (Frequency Hopping Spread Spectrum) systems, it is resistant to electrical noise.

Dogbone: The shaft used to transfer power from a transmission outdrive to the drive axle. Because of the roll pins found at each end, the finished product resembles a dog bone.

Double Wishbone: A type of suspension design that uses two wishbone arms (parallel to the ground and each other: one for the main suspension arm and one for the upper arm) to help maintain a constant tire camber as the suspension is compressed. Most RC cars have this type of suspension design. Older RC cars used different suspension technologies that are no longer in use in RC today including swing-arm and trailing arm suspensions.

Downforce: The effect of air contacting the car body’s sloped surfaces. Downforce is created by the air dam, hood, windshield, roof, spoiler(s) and wing(s) of the car. More downforce increases drag and slows the car, but raises the tire temperature, making the car easier to drive. Less downforce raises the top speed by reducing drag. The car should be set up so that it can drive with minimal downforce.

Drag: In car design, drag is the force of air that slows down a car. The lower the drag of the car (the more aerodynamically efficient it is), the faster the car can go while using the same amount of power.

Drag Link: Another term for an Ackerman link.

Droop: The measure of shock droop is the amount of uptravel the chassis will have with the car weighed with its full running gear (servo, batteries, motor, etc.), settle the chassis (pressing down on the chassis then releasing), then lift each end of the car until the tires lift off the ground. The total upward movement of the chassis at each end is measured as droop.

Dual Rate: An adjustment found on some radios which allows limitation on the distance a servo arm will travel.

Dump: A term used to describe when a battery’s charge is running out.

Dyno: A computerized equipment that measures the efficiency of a motor and which can be used to select the appropriate gearing. It is mostly used by pan car or oval racers.


E-Clip: A small device that holds cylindrical parts like hinge pins in place.

Electric: This general term usually refers to the power source of the car using an ESC, an electric motor and a battery pack.

Electric vs. Gas Cars: Electric vehicles are the most popular choice in RC car racing. They are quick, quiet, easy to build and comfortable for the beginning RC enthusiast to drive. The electric cars are powered with a rechargeable battery that can be charged in as little as 15-20 minutes. Gas vehicles are powered by a small two-cycle engine burning glow fuel, and many modelers enjoy the realistic sound and smell that goes along with gas powered racing. See the Differences between electric and combustion engine cars article for detailed information.

Electronic Speed Controller: An electronic device that takes the power from the battery pack and the signal from the receiver and measures a certain amount of power to the car’s motor. Only used in electric RC cars, boats and planes.

Endpoint Adjustment: This radio feature adjusts the length of servo travel in one direction (a single channel will have adjustments for two endpoints). If a driver's car or truck can make a tighter left hand turn than it can a right hand turn, endpoint adjustments can correct the problem by allowing to adjust the servo to travel the same distance in both directions. In combustion engine cars, endpoint adjustment can allow a driver to set the Carburetor and Brake settings servos.

Engine: Refers to a fuel-powered engine RC vehicle.

Epoxy: A two-part resin/hardener glue that is extremely strong. Used for critical points in the aircraft where high strength is necessary.

Expanded Scale Voltmeter (ESV): A device used to read the battery voltage of the on-board battery pack or transmitter battery pack.


Fade: see Brake Fade.

Failsafe: A device that is built into a receiver or that plugs between the receiver and servos that prevents a runaway car in the case of battery failure or loss of signal.

FHSS (Frequency Hopping Spread Spectrum): A 2.4GHz radio system which switches from one “free” frequency to another every few milliseconds. While jumping from one to the other frequency, the radio is not spending much time on a specific frequency keeping out interference. See also: DMSS.

Field Charger: A fast battery charger designed to work from a 12-volt power source, such as a car battery.

Final Drive Ratio: The transmission ratio determined by combining the internal drive ratio and the spur/pinion combination with this specific formula: spur gear tooth count divided by pinion gear tooth count multiplied by the internal drive ratio or spur / pinion * internal drive ratio = final drive ratio.

Fixed Link: A type of linkage that cannot be adjusted and is usually used in ready-to-run cars for camber and steering links. Easily replaced with turnbuckles to allow for adjustments.

Flex: A measurement of how much a certain part will bend under varying degrees of pressure or force. Every part will bend or flex, some more than others.

Flush: Refers to a part being externally snug and tight against another part and/or material.

Flux: Actually rosin, but often referred to as “flux”; helps the flow of solder.

FM: Short for Frequency Modulation a radio frequency used in RC radio transmitters and receivers.

Foam Donuts: Literally donut-shaped pieces of foam mounted on wheels mostly on pan cars and touring cars. Some race tracks are able to make use of foam tires (such as indoor carpet tracks for electric cars, or very smooth and clean outdoor tracks for nitro cars), but most racers use rubber tires. Foam tires have the advantage that inserts are not needed, they offer better grip than rubber tires, they can last longer, and racers can use rollout calculations to figure out their gearing. However, ride height must be adjusted as the foams wear out, and on a 4WD car the wear must be closely monitored to make sure the car does not pull to one side as the car moves.

Foam Insert: A foam ring or donut that is used in soft compound tires for support. Foam donuts are inserted in between the wheel and the tire and are glued to the wheel. Most soft compound tires come with a open cell foam insert.


Gauge: A standard of measure used to determine the thickness of wire.

Gear: A general term that normally refers to either the spur gear or pinion gear.

Gear Differential (Gear Diff): A differential that uses a series of gears to provide the differential action, allowing one car wheel to rotate more than another in a turn. Gear diffs are harder to adjust than other diffs but are much easier to maintain, because they must be sealed to keep the grease inside from coming off the gears. Tuning a gear diff can only be accomplished by changing the weight (viscosity) of the grease inside the gear diff case. The looser (to a point) a diff is, the more traction there is at that end of the car.

Gearing: In general terms, this refers to the ratio of the spur gear and pinion gear, when compared to the internal drive ratio of the car.

Getting Lapped: A term used when the lead car in a race is passing another car. That car loses a lap or goes a lap down to the leader. If a driver is getting lapped, it’s usually good etiquette to let the leader past in a turn by going wide through the corner. This is even more important if the leader is battling with another car. See the Racing article for detailed information.

Glitch/Glitching: Refers to a car losing control temporarily, another term for interference. This happens when the signal from the radio transmitter to the receiver is interrupted for some reason.

Glow Plug: The heat source for igniting the fuel/air mixture in a glow combustion engine. When starting the engine a battery is used to heat the filament. After the engine is running, the battery can be removed. The wire filament inside the plug is kept hot by the “explosions” in the engine’s cylinder.

Glow Plug Igniter: A powered device (usually 1.2V), which connects to a glow plug. Used to ignite the filament in the glow plug in order to start the engine

Graphite: Graphite is a stiff, lightweight composite material commonly used in RC car parts. It is popular choice in RC racing because of its advantages in weight and strength. It has a layered, planar structure that gives it a remarkable strength-to-weight ratio. Since it is more brittle than aluminum Graphite is mostly used in areas that do not have continuous impact such as chassis, shock towers and plates.

Grooving: A term used to describe the way some tires have a tendency to develop a groove on the inner edge of the tread as they wear. This is less likely to happen to belted tires or tires with foam inserts. Grooving is also a condition that occurs when a car has too much negative camber.


Hardware: Articles made of metal used to assemble a vehicle, e.g., screws, nuts, washers, etc

Hinge Pins: Metal bars that secure arms with knuckles. They are usually fastened by e-clips on both ends.

Hit (or to be hit): Sudden radio interference which causes a model car or truck to drive in an erratic manner. Most often caused by someone turning on a radio that is on an identical frequency, but can be caused by other radio sources. Mostly solved by using 2.4Ghz radio and receiver.

Hook: When the rear end of a vehicle has a tendency to kick out when turning with the throttle on. Sometimes known as over steer.

Horizontal Load: When cornering, the force applied to an individual tire in the direction parallel with the road surface.

Hub Carrier: Also called uprights, parts of the suspension holding the axles and bearings the wheels of the car turn on.


I.F.M.A.R.: International Federation of Model Auto Racing. The governing body that controls World Championship racing in RC Cars. See the IFMAR article for detailed information.

Inner Foams: Another term for foam inserts or inserts.

Inserts: Foam strips or donut-shaped cutouts that support a tire on a wheel. The car can be tuned with inserts, much like full-size race cars are tuned with tire air pressures.

Interference: see glitching

Internal Drive Ratio: A measure of the teeth of a car’s gears and pulleys. For RC cars, dividing the number of teeth on the ball or gear diff pulley or gear by the number of teeth on the smaller drive pulleys.


Kick-Up: While caster refers to the upward angle at the front wheels of the car, kick-up refers to the upward angle of the front suspension arms. Technically, buggies and off-road trucks have kick-up, not caster, but since they are so similar in description most people use the term caster.

Kingpin: The pin in the steering assembly on which the steering spindles rotate.

Kit: A car, truck, boat, airplane or helicopter that requires the modeler to do most/all of the building and finishing work. Modelers are likely required to add their own power plant, radio system or both.

Knuckles (Uprights): All RC cars have front and rear knuckles. They secure the drive shafts to the wheels. Front knuckles are also used for steering. Using bearings maximizes performance of a vehicle.


LED (Light-Emitting Diode): A light-emitting diode (a semiconductor diode which glows when a voltage is applied) used on everything from speed controllers to chargers or tail lights.

LiIon Battery: Lithium Ion Battery are a lighter type of battery and have much lower (5%) discharge rate than NiCds or NiMHs (30%).

LiPo Battery: Lithium Polymer Battery. Derived from Lithium Ion batteries, they are compact and light batteries with the ability to offer 30% more power in less space than comparable NiCds and NiMHs. Must be used with a LiPo-compatible balancing charger. Lipo batteries can be dangerous tu charge and use. See the Lipo article for detailed information.

Load Up: A term used to describe a tire that is completely packed with dirt around the lugs or spikes. This usually happens on a wet tracks with loose dirt.

Locknut: A type of nut that features a nylon insert that helps to grab the threads of a shaft or bolt, helping prevent the nut from loosening. Commonly used on axles and other critical areas of RC cars and trucks.

Longitudinal Flex: The flex of a chassis when both ends are being forced toward each other.

Loose: See Over steer


Main or Main Event: In RC car and truck racing terms, this refers to the final race of the day in each class in which drivers are entered in.

Matched batteries: Refers to batteries being matched and paired in order to either improve running time or overall battery power. Matched batteries can be paired according to the batteries voltage.

Micro: A small scale RC 1/16th scale and below is considered micro.

Mid-Narrow: see width, wheel.

Milliamp: A rating given to batteries, generally the higher the milliamp rating, the longer the cell can provide power.

Molded Inner Foam: A form of tire insert that is molded in a special mold instead of cut out of foam sheets. While more expensive, the molded inner foam stays in place on the wheel and does not move side to side as the car goes through cornering forces.

Monocoque: A type of car construction having the skin act as the main structural member, with a relatively light internal structure.

Monster Truck: A specialized off-road vehicle with a heavy duty suspension, four-wheel drive (some 2WD Monster Trucks exist) and oversized tires. It is mainly designed and used for bashing thanks to the highest ground clearance of all RC vehicles, large wheels and tires, and its thick reinforced parts.

MOSFETs: Two acronyms used as one term: MOS-metal-oxide semiconductors, and FET-field-effect transistor. MOSFETs are used as switches in electronic speed controls to control the amount of current passed from the battery pack to the motor.


Narrow: See width, wheel or width, chassis

Newbie: A beginner in the RC hobby.

Ni-Cad: The abbreviation for nickel-cadmium.

Ni-MH: The abbreviation for nickel-metal hydride.

NiCd Starter: A self-contained battery and glow plug clip, used when starting a combustion engine.

Nickel-Cadmium (NiCd, Ni-Cad or NiCad): Rechargeable batteries which are typically used as power for radio transmitters and receivers.

Nickel-Metal Hydride (NiMh): Rechargeable batteries, which are typically used as power sources for cars, trucks and boats as well as receiver packs. They have no cell memory, but feature slightly less voltage than nickel-cadmium batteries.

Nitro: Nitro-methane, a fuel additive which increases a model engine’s ability to idle low and improves high speed performance. Ideal nitro content varies from engine to engine.

Nitro Content: A measure of the amount of nitromethane that is included in a mixture of nitro fuel. The normal amount of nitro content for fuel is 20% (when used in cars). Racers will use 30% or even 40%, but using a higher nitro content will shorten the life of the engine, which makes the high content fuels more suited for serious racers only.

Nylon: A type of plastic used in many RC kits. There are many types of nylon: High-Impact Nylon is able to flex with crash impacts to resist breaking. Many wheels are made from high-impact nylon, as well as many of suspension arms and shock towers. Fiber Reinforced Nylon is a plastic that is mixed with fiberglass fibers to produce a stiffer plastic piece. The ratio of fiber to plastic will determine the stiffness of the piece. If it is too stiff, the strength advantage is lost because the piece can break too often. Graphite Reinforced Nylon is another type of fiber reinforced nylon, except that instead of fiberglass fibers, the plastic is mixed with graphite fibers, the same type of fibers that make up the graphite mesh in woven graphite pieces. The ratio of graphite fiber to plastic will determine the stiffness of the piece. If it is too stiff, the strength advantage is lost because the piece can break too often.


O-Ring: A donut-shaped circle of rubber or silicone that seals rotating or sliding shafts, used in areas like shock absorbers and differentials.

Off-Road: Any type of running surface that is not on a paved surface. Off-Road can mean gravel, loose or hard-packed dirt, grass, etc. Racing classes that run on off-road surfaces include buggies, trucks, truggies and usually rally cars. See a list of off-road cars.

Off-Road Buggy/Truck: Off-road buggies and trucks are the most popular RC land vehicles. Available in gas or electric, these cars sport full-travel suspensions, and high ground clearance. Their knobby rubber tires give them the ability to tackle any dirt terrain. See a list of buggies and a list of Truggies.

Offset: see Wheel Offset

Ohm: A measure of electrical resistance.

On-Resistance: The measure of electrical resistance, at full throttle, of an ESC at a given temperature. As the temperature increases, the on-resistance increases. A lower on-resistance will give more power. A lower on-resistance also means the ESC will run cooler.

On-Road: Usually refers to running cars on a paved asphalt or tarmac surface. The term could also refer to a class of cars, such as touring cars, pan cars, etc.

On-Road Car: On-road cars are built for racing on smooth, paved surfaces and are available in gas or electric.

One-Way: A term that refers to either one-way diffs or one-way pulleys..

One-Way Bearing: A special and expensive type of bearing that will only allow a shaft to turn in one direction.

One-Way Diff: At some points on a race track, the inside wheels can lift up because of high cornering forces. This causes a normal ball diff or gear diff to unload. A ball diff prevents diff unloading because it does not allow the tire to spin less than the speed of the belt that turns the pulley. One-way diffs take getting used to and requires using very light braking power or none at all. When brakes are applied to a car using one-way diffs only the rear wheels will stop, making the car spin out very easily. Most drivers will need practice to get used to one-way Diff., but for racers on high-grip surfaces they can be a valuable tuning aid.

One-Way Pulley: One-way pulleys operate in the same manner as one-way diffs, except the one-way action takes place on a gear shaft instead of the front axle of the car.

Outdrive: The part of the differential that outputs power to dogbones or universal dogbones.

Oval: The American-style stock car type of racing, where cars compete on oval tracks of different shapes (true oval, square oval, tri-oval, etc.) and are tuned to only go straight or left. In RC terms, most oval race cars are pan cars, with all the weight (batteries, electronics, etc.) on the left side so the car is the most stable when turning left.

Over geared: The condition where a gear ratio is too low for the motor. This results in excessive motor heat and causes the motor to draw more amps from the ESC.

Oversteer: A situation in which the front tires have more traction than the rear tires. This causes the rear tires to lose traction in comers. Drivers may need stickier (or newer) tires and more rear downforce to solve the problem. Shock and weight settings may need adjusting too.


Pan Car: In RC terms, this is a car that is made from a flat pan of graphite or fiberglass, with an independent front suspension and straight-axle rear pod. These cars are rear-wheel drive only and use foam tires. RC Formula 1 cars fall into this category, although the front suspension uses much longer arms and the chassis is narrower.

PCM (Pulse Code Modulation): A type of transmitter and receiver that uses digitally encoded signals and is less prone to glitching than FM radio systems.

Peak Charger: A peak charger automatically shuts off when a battery is fully charged.

Pinion Gear: In electric Rc cars, this is the gear that is attached to the car’s motor, which in turn spins the spur gear, turning the rest of the drivetrain.

Pitch: The measure on a pinion gear or spur gear of how many teeth fit per inch. On a 64-pitch gear, 64 teeth will fit within one inch; on a 48-pitch gear, 48 teeth will fit in one inch.

Pivot-Ball Suspension: A type of suspension system brought to scale Touring Cars from 1/8 scale Nitro cars. Instead of the more common lower suspension arm/upper turnbuckle link, the pivot-ball suspension uses inner hinge pins and screws on the outer pivots that adjust camber and track. The caster is adjusted by moving clips on the inner upper hinge pin.

Planetary Gear Diff: A type of differential that has small gears rotating around the center drive gear.

Power Panel: 12-volt distribution panel that provides correct voltage for accessories like glow-plug clips, fuel pumps and electric starters. Usually mounted on a field box and connected to a 12-volt battery.

Preload: The amount of tension on a spring, via the spring collar, before a shock is compressed.

Programmable or Computer Radios: High-tech radios with a full set of programmable transmitter with features such as multiple car memory, preprogrammed commands (throttle sensitivity, braking, etc. at the touch of a button) and much more.

Punch: In RC terms, this means the same thing as acceleration. Driving full punch means a driver is on the throttle all the time.

Push: See Understeer



Radio: Refer to Transmitter

Radio-Controlled: Refers to how RC vehicles are controlled by the use of a Transmitter.

Rally: An RC car similar to a touring car but with treaded tires, slightly longer shocks and some protection for the drivetrain. A rally car is generally able to travel on any on-road surface, as well as gravel and hard-packed or loose dirt.

RC: An abbreviation of radio-controlled.

Ready To Run (RTR): See RTR.

Reamer: An angled tool with a rough surface used to enlarge holes to mount a Body onto the chassis.

Receiver: The electronic device that receives the radio transmissions from the radio transmitter. Through wire plugs inserted into the receiver case, the receiver passes signals to the steering servo and electronic speed control or throttle servo.

Receiver Cover: A plastic or vinyl cover that protects the receiver from fuel, water, mud, dust and dirt.

Resistance: The resistance of electricity flow through a circuit, or connection. Resistance is measured in units called ohms.

Resistor: An apparatus possessing resistance to electrical current. When attached to a Ni-Cd battery, a resistor will drain the power that is in the battery.

Resistor-Type Speed Control: Mechanical speed controls that possess a wiper arm and resistor. The resistor has different steps that act as different speeds as the wiper moves across the surface of the resistor.

Ride Height: The space between the lowest part of the chassis and the ground, measured with all of the car’s electronics installed; racers measure the front and the rear ride heights separately. There should be enough ride height so that the suspension can be engaged enough to soak up whatever bumps and dips occur on the track, but the chassis should be low enough to the ground so there isn’t too much chassis roll (related to shock settings).

ROAR: Radio Operated Auto Racing. US National body to standardize and sanction RC car and truck racing.

Rod End: Similar to a ball cup/ball end combination, except that a rod end is a plastic eye that holds a metal or plastic pivot. A screw goes through the pivot and is secured in a bulkhead, suspension arm or other area.

Rollcenter: An imaginary point at the front and rear of the car where the chassis rotates around. Affected by the position of the uprights and rotation points of the suspension arm and upper links, the rollcenter can be changed on an RC car by adding spacers underneath the rear bulkhead, moving the uprights up or down in relation to the arm, and other methods.

Rotating Mass: Refers to the weight of the rotating parts in any car. For an RC car, this includes the diffs, wheels, universal dogbones, belts, pulleys, flywheels, crankshafts, spur gears and spur gear hubs. The lighter these parts are, the faster the car will accelerate and brake, because less force is needed to get these parts moving. Most people agree that reducing one unit of weight (ounce, gram) equals saving between three to four units of weight that does not rotate.

RPM: Rotations Per Minute. The number of times an engine, motor, wheel, gear, etc., will turn in a minute. In RC racing this is most important for electric motors and nitro engines.

Runtime: A term that details how long an RC vehicle will run or last on one battery pack or fuel tank.


Scale: Refers to the general size of the car. Many companies offer radio control cars in several different sizes: 1/18, 1/12, 1/10, 1/8, 1/5 and 1/4 scale. The smaller the number after the 1, the larger the actual scale car is. Most popular cars are of the 1/10 or 1/8 scale size but there are many types of kits that fall under this size label: Buggy, Truggy, Monster Truck, Touring Car and more.

Schottky Diode: A semiconductor diode that sits between the motor and the ESC and tries to avoid current travelling back to the ESC from the motor causing it to blow up.

Sedan: In general terms, this refers to a 4-door car that has a separate trunk. In RC terms, this refers to a car that is generally 1/10 scale in size, and is one of the more popular form of on-road RC racing.

Self Tapping: A screw that creates threads in the material it is penetrating.

Servo: A small device used for steering (and throttle with nitro cars). The servo output shaft rotates proportionately to the input from the transmitter. The servo contains a motor and an electronic controller.

Servo Horn: A plastic or aluminum part that attaches to the servo and links the servo and the steering linkage.

Servo Reversing: A transmitter feature that allows to install the servos where they can give the best pushrod routing without concern about the direction of servo rotation thanks to a function that reverses the direction of rotation.

Servo Saver: Usually a servo horn that uses a spring to absorb sudden shock or impact coming from the servo linkage. This helps prevent breakage of the servo.

Shock Oil: The silicon-based oil in a shock. Measured by viscosity, the lower the number, the lighter the damping.

Shock Piston: The small plastic (or nylon) disc that travels up and down in the shock body. It uses holes of different sizes to regulate the rate at which the shock compresses and rebounds.

Shock Tower (Damper Plate): A plastic, graphite, carbon or aluminum part that secures the shocks to the main component of the car.

Sidewall: The side of the tire that extends from the wheel up to the top of the carcass.

Skid Plate: A plate, commonly made of plastic, aluminum or titanium, that protects the underside of a vehicle. Typically used in offroad vehicles.

Slipper Clutch: A device found primarly in off-road vehicles that allows the spur gear assembly to slip under excessive loads. This protects the drivetrain from sudden jolts and, when set properly, helps control the vehicle on slippery surfaces.

Slop: Excessive free movement in a control system. Often caused by a worn out ballcups. This unwanted condition allows the control surface to move without transmitter input.

Spoiler: Often referred to as a wing, a spoiler disturbs the air flowing over the body to create downforce on the car.

Sportsman Class: Drivers that have won some races and are pretty quick around the track are considered Sportsman but are not yet in the Expert/Pro class.

Spring Rate: The stiffness of the springs. Generally, softer springs add traction, harder springs lessen traction. Springs are ‘rated’ by a number value.

Spur Gear: The gear that is attached to the differential or transmission.

Squirm: The movement of a tire between the ground and the wheel. This can be side-to-side movement, or front-to-rear movement. Softer compounds typically have more squirm. Can be corrected by using a different internal insert.

Steering Knuckle: The part of the car’s front suspension that steers the wheels. The steering turnbuckles connect the bellcrank and steering knuckles.

Stroke: How far the shock absorber can compress. Can be limited externally by a clips or a threaded nut on the outside of the shock body.

Suspension Arm: See A-Arm.

Sway Bar: See Anti-Roll Bar.


Tamiya plug: A type of white electrical connector usually used to connect a battery to a speed controller. It comes stock on many ESC and batteries.

Throttle: Refers to the trigger on pistol-grip style transmitters, or the right stick on dual-stick transmitters.

Tie-Rod: The rod assembly used to connect the steering bellcranks to the steering knuckles. Also used for camber adjustments. Also known as a turnbuckle.

Tire: All RC cars run on some sort of tire. Tires come in different tread designs (for different surfaces) and different compounds (from hard to soft, again, for different surfaces). Purchased tires also include foam inserts. These help support the tire under loads.

Titanium: A metal alloy used to manufacturer parts, such as turnbuckles and hinge pins, that is extremely light and very strong.

Toe-in: A condition when the front edge of both tires are closer together than the rear edge of both tires. Toe-in will make a car more stable under acceleration but decrease turn-in steering.

Toe-out: A condition when the front edge of both tires are farther apart than the rear edge of both tires. Toe-out increases turn-in steering, yet reduces stability under acceleration and through bumpy sections.

Top Deck: A part that connects the front and rear bulkheads together (and sometimes a center bulkhead). They can come in plastic, carbon fiber or metal (typically aluminum).

Top End: A vehicle’s final acceleration rate. For nitro engines, top end refers to the high-end needles.

Torquey: A term used to describe a motor’s brute strength during acceleration.

Touring Car: A specific on-road car class of RC. Touring Cars are fast and precise and can hit extremely high speeds in short distances. They are available in either nitro or electric powertrains.

Track Width: The width of the car, measured from the center of the front axis wheels and the rear axis wheels. A wider stance is more stable and gives better cornering, but with a wider frontal area the car experiences more drag, slowing it down on long straights.

Traction Compound: See Compound.

Traction Roll: If a vehicle has too much traction, it may roll over during a high-speed turn.

Transmission: The transmission of a car houses a number of different sized gears (including the differential) that allows the RC vehicles drive ratio to be reduced. This helps with gearing while using different sized tires.

Transmitter (Tx): The hand-held radio controller. This unit sends out the commands to the receiver in the vehicle.

Transponder: A small device, that when installed in a vehicle, will count a car’s laps. The signal is picked up when a car travels over a ‘transponder loop’.

Trickle: A low-rate charge, usually below 0.5 amp.

Truck: A 2wd or 4wd offroad RC car modeled after CORR style racing trucks.

Turnbuckle: A threaded rod that has the screw threads facing opposite directions so adjustments can be made without removing the rod. Also known as a Tie-Rod.

Tweak: An unwanted condition in which more pressure is applied to one side of the chassis than the other. A vehicle that has a tweak will pull to one side under acceleration and braking.


Understeer: A situation in which the rear tires have more traction than the front tires. This causes the vehicle to have inadequate steering.

Unloading: At some points on a race track, the inside wheels can lift up because of high cornering forces. This causes a normal ball differential or gear diff to transfer all the available power to the wheel that is in the air. This is because the differential will put any power at the wheel that is the easiest to turn.

Unsprung Mass: That portion of the total mass of a vehicle which is not supported by the suspension. Unsprung mass is comprised of wheels, tires, hubs, hub carriers, and approximately 50% of the mass of the suspension links, drive shafts and shocks (if mounted outboard).

Upright: See Hub Carrier.

Uprights: See Knuckles.


Venturi: 1. A short tube with a constricted throat used to determine fluid pressures and velocities by measurement of differential pressures generated at the throat as a fluid traverses the tube. 2. A constricted throat in the air passage of a carburetor, causing a reduction in pressure that results in fuel vapor being drawn out of the carburetor bowl.

Vertical Load: The amount of force applied to an individual tire in the direction perpendicular to the road surface; the forward driving force of the tire.

Volts: The three most basic units in electricity are voltage (V), current (I) and resistance (r). Voltage is measured in volts, current is measured in amps and resistance is measured in ohms.


Wheel: Fits inside the RC car tire. They are available in many different styles and colors.

Wheel Offset: This is in relation to track width, but refers specifically to the wheels of the car. The more offset a pair of wheels has, the wider the track and overall width of the car will be.

Wheel Spin: A term used when a tire loses grip, usually during acceleration because of too much power on a slippery surface.

Wheelbase: The distance between the front and rear axles of a car. A longer wheelbase gives a bit more stability, while a shorter wheelbase gives quicker turning and better acceleration, because the weight of the car is closer to the wheels (in relation to the long axis).

Winding: Used in electric motors to refer to the shellac coated wire that makes up the electromagnetic component. When a current is passed through the winding a magnetic field is created and usually "focused" by wrapping it around an iron metal core to increase its field strength.

Wing: See Spoiler.

WOT: A abbreviation for Wide Open Throttle.


Y-Harness: A wire that permits two servos to be plugged into a single channel in a receiver.


Z-Bend: A simple Z-shaped bend in the wire end of a pushrod, which is used to attach the pushrod to a servo output arm.

Z-Bend Pliers: An inexpensive plier type tool used for easily making perfect Z-bends.

Zip Tie: A nylon tie wrap, named ‘zip’ tie because of the sound it makes as you tighten it.

“Hydra-Drive”: A fluid slipper clutch, manufactured by Team Losi, that increases rear traction.

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