Sunday , 27 November 2022

RC Car Glossary

Beginner’s Guide to RC Cars – RC Car Glossary

Not sure what Caster is? What about Expotential? Never seen (or heard) of an Armature before? Well CompetitionX is here to help! Below is an extensive Radio Control Glossary from A-Z! New definitions are added all the time.

-Quick Jump-
# / A / B / C / D / E / F / G / H / I / J / K / L / M
N / O / P / Q / R / S / T / U / V / W / X / Y / Z

Generally, this is the smallest nitro type engine that is available for RC cars. Many kits come equipped with a .12-size engine. Some .12-size engines are more powerful than many .15-size engines, which indicates they are more efficient, have more tuning capability and/or larger carburetor openings. The “.12” refers to the displacement size of the engine in cubic inches, much like a full-size engine.

This is the second-largest nitro engine that is available for RC cars. Most RTR cars come equipped with a .15-size engine. The “.15” refers to the displacement size of the engine in cubic inches, much like a full-size engine.

Another larger nitro engine that is available for RC cars. It usually has a much larger case and head than the .12 or .15’s. These are common in most monster trucks. The “.21” refers to the displacement size of the engine in cubic inches, much like a full-size engine.

This is the largest nitro engine that is available for RC cars. It’s case is the same as a .21, but the piston and sleeve have a larger outer diameter, resulting in a larger bore. As the other engines, the “.28” refers to the displacement size of the engine in cubic inches.

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.

Spread Spectrum. The latest radio band available for RC 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. Aluminum alloys are used extensively due to their high strength-to-weight ratio with 6061-T6 alloy being 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.

The lower arm of a suspension assembly, often times resembles the letter “A”.

ABC / Non-Ringed:
These letters stand for Aluminum, Brass and Chrome or a composite such as nickel. 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.

Acronym for Anti-Lock Braking System. The ABS function is integrated into some higher end transmitters (such as the Airtronics M11). It is adjustable to allow you to use full brakes without locking up the tires, possibly causing an uncontrolled slide.

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

The degree of difference in the steering angle between the inside and outside wheel when a vehicle is turning. See RC Suspension Tuning: Ackermann.

Ackermann Link:
The center link of the bell crank steering system that connects the two steering arms. See RC Suspension Tuning: Ackermann.

Adjustable Travel Volume:
ATV allows you to preset the maximum travel of a servo to either side from its neutral position. Such settings help adjust control action to suit your driving style. Also known as ATV.

Refers to the movement of air over the body and wing of an RC car. See RC Suspension Tuning: Aerodynamics.

After-Run Oil:
An oil used to help protect and lubricate a nitro engine after use. After you’re done running your nitro engine, it’s recommended that you 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 diverts, air around the car instead of under it. Air under the car can produce lift. Most RC bodies for Touring Cars have air dams built in.

A strong, lightweight metal that is easily machined. Available in different ‘hardness’, aluminum is used for (in RC) chassis, shock towers, top decks and suspension components because of it’s light weight and durability.

Acronym for Amplitude Modulation. AM transmitters in RC are considered “budget” transmitters, what most newcomers to RC will start out with. Most hobbyists will be fine with an AM transmitter, but some racers can benefit from FM or PCM transmitters. An AM transmitter is susceptible to more glitching than these other, more expensive, computer transmitters.

Amateur Class:
See Novice Class.

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

The process of adding color to the machined part.

Anti-Roll Bar:
Anti-Roll Bars link the left and right sides of the car together (attaching to the suspension arms). Their purpose is to help prevent body roll through the corners. A thin bar allows more body roll, a thick bar prevents body roll. This is a useful tuning tool for onroad cars on flat, high traction surfaces. Also known as an Anti-Sway Bar. See RC Suspension Tuning: Anti-Roll Bar.

The angle, from horizontal, of the inner rear hinge pin in relationship to the chassis. Anti-squat helps to keep the rear suspension from squatting (compressing) under acceleration. See RC Suspension Tuning: Anti-Squat.

Anti-Sway Bar:
See Anti-Roll Bar.

The armature is the internal spinning part of an electric motor.

In a RC electric motor, arching is caused by voltage jumping from the brush to the commutator due to poor or corroded contact between the two components. Arcing will cause excessive heat, resulting in premature brush and commutator wear.

ARTR, or Almost-Ready-To-Run, is a designation used for vehicles that come pre-built from the factory minus the electronics. The ARTR vehicles cost a little more than a kit but not as much as a full RTR. This option is great if you want to add your own electronics to a particular vehicle you really like. See Beginner’s Guide to RC Cars – Build Types: Kit, RTR or ARTR.

See Adjustable Travel Volume.

What a wheel of a car spins on.

Axle – Inline:
Describes the axle being “inline” with the kingpin. See RC Suspension Tuning: Axle, Inline.

Axle – Trailing:
Describes the axle trailing the kingpin, or behind it. See RC Suspension Tuning: Axle, Trailing.

Back Marker:
Any racer that is being lapped.

Ball Bearing:
A ball bearing is a bearing assembly which uses captured balls as the rolling elements. Ball bearings are used in wheels and other rotating parts on RC cars or trucks, allowing the vehicle to roll more freely. This allows the nitro engine or electric Motor to power the vehicle to its fastest speeds. See RC Suspension Tuning: Ball Bearings.

Ball Cup:
The small, plastic ‘cup’ shaped piece at the end of adjustable turnbuckles. Ball cups snap on to ball ends to provide a ridid, adjustable link.

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. This allows 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. See RC Suspension Tuning: Differential.

Ball End:
A small, metal ball that has a hex shaped base. Moved around (to different locations in a given area), they aid in adjusting certain tuning options.

Used to power any electric powered vehicle. Batteries come in many different sizes for all different scales of RC vehicles.

Battery Eliminator Circuit:
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. Also known as a BEC.

Acronym for Bottom Dead Center. When a piston is at the very bottom of it’s stroke.

See Battery Eliminator Circuit.

A bellcrank is used as a steering mechanism in most RC vehicles. It usually consists of 2 ‘posts’ connected by a center link. Each post also has a link running to the left and right steering knuckle.

Acronym for Button Head Cap Screw.

“Big Block”:
In RC terms, this refers to any .21 size (or larger) engine.

A large round bar stock used to manufacture aluminum parts.

The process of removing air and excess oil from shock absorbers, as in Bleeding the Shocks.

Blue Groove:
A term used when dirt tracks have been smoothed and packed down along the optimal racing line. A bluish tint results from tire wear along this line.

In RC terms, the body is the thin (usually polycarbonate) 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, making it possible to run a street truck body, then change it for a sedan body. Also known as shell or lid. See RC Suspension Tuning: Aerodynamics.

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

Body Reamer:
The body reamer is a must-have tool for creating perfect body post holes in polycarbonate 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. Body Roll is prevented using and Anti-Roll Bar.

This is the diameter of the cylinder hole in the engine block for the pistons.

Bottom End:
A vehicle’s acceleration rate from a dead stop.

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.

Brake Check:
A driving tactic that is used to disturb a racer’s concentration. A car that is being followed closely by another car can abruptly slow down in a section of the track where braking normally doesn’t occur, causing the following car (and other cars) to swerve to avoid the car in front. While frowned upon, this tactic can help the lead car in a pack pull away.

Brake Fade:
A term used when a car’s brakes heat up and start to lose stopping power.

The process of running a nitro powered engine at idle speeds to prepare it for general use. The generally accepted method is to run the engine very rich (the exact needle valve adjustment will vary from engine to engine) for at least 3-4 tanks while the car is on a car stand.

Broached Ball End:
A standard ball end with a hex wrench ‘key’ machined into the head of it.

A small 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.

A 2wd or 4wd offroad RC car. They have open wheels, small bodies/cockpits, a huge wing and are very fast.

A main structural part of any RC car. Typically, the bulkhead attaches to the chassis while other parts (shock tower, top deck, etc) attach to it.

The changing of steering angles while the suspension is moved throughout its range of travel. Generally, not a desired action. See RC Suspension Tuning: Bumpsteer.

A metal or nylon ball bearing substitute. These are common in most RTR vehicles. There are (in almost every case) ball bearing sets for cars that come with bushings.


C-Hubs (Caster Blocks):
Shaped like the letter “C”, this part holds the front knuckles and placed on the front arms.

Acronym for “Cyanoacrylate”. CA is an instant type glue that is available in various viscosities (Thin, Medium, Thick, and Gel). These glues are ideal for gluing RC car or truck tires and wheels together.

The angle, from vertical, of the wheels. Negative camber is when the top of the tire is closer to the center of the vehicle than the bottom of the tire. Negative camber is commonly used to add stability in bumps. Positive camber is when the bottom of the tire is closer to the center of the vehicle than the top of the tire. Positive camber is not commonly used. See RC Suspension Tuning: Camber.

Camber Link:
The rod assembly used to connect the front caster block to the front bulkhead and the rear hub carrier to the rear bulkhead. They are adjustable. Some RTR links, however, are fixed. See RC Suspension Tuning: Camber Link Locations.

A small electronic component used as a filter to reduce radio noise generated by an electric motor.

Car Stand:
A Car Stand is simply a prop that the RC car sits 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 a nitro engine break-in.

Carbon Fiber:
An extremely strong thin fiber made by pyrolyzing synthetic fibers, such as rayon, until charred. Carbon fiber is used, in RC, to make strong, lightweight parts such as chassis, shock towers, top decks, etc.

The part of the engine which controls the speed or throttle. Carburetors come in either Rotary (barrel) or slide.

The main “body” of a tire.

The angle, from vertical, of the kingpin in relation to the ground. Caster can have a great effect on how a vehicle enters and exits turns and corners. Increasing caster (positive), so that the kingpin is angled back, will generally increase steering going into a corner and a slight decrease in steering coming out. Negative caster will decrease the amount of steering going into a corner, but will increase the amount of steering in the middle and while exiting that corner. See RC Suspension Tuning: Caster.

Caster Blocks:
See C-Hubs.

Acronym for Cubic Centimeter. cc is a measurement of engine size and only used with small engines.

Another term for batteries, but in a singular reference (such as, look at this cell). This generally refers to the nickel-cadmium or nickel-metal hydride batteries used in RC cars.

Center of Gravity (CG):
The point on the chassis at which the vehicle balances with all components installed. C.G. is the three-dimensional balance point of the car. That is, there is a vertical C.G. as well as a horizontal C.G. All forces acting on the chassis can be considered to act through the chassis’ center of gravity. Ideally, a vehicle’s center of gravity should be as low as possible. Also known as CG or COG.

A device used to charge and recharge batteries.

The main platform of a vehicle to which all the other components attach. Typically made of aluminum, plastic or carbon fiber. See RC Suspension Tuning: Chassis.

In RC car racing, the “class” refers to the type of RC car you have, and what “class” it would race in. Classes consist of Touring Car, 2WD buggies, 2WD trucks, 4WD buggies, etc. These classes are further divided by the mode of power, either electric or nitro. Next will be your driving experience, either Novice, Intermediate, Sportsman or Expert/Pro.

Clutch Bell:
Equal to a pinion gear on an electric motor. The clutch bell houses the clutch shoes which, under predetermined RPM’s, expand and come in contact with the clutch bell. The friction causes the clutch bell to spin which, in turn, rotates the spur gear and sends the vehicle in motion.

Clutch Shoes:
Clutch shoes are attached to the engine flywheel and expand under increasing RPM to contact the clutch bell. The clutch bell spinning makes the spur gear turn, and the car moves forward!

Closed Cell Foam:
A type of foam that is molded, normally used inside RC Car tires. More expensive than open cell foam, it holds its shape better and creates a more consistent feel.

A weighted fuel pick-up used in a fuel tank to assure the intake line is always in fuel.

CoG (or CG):
See Center of Gravity.

Cold Solder Joint:
A solder joint with poor electrical integrity. It is not mechanically, or electrically solid, and has a rough or grainy look. Cold joints can cause radio interference.

The top part of the armature. Typically referred to as the Comm. The comm transfers the current from the brushes.

Compound (Tire):
The type of rubber that a tire is made of. A softer compound will usually have more traction than a harder compound, but will often wear quicker.

The pressure that builds in a glow engine as the piston moves through the up-stroke.

A contest at racing events where vehicles are judged on their appearance.

Connecting Rod:
The rod that connects the piston to the crankshaft in a glow engine.

Contact Patch:
The “footprint” of a tire; the part of a tire which comes in contact with the road surface.

A (flathead) screw with a tapered head; a hole with an angle that accepts a flathead screw. (countersunk chassis).

In a glow engine, the main shaft to which the connecting rod, flywheel and clutch bell are mounted.

Small, interchangeable elements tuned to resonate at an exact frequency. This allows the transmitter (Tx) and receiver (Rx) to operate on the same frequency. Crystals may be purchased separately and in many different channels.

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.

Acronym for Constant Velocity Drive. Similar to a dogbone, the CVD uses a ball-type setup that connects the bone to the axle.

Damper Plate:
See Shock Tower.

Damping (not DAMPENING!):
The resistance caused by fluid in a shock body when the shock piston moves through it. Heavier oil, more damping.

Delrin is a man-made material patented by DuPont. It is a plastic that has the strength of metal. It is much denser and stronger than nylon (a material commonly used in RC gears). Delrin performs significantly better than plastic.

This is a slang term used in the RC world. It means that after all the hard work of tuning your suspension, shock oil, diff oil and other adjustments, your buggy is finally tuned.

Differential (Diff):
The part of the drive train which allows powered wheels (front or rear) to rotate at different speeds. This is important since, when turning, the outside wheel travels farther and faster than the inside wheel. See RC Suspension Tuning: Differential.

Differential (Diff) Balls:
In a ball differential, the balls float within the diff gear and cause the opposite side to rotate in the opposite direction when the diff gear is held and one outdrive is turned. See RC Suspension Tuning: Differential.

Differential (Diff) Rings:
The metal rings that the diff balls run against. See RC Suspension Tuning: Differential.

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.

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

Acronym for Dual Modulation 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. See also: FHSS.

Acronym for Direct Sequence Spread Spectrum. Digital sequence modulation applied to the carrier frequency. Looks like noise on a spectrum analyzer. The recommended form of modulation used by FHSS for transmitting data.

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 dogs bone.

Double Wishbone:
A type of suspension design that uses two wishbone arms that are parallel to the ground and each other – one for the main suspension arm and one for the upper arm. This helps maintain a constant tire camber as the suspension is compressed.

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. See RC Suspension Tuning: Aerodynamics.

Draft is the area directly behind a car where the air is disturbed and there is very little wind. Vehicles in a draft will be faster than the car creating the draft because the car in the draft does not have to use power to move the wind…it is merely using the power to propel the vehicle.

Resistance encountered that impedes motion or movement.

Drag Link:
The ‘link’ that connects two posts of a bellcrank system.

Droop is the amount of down travel the tires have when lifting up on the chassis. See RC Suspension Tuning: Droop.

Dual Rate:
An adjustment found on most transmitters which allows adjustment of the distance a servo arm will travel.

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

An expensive piece of computerized equipment that measures the efficiency of a motor.

A small device that holds cylindrical parts (like hinge pins) in place on the car.

RC vehicles powered by batteries are considered Electric Powered RC cars. All will have an Electronic Speed Control (ESC) to regulate the speed, an electric motor to provide the movement, and a 5 or 6-cell (sometimes more) NiMh battery pack (or 2, 3 or more cell LiPo) to provide the power.

Electronic Speed Control:
Also known as an ESC. Electronic speed controls replace the mechanical speed control and servo, providing enhanced power efficiency and precision in an electric RC car, truck or boat. In addition, they are lighter which improves the performance of most electric models. Also known as an ESC.

Endpoint Adjustment:
This transmitter feature adjusts the length of servo travel in one direction (a single channel will have adjustments for two endpoints). If your car or truck can make a tighter left hand turn then it can a right hand turn, endpoint adjustments can correct the problem by allowing you to adjust the servo to travel the same distance in both directions. Also known as EPA.

In RC terms, an engine is what powers a nitro car. It requires Nitromethane (or a gas mixture for large scale vehicles) to propel the vehicle forward.

A two-part resin/hardener glue that is extremely strong. It is generally available in 6 and 30-minute formulas. Used for critical points where high strength is necessary.

See Electronic Speed Control.

Expanded Scale Voltmeter:
Device used to read the battery voltage of the on-board battery pack or transmitter pack. Also known as ESV.

Expert Class:
The highest level or racing available. The drivers in this class are extremely fast and typically have multiple sponsors.

Exponential Rate:
This refers to the servo travel that is not directly proportional to the degree of control input. A negative exponential rate makes the control response milder around the servo’s center point, but it becomes increasingly stonger as this input approached 100%.

See Brake Fade.

A failsafe system returns the servos to a predetermined position should the transmitter signal be lost or interrupted.

See Final Drive Ratio.

Acronym for Flat Head Cap Screw.

Acronym for 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, you are not spending much time on that frequency and this keeps out interference. See also DMSS.

Final Drive Ratio:
The transmission ratio determined by combining the internal drive ratio to the pinion/spur combination using this formula: Spur Gear divided by Pinion Gear multiplied by the Internal Drive Ratio. Also known as Final Drive or FDR.

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 for experienced racers who want to alter the car’s setup.

A measure 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.

This is where there is too much fuel in the combustion chamber of an engine, causing it to choke and not fire due to increasing pressure.

When a part is externally snug and tight against a part and/or material

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

The larger metal wheel behind the clutch bell that aids the engine’s crankshaft with momentum and idling. Also used to start a glow vehicle not equipped with a pullstart.

Acronym for Frequency Modulation. FM transmitters are considered a better transmitter than the cheaper AM transmitters because of reduced glitching.

Foam Insert:
A foam ring or donut that is used in soft compound tires for support.

Fuel Tubing:
Flexible silicone tubing that is used to transfer fuel from the fuel tank to the carburetor.

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

A general term that normally refers to either the spur gear and pinion gear.

Gear Differential:
A differential that uses a series of gears to provide the differential action, allowing one wheel to rotate more than another in a turn. Gear diffs are harder to adjust than ball diffs but are much easier to maintain because they must be sealed to keep the grease inside from coming out. Tuning a gear diff can only be accomplished by changing the weight (viscosity) of the grease inside the gear diff case. See RC Suspension Tuning: Differential.

Refers to the ratio of the spur gear and pinion gear when compared to the internal final drive ratio of your vehicle. See RC Suspension Tuning: Gearing.

Momentary transmitter problem that can cause your car or truck to go out of control. See Failsafe.

Glow Plug:
The heat source for igniting the air/fuel mixture in the 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 heat the filament in the glow plug in order to start the engine.

A stiff, lightweight, space age composite material commonly used for chassis, suspension arms, shock towers, and other parts of a vehicle’s chassis.

This is the fast way around the track. Also known as “the racing line”.

A sharp, 180 degree turn on a track; when viewed from above, it resembles a hairpin.

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

A bent piece of aluminum tubing used on Nitro cars that transfers exhaust gases from the engine case to the tuned pipe or muffler.

Heat Sink:
Made of a heat conductive material (typically aluminum), a heat sink is used to dissipate heat over an increased surface area.

Hinge Pin:
A straight pin of steel or titanium that allows the suspension arms to pivot.

Hit (or to be hit):
Sudden transmitter interference which causes your model car or truck to drive in an erratic manner. See Glitch.

A term used to describe the initial lead at the start of a race.

When the rear end of the vehicle has a tendency to kick out when turning with the throttle on. Also known as oversteer.

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

Hub Carrier:
These are the parts of the suspension that hold the bearings and axles. Also called uprights.

A fluid slipper clutch, manufactured by Team Losi, that increases rear traction.

Idle Bar Plug:
This type of glow plug has a “bar” across the tip to help prevent raw fuel from being splashed onto the glow element. Too much raw fuel will cool the glow plug and prevent it from igniting the air/fuel mixture. This type of glow plug is not often used on RC cars or trucks.

See Foam Inserts.

See Glitch.

Intermediate Class:
Graduates of the Novice Class. These drivers have attained enough skill to get around the track fairly well. They might have also won a few races in the Novice Class.

Internal Drive Ratio:
A measure of the teeth of a car’s gears and pulleys. See RC Suspension Tuning: Gearing.


The angle of the entire front suspension, from horizontal, in relationship to the rest of the chassis. See RC Suspension Tuning: Kickup.

The hinge pin on which the steering knuckles rotate.

A car or truck assembly. Modelers are likely required to add their own electronics and radio system. See Beginner’s Guide to RC Cars – Build Types: Kit, RTR or ARTR.

Knuckles (Uprights):
Also known as Steering Knuckles, they secure the drive shafts to the wheels. Front knuckles are also used steering. Use bearings to maximize performance.

(Being Lapped) A term used when the lead cars are passing backmarkers, putting them one (or more) laps down.

A term used to describe the way an engine is running when it is not drawing enough fuel compared to the amount of air. This will cause the engine to run hot and, if not corrected, can cause engine damage.

Acronym for Light-Emitting Diode. Those little red lights you see on everything from electronic speed controllers to chargers.

Acronym for Local Hobby Shop.

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

LiPo Battery:
Lithium Polymer Battery. Derived from Lithium Ion batteries, they’re compact and light 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.

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.

A nut that used a nylon insert to help ‘lock’ the screw in place.

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

See Oversteer.

Low End Needle Valve:
A valve for tuning a 2-stroke engine in the lower band of its RPM range. Properly adjusting the low end helps ensure a smooth transition from low to high speed.

Acronym for Low Speed Needle. This needle found on nitro engines controls the idle and just off idle air/fuel mixture. Proper adjustment of this needle will allow a consistent idle as well as immediate and explosive acceleration. Adjustment of this needle should be done after the high speed needle is properly set.

Acronym for Milliamp Hour. A measure of a battery’s total capacity. The higher the number (ex. 2400 mAh, 3400 mAh) the more charge a battery can hold and usually, the longer a battery will last under a certain load. Typical rechargeable receiver battery packs are in the 800-1400 mAh range. Typical RC car batteries are in the 4200 – 5800 mAh range.

Main Event:
The final race after qualifying. Also known as the Main.

See Turn Marshal.

A small scale RC, usually in the 1/16 scale or smaller category.

A rating given to batteries. Generally speaking, the higher the milliamp rating, the longer the cell can provide power.

Milliamp Hour:
See mAh.

Molded Inner Foam:
See Foam Insert.

Monster Truck:
Monster trucks are Big! They are the king of the hill in any group of RC vehicles. Designed for torque instead of speed, these car crushers can move up hills, down slopes and over unsuspecting cars by virtue of sheer, brute power.

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.

In RC racing, this generally refers to an electric motor.

A device attached to the exhaust outlet of the engine to reduce noise and increase back pressure which helps low speed performance.

Muffler Baffle:
A restrictor plate inside the muffler which reduces engine noise. This plate can be removed to increase power, but will increase the engine noise!

Needle Valve:
Adjustment on a carburetor used to set proper air/fuel mixture. Some carburetors have separate needle adjustments for low and high throttle. Typically, turning the needle clockwise (screwing in) leans the mixture (less fuel); turning the needle counter-clockwise (screwing out) richens the mixture (more fuel). However, there are a few exceptions–refer to the engine manufacturer’s instructions.

Neutral Position:
Referring to servos, this is the position the servo is at when it is idle.

A beginner in the hobby.

Acronym for Nickel-Cadmium. Rechargeable batteries used as power RC transmitters and receivers.

NiCd Starter:
See Glow Plug Igniter.

Acronym for Nickel-Metal Hydride. Rechargeable batteries used to power RC transmitters, receivers and the vehicles themselves. NiMh cells do not have the same type of ‘cell memory’ as NiCd batteries do. This translates to less maintenance for the end user.

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. Refer to the engine manufacturer’s instructions for best results. Nitro content in fuel is indicated by the percent of the fuel. Also known as Nitromethane.

Nitro Powered:
Any vehicle powered by any size nitro engine.

See Glow Plug Igniter.

Novice Class:
The beginner class. This is where the new racers start out. Also know as the Amateur Class.

A type of plastic used in many RC kits.

Offroad Car:
Offroad buggies and trucks are the most popular land vehicles. These cars sport full-travel suspensions and high ground clearance. Their knobby rubber tires give them the ability to tackle any dirt terrain. These cars are available in nitro or electric, and in many different scales. On a dirt track or at the park, these offroad are great fun.

See Wheel Offset.

A measure of electrical resistance.

Refers to a One-Way front differential. 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 planetary gear diff to “unload”. A one-Way prevents differential unloading because it does not allow the tire to spin less than the speed of the belt that turns the pulley. One-Way differentials usually provide a TON of steering but, in exchange, reduce the effectiveness of brakes (only applying brakes to the rear tires). See RC Suspension Tuning: Differential.

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 you more power. A lower on-resistance also means the ESC will run cooler.

Onroad Car:
Onroad RC cars don’t have the beefy suspension that the offroad RC cars have, but they are impressive in their authentic looks and all out speed. Built for racing on smooth, paved surfaces, they are available in nitro or electric, and in many different scales.

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

The piece that mount on either end of the differential gear and transfer power out of the transmission.

The condition where a final 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.

A situation in which the front tires have more traction than the rear tires. This causes the rear tires to lose traction in corners.

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.

Acronym for Pulse Code Modulation. A transmission system that uses digitally encoded signals. A PCM transmitter is less likely to glitch than an AM or FM transmitter.

The point at which a battery no longer takes a charge.

Peak Charger:
A peak charger automatically shuts off when your battery is fully charged. This means longer run times for your vehicle. Peak chargers are nearly foolproof, if you forget to turn it off, the charger does it for you.

Pinion Gear:
The gear that attaches to the motor shaft. See RC Suspension Tuning: Gearing.

The piston fits into an internal cylindrical part of an engine called the sleeve, and slides up and down during the combustion cycle. The piston turns the the engine’s crankshaft via a connecting rod, converting the energy of combustion into rotational torque.

The number of teeth per inch on the gear. The higher the number, the smaller the teeth, ie a 30T (or 30 Tooth) 48 pitch gear has larger teeth than a 30T 64 pitch gear, however the 64 pitch gear allows more adjustment between gear ratios.

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 Differential:
A type of differential that has small gears rotating around the center drive gear. See RC Suspension Tuning: Gearing.

Pole Position:
See Top Qualifier.

An opening in the sleeve of a nitro engine. Modifying the port size and shape can affect the power and fuel consumption of an engine.

A method of gaining more power from a nitro engine. If done correctly, you can get more power. If not done correctly, you will have possibly more power but much worse fuel consumption, or not run at all!

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.

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

Programmable or Computer Transmitter:
These high-tech transmitters are not inexpensive but allow a full set of programmable transmitter features like multiple car memory, preprogrammed commands (throttle sensitivity, braking, etc. at the touch of a button) and much more.

A mechanism that allows the starting of a nitro car engine without the need for a separate engine starter box. It is attached to the back of the nitro engine.

RC racers’ term used to describe the amount of acceleration a car or truck possesses.

A term used to describe a vehicle with understeer. Also known as understeer.

When you attend an RC car race, you will normally have two or three qualification races, then you will race in your Main Event. Typically your best (fastest) qualifying run will determine which main event you will be in.

Race Director:
The person running and organizing the race. Responsible for calling the drivers to the stand, making sure each car is in the correct spot on the starting grid, calling traffic if necessary, etc.

Racing Line:
This is the fast way around the track. Also known as the groove.

See Transmitter.

Acronym for Radio Controlled.

Ready To Run:
Some cars and trucks are available pre-built and will be indicated by the term RTR (Ready-To-Run). The RTR vehicles cost a little more but typically come with everything you need (except a battery and charger). If you’re not interested in building your car, this is an option for you. See Beginner’s Guide to RC Cars – Build Types: Kit, RTR or ARTR.

An angled tool with a rough surface used to enlarge holes…to mount a body to the chassis for example.

Receiver (Rx):
An electronic device that receives the signal from the transmitter.

Receiver Pack:
The battery pack that provides power to the onboard electronics in nitro powered vehicles.

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

An apparatus possessing resistance to electrical current. When attached to a 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.

A term used to describe the way a nitro engine is running when it is drawing too much fuel compared to the amount of air.

Ride Height:
The point at which the vehicle naturally rides when fully loaded with the necessary equipment. See RC Suspension Tuning: Ride Height.

Radio Operated Auto Racing. National body to standardize and sanction R/C car and truck racing.

Roll Bar:
See Anti-Roll Bar.

Roll Center:
A point about which the sprung mass of the vehicle will roll under influence of centrifugal force. See RC Suspension Tuning: Roll Center.

Roll Out:
Roll Out is a measurement that helps calculate gearing. It is something that is used more for foam tire setups, but can be applied to rubber setups, also. See RC Suspension Tuning: Roll Out.

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 you can make these parts, 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.

Acronym for Revolutions Per Minute. The number of times an object completely rotates (360 degrees) in one minute.

See Ready To Run.

Run Time:
How long an RC vehicle will run on one battery pack or tank of fuel.

Sand Bagger:
Term used for a good racer running in to low of a main or class, usually resulting because they are to chicken to run with people of their same ability level (ie, sportsman racer running in the novice class).

This term refers to the size of the RC vehicle. 1/10th would equate to 1/10th the size of a real car. 1/18th, 1/18th the size of a real car. 1/5th, 1/5th the size, etc. See Beginner’s Guide to RC Cars – RC Scale.

Schottky Diode:
Helps with more consistent braking, more efficient motor operation and allows cooler operation of electronic speed control. Schottky diodes are only recommended on forward only, no reverse electronic speed controls.

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

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:
Attaches to the servo and is the link between the servo and the steering linkage.

Servo Reversing:
This transmitter feature allows you to install the servos where they can give the best pushrod routing without concern about the direction of servo rotation. When your installation is complete, turn on your transmitter and check each channel. If a channel operates opposite of its intended direction, a simple flick of a switch (in the transmitter) can correct the problem.

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.

Acronym for Socket Head Cap Screw.

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

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. See RC Suspension Tuning: Shocks.

Shock Tower:
A reinforced piece, attached to the chassis, that allows the shocks to be mounted. Shock towers usually have multiple mounting locations (for tuning), and can come in plastic, carbon fiber, or metal (typically aluminum). See RC Suspension Tuning: Shock Mounting Positions.

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.

The internal cylindrical part that houses the piston in a nitro engine.

Slide Carburetor:
A highly modified, car-specific type of carb that has the barrel of the carb slide along its axis instead of turning. This provides a quicker response at the expense of a complicated set-up procedure. This type of carb has almost become the industry standard for the RC Hobby. Two or three needle valves control the fuel intake at different RPM ranges.

Slipper Clutch:
This device (found primarly in offroad vehicles) 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. See RC Suspension Tuning: Slipper Clutch.

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.

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

Any racer that has attained a pretty high level of racing (or, in a lot of cases, can be a VERY good company representative) can gain sponsorship help. Manufacturers typically sponsor drivers in hopes of getting their product into the winners circle, showing that their product can win races.

Sportsman Class:
Drivers that have won some races and are pretty quick around the track are considered Sportsman. Sportsman drivers typically do not (or should not) have any sponsorship help (if they do, they should be 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. See RC Suspension Tuning: Gearing.

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.

Starting Grid:
The order the cars are lined up at the start of a race.

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

Steering Throw Symmetry::
Steering Throw Symmetry is the action of your steering having equal throw to both the left and right. It ensures your car will turn equally in both directions. If for some reason it doesn’t, the throw can be easily adjusted using the steering turnbuckles. See RC Suspension Tuning: Steering Throw Symmetry.

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.

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

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

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.

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

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. See RC Suspension Tuning: Toe In.

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. See RC Suspension Tuning: Toe Out.

Top Deck:
Included on almost every onroad car, the top deck connects the from and rear bulkheads (and sometimes a center bulkhead) together. 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.

Top Qualifier:
The fastest car in qualifying gets the inside front row starting position on the starting grid for the main event. Also known as TQ.

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

Touring Car:
A specific onroad 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.

See Top Qualifier.

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. See RC Suspension Tuning: Track Width.

Traction Compound:
Used to soften foam or rubber tires in onroad and offroad racing. A mixture of different chemicals that usually have a strong, unpleasant odor.

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

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, that you input, to the receiver in the vehicle.

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

A low-rate charge, usually below 0.5 amp.

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

Tuned Pipe:
A highly modified muffler that increases the power from a nitro car’s engine.

Turn Marshal:
Persons assigned to correcting vehicles that are upside down or stuck on the race track. Racers are usually expected to turn marshal immediately following their race.

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.

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. See RC Suspension Tuning: Tweak.

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

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).

See Hub Carrier.

Vapor Lock:
This occurs when an engine has been running at an excessive heat, normally for 15 minutes or more. The crankcase heat transfers to the carburetor, boiling fuel before it enters the combustion chamber.

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.

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. If we compare an electrical system to a water system, it would shake out like this: The voltage is equivalent to the water pressure, the resistance is equivalent to the pipe size and the current is equivalent to the rate at which the water is flowing. The relationship between these three can be stated as follows: I = V/r (Current in Amps is equal to voltage divided by resistance) So, using our water analogy, let’s say you had a power nozzle on your hose. If you open the faucet more, you will increase the pressure in the hose and the water will flow faster. In electrical terms, increasing the pressure is like increasing voltage and the resulting increase in flow is an increase in current.

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

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). See RC Suspension Tuning: Wheelbase.

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.

See Spoiler.

Winners Circle:
Where you want to be at the end of ANY race! It consists of the top 3 drivers in any race.

Acronym for Wide Open Throttle.


A wire that permits two items (like servos) to be plugged into a single channel in a receiver.

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.

Other Beginner’s Guide to RC Articles
RC Car Categories
Build Types: Kit, RTR, ARTR
Electric or Nitro
RC Scale
Buying Your First RC Car
RC Car Anatomy Files
Before Your First Drive
The Basics of Driving
RC Car Glossary