This master list of RC Terms has been collected to help new and even experienced RCer’s learn or brush-up on all types of terms used in the hobby. This is a continuation of the Terms seen every issue in our magazine and we will continue to update it as time goes on; please check back often.

Alphabetically from A - H

A-Arm.
This generally refers to the upper and lower suspension arm of a vehicle; the arm’s 2-point chassis hinge and single point mount at the hub resembles the letter “A”.

After-Run Oil.
Just what it sounds like. 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.
To prevent a car from lifting off the track at high speeds, most touring car bodies have an extension or air dam in the front bumper that is designed to keep air from getting under the car.

AM.
Amplitude Modulation. Most RTR or ready-to-run kits come with an AM radio system, which is suitable for most newcomers. More serious racers will opt for FM or PCM radios that are less prone to glitching.

Anti-squat.
This refers to the angle of caster on the rear wheels. Raising the front of the hinge pins of the rear arms gives a caster (anti-squat) angle and helps to transfer the power more evenly, keeping the front of the vehicle from lifting under heavy acceleration.

Ball Cup.
This is a “cupped” plastic piece that snaps onto a ball end to provide a pivot point—usually for suspension movement. Using this type of assembly instead of a rigid system allows the cup to pop off in the event of a crash, instead of breaking. Using turnbuckles with ball cups allows for more tuning flexibility.

Ball End.
The ball end is a metal ball with a hex and screw threads on one end. A ball cup attaches over the ball end to provide a pivot point.

Battery Elimination Circuitry (BEC).
A BEC allows an electric vehicle's main battery pack to power the radio receiver as well as the motor eliminating the need for a separate receiver pack.

Bearing.
This is essentially a metal “donut,” with tiny balls inside which permit rotating shafts to spin more efficiently. Bearings are widely considered to be the first upgrade necessary for any kit that includes bushings.

BEC (Battery Elimination Circuitry).
Built into an ESC, this circuit uses an electric vehicle’s main battery pack to provide power to the radio equipment, without the need for a separate receiver pack.

Bellcrank.
Steering mechanism used in most RC vehicles that consists of two posts joined a link. Each is connected to a left or right steering knuckle with a turnbuckle with one post connected to the steering servo.

Big Block.
Refers to engines that are .21 size or larger and .15 size engines that use the engine case of a .21

Bleeding.
When building or rebuilding shock absorbers, it is necessary to remove all of the air and any excess oil. This is known as bleeding the shocks.

Blue Groove.
This term refers to dirt tracks that have been smoothed out and packed down along the optimum racing line over time. A blueish tint results from tire wear.

Body Reamer.
The body reamer is a must-have tool for creating perfect body post holes in Lexan bodies and other semi-soft materials.

Break-In.
A new nitro engine has to go through a break-in procedure to mate the engine’s piston to the cylinder sleeve. This provides a longer life expectancy between rebuilds. Recommended procedures will vary by manufacturer and engine. Generally, an engine will need to be run rich and at no more than half throttle for the first 2-3 tanks of fuel. The entire procedure can consist of anywhere from 3-5 tanks of fuel, depending on the individual engine's instructions.

Bulkhead.
A very fundamental part of your R/C vehicle. Several major components rely on the bulkhead to join them to the chassis. Shock towers, upper chassis plates and suspension arms. Differentials are sandwiched between the left and right bulkheads.

Bushing.
A metal, and sometimes nylon, "donut" that supports a rotating shaft (like an axle). Most metal bushings are made out of something like Bronze Oilite, a metal that is permanently lubricated.

Camber.
This refers to the angle of the tires in relation to the ground, as seen from the front and rear of the vehicle. Zero camber (90 degrees) refers to tires that are exactly perpendicular to the ground. Tires leaning toward each other have negative camber, while tires leaning away from each other have positive camber. A general rule of thumb is to have a slight bit of negative camber and to be sure both tires maintain the same camber angle. For the most part you should always avoid positive camber.

Carburetor.
This can also be referred to as a carb. This part of the engine controls the ratio of fuel and air entering the engine. There are two types of carbs: slide carbs, where the barrel slides along its axis instead of rotating; and rotary or barrel carbs that rotate. The rotary carb is most common among RTR kits and is fine for most applications. The slide carb provides a quicker response and is therefore more desirable to the more serious enthusiast.

Center of Gravity (CG).
The higher your chassis components sit above your wheel's axles, the higher the CG of your vehicle. As a result, it may roll over more easily during tighter turns. Keeping your CG as low as possible will provide a more stable vehicle.

Chassis.
Made from aluminum, plastic composites or woven carbon fiber, this is the main platform to which all other components attach.

Clutch Bell.
The clutch bell attaches to the crankshaft of a nitro engine and meshes with the spur gear, performing the same function as a pinion gear on an electric motor. Changing the number of teeth on a clutch bell alters the way a vehicle performs. Fewer teeth produce more low-end torque, whereas more teeth increase top-end speed.

Clutch Shoes.
Clutch shoes are made from aluminum or a composite material and are attached to the engine flywheel. They expand under increasing RPM to engage the clutch bell that, in turn, engages the spur gear to make the vehicle move.

Comm Lathe.
An electric motor’s commutator will wear over time. This lathe is used to cut thin layers of material until the surface is like new.

Crank Shaft.
The shaft that the flywheel and clutch bell are mounted to. It is attached at the back to the piston by means of a connecting rod. The up and down motion of the piston causes the crank to rotate.

Crystal.
A small interchangeable element in radio systems that determines what frequency that radio will operate on. You will find a crystal in the transmitter and in the receiver.

CVD.
Abbreviation for Constant Velocity Drive. A type of drive shaft that uses a ball type set up that functions similarly to a universal drive shaft. Although "CVD" is a trademark of MIP (Moore's Ideal Products, Inc.) it has become commonly used to describe any drive shaft of this type.

Damping.
The rate at which a shock is compressed or rebounds. Most RC kits now contain shock absorbers that are filled with fluid/oil. Without this fluid, the shocks are bouncy and provide very little benefit where control is concerned. By changing the weight of the oil or the type of shock piston, or both, you can change the damping rate to tune your car to a specific track and/or driving style.

Differential.
A differential is a unit that transfers power from the input to output shafts. The differential, or “diff,” enables the outside wheel of a vehicle to spin faster and travel farther than the inside wheel during a turn.

Discharger.
Many battery chargers include a built-in discharging function. A better way to discharge your packs, however, is with a separate discharger that connects directly to the battery pack. One common style looks like a row of small light bulbs.

Dogbone.
A metal driveshaft with a ball at each end that has a pin going through the center; the pin fits into a slot in the outdrive to transmit drive train power.

Drag Link.
A bellcrank steering systems consists of 2 posts connected by a bar. This bar is the drag link and is also referred to, by some, as Ackerman link.

Dual Rates.
This refers to a switch that regulates the sensitivity of transmitter control input. This is a useful function for many beginners, who tend to over-control their vehicles.

Dyno.
Short for dynomometer. A device used to rate and compare electric or nitro engines. It measures things like RPM, torque, HP, efficiency, power, amp draw and some will provide powerband graphs.

ESC. Electronic Speed Control.
An electronic component that controls throttle input by regulating the current being sent through the motor.

Exponential Rate.
This refers to 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 stronger as the input approaches 100%.

Fail Safe.
If the transmitter’s signal is lost or interrupted a fail safe unit returns the servo to a predetermined position to avoid dangerous runaways. A battery failsafe is a safety feature which brings the throttle servo down to idle as a warning that the receiver battery's voltage is getting dangerously low.

Fixed Link.
Camber and steering links on many RTR (ready to run) vehicles use a non-adjustable link. These can usually be upgraded with turnbuckles as the driver’s skill improves, as he is looking for more adjustability.

Flywheel.
The flywheel is the larger metal wheel that sits behind the clutch bell and aids the engine's crankshaft with momentum and idling. For more torque and smoother idle use a heavier flywheel; for improved top speed and throttle response use a lighter flywheel. On non-pull start models it also represents how to start the engine with the use of a bump starter or starter box.

Foam Inserts.
These inserts are used inside tires to help them retain their shape. Different densities are available for use on different track surfaces.

Fuel Gun.
A rapid fuel delivery system used during nitro races. Generally speaking, they deliver 75ccs of fuel in just a second or two.

Glitch.
Otherwise known as radio interference, a glitch refers to a momentary lapse in signal transmission. There are external sources that cause glitches, (like overhead power lines,) but consistent glitching is most likely the result of something in the vehicle itself, such as metal-to-metal rubbing as you might find with control linkages.

Glow Plug.
Resembles a miniature spark plug. A glow plug supplies the necessary heat for igniting the fuel/air mixture in an engine. A battery-powered unit sometimes called a glow starter is installed over the plug to heat the small wire filament inside the chamber. After the engine is running, the glow starter can be removed since the wire filament inside the plug is kept hot by the engine's "explosions within the chamber.

Header.
This is the aluminum exhaust coupling that attaches to the engine’s exhaust port. A muffler or tuned pipe is usually attached to this bent piece of aluminum tubing.

Hinge Pin.
This is a straight metal pin that connects the suspension arm to the bulkhead, and it allows the arms to pivot up and down.

Hub Carrier.
This housing supports the drive axles of a vehicle, and uses bushing or bearings to keep the shaft turning smoothly.

Hydraulic Lock.
Also know as hydra lock, the term refers to when the engine becomes flooded with fuel preventing the piston from compressing in the combustion chamber. Engine damage can result if the crankshaft is forced to rotate without relieving the pressure. If this happens remove the glow plug, turn the vehicle upside down and briefly crank the engine to drain the excess fuel.

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