Phone Order Support: US +1(626)404-7382 | UK +44(020)8133-9382 | HK +(852)2858-6382

RC Glossary


New to the RC Hobbies? What does buggy, bulkhead, nitro mean in radio control car hobbies? Check out the glossary for remote control cars below.


  • Race (Bearing) --
  • Refers to the rotating rings of a bearing. There are 2 races: the inner race, which is the small inner ring that the shaft or axle slides into, and the outer race, which is the large outer ring that encompasses the outer edge of the bearing. The races can rotate independent of each other, and the bearing balls or pins are sandwiched between them.

  • 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, and other duties.?

  • Racing Line --
  • The fastest way around the track. Not always a straight line from corner to corner, the racing line is often flowing and smooth, representing feints into hard corners and drifts coming out of corners.

  • Radio --
  • Refers to the transmitter used in RC, which may be a pistol grip (wheel) or gimbal (stick) style.

  • Radio System --
  • The electronics needed to control an RC model - i.e. the transmitter (radio), receiver, and servos. Many people also consider the batteries and ESC (for electric models) as part of the radio system.

  • Radio Tray --
  • A deck or tray on many models that holds the major electrical components, such as the servos, batteries, and receiver. This tray is designed to be easily removed with all of the components attached for quicker maintenance and cleaning.

  • Rake --
  • Refers to a model's attitude when one end is lower than the other. Rake is usually adjusted with preload or droop. A model with forward rake has the front of the chassis lower than the rear, which helps to reduce understeer. Rear rake (rarely used) has the rear of the model lower than the front, which increases stability. Oval racers also commonly rake the model left to right.

  • Rally --
  • "A newer class of RC cars, popularized by the HPI RS4 Rally. At first glance appearing to be a touring car with treaded tires, a """"true"""" rally car will feature 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."

  • Ramp --
  • Refers to the ability of the center port of a nitro engine to pack the crankcase with the air/fuel mixture.

  • RC- R/C - Radio Control --
  • Refers to controlling an object with radio waves or frequencies. For the purposes here, this means controlling 'scale' car and truck models. In 1898, Nicola Tesla built the first known radio controlled vehicle - it was a boat.

  • Ready To Run --
  • A term that usually means a kit is at least 95% assembled, with minor finishing work being the only requirements to getting it ready. Some painting, tire mounting and minor assembly (such as attaching body posts and body clips) may be necessary, and a nitro-powered car will require break-in.

  • Rear Exhaust --
  • Refers to a nitro engine with the exhaust port on the rear of the block as opposed to the side. Rear exhaust engines tend to be more efficient than side exhaust engines since the air/fuel mixture follows a straighter line through the block to the exhaust port. Rear exhaust engines almost always use a round exhaust port on the engine block.

  • Rear Pod --
  • Found on pan cars, the rear pod holds the motor plate, motor, and rear axles. It is usually connected to the chassis with a flex plate.

  • 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.?

  • Receiver Pack --
  • The battery pack that provides power to both the steering and throttle servos in a Nitro car.

  • Reduction Gears --
  • A series of gears designed to lower (reduce) a gear ratio or to improve torque. Reduction gears are commonly used with on board starting systems to increase torque, but may be available as 'bolt on' assemblies used to increase torque on crawlers and monster trucks.

  • Regenerative Power --
  • While braking, high frequency ESCs send excess voltage back to the battery (like a mini recharge), increasing run time.

  • Resistor --
  • An electrical unit that eliminates excess electrical current by converting it into heat.

  • Reverse Lockout --
  • A function on most high end ESC's that allows the user to eliminate the ability of the motor to rotate backwards, leaving only forward and brake. Nearly all sanctioned races and many club tracks have rules requiring reverse lockout on electric models for safety reasons.

  • Rich --
  • A condition referring to engines where the engine is getting too much fuel. If you accelerate from a stop and the engine dies, you are probably running too rich and should lean out the engine's low speed idle adjustment a little (by turning the needle valve or low-end adjustment slightly clockwise).

  • 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. Adjustable on the RS4 kits by the shock spacers provided with the kit. 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).

  • Ride Height Gauge --
  • A stepped or wedge-like tool with measured markings - used to measure the ride height of a model.

  • RIM --
  • The tire is attached to the rim and the rim is attached to the axle. Please do not deviate from this formula - it has been done this way for ages and seems to work well. For race purists, dish rims seem to be the hot ticket, but rims are available in many styles, offsets, and materials. Note that most rims are not interchangeable between models (or, in the case of 2WD models, they may not be interchangeable between the front and back), so make sure you pick up the proper rims for your ride. You will have to use CA to glue the tires to most rims (clean the area well first), but beadlock rims are available for many off road applications. Foam tires virtually always come mounted on the rim. Most rims either key directly to pins in the axles or to hexes, depending on the model.

  • Ring Gear - Crown Gear --
  • The 'flat' bevel gear that caps the diff assembly inside a gear diff case. The ring gear is spun by the input gear.

  • Rocker - Cantiliever --
  • A 'V' shaped, bellcrank style of pivot arm used on models with inboard or horizontaly mounted shocks (such as some F-1 models, rock crawlers, and monster trucks). A pushrod transfers motion from the suspension arms to the rockers, which transfer the motion to the shocks. Altering the angle or length of the rockers acts much like altering shock angle.

  • 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.?"""

  • Roll Bar --
  • Mainly found on monster trucks, this is a metal or plastic 'loop' that is attached to the chassis to help protect the components during a roll over. The roll bar often doubles as a carrying handle when the body is off.

  • Roll Cage --
  • A protective assembly that attaches to the chassis - this may be a welded tube frame, bolt together alloy parts, or custom built. Roll cages are usually aftermarket upgrades for monster trucks, but have found their way onto other types of models as well (such as custom drag cars and scale models). Roll cages add quite a bit of weight to the model, but may be the best insurance against damage to the components, protecting them better than any lexan body. In fact, many roll cages are a work of art that may tempt you to run your ride without a body - go ahead, you're covered.

  • Roll Center --
  • Basically, roll center is an imaginary axis that the model pivots (rolls) around when leaning side to side, such as while cornering. Roll center affects the steering response, weight transfer, chassis roll, and even camber gain of the model. Roll center is based on the geometry of the suspension, and is dependent on many factors, including: the length and position of the suspension arms, the length, position, and angle of the camber link (turnbuckle), the vertical position of the hub in relation to the suspension arms, and even tire diameter. Roll center is determined separately for the front and rear of the model. In general, a higher roll center decreases chassis roll - while a higher roll center on the front of the model increases on power steering response, but decreases off power steering response. Raising the roll center is commonly achieved by shortening the camber link or raising it's outboard mounting location. In general, a lower roll center increases chassis roll - while a lower roll center on the front of the model increases low speed steering response, but decreases high speed steering response. Lowering the roll center is commonly achieved by lengthening the camber link or lowering it's outboard mounting location. A lower roll center commonly magnifies camber gain, and the model will tend to transfer weight to the end with the lowest roll center. When adjusting roll center, always take into account the roll slope to avoid unbalancing the model. Note that this is an extremely brief overview, as roll center may be the most complex adjustment available on any ride.

  • Roll In --
  • Refers to a body roll effect where the inside of the chassis remains at the same relative height while cornering, and the outside of the chassis lowers. This is the preferred reaction as it places weight over the outside tires for increased traction.

  • Roll Over --
  • Refers to a body roll effect where the inside of the chassis rises while cornering, but the outside of the chassis remains at the same relative height. This reduces traction and makes the model prone to flipping (rollover).

  • Roll Over Antenna --
  • Roll over antenna are rare, but a basher's dream. This is simply a stiff but flexible rod (like a fishing pole rod) resembling a tapered antenna tube. The roll over antenna is either mounted to the chassis or body of the model. The idea is that when the model rolls over (goes wheels up), the roll over antenna will apply enough pressure to flip the model back onto it's wheels. Those of you that are familiar with battle bots may recognize this concept as a SHREMECH or SRM (Self Righting Mechanism), though it doesn't seem to work as well - which is about 50% of the time.

  • Roll Slope --
  • An imaginary line drawn from the front roll center to the rear roll center of the model, indicating the angle (slope) of the roll center across the chassis (i.e. which end has a higher roll center and which end has a lower roll center). When changing the roll center on one end of the model, it always affects the roll center of the other end, such as lowering the front roll center raises the rear roll center. An upward roll slope (the front roll center is higher than the rear roll center) increases high speed steering response. A downward roll slope (the front roll center is lower than the rear roll center) increases low speed steering response. Always consider roll slope when adjusting the roll center to avoid unbalancing the model.

  • 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 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.?

  • RPM --
  • Rotations Per Minute. How many 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.

  • RTR --
  • "A term standing for """"Ready To Run"""""""

  • Runtime --
  • A term that means how long an RC kit will run or last on one battery pack or fuel tank.

Top Brands

rcmart traxxasrcmart Speed Passion

rcmart 3racingrcmart Speed Passion

rcmart 3racingrcmart samix

rcmart Yeah Racingrcmart Pro-Line

rcmart Wrap Up Nextrcmart rpm

rcmart Gmade Crawler GS01rcmart Xtra Speed

rcmart hobby wingrcmart skyrc

rcmart orcarcmart MST Drift Tire Wheel RC

rcmart GPMrcmart Xray

rcmart Team Associatedrcmart Holmes Hobbies

rcmart Tamiyarcmart ABC Hobby Body

rcmart TBR T-Bone Racingrcmart Jconcepts

rcMart first-sale-2019-190102

rcMart Flash-Sale-173rd-190110-touring

rcmart Reduced Shipping Save Big weekly deals
rcmart crawler Accessories
rcmart traxxas trx-4
rcmart Xpress Xpresso Car Kit
rcmart xray t4
rcmart 3racing D4 RWD hop up parts
rcmart Axial yeti hop up parts
rcmart GOM 1/10 GR01 4WD Rock Buggy Car Kit
rcmart Axial SCX10II hop up parts
rcmart Axial SCX10 hop up parts
rcmart traxxas e-revo
rcmart traxxas slashy 4x4
rcmart blog RC NEWS
rcmart Exclusive Special Offer GPM Racing 400 days Warranty