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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.


  • 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. Some new servos can be programmed?.

  • False Peak --
  • This may happen when charging fully depleted battery packs or packs that have been sitting around during the off season - the charger will read that the batteries have reached peak waaay before they are fully charged. If your old stick pack just peaked in 45 seconds, you can bet it's a false peak. Like the message under your soda lid says, 'please try again'. Cycling your pack will usually end false peaks.

  • FDR --
  • Abbreviation for Final Drive Ratio.

  • Feint --
  • When coming up on a corner, to make a quick maneuver in the opposite direction to get a better line through the corner.

  • Ferrite Magnets --
  • "The common, cheap magnet found in most budget """"sealed can"""" electric motors."

  • FET íV Field Effect Transistor --
  • "A transistor that controls the output current through a variable electronic field, supplying more amps with less resistance. FETs are most commonly used on servos and ESCs. In the case of """"stacking"""" FETs, the electrical resistance is distributed across the number of resistors used, reducing resistance even further."

  • FHSS (Frequency Hopping Spread Spectrum) --
  • A broadband, 2.4 GHz broadcasting modulation that constantly hops across all available 2.4 GHz frequencies to prevent interference.

  • Field --
  • Refers to the magnet or series of magnets inside an electric motor.

  • Filter Groove --
  • The groove or lip on a carb body that a zip tie is tightened against to hold the filter neck in place.

  • Filter Neck --
  • The silicone or rubber tube that connects the air filter to the carb of a nitro engine.

  • Final Drive Ratio --
  • The transmission ratio determined by combining the internal drive ratio and the spur/pinion combination. It is found by multiplying the primary gear ratio (PGR) by the internal gear ratio (IGR). EXAMPLE: a model with a PGR of 3.818 and an IGR of 1.7 would have a FDR of 6.49:1 (3.818 x 1.7 = 6.49). Not including rollout, this is the total ratio of a model's drivetrain. If you are trying to match the gearing of another driver who uses a different pitch pinion/spur combination (64 pitch instead of 48 pitch, etc.), or a driver that uses another brand of car, you can use this formula to get a better idea of what to use. Just get the internal drive ratio of the other car and find out the pinion/spur gears that are used, then adjust your gearing to match the final drive ratio of the other car. Remember to account for the motor being used, modified motors vary widely as more or less turns are used, and even stock motors are different from their construction, brush or spring usage, etc.

  • Fixed Link --
  • A type of linkage that cannot be adjusted, usually used on ready-to-run cars for camber and steering links. Easily replaced with turnbuckles for experienced racers who with to alter the car's setup.

  • Flameout --
  • This happens when a nitro engine stalls (quits) because of the lack of heat (flame) from the glow plug. This is usually caused by an overly lean fuel mixture or a fouled glow plug.

  • Flashing --
  • The excess material left over from the molding process of plastic or rubber parts. Use a ,11 hobby knife to carefully trim flashing from the parts, especially in low tolerance areas such as shock pistons, gears, and tire beads.

  • Flat Pack (Battery) --
  • Refers to a battery pack that has the batteries lined up in a row side by side, and may have 1 or 2 cells rotated, depending on the pack. This type of pack is common for micro electric rides and RX packs, where 5 cells are commonly used.

  • Flat Wire --
  • Refers to the type of wire used for the windings (coils) of an electric motor. Compared to round wire, flat wire (rectangular or oval) can be wound closer to the armature, resulting in increased efficiency and power, as well as a faster spool up.

  • Flex --
  • 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.

  • Flex Plate --
  • Usually found on pan cars, a flex plate is a strip (usually of alloy, fiberglass, or carbon fiber) that connects the rear pod to the main chassis. The flex plate acts as the rear suspension, and altering the plate's material and / or thickness helps tune the suspension action. In some cases, the flex plate may be a cutout of the main chassis that allows the rear of the chassis to flex. Also See T BAR

  • Flooding --
  • A nitro or gas engine becomes flooded when too much fuel collects in the carb or crankcase. At this point, the engine will not start, and if flooding continues, it will probably result in hydralock. Flooding is the result of over priming, trying to start an engine with a fouled plug, or an extremely rich needle valve setting.

  • Flyby --
  • To overshoot the downside landing of a jump, resulting in a fast, 'nose down' attitude.

  • Flywheel --
  • The flywheel helps the engine's crank shaft maintain momentum and aids in idling. A heavier flywheel will aid in torque (pulling power and acceleration), while a lighter flywheel will aid in top speed but may cause trouble with engine idling.

  • Flywheel Cone - Collette --
  • A slotted, conical washer that sits in a recess on the engine side of a flywheel. As the clutch nut is tightened, the cone compresses and 'locks' the flywheel to the crankshaft.

  • Flywheel Wrench --
  • A flat, slotted tool designed to fit over the clutch pins on a flywheel and prevent the flywheel from turning while loosening or tightening the clutch nut. A flywheel wrench is commonly preferred to a piston locking tool, since it produces no pressure on the con rod.

  • FM --
  • Short for Frequency Modulation, an FM radio in RC is considered a better radio than the cheaper AM radios because an FM radio will have less glitching than an AM radio. Most hobbyists will be fine with an AM radio, but racers can benefit from FM or PCM radios.

  • Foam Donuts --
  • Literally donut-shaped pieces of foam, these are mounted on wheels so that pan cars and touring cars can use them. Some race tracks are able to use 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 have better grip than rubber tires, they can last longer than rubber tires, 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 Inserts --
  • In the early days of RC, tires were either foam (for on-road use) or hard rubber (for off-road). The foam donuts did not need inserts, and the off-road tires were hard enough that they could support the weight of the car without collapsing. As tire and car development continued, the tires got softer and required inner foams to make the tire keep its shape on the track. Touring car development followed the same trend as off-road tires: early tires were made of a hard enough rubber that no inner foam was necessary, and eventually tires got soft enough to require them. Most soft compound tires come with a open cell foam insert, while modern sedan racing tires since about early 1999 come with no foams at all, so racers can choose the best molded inner foam for their specific needs. If you do not race, you can use (and re-use, when the tire is worn out) the standard open cell foam insert that comes with your tires. If you do race, you would be well advised to ask around at your local track to find out what tire and insert combination works best!

  • Foam Spacer - Foam Thingy --
  • A coarse foam donut that is slipped over the ball stud before the ball cup is popped into place. It helps to keep dirt and grime out of the assembly while allowing smooth operation.

  • Foam Tires --
  • Tires molded from foam. These tires usually come from the factory glued to the rim, and offer the best traction for clean, smooth surfaces. Foam tires may need to be trued (cut) before using. Foam tires are available in a multitude of compounds (soft to hard), and usually range in widths from 26mm to 35mm.

  • Four Link Suspension --
  • A type of suspension link set up used on solid axle monster trucks and rock crawlers. This uses 4 rods or links to connect the axle to the chassis - the rods prevent the axle from shifting side to side, front to back, and twisting or rotating. The lower links are usually parallel to each other and mount to the outside of the chassis, while the upper links mount inside of the chassis, and may angle inward towards each other at the top (a.k.a. a triangulated link). This tends to be more stable than a 3 link suspension, but may result in reduced articulation. Adjusting the length of the upper or lower links affects how the axle transverses obstacles, much in the same way that adjusting caster affects independent suspension models. Wheelbase is also commonly altered by adjusting the link length.

  • Four Stroke - 4 Stroke - Thumper (Nitro Engine) --
  • An RC nitro engine that fires once for every 2 up and down cycles of the piston, as opposed to a 2 stroke that fires once for every up and down cycle of the piston. 4 stroke engines use a valve system similar to 1:1 vehicles, complete with valves, pushrods, rockers, and a crank driven cam. So, you won't find any ports in the sleeve (since intake and exhaust is taken care of by the valves), but you will find ring(s) on the piston because 4 strokes require more compression than 2 strokes. 4 stroke engines are known for insane torque and excellent fuel economy, but are also known for lots of vibration - so pad those electronics and make threadlock your friend.

  • Frame Rate --
  • Refers to the time interval between the point when a receiver sends a signal to the servo and the time the receiver is updated on the servo's position.

  • Franken Tire --
  • Refers to a hand modified rubber tire that is created by combining two or more different tires into one. This is done by cutting both tires along the tread, then splicing the two together with CA to form two separate tread patterns on one tire.

  • Free Rev --
  • "Refers to applying throttle while the drive wheels of a model aren't on the ground - such as holding the model in the air and """"gunning it"""" to watch the wheels spin. This can damage drivetrain components, engines, motors, and even electronics (in electric powered models), so keep 'er planted if you're going to throttle up. Breaking in a diff by lifting the tires on one side and applying partial throttle is fine, and not considered free revving."

  • Free Spin --
  • "Refers to running an electric motor full tilt without a load - such as pegging the throttle without a pinion installed or testing """"how fast can this puppy go"""" before even installing it in your ride. Free spinning a motor can cause serious damage to the bearings or even kill some brushless motors. Low voltage break in is fine, just don't wind 'er up."

  • Free Style --
  • A driving style or competition based on stunts, such as powerslides, donuts, and backflips. Doing wheelies up and down the street is basically a form of freestyle. Freestyle is usually reserved for off road models, since wheelies and backflips are kinda' hard to pull off with touring cars.

  • Frequency (Reference) --

  • Frequency - (1) ESC --
  • Frequency refers to the number of times an ESC switches the motor on and off per second, expressed in Hz (hertz). Basically, there are low frequency ESCs and high frequency ESCs. Low frequency ESCs (i.e. budget models) usually operate in the 1 Hz range (60 'pulses' per second) and are best used with stock motors. Low frequency ESCs do not regenerate power, and will not feel as smooth as high frequency ESCs. High frequency ESCs commonly operate in the 1,000 to 3,000 pulses per second range. Only high frequency ESCs regenerate power, as well as reducing motor arcing.

  • Frequency - (2) RADIO --
  • "Frequency is a measurement of the number of oscillations (vibrations) per second of a radio wave, expressed as Hz (hertz), MHZ (megahertz) or GHz (gigahertz). If you think of frequencies as rolling waves, the distance from the peak of one wave to the peak of the next determines the frequency. The farther apart these waves are, the more susceptible the frequency is to interference, and likewise, the closer these waves are, the less susceptible they are to interference. The higher the number of the frequency is, the closer the """"waves"""". Frequencies are used by the transmitter (TX) to communicate with the receiver (RX). A TX and RX can only communicate if they are on the same frequency and same channel."

  • Frequency Checker --
  • A small, handheld electronic device that constantly scans for, and displays, any radio frequencies currently being used in the area. This lets you know whether or not it is safe to power up your transmitter.

  • Frequency Clip --
  • Step 1 - You will find a frequency board at your local track with a clip or tag for each available frequency used. Do not turn on your transmitter unless you have the clip that matches your transmitters frequency (channel) in your possession. A frequency clip is used to ensure that no interference is caused by 2 or more drivers using the same channel at the same time in the same area. If your transmitter uses spread spectrum technology (2.4 GHz), skip to Step 2. Step 2 - Race.

  • Frequency Hopping Spread Spectrum --
  • See FHSS

  • Friction Peg --
  • Small cylindrical composite pegs used on some slipper assemblies to provide the grabbing force (friction) between the spur gear and pressure plates. These pegs are inserted into holes in the spur gear and act like the pads on dual pad slipper systems.

  • Friction Shock --
  • The cheap - O RC shock. This is basically a rod that slides in a tube. The spring may be inside or outside the tube, but either way, the shock relies on friction between the rod and tube to provide damping, rather than the piston/oil combo of oil filled shocks. The damping action may be altered by coating the rod with various thicknesses of oil or grease - however, this is messy, and friction shocks will still tend to feel 'springy'.

  • Front Bearing --
  • Refers to the bearing that supports the front portion of a nitro engine's crankshaft or the pinion side of an electric motor's shaft. The front bearing is usually of heavy duty construction to withstand the heavier loads on the front of the crank or shaft. For nitro engines, the front bearing is sealed to prevent fuel leakage.

  • Fuel Bottle --
  • A soda sized bottle with a long aluminum neck used to fuel nitro models. The bottle is squeezed and released to siphon fuel out of the jug, then squeezed to force it quickly into the fuel tank. The long neck allows the fuel to reach the tank with the body still on the model. If you are too lazy to do dishes, don't use the fuel bottle for your Kool-Aide - the nitro residue left inside is poisonous. More importantly, the Kool-Aide will contaminate your fuel the next time you fill up your model.

  • Fuel Filter --
  • An element placed between the fuel tank and carb of a nitro powered model to trap contaminates in the fuel before they reach the engine and cause damage. A fuel filter is commonly 'spliced' into the fuel line, but may also be integrated into the fuel tank. Common fuel filters use a fine mesh screen or sintered stone to capture debris. When using a fuel filter, make sure the screen or stone end is on the exit (carb) side of the fuel line to prevent clogging.

  • Fuel Foaming --
  • Vibration may mix air with the fuel inside the fuel tank, causing it to bubble or foam, which?may starve the engine of fuel and cause it to die. The best way to prevent fuel from foaming is to make sure your fuel tank is as isolated from the chassis as possible. This is usually done by placing rubber O rings between the mounting points and the?tank mounts.

  • Fuel Gun --
  • This is basically a fuel bottle on steroids. Stick the nozzle of the fuel gun in the fuel tank, pull the trigger, tank is full. Done deal. In essence, a fuel gun uses gravity to fill the tank as fast as possible. A shut-off valve in the nozzle detects when the fuel tank is full and cuts the feed to prevent over-filling.

  • Fuel Line --
  • This is the tube that carries fuel from the tank to the carb of a nitro engine. Fuel line is almost always silicone fuel tubing, but can also be custom fit 'hard line', such as aluminum tubing.

  • Fuel Line Clips --
  • Small wire springs used to hold silicone fuel tubing on the nipple.

  • Fuel Tubing --
  • A flexible silicone tube used to transfer fuel from the tank to the carburetor of a nitro engine, or to transfer air pressure from the pipe or muffler to the tank. Fuel tubing can also be used for other things, such as: brake linkage resistance, shock limiters, or to hold up loose pants.

  • Fuelie --
  • Refers to the 2 cycle, gas powered engines found in larger scale models. Also refers to a gas powered model, or a person that runs or prefers gas engines.

  • Full Lock --
  • Refers to the maximum distance the front tires can turn left or right without binding.

  • Full Size --
  • "After talking about RC cars all day, you may want to discuss real cars with your friends - use the term """"full-size"""" to make the distinction!"""

  • Fused Lead --
  • An electrical wire that runs through a fuse to avoid excess current from traveling through it.

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