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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.


  • Washout --
  • Refers to a model loosing traction due to a lack of pressure on the tires, usually caused by shock springs that are too soft or an improperly adjusted rear wing.

  • Water Dip Break In (Brushed Electric Motor) --
  • A method used for breaking in new stock (closed endbell) brushed electric motors. This consists of holding the motor by the wires and submerging it in a glass of water, then attaching it to a 3 volt power supply (A.K.A. 2 1.5V alkaline batteries) and letting it run for 3-4 minutes. This helps to seat the brushes and wear in the bushings, and may net up to a 20% increase in power.

  • Waterproofing --
  • Unfortunately, most electronics for RC models are not waterproof - this can lead to damage if you run your ride in wet or snowy conditions. Some companies do offer waterproof ESCs and servos, but if you're not ready to pony up for new electronics, here are some tips for DIY waterproofing:

    - BATTERIES - Stuff your batts in a balloon with the leads running out of the open end, use a rubber band or zip tie to seal the end, then apply thick marine grease to the area. This works for power packs and RX packs.

    - ESCs - Use shrink tubing and apply thick marine grease on soldered connections. Also apply thick marine grease around the area where the servo lead exits the ESC. Do not wrap the case or electronics - ESCs can get very hot (and can melt anything used to wrap them). They need access to air to stay cool. You might consider creating a lexan splash guard to help keep excess water from reaching the ESC body.

    - RECEIVERS - The same waterproofing trick for batteries also works well for receivers. Stuff your RX in a balloon with the leads and antenna running out of the open end, use a rubber band or zip tie to seal the end, then apply thick marine grease to the area.

    - SERVOS - Apply thick marine grease around all seams, screw heads, and where the servo lead exits the case. Also, apply thick marine grease around the output shaft (it helps to remove the servo arm before doing this). For a more permanent and durable waterproofing, use clear silicone caulk instead of grease around the seams, screw heads, and servo lead. Don't use caulk on the output shaft - the reason should be obvious.

    - TRANSMITTER - If you have decided that you can gain more speed by using a hurricane as a tail wind, then you will need to protect your radio as well as the onboard electronics. The simple solution is to use a small trash bag - just stuff your TX and hands in the bag and you're good to go. If you use a clear bag, there's a better chance that you'll be able to see the display, but there's no guarantees once the bag is wet.

  • Weight (1) Fluid - WT --
  • Refers to the relative viscosity (thickness) of shock and diff oils (fluids) as rated on a viscometer. The lower the number, the thinner (lighter) the oil. Shock oil weight is commonly rated in 5's (20WT, 25WT, 30 WT, 35WT, ect.), and diff oil is commonly rated in 1,000's (4,000WT, 5,000WT, 6,000WT, 7,000WT, ect.). Altering shock oil WT is a valuable tuning aid, as long as it is paired with the proper springs. For shocks, a lighter (thinner) WT = faster bound and rebound, while a heavier (thicker) WT = slower bound and rebound. For sealed diffs, a lighter WT diff oil loosens the diff, while a heavier WT tightens it. During long runs, oils tend to 'thin out' due to heat and contamination - if you're looking at a long main, consider running a WT or two of thicker oil to compensate for this. Also note that oils thicken in cold weather, so to stay consistent, you may want to run a WT or two of thinner oil than your summer setting if you are currently wearing a parka.

  • Weight (2) Wheel --
  • Wheel weights are an important tuning tool for rock crawlers. They add weight to the rims (duh), which lowers the center of gravity (CG) and helps the tire carcass deform around obstacles (adding traction). Wheel weights may be self adhesive, glued on, or bolted on - depending on the weight and rim style. Some people have even just tossed a select number of ball bearings in the tire carcass to add weight.

  • Wheel --
  • Tires are mounted on wheels for stability and precision. Wheels come in several different widths to fit tires of different widths.

  • Wheel Nut --
  • A nylon lined (locking) nut used to hold the rim to the axle. Check these puppies often to make sure they're tight (not too tight - make sure your wheel still turns), since loosing a wheel just might cause problems.

  • 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. Most HPI sedan wheels are 0mm offset, meaning the edge of the wheel hub that comes in contact with the axle hex adapter is exactly in the middle of the wheel. Some of our sedan wheels (like the 3mm Offset Mesh and Super Star wheels) feature an offset of 3mm, which widens the car a total of 6mm.

  • Wheel Spin --
  • Occurs when a tire loses grip, either during acceleration (normally because of too much applied throttle), or through a turn (normally because of a high side load on the tires.

  • Wheel Tension --
  • The relative resistance of the steering wheel is adjustable on most high end radios (transmitters), making the wheel easier or harder to turn. This is used to fine tune the wheel for your driving style. Wheel tension is adjusted by turning a recessed screw that is usually located at either the front of the main radio body or underneath it near the steering wheel (dust off your user's manual for more details).

  • Wheelbase --
  • Refers to the distance between the center of the front axle and the center of the rear axle. Shorter wheelbase models tend to have better turn in, while longer wheelbase models tend to be more stable at high speeds.

  • Wheelie Bar --
  • A component attached to the rear of a model to prevent it from flipping over backwards during hard acceleration. This is usually used on models with a high CG that are prone to pull wheelstands (such as monster trucks) or high powered models (such as drag cars). Wheelie bars may be a simple, flexible plate (such as fiberglass), molded plastic, or an adjustable, shock supported alloy component. Either way, a pair of small wheels or bearings are attached to the end to reduce friction while the bar is in use. Note that the higher you mount the wheelie bar wheels from the surface, the higher wheelstands your model will perform.

  • Wide --
  • see width, wheel or width, chassis

  • Width# Chassis --
  • "When referring to bodies or chassis designs, we often hear about """"width"""". This is measured from the outside edges of the wheels, front and rear. Most hobbyists will at some point worry about fitting a narrow body on a wide car, or a wide body on a narrow car. At this time, most electric sedans are 180mm to 190mm wide, and most Nitro sedans are 195mm to 200mm wide. Because of the extreme popularity of Nitro sedans, many newcomers to RC want to know if they can fit narrow bodies on their car, bodies that aren't yet available in wide sizes. Sometimes there isn't a problem with fitting, but this will vary from body to body. Most narrow bodies on wide cars will have some wheel rubbing."

  • Width# Wheel --
  • "Another area where the term """"width"""" is used. Many tires and wheels are 26mm wide, this is considered """"standard narrow"""" or """"narrow"""" width. Early in the history of touring cars, some companies (HPI included) offered 31mm tires and wheels, called """"wide"""" since they are the widest ever offered for touring cars. A few years ago, some companies offered 22mm """"super narrow"""" tires and wheels for less rotating mass. These were never legalized for sanctioned racing, and worldwide rules organizations kept the tires between 24mm and 26mm, so the most recent development in tires has been the 24mm """"mid-narrow"""" tire and wheel, which is a great compromise between the light weight of the super narrow wheels and the contact patch of the narrow tires. See our Tires and Wheels sections."

  • Wing --
  • As opposed to a spoiler, which has no space between the car body and spoiler itself, the wing is raised off the mounting surface using posts of some sort. Most wings have upright 'rudder' supports, or side plates, which help stabilize the car in the straights. To help tune your car: A track with many turns and short straights will need small side plates, which won't interfere with turning too much but still give you stability in the straight. A track with many straightaways or two or more long straights could use larger side plates for more straight-line stability. See angle of attack for an explanation of how to use a wing.

  • Wing Mount --
  • A mounting system for rear wings that is usually attached directly to the rear shock towers or body mounts. This provides as much downforce as possible directly to the rear wheels. Some wing mounts may offer the ability to adjust the wing angle, height, or forward and rearward position to fine tune the downforce. Wing mounts are most commonly found on dragsters, buggies, truggies, and some monster trucks.

  • Wishbone --
  • An older name for a suspension arm. Suspension arms used to be shaped like wishbone from a chicken or other bird. Cars using a pivot-ball suspension (like the HPI Proceed) still use wishbone-shaped suspension arms because of the design requirements. Also used to refer to a double wishbone suspension.

  • Worm Gear --
  • A type of gear resembling a screw (think Archimedes Screw). This type of gear is rare in RC, but may be found in the diff cases of crawlers, since it helps the model to hold position?without rolling?(much like a mechanical drag brake).

  • Wrench --
  • A term referring to the assembly, disassembly, tuning, and maintenance of an RC model.

  • Wrist Pin --
  • A thick metal pin that attaches the con rod to the piston. Most wrist pins are held in place by C clips in the piston wall, but some are simply held in place by the sleeve (a.k.a. floating wristpins).

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