Like any sport or hobby, radio control car racing uses a whole host of technical phrases that you need to learn. This guide will help you understand some of the more commonly used jargon of the RC world.
Battery capacity – The capacity of a pack of batteries is determined by the mAh (milliamp-hour) figure on the side of a single cell. The latest batteries on the market have around 4.200 to 4,300mAh.
Battery pack – This refers to the pack of cells fitted to an electric car that provides power to the motor. The higher the capacity (mAh), the longer the car will run, but the more expensive they are to purchase. Entry-level battery packs are generally supplied in stick pack format, usually with an industry-standard connector that links the battery to the speed control.
Peak detect – This is the most popular charging method, where the fast charger detects that the pack has reached its peak voltage and switches off the charging process. To do this, the charger continuously monitors the overall pack voltage and actually stops charging once the pack begins to be overcharged when instead of going up, the voltage drops. A fully charged battery will always be warm to the touch. This heat is created by the charge rate (Amps) or the overcharge level. On most modern-day competition-spec chargers, this is adjustable.
Saddle pack – Refers to the layout of a battery pack where the cells are arranged in two groups and joined by a wire piece. This design allows the battery to be positioned where the manufacturer wants the weight.
2WD – This abbreviation describes a car with two-wheel drive, and in most cases, the two wheels are the ones on the rear axle. One-tenth scale off-road buggies come in either 2WD or 4WD platforms. Two-wheel-drive cars are more challenging to drive than their 4WD relations but are simpler to build and maintain.
4WD – Four-wheel-drive cars have all four wheels receiving power, which gives them greater grip and makes them easier to drive. One-tenth scale off-Road buggies come with either 2WD or 4WD drivetrains.
CVD – Short for ‘constant velocity driveshaft,’ the type of driveshaft fitted to most four-wheel-drive competition cars. The pivot ball design aims to minimize power loss while still allowing free movement in all directions so that the suspension can function correctly.
Differential – A differential or ‘diff’ allows one wheel to rotate at a different speed to the other, which means that when a car’s cornering helps it maintain speed through the tum. There are two versions of differential, a ball-type and a gear-type. The former uses a circle of small ball bearings held between two metal rings: a screw through the middle adjusts the pressure applied, which in tum alters the differential’s action -this can then be used as a tuning aid. Gear-type differentials aren’t externally adjustable but rely on a lubricant, either grease or silicon oil, to control internal components’ speed. Gear-type diffs are generally more robust than ball-type, with the latter requiring more maintenance.
Dog-bone – As the name suggests, this is a driveshaft that looks like a dog bone. They’re usually fitted to introductory specification kits due to their simplicity and strength. Most manufacturers will offer upgrades for dog-bones in the form of a universal Joint (UJ) or constant velocity CVD) driveshaft.
One-way – This device allows the front wheels of a four-wheel-drive car to freewheel off power but then transmits the drive to all four wheels again under acceleration. It’s installed either as a replacement for a front differential or on the center layshaft. Using one-way increases the amount of steering off-power, but under braking, only the rear wheels are slowed down, so you have to apply the brakes in a controlled manner to avoid the rear sliding or spinning out. In off-road, some drivers will use this characteristic to help negotiate comers.
Pinion – The small gear fitted to the end of an electric motor. The more teeth on the pinion, the higher the car’s top speed will be, but at the expense of acceleration and battery duration. There’s also a pinion gear inside a gearbox where there’s a 90° transfer of drive. The term again refers to the smaller one, with the larger one on the differential being called the crown gear.
Slipper clutch – Fitted to off-road vehicles, a slipper clutch provides a form of traction control that makes the car smoother to drive by taking away some initial acceleration. Slipper clutch pads are sandwiched between plates, and the amount of slip can be adjusted by loosening or tightening the spring. You run the slipper clutch looser on slippery tracks than on high grip tracks. The slipper clutch will help stop rear-wheel-drive cars from pulling a wheelie and save the transmission on 4WD vehicles from getting damaged by the shock and Impact when landing from large jumps.
Spur gear – This is the large gear driven by the pinion gear attached to the motor. A smaller spur gear will increase a car’s top speed but at the expense of acceleration. Spur gears are available with different numbers of teeth to allow the gear ratio to be adjusted and different diametrical pitch (DP) depending upon the use and application. The DP of the spur gear has to be the same as that of the pinion
Two-speed – A system of two different ratios fitted to monster trucks and racing cars. The system allows the engine to work on a bigger ratio at first to achieve good acceleration, then at a preset point – normally governed by the rpm of the engine – a centrifugal clutch allows the gear to shift into the lower ratio to provide a high top speed.
Discharge tray – These trays or discharge boards, as they’re often referred to, allow you to discharge any remaining power from your battery pack at the end of a race. Unlike a normal discharger, the tray discharges the cells individually, which offers better conditioning of the cell than discharging the pack as a whole. The tray has one resistor for each cell and the pack clips.
Wind – This is how a motor’s performance is assessed and refers to the number of wires wrapped around each pole of the armature inside the motor. The acceleration, current draw, and rpm are governed by the overall amount of wire used. If two motors use the same wire, a lower wind like a six-tum will have greater RPM than a nine-tum. These motors can also be manufactured in single- double-, triple- or quad-wind formats. A single-wind has one wire on each pole, whereas a quad will have four. See also ‘turns.’
Turns – The number of times the wire is wound around an electric motor’s armature stack. Varying the number of tums of wire on each pole changes the magnetic field strength, so a motor that has a lower number of turns will achieve higher rpm, albeit at the detriment of less torque and higher current draw. Lower performance RC models often come with higher numbers of tums, making them easier to drive and offer longer run times between recharges. Likewise, the fastest drivers use very low-turn motors to achieve the best on-track performance. See also ‘wind.’
Timing ring – This is part of a modified electric motor and a removable item that holds the endbell. The endbell can be rotated along with the ring so that the timing can be adjusted. More timing (called advance) increases the RPM and the current draw, whereas less timing can make the motor smoother. Electric motors always run some degree of advance, indicated on the side of the motor can. You should only reduce the amount of timing within the bounds indicated by the manufacturer.
Sub-C – All 1:10 and 1:12 scale electric kits use sub- C sized cells or batteries, ensuring parity between manufacturers. The size refers to the physical dimensions of the cell rather than its capacity
Skimming – The commutator on a brushed motor wears due to its contact with the brushes. It is returned to perfect condition by being ‘skimmed’ using a special lathe, which removes the burnt copper material.
Schottky diode – A small directional diode that’s soldered across the terminals of an electric motor to reduce the arcing that occurs under braking. It’s one way to suppress the tiny electrical signals generated by an electric motor resulting in a radio glitch.
MMPR – Millimetres per revolution.
Magnets – Most modem-day electric motors feature a pair of magnets inside the motor that creates a magnetic field. This field is opposed by the magnetic field generated by the coils of wire on the armature.
Matching – A process used by battery specialists to cycle individual cells to determine key elements such as overall capacity, voltage, and resistance. By selecting a pack using cells that are as similar as possible, the performance is improved over a pack of random cells.
LiPo – Lithium Polymer is the latest type of RO battery cells and can be used in transmitters and powering cars. They offer several benefits, including high voltage and high capacity, but are extremely fragile to use and require a LIPO-compatible charger.
EMF – This is generated by a motor during braking and is a potential source of interference and accentuated arcing that causes wear to the Commutator.
Endbell – This is the end of the motor that contains all the important elements, such as the brushes, springs, and soldering tags. On more powerful and expensive motors, the endbell can be removed to make changes to the set-up and allow the armature to be removed from the motor can for maintenance.
Electronic speed control – Often referred to as an ESC or simply the speedo’, this invaluable component translates your input from the transmitter into the amount of power put through to the motor. Modem-day speed controls are very complex and technical and offer different profiles to alter the torque curves and adjustable braking levels and programs to suit different tracks and conditions.
Armature – The central part of a motor that rotates inside the can. The armature’s shaft extends at both ends, more notably at the non-endbell end, where there’s a flat part for the pinion to attach to. Coils of wire are wrapped around the armature’s stack to produce a magnetic field that opposes the one created by the two magnets in the can.
Brush wear – The brushes on an electric motor will wear during use, and after a period of time, will require replacing. If conditions are very wet, brush wear is accelerated, and you should protect the motor against water impregnation. Soft brushes wear faster than harder ones, although you can affect the wear rate by the brush spring tension. Different combinations can be used to tune motor performance to the track conditions.
Brushes – Fitted to an electric motor, brushes transmit electrical current from the speed control’s wires through to the commutator. They’re held place by metal guides on one end of the motor and are pushed up against the commutator’s surface by unique springs. A range of different brush compounds can be used to change the motor’s power output and performance.
Brushless – A type of motor that, due to its design, doesn’t require brushes to work. Brushless motors are much more complicated than their brushed counterparts in how they work, but due to their design, they demand less maintenance. There are two types – sensored and sensorless. The former utilizes a sensor lead that connects from the motor to the speed controller and tells the latter the armature’s position inside the motor can. A sensorless system doesn’t need this lead and is less common, especially in competition racing.
Can – The steel tin-can-shaped part of an electric motor into which the magnets are fixed. The armature slots into a bearing in one end of the can and into the motor endbell at the other.
Commutator – This is the copper part of the armature located at one end of an electric motor. The motor’s brushes sit against the commutator to conduct the power around the coils wrapped around the armature.
Channels – This term is used to describe the number of RC control operations. For example, most radio control cars require two channels – one for the steering and a second for controlling the throttle and brakes. More expensive radio equipment can have many more channels to control things, such as switching between the forward and reverse gears on a Nitro RC car.
Decals – A term often used to describe stickers. Some decals can be applied using water to help position them, but most are adhesive-backed for simplicity.
DP or diametrical pitch – This technical phrase relates to the spur gear teeth’ profile. Most classes adopt a standard diametrical pitch. For example, 1:10 electric models generally use 480p while 1:12 use 64dp. The smaller the number, the more open and aggressive the profile, with fewer teeth used over the same distance.
Model memory – A feature in some transmitters allows different settings to be programmed and stored for multiple RC cars.
Mesh – The relationship between two interlinked gears, usually the spur and pinion on an electric car or the main gear and clutch bell on a nitro-powered model. If you set the mesh too tight, it can affect power and make the components operate hot due to the friction. Set the mesh too loose, and you run the risk of damaging the gears. Generally, a perfect mesh will also run a lot quieter than one that’s too tight or too loose, as this can be rather noisy. A neat trick to setting the mesh is to feed a piece of paper between the pinion and spur gear. Press the gears together, and then tighten the screws. Roll the gears, and the paper can be removed, leaving a perfect mesh.
Rotating weight – All the rotating parts on a model car, such as the wheels, driveshafts bearings, differentials, drivetrain, and gears.
Sprung weight – The weight of the chassis and all the parts mounted on it. These are the bits that bounce up and down on the springs of the car, such as the chassis itself, the shock towers, the radio equipment, and the engine.
Underbody – A molded Lexan cover used to protect the radio equipment during wet-weather operation. These are very popular on a 1:10 scale touring cars that compete in both damp and wet conditions since touring car bodies don’t fit/tightly around the chassis. It’s easy for water to penetrate damage expensive electric components such as the speed control.
Unsprung weight – The moving suspension parts of a car that move up and down with the wheels, sit underneath the springs and have to react to all of the lumps and bumps on the track.
Deck – A term used to refer to a chassis level, as in the top deck (upper level) or chassis deck (lower level).
Titanium – A metal with several benefits over steel or something similar in that it’s light and yet strong. Unlike aluminum, titanium has greater strength but is equally as light. For this reason, it’s used on key areas that take a lot of abuse, such as hinge pins, shock shafts, and turnbuckles.
Anodised – Although this process actually hardens the exterior surface of a metal part, most people believe anodizing to be no more than a way of changing its color. Though many different colors are available, many manufacturers stick to just one, to identify their parts from others!
Body posts – These are molded plastic posts that are screwed to the car’s chassis to support the bodyshell—usually, four posts (sometimes five), with one at each comer. As there’s a massive range of bodyshells available, the posts’ height is adjustable, so that body’s position can be raised or lowered.
Carbon fiber – A modern composite material that’s both light and stiff. It’s found on competition models and is used to limit flex and aid set-up.
FET servo – A FET servo offers better performance than a standard unit. These high-torque, high-speed units may require more power from the battery, but they’re easily able to handle the demands of large, heavy wheels.
ABS – Anti-lock braking systems are built into the speed control of electric cars and some of the more elaborate transmitter units of nitro-powered models. To prevent the brakes from locking, the transmitter pulses the servo very quickly under braking, just like some of the systems adopted by full-size car manufacturers.
Anti-roll bar – This is normally a small metal bar mounted from one side of the car’s suspension to the other, with the bar held in the middle to act as a fixing point. An anti-roll bar allows the wheels to retain independent movement, but added pressure is placed upon the bar, which stiffens the wheel’s action on the other side when one wheel goes up. If the wheels go up together, the anti-roll bar does not affect. Fitting an anti-roll bar to the car’s rear can prevent it from pushing wide in the comers.
Shock absorber – Fitted to almost every RC car, a shock absorber is fitted between the wishbone and the chassis to allow it to ride the bumps. Shock absorbers, or ‘shocks, are a tuning tool and can be changed to alter the way a car drives. Whilst most competition-spec kits have one shock per comer, other RC models – such as monster trucks – can have up to ten fitted. See also ‘dampers.’
Piston (shock absorber) – This is the part of the shock absorber that passes through the oil. How soft or heavy the damping action feels depends upon the size of the holes in the piston. You can change pistons to adjust a car’s handling or use different oils.
Undertray – Like an underbody, an undertray is used to protect the chassis and its contents from dirt and water. They’re fitted to many off-road cars that compete on surfaces such as grass and dirt where there’s a lot of spray coming off the tires. An undertray is normally screwed to the chassis and fits the bodyshell tightly.
UJ or universal joint – A driveshaft featuring UJ linkage allows incredible articulation. Although a dogbone driveshaft (named after its shape) is more straightforward in design, it isn’t of such high quality and can’t handle as much movement without risk of falling out in off-road applications. A UJ system also offers better performance due to reduced play in the drivetrain.
Underbody – A molded Lexan cover used to protect the radio equipment during wet-weather operation. These are very popular on a 1:10 scale touring cars that compete in both damp and wet conditions since touring car bodies don’t fit/tightly around the chassis. It’s easy for water to penetrate damage expensive electric components such as the speed control.
Heatsink – A finned aluminum piece connected to motors, nitro engines, or speed controls. The heatsink’s mass of material draws heat away and allows it to run cooler.
Hop-ups – Upgrade parts or aftermarket accessories that improve your RC model’s look or performance.
Lexan – Technically referred to as polycarbonate, Lexan is the plastic material used to make bodyshells. In its pure form, the transparent colorless Lexan is placed over a mold to create its shape. Lexan bodies are painted on the inside so that the paint is protected from scratching and flaking. Many modern-day RTR kits come with ‘pre-painted’ bodies that are actually molded using a pre-colored or multi-colored sheet of Lexan.
Servo horn – A molded plastic or alloy item that fixes to the output gear of the servo and allows the servo to connect to the steering linkage
Servo reverse – System enabling the commands on a transmitter to be reversed without having to adjust the fitting of the servos.
Turnbuckles – Turnbuckles are fitted instead of threaded rods to connect the suspension or steering. One end has a regular thread, while the other has a left-hand thread. This allows for fast adjustments in length if you change the set-up.
Bushing – A simple alternative to a metal bearing, often found on entry-level specification models or in places where it’s impossible to fit a bearing. A bushing is much cheaper to make and is usually constructed from a soft material such as bronze or plastic. Replacing these early on will reduce wear and increase performance and offer better reliability.
Bearing – Often called a ball race, a bearing is made of metal and is fitted in areas such as the hubs and gearboxes where there are rotating parts. Inside the inner and outer races are tiny balls that allow the inner surface to move while the other stays in a fixed position. A bearing is a much better alternative than a bushing. It has less friction, works more smoothly, and reduces wear. Bearings need to be lubricated with suitable oil and prevent wear and heat build-up. If mistreated, a bearing can lock and cause premature component wear and poor handling.
Wing – Fitted to the boot area of a touring car, a rear wing is used to create downforce that helps the car generate grip at high speed. An off-road car uses the same principle to balance the handling and make the car jump better through the air.
Trued and glued – A term used for foam tires supplied already glued to a set of rims and have been trued perfectly round and to a set diameter. This allows them to be fitted and used immediately after purchase. Doing the job yourself takes time, requires specialist tools, and is also quite messy!
Temperature gun – Used by nitro racers to test their engines’ temperature. The reading can help tune the engine to achieve the best performance. A nitro engine has an ideal working temperature window: if it gets too hot when the settings are too lean (not enough fuel), performance can become erratic, and the engine’s life can be reduced. If the settings are too rich (too much fuel), the engine will never reach its full potential and may again be damaged.
Silicon oil – This type of oil is used inside shock absorbers and geared differentials. In a shock, it slows down the return spring effect (on the outside). Otherwise, the suspension would be very bouncy. Altering the oil Viscosity is used to modify the handling over bumps as well as through comers. Using oil also slows down the speed in a geared differential. Lighter oils are better on bumpy tracks and make the car easier to drive, whereas thicker oils work best on flatter, faster tracks.
Double-sided tape – As the name suggests, unlike regular tape that’s only sticky on one side, this padded material is sticky on both sides and is used to secure electrical components in a car. Though used principally in electric-powered cars, it also secures the receiver in nitro models.
CA – Cyanoacrylate is the technical name for the solution we know as superglue. It’s used to hold rubber tires to their rims and for other small jobs, as it’s easy to use and sets quickly
After-run oil – After finishing with their engine for the day, nitro owners put after-run oil into it to prevent corrosion and give its internal parts a protective coating.
Air filter – As its name suggests, an air filter cleans the air before it enters the engine via the carburetor. The filter is soaked in filter oil, which improves its filtering qualities, and should be cleaned and re-oiled at regular intervals to maintain performance. If an air filter isn’t oiled or fitted correctly, it’s possible to wear an engine out in a matter of minutes, as fine dust destroys the internal components.
Comm lathe – A small purpose-built lathe used to skim a thin layer of copper from the electric motor commutator. For an electric motor to operate efficiently, it’s important to ensure good contact between the brushes and the commutator. The best method is to regularly fit new brushes and skim a clean surface on the commutator.
Rich – A situation where a nitro engine is being supplied with too much fuel. The carburetor can be adjusted to allow more or less fuel into the engine. So if it’s running rich, the main or high-speed needle should be adjusted by turning it clockwise to lean it and restrict the flow. Often an engine that’s too rich won’t achieve maximum speed and blow a lot of smoke from the exhaust.
Nitro – A kit that uses an internal combustion (C) engine rather than an electric motor. The term comes from the small quantities of nitro-methane added to the specially blended fuel that’s used. This comes in a range of types. The bigger engines will operate with a greater percentage of nitro in the fuel, the most common proportions being 10 percent for a 12ci size engine through to 30 percent for a 21ci or 30ci engine. Changing nitro fuel types or manufacturers will require the engine to be adjusted accordingly.
Lean – A situation where the carburetor on a nitro engine is supplied with less fuel than it needs. Running an engine a little lean will improve the fuel economy but can cause the engine to get too hot. Continuous lean running will cause premature failure and speed up the engine’s wear rate. When an engine is over lean, it will regularly stop and become erratic in its performance.
Glow plug – A device used to start and keep a nitro engine running. A battery inside the glow plug heats a tiny platinum alloy wire to create enough heat to make the coil glow. This then ignites the fuel/air mixture inside the engine when it’s turned over. Once the engine is up to temperature, the battery can be removed. The heat generated by the compression is sufficient to keep the glow plug hot enough to continue igniting the mixture. A bad glow plug will often cause an engine to run erratically or stop.
Carburetor – The carburetor or ‘carb’ fitted to an engine controls the mixture of the fuel and air that enters the engine. It’s adjusted to ensure that the correct proportions of air and fuel are used to create a flammable mixture that will ignite to produce power when drawn into the engine’s combustion chamber.
Clutch – Just like on a full-size car, the clutch transmits the engine power to the wheel in a nitro-powered RC car. The clutch can often be adjusted or changed to alter the engagement point to suit the track conditions or engine power.
Crankcase – The main aluminum case of a nitro engine, into which all of the components fit. Many crankcases have small cooling fins built into them to ensure that the engine doesn’t get too hot.
Crankshaft – The part of a nitro engine that converts the piston’s reciprocating movement up and down in the cylinder into a rotary motion. The clutch bolts onto the end of the crankshaft
Piston (engine) – In an internal combustion engine, the piston fits tightly inside its liner as this I what creates the compression that makes the heat that allows the fuel/air mixture to ignite. This then drives the piston down and in tum transmits drive through the crankshaft to the car’s transmission.
Pull-start – A recoil system used to quickly turn over a nitro engine and start the combustion process. Modem pull-starts use short cords that are firmly tugged to start the engine. Most entry-level engines come with a pull-start as these are simple and reliable, whereas more expensive kits may include an electric starter or similar feature. Due to the weight incurred with a pull or electric start arrangement, competition engines have neither and utilize a starter box to bump-start the engine using the flywheel.
Internal combustion – A type of engine used in radio control cars, IC, or internal combustion, referring to its method of producing power. Many people refer to a model that features an IC engine as a ‘nitro’ or ‘gas’ kit.
Gurney – Named after the person who came up with the principle, the Gurney, or Gurney flap, Is a vertical section of a wing that increases downforce and creates more drag.
World Champion – Every racer’s ambition is to be the best in the world. World Championship events occur every two years for the major classes and allow only the very best drivers from each country to take part. These qualify through their National Championship and represent their country against up to 139 other racers.
Understeer – When a car doesn’t want to tum into a comer and pushes wide instead – usually because the front tires aren’t generating enough grip, it’s described as understeer. Slowing down is often sufficient to make the car turn-in, but to maintain speed around a comer, the car’s set-up has to be changed by altering the tires, shock absorbers, or weight distribution.
Transponder – Available in two forms, either as a handout or a personal item, a transponder unit is fitted your car before a race and counts your laps as the unit passes over a particular area of the track, called the loop. Each time your car passes over the loop, the computer receives a signal and adjusts your race details. Transponder systems are incredibly accurate and measure the laps within a thousandth of a second.
Transmitter pound – An area set aside for transmitters’ storage when they’re not being used. A pound is part and parcel of large race meetings and eliminates someone’s chances of accidentally turning their radio on when another race is being run. If that radio is on the same frequency as another, there’s a good chance that it will cause interference, and cars could go out of control.
TQ – An acronym for ‘top qualifier,’ meaning the driver who’s at the top of the timesheets at the end of each round of qualifying. The TQ, when qualifying ends, will start the A final from pole position.
Stock motor – Arguably the most popular class of electric racing. A stock motor uses specific components to control its cost and performance, which keeps the playing field very level. It has fixed timing, uses bushes rather than bearings, and comprises a single strand of fixed gauge wire wrapped 27 times around the armature (referred to as a ’27×1′).
Scrutineering – Before or after a race, a car must pass through scrutineering where race officials called scrutineers will check that the vehicle complies with all the rules concerning equipment used, dimensions, and weights.
Rostrum – A raised section of a racetrack where the drivers stand during a race to control their cars. This can vary from track to track, as indoor venues tend to use wooden benches of a stage, whereas outdoor tracks tend to have a dedicated rostrum. Having all of the drivers together ensures that each gets a similar view of the racetrack and minimizes radio interference. Your car is only close to the other drivers’ radio transmitters when it’s too close to your own.
Qualifying – The mechanism used to determine the fastest cars at a race meeting. Different qualification methods are used. FTD qualifying sorts the drivers who completed the most laps in the allotted time. Round-by-round qualifying awards points for the finishing order in each round, drivers then being sorted to their total points. Round-by-round is used when track conditions are expected to change significantly during a race meeting since it may prove impossible to complete more laps when the track’s badly nutted or soaking wet.
Race director – The official charged with running a race meeting. The race director will call the drivers to the rostrum, make sure the laps are counted accurately and ensure that each driver marshals the race following his own.
Racing line – The fastest route around a racetrack but not necessarily the shortest, as it rarely follows the track’s shape. The racing line is a smooth, flowing route that maximizes the circuit’s width. It makes the comers less sharp and ensures that cars can achieve the highest possible comer speeds.
Pole position – When you reach the end of qualifying, you get to race your final, and if you’ve come out as the TQ or top qualifier, you win ‘pole’. When you start from the pole, you’re in the best position, with the other cars all behind you on the staggered grid. The driver in the pole chooses which side of the grid they want to start from and displays a number ‘1’ sticker on their car.
Oversteer – This occurs when a car’s rear loses traction and slides, making the vehicle tum harder than expected. To avoid oversteer, you can either increase the grip at the rear or reduce the grip at the front. In on-road racing, a touring car will oversteer if the rear wing is changed for one with less downforce since there’ll be less effect on the car’s rear.
Mogul – A type of bump on an off-road track, similar to those encountered in skiing. Moguls require skill both when setting the car’s suspension, absorb some of the bump energy, and choose a driving line that minimizes the risk of the car becoming unsettled or crashing.
Loop – The part of an RC racetrack that registers transponder signals as cars pass over it to count the laps and measure lap times.
Lapping – Term used when a car has gained a whole lap over a slower car and overtakes it. When being lapped, it’s good manners to drive wide around a comer and let the faster car by, especially during qualifying.
IFMAR – The International Federation of Model Auto Racing sanctions the major model car classes’ official World Championship events. The venue for the event is usually alternated between EFRA (Europe). FEMCA (the Far East). FAMAR (South America/South Africa) and ROAR (North America).
Hooked up – American slang for a car getting good traction.
FTD – This stands for the ‘fastest time of the day’ and refers to a qualifying system where the driver who completes the most laps in the allotted race time takes pole position for the A final. At the end of qualifying, the drivers are sorted into order, with the fastest at the top, based on their best single performance. The drivers who completed the most laps go into the A final.
EFRA – The European Federation of Radio Automobiles is the European governing body for RC car racing. It sets the rules and the race calendar for the European Championships and Other prestigious events.
Drifting – One of the most recent classes in RC drifting is all about control and style rather than speed around the track. Hailing from the US and Japan, it’s developed from a form of full-size competition growing in popularity worldwide. Marks are awarded to the drivers who demonstrate the smoothest slides, the best control, and the longest drifts through a comer.
A final – The final race of the day, populated by the best drivers at a meeting. These may have set the fastest lap times or have been the most consistent at the meeting during qualifying. The winner of the final is the overall winner of the race meeting, and at large events can take home a trophy or plaque to signify their achievement.
Additive – A special liquid used to soften the surface of both rubber and foam tires to increase the amount of grip they generate.
B and C finals – Drivers who don’t make the final are classified in lower finals. Usually, an A final is made up of the top ten drivers, and in such instances, drivers from 11 to 20 go into the B final, drivers 21 to 30 go into the C final, and so on.
Backmarker – A slow-moving car that the leaders are lapping is referred to as a backmarker. Race officials will always ask the driver of a backmarker to act courteously and move out of the way of faster cars.
Berm – A banked bend that’s usually found on an off-road track. This term is also used in BMX racing.
BRCA – The British Radio Car Association is the official governing body for RC racing in the UK. Joining the BRCA entitles the license holder to insurance coverage and other benefits. A BRCA license is required to compete at sanctioned events in the UK.
Chunking – Foam racing tires’ chunk’ when a lump of the foam is ripped out, often resulting from colliding with another car or a track marker.
Clipping point – The apex of a corner, usually indicated on the track by a colored marker. The racing line through a comer involves aiming for the apex or clipping point.
Starter box – Most competition nitro engines rely on a starter box to turn them over, like a bump start. Whereas lower spec or RTR engines come with a pull-start, race-spec examples eliminate a recoil system’s weight by using a starter box. The car locates on the box, and pushing it down makes a connection that spins a rubber wheel inside and bumps it against the engine’s flywheel. Turning the engine over for just a few seconds is enough for it to fire.
Modified motor – Modified motors come in a range of designs and performance ratings. The facing class allows any modified motor to be used, Whereas other classes are limited to a single specification motor to control performance and costs.
Glitch – A term used to describe the momentary loss of radio contact with the car. There can be various causes, but unreliable electrical connections, a broken receiver aerial, or insufficient electrical motor suppression are common. Sometimes a change of frequency can provide a cure, particularly if the new frequency is spaced further apart from the other race cars. Severe glitches are usually called radio interference.
Crystals – Crystals come as a matching pair; one goes in the transmitter, the other in the receiver. They determine the specific radio frequency the car will operate on. This must not clash with the frequencies assigned to other cars in a race.
Frequency – A transmitter operates on a changeable frequency used to send signals to the receiver. The frequencies allowed for use with model cars are approved by the Government and can differ from country to country. Only specific frequencies on the 27MHz, 40MHz, and 2.4GHz bands are allowed in the UK.
Tweak – Term applied to an on-road chassis that may not handle the same when turning left and right.
Dialed – An American term used to describe a well-balanced car that handles excellently.
Ackermann – Named after its inventor, the ‘Ackermann angle’ is the inside wheel’s relationship compared to the outside when the steering is on full lock. More Ackermann’ is where the inside wheel is at a greater angle (more lock) than the outer one. Ackermann helps make a car turn and is often adjustable by moving part of the steering linkage.
Viscosity – Term used to describe how thick oil is. Shock oils and diff oils come in a range of different viscosities, which can be used to tune the handling. Different oils affect how hard or soft the suspension is to push up and down (static damping). Changing the oil will affect how the car performs through a comer from turn-in to mid-comer and exit. The oil also controls the way the car reacts to bumps.
Weight distribution – Most cars are designed to have 50:50 weight distribution left to right, although this is rarely the case with the front to back balance. If the left-to-right ratio is very different, the car won’t have the same turning performance from one side to the other. For balanced handling, the front-to-rear ratio on both the left-hand and right-hand sides of the car should match the whole car’s front-to-rear weight distribution.
Wheel offset – Offset is measured in millimeters and, depending upon the amount, refers to where the stub axle sits in relation to the center of the wheel’s width. For example, 3mm offset wheels increase the car’s overall width (track) by 6mm. Generally, though, the majority of touring car rims are zero offsets.
Wheelbase – The distance between the center of the front axle and the same point on the rear axle. Most competition cars feature an adjustable wheelbase so that the driver may adjust it to a shorter wheelbase to improve tum-in and acceleration or a longer wheelbase if more stability is needed.
Trim – Parts of the transmitter located in and around the throttle and steering that allows the car to be set up so that it goes in a perfectly straight line and ensure that when the transmitter is left in the neutral position, the throttle isn’t operating in either forward reverse modes
Track – Measured from the very outside of one wheel to the opposite side, track affects the stability and handling of a car. A wider track offers greater stability over a narrower one, whereas if you make the front track narrower, you can increase the amount of steering.
Toe-in/Toe-out – Best looked at when viewed from overhead, a car is described as being toe-in When the forward-most part of the wheel points Inwards. With toe-out, the front of the wheel will point outwards. This is a great tuning tool, as toe-in – either on the front wheels or the rear wheels – increases stability. As you decrease the amount of toe in the car will feel pointier. Whereas toe-in or out is an option on the front wheels, the rear wheels will always have some element of toe-in, as this generates lots of forwarding grip under acceleration.
Steering rate – A transmitter control that enables you to adjust the amount of movement in your steering servo. The usual range of adjustment can be from full down to as little as 20 percent.
Spring rate – refers to the stiffness of a set of springs. A soft set will typically increase the traction at that end of the car. Go too soft and the car may be sluggish to respond when entering comers and will roll and pitch excessively under cornering and braking. If the spring rates have to be changed significantly, the oil or damper pistons may need to be altered.
Shock travel – This term describes how much movement a shock has, which can be changed by altering the number of shock travel limiters the absorber has inside it. This reduces the suspension droop or down travel and speeds up the direction change during cornering. On smooth high-grip surfaces such as carpet, adding limiters to reduce the travel will sharpen the handling. Taking limiters out to increase the amount of shock travel will help on bumpy tracks or where there are big jumps
Servo throw – A servo operates in both directions, and the throw must be set to be the same, left to right. You can use the endpoint adjustment (EPA) on more expensive transmitters to ensure that this is achieved.
Ride height – The ride height is the distance between the lowest part of the chassis and the ground and should be set just high enough to allow the suspension to work effectively. If the ride height is set too low, the shock absorbers won’t be able to soak up the bumps because the chassis will bottom out, whereas too much ride height can result in excessive chassis roll when cornering, which may cause the car to pick up its inside wheels or even flip over. A car should be run as low as possible without adverse effects on handling.
Roll centers – Points at the front and rear of a car about which the chassis rotates. Drawing a line between them gives them the roll axis. The roll centers’ position affects the car’s handling and will be different from kit to kit. Altering the position of the suspension links can change the roll centers.
Pack – The rate at which a shock absorber piston reacts to any quick, sharp movements from the suspension. Fewer or smaller holes in the piston have the effect of slowing down the reaction, and the shock absorber is said to have more pack. This is used as a tuning feature, as it can help reduce the impact when the car lands from jumps or travels through a series of medium to large jumps. Generally, you’d use less pack on a bumpy track and more on one with large jumps that result in heavy landings.
Kick-up – The angle at which the suspension arms are mounted at the front of a car. Kick-up can be adjusted by changing the suspension arm mounts or another part of the chassis. Generally, more kick-up helps on bumpy surfaces, whereas less kick-up gives a more aggressive feeling to the steering.
Inserts – Made of either foam or sponge, an insert is doughnut-shaped and placed inside molded rubber tires to provide a firmer feel and ensure that it retains its shape. The shape, material firmness, and dimensions of the insert can be used to alter a tire’s characteristics.
EPA – End-point adjustment, a transmitter feature that allows you to ensure the servos move to their maximum position without straining, which can cause damage.
Droop – This is the amount of down travel that the suspension offers. You generally run more droop on tracks with large jumps or bumpy surfaces, as this provides greater shock movement to handle such demands.
Downforce – An invisible effect occurs when the air hits the bodyshell or the wing on a car. Increasing the downforce level will offer better control in corners but will slow the car down on the straights due to the increase in drag.
Dampers – Another name for the shock absorbers. Dampers have the task of keeping all four wheels on the ground at all times, giving the tires their best chance to grip. The dampers on a model car can be highly tunable, with different springs, oil weight, pistons, limiters, and mounting points available to change the handling characteristics. Soft dampers make the car less responsive but more forgiving to drive. See also ‘shock absorbers.’
Bottoming out – A chassis is said to ‘bottom out’ when it scrapes the ground, at the front or rear. This can be caused when the ride height is too low. Off-road cars can bottom out regularly off large jumps, which is more acceptable than in on-road racing, in which bottoming out is a sign of a poor suspension set-up and can have a detrimental effect on the handling.
Bump steer – When the toe angle changes as the suspension move up and down, it’s described as ‘bump steer.’ Typically, this only occurs on the front wheels, but it can happen on the rear suspension in some cases. Bump steer isn’t necessarily a bad thing, and it can be used as a tuning aid, although most racers try and set their chassis without it. It can be altered by raising or lowering one end of the pivot point on the steering linkage that connects the hub to the inner steering rack or bell crank.
Anti-squat – This is the angle at which the rear wishbones sit when viewed from the side. As the name suggests, anti-squat prevents the rear suspension from squatting under acceleration and can be used as a tuning aid to improve the car’s performance under acceleration or over bumps. Most cars use between 1° and 3° of anti-squat, although you can run at zero in extreme circumstances.
Camber – When viewed from the front of the car, camber is the angle between vertical and a line passing down through the middle of the wheel parallel to the wheel hub. The camber is said to be negative when the top of the wheel leans towards the car and positive when the top of the wheel leans out. The camber angle will change during cornering due to the chassis’ movement on the suspension. Most radio control touring cars will use a negative camber angle of around 2° on the front wheels to give good tire contact in the corners.
Caster – When viewed from the car’s side, the caster is the angle between vertical and a line drawn through the upper and lower outboard suspension pivot points. The upper pivot is always slightly behind the lower one at the front of the car, creating a self-aligning force that helps to pull the front wheels back into the ‘straight-ahead position when exiting a bend. The caster needs to be set the Same on both sides of the car.
Truggy – The name given to 1:8 scale nitro off-road trucks, derived from the fact that they were converted 1:8 buggies fitted with truck bodyshells.
Stadium truck – 1:10 scale 2WD trucks powered by either a nitro engine or an electric motor. They were made famous in the United States and are very popular over there due to their simplicity and the popularity of trucks in general.
Scale saloon – An older name for a 1:10 scale touring car. Electric powered scale saloons are 190mm wide, whereas 1:10 nitro-powered saloons are 200mm wide. Both aim to look similar to the cars raced in full-size touring car events.
RTR – Ready-to-run.
Rallycross – The term used to describe a nitro-powered 1:8 scale off-road car. Powered by a 3.5cc nitro engine, these 4WD cars can tackle bumpy terrain at high speeds.
Pan car – An American phrase used to describe a rear-wheel-drive on-road car that uses a chassis made from a flat pan’ of graphite, carbon fiber, or fiberglass. These specialized circuit cars are extremely fast but require a very smooth tarmac or carpet surface to race on.
Monster truck – One of the most popular RC categories. Though Monster Trucks can be powered by Nitro engines, the most common examples are powered by either Brushed or Brushless electric motors. The trucks are either 1:10 or 1:8 scale and feature huge wheels and tires, massive ground clearance, and long-travel suspension. That said, there are some micro-scale monster trucks for use indoors that retain the principle of ground clearance and large rubber tires.
Micro RC cars – A tiny scale RC car that ranges from 1:18 to 1:24. Cars of this size can be raced indoors at home and are often sold ready- built and complete with a radio transmitter.
Large-scale – The biggest RC cars, ranging from 1:4 through to 1:6 scale. Large-scale kits are powered by large two-stroke 22cc engines that use regular unleaded fuel mixed with oil due to their huge size. These impressive models also require large areas to race on and possess different characteristics to smaller kits, such as mechanical brakes on the front and rear axles and other innovative features.
Buggy – A popular general term used to describe 1:10 Off-road cars available in either 2WD or 4WD formats. They can race on specialist tracks that incorporate many surfaces, including grass, dirt, Astroturf, concrete, tarmac.