A to Z Index of Radio Control Car terms (updated 1/3/2018)

Just click on the first letter of the item you require.

| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |


ACKERMAN ANGLE - this angle is usually fixed on all but the most expensive race cars. It governs how the front wheels move relative to each other when going around a bend. Try to imagine a car going round a roundabout when viewed from above. The inside of the car is going around a much smaller circle than the outside of the car, hence the inside wheel needs to turn more than the outside wheel. This is what the ackerman angle achieves. For perfect ackerman effect, a line drawn through the kingpin and the centre of the ball joint on the steering arm should intersect the centre of the rear axle

ALLEN KEY - these are made of hexagonal bar, usually bent onto an "L" shape and used to tighten / loosen Allen screws used to hold parts of the car together. Some Allen keys come in the same form as a screwdriver, having a handle and a straight hexagonal blade, others have a "ball" end on them allowing use a an angle to the screw. They come in both metric and imperial sizes and they are not interchangeable. Japanese and European made cars use metric sizes and American made ones use imperial.

ANTI-ROLL BAR - this is a torsion bar that links the suspension on one side of the car to the suspension on the other side. It is used to prevent body roll that can cause the camber angles of the wheels to change giving a loss of grip. This could also be achieved using stiffer suspension springs, but an anti-roll bar still allows the suspension to be soft for bumpy ground but is effectively stiff for roll.

Return to Top of Page


BATTERIES - are the heart of the car, once it goes flat the car stops. Most batteries now LiPo with LiPo which are much lighter and higher capacity than the older NiCd or NiMh batteries. For LiPo batteries the higher the "C" number the better the battery 50 - 60C is good, but the best batteries have a C rating of 90 or more. LiPo batteries must be charged in a special flameproof bag

BEARINGS - These are used instead of the plastic or metal bushes supplied with the basic kits as they have much less resistance and do not wear out anywhere near as quickly. They can be fitted as an upgrade or "hop-up". They do eventually wear out or become rough in operation, often due to dirt getting into them. They can be cleaned out with motor cleaner and re-oiled. Not all bearings are equal, some have metal shields to keep out dirt, some have rubber seals and the best have Teflon seals.

BODYSHELL - These are made of Lexan which is a clear polycarbonate material, and are painted on the inside. It is best to mark out the mounting holes before painting, and to start with the darker colours first when using more than one colour. Certain bodyshells seem to perform better than others on different chassis.

BRCA - British Radio Car Association - the controlling body for radio controlled car racing in the UK

BRUSHES - are used in brushed motors, but the latest motors are brushless and do not have them. Brushless motors need much less maintenance then brushed motors and are more efficient.

BUMP STEER - is where the front wheels turn as the suspension is moved up and down. This is not desirable, as the car tends to move from side to side as the wheels move up and down. It is caused by the steering links not being parallel to the wishbones.

Return to Top of Page


CAMBER - This is the angle the wheels are to the vertical, positive camber is where the tops of the wheels are further apart than the bottom when viewed from the front or rear. Negative camber is what is needed for good handling and grip, and this is where the tops of the wheels are nearer together than the bottoms. It is measured in degrees and somewhere between 1 and 2 degrees negative is a common setting.

CASTOR - this is the angle of the front kingpin when looked at from the side, the kingpin will angle from the rear of the car at the top, to the front of the car at the bottom. Think of bicycle front forks, basically it means that the car steering will tend to centre and run straight. It can be changed on some cars by moving the top wishbone, and on others by fitting different suspension uprights, on more basic cars it is fixed.

CCCV - this stands for Constant Current Constant Voltage and describes how the latest battery chargers charge LiPo batteries. Initially they will charge at a constant current say 6amps until the maximum battery voltage of 8.4 volts is reached, the charger then gradually reduces the charging current so that the maximum voltage is not exceeded, ramping down to a minimum of typically 1 amp, and then cuts off.

CRYSTALS - These plug into the radio and transmitter to ensure that it operates at one chosen frequency so that you only control one car with your transmitter. The crystals come in matched pairs over a range of frequencies. The 2.4Ghz radios do not need crystals.

CHARGER - used to recharge the batteries before a race. Chargers come in many designs, from the simple trickle charger that has to be left on for 12 - 16 hours, to the microprocessor based chargers that can charge at up to about 6 amps, discharge, and cycle batteries. They can be either mains powered or run from a 12 volt car battery. The best chargers can monitor the performance of each of the cells individually, and some can even be connected to computers or printers to record the charge cycle. LiPo batteries need a special charger and ones for NiCad or NiMh are not suitable.

CORALLY CONNECTOR - a trade name for a battery connector. These are like a bullet and a sleeve that fit together tightly, and are gold plated to ensure a good electrical connection. Some of the cheaper connectors found on the basic cars will melt when used with the more powerful motors used for racing. Originally these were 4mm diameter, but with the latest LiPo batteries 5mm ones are now being fitted.

Return to Top of Page


DAMPER - often called a Shock Absorber. These are what the coil spring for the suspension is usually fitted round. The best ones are filled with oil and have aluminium bodies. Cheaper ones can be made with plastic bodies and may rely on friction for the damping effect. A damper works by forcing oil from one side of the piston to the other through small holes in the piston. The oil can be changed for a thicker one (more viscous) and the piston in the damper can be changed for one with more or less holes. Generally the stronger the spring the thicker the oil required in the damper.

DIFFERENTIAL - There are two main types of differentials used in electric powered cars, gear and ball. Generally gear diffs are lighter and require less maintenance. They are generally filled with thick silicon oil and getting the right visosity oil is the secret to making these work efficiently. Ball diffs have a set of balls sandwiched between two sprung loaded plates, and the spring tension can be adjusted, too loose and the diff will slip, too tight and it will not work properly as a differential.

DISCHARGER - the opposite of a battery charger, it is used to partially discharge a battery pack after a race to until it is charged for its next use. The better dischargers measure how much power was left in the battery so that serious racers can decide whether they can run a higher gear ratio in the next race.

DROOP - this is the amount that the suspension can drop when the wheels are off the ground. The optimum droop setting is usually listed in your kit build instructions if it is adjustable. It should be the same from side to side so both front wheels will have the same droop.

Return to Top of Page


ESC - Electronic Speed Control, these are used to control the speed of the motor in the vehicle. They receive a signal from the radio receiver and regulate the output power proportional to the input. They typically have a motor rating such as 13.5 turn minimum, which means they are not suitable for motors with fewer turns as these can draw more current and overheat or burn them out. The more expensive ESC's for brushless motors are often programmable using a hand held unit. The latest ones can have a WiFi link attached and can then be programmed from your mobile phone.

Return to Top of Page


FET - Field Effect Transistor. These are a particular type of power transistor used in electronic speed controllers to switch the current to the motor on and off as required. They have a very low resistance and so let most of the power through to the motor rather than getting hot themselves.

FREQUENCY - this is usually associated with the radio equipment, as each car in a race needs to be on a separate frequency to avoid interference. The latest 2.4GHz radios do not need crystals and automatically find an unused frequency to use.

FTD - Fastest Time of the Day, literally what it says. See also TQ

Return to Top of Page


GEAR RATIOS - This is the ratio of the number of turns of the motor needed to produce one turn of the driving wheels. It is often quoted as a ratio 7.5:1, which means that it is a reduction gearbox, needing seven and a half turns of the motor for each turn of the wheel. Sometimes it is quoted in millimetres per rev (mm/rev) which is the distance the car will move for one turn of the motor. You might have a ratio of 30mm/rev.

GREASE - there are many different types of grease and only the type recommended by the kit manufacterer should be used, the grease recommended for ball differentials is different to that for gears and other applications.

Return to Top of Page


HEAT SINK - these are used on motors and electronic speed controllers to help keep them cool during a race. Motors become less efficient when hot and an additional clip on heat ink can help with cooling. Cheaper speed controllers often have large or clip-on heat sinks as the FET's used are not so efficient and have a higher resistance causing them to get hotter than ESC's with better FET's. Using motor with lower turns than that recommended for the ESC can overheat it even with an additional heat sink and cause it to burn out. Many heat sinks also have small fans on them to increase their cooling capacity

HINGE / HINGE PINS - these are commonly used to join the suspension arms to the chassis. The basic hinge pins are made of steel, but the better ones are made of Titanium which is both stronger and lighter.

HUBS - these are the parts that the wheels attach to, some people include the part of the axle and the suspension upright in what they call a hub.

Return to Top of Page


INTERFERENCE - This is where you get problems with the radio signal to your car, it is usually caused by someone else turning on their transmitter on the same frequency as yours. This can only happen on 27MHz and 40Mhz transmitters as the 2.4GHz radios use frequency hopping techniques and find their own frequency that no one else is using.

Return to Top of Page


JOINT - these are more often called ball joints and are used on the suspension at one or both ends of the suspension arms, and on the steering linkage. They allow movement in more than one plane or axis whereas a hinge pin will only allow movement in one plane.

Return to Top of Page


Return to Top of Page


Return to Top of Page


MOTORS - These are what get your electric powered car moving. The motors come in a variety of designs from the most basic supplied with some kits to the very powerful ones used for top class racing by the team drivers. The two types are known as "brushed" and "brushless" motors. Brushed motors all have a number of turns of a wire wound around each of the three poles of the rotor. This is a relatively thin wire and therefore the current and hence the power is fairly low. These motors are being superceded by brushless motors as these need less maintenance and are more efficient. Brushless motors have three power wires between the ESC and the motor plus a small multicore signal lead. LRCCC limit cars to either a 17.5 turn motor in 1/10th saloon cars or a more powerful motors when racing on carpet.

MOTOR SPRINGS - There are many types of brushed motor springs, they come in different strengths and different angles, often the differences are signified by the colour of the spring. They hold the brush in contact with the commutator so that the power can be passed to it.

Return to Top of Page


Return to Top of Page


OVERSTEER - This is where the rear of the car tends to slide out further than the front on a corner, causing the car to spin in the worst case.

Return to Top of Page


PINION - This is the small gear fitted to the motor. They come in range of sizes, measured in the number of teeth on them from around 15 to 35 teeth. There is more than one pitch of gear, and they are not interchangeable.

Return to Top of Page


Return to Top of Page


RADIO GEAR - This is the term given to the Radio Receiver and Transmitter, which are described separately

RIDE HEIGHT - this refers to the clearance between the bottom of the chassis and the ground, generally for saloon car racing, the lower the better, but for offroad racing much higher ground clearance is required. As a guide it is usually best to have the wishbones parallel to the ground for offroad and to have the driveshafts parallel to the ground for onroad racing where 4 - 6 mm ground clearance is common.

Return to Top of Page


SERVO - This is a device that converts the electrical output of the radio receiver to a mechanical output. Servos use a small motor through a reduction gearbox to give an angular output, they get the power from the 5volt supply in the radio receiver. The specification is given in torque of the output, generally the higher the better, and speed of travel over a measured angle, the quicker the better. Some servos have metal gears, which are much stronger than plastic ones, but much heavier, and the better servos have ball bearings instead of plastic bushes on the output shaft.


SPUR GEAR - is the large gear that the pinion on the motor meshes with to drive the car. Spur gears can be in a variety of sizes to suit the track and conditions, the larger the spur gear the lower the overall gearing.

Return to Top of Page


TEFLON - a trade name for a material that has a very low coefficient of friction ( its very slippery) and is used in bushes and for seals on ball races.

TOE IN/OUT - When viewed from above the wheels can be seen to be nearer together at their front edge than he rear edge, this is toe-in, and is usually found on the rear wheels of most cars, the more slippery the surface the more rear toe-in is required. It can be adjusted by either fitting different hubs machined for different toe-in angles, different inner pivot blocks, or by adjustable linkages. Typical rear toe-in would be 3 degrees. Or the front, toe-out is more normal as it makes the turn-in on corners more positive, 0 - 1 degrees is about a normal range depending on the car and the track surface.

TQ - Top Qualifier, the fastest driver during the qualifying heats, see also FTD.

TRANSMITTER - This is the piece that you hold and translates the movements of the sticks into a radio signal that is transmitted to the receiver in the vehicle. There are specific radio frequencies that you are allowed to use for radio controlled cars, and these are different from those used in America. The 27MHz AM radios are generally the cheaper ones that come bundled with starter kits. These are perfectly good for all classes of driver, but the extra features generally found on the more expensive 40MHz FM radios can help the more experienced driver. The latest 2.4GHz digital radios have such features as memories for several models, timers, servo travel limit adjusters, non-linear outputs to allow for the way you drive and much more.

TRANSMISSION - this is the term given to the gears and / or belts that pass the power from the motor to the wheels. The less rotating mass the better the acceleration will be. Fitting ball races throughout the transmission reduces friction and allows more speed / duration from the same battery.

TRANSPONDER - a small transmitter fitted to the vehicle that triggers the timing equipment. They usually come in sets of 20, numbered 1 - 10 in two different colours, then alternate races use the different sets for timing. A common mistake is to forget to fit the transponder so that the lap timing computer does not count any laps. Fitting the wrong colour transponder upsets the race organiser, but the laps will be counted by the timing system. Racers are encouraged to buy a personal transponder that is fitted permanently in their car rather than the shared club transponders.

TURNBUCKLES - These are the threaded rods used to link parts of the suspension together. They have a left hand thread on one end, and a right hand thread on the other, with a ball joint screwed on each end. Turning the turnbuckle alters the length of the rod without removing it. Turnbuckles are made of steel in basic kits, but can be replaced with titanium which is both stronger and lighter. A tie-rod does not have a different handed threads on each end and has to be taken out to adjust the length whereas a turnbuckle can be adjusted for length in-situ.

TYRES - there is an almost limitless range of tyres in different tread patterns, different sizes and different rubber compounds and different foam inserts. Usually there are just one or two types that work really well for each track condition and most people end up with the same tyres at the end of the day. The hardness of the tyre compound is signified by a colour code, different manufacturers have different colour codes so you need to learn which is which. As an example, Schumacher use white, yellow, green and blue going from soft to hard, while other have pink and silver colours in their range. At Louth, narrow Schumacher Minipin tyres in yellow compound with soft foam inserts are recommended.

Return to Top of Page


UNDERSTEER - This is where the car tends to drift to the outside of the bend and will not turn in tightly. It is the opposite of oversteer. Typical ways to get rid of understeer are to fit softer front springs, remove the front anti-roll bar if fitted, or fit a rear anti-roll bar.

Return to Top of Page


VERNIER CALIPER - is a measuring tool that is most useful for accurately measuring the length of track rods or turnbuckles.

Return to Top of Page


WISHBONE - this is another name for a suspension arm, the piece that links the wheel hub to the chassis. These need to be vey strong to withstand the knocks to the wheels when you hit a track marker, so are usually made out of a tough plastic. They can also be made from graphite reinforced plastic or aluminium.

Return to Top of Page


Return to Top of Page


Return to Top of Page


Return to Top of Page