How to choose an ESC and Motor for your RC

There are a lot of different types and sizes of RC Vehicles, and there is a big range of different RC products available for your RC Vehicle. Which brings me to the question,
How do you know what ESC or Motor to buy for your RC Vehicle?
Choosing a suitable Electronic Speed Control (ESC), and a suitable motor can be difficult, especially if you're new to the RC - ing world.  So if you are thinking about buying a new ESC or Motor, there are a few things to take into consideration. Lets go over the basics of what you will need to know, and hopefully it helps you choose the correct ESC and / or motor for your RC Vehicle.
Ok, Lets start with the ESC.

Electronic Speed Control (ESC)

Choosing the correct ESC depends on what motor you use to run your RC Vehicle. The ESC and the motor need to be compatible with each other.  If for example you have a brushless RC Vehicle, then you need an ESC for a brushless RC Vehicle not a brushed one.
You should also check if the ESC is for a motor that is sensored or sensorless, or can it handle both types of motors. Checking this information is important.
The last thing you need to check is if the ESC can handle the type of battery voltage and motor specifications. An ESC will generally have a motor limit in kv's  or turns (which you need to follow). If the ESC specs say the motor limit is 8.5T on a 2S Battery, then you must use a motor that has 8.5 turns or more.                        
If the ESC specs show a kv rating instead of a turn rating - then you should choose the motor with a kv value lower than the kv limit stated in the specifications.   
Don't forget it is important to make sure the ESC fits into your RC Vehicle properly. Another thing you should also consider is whether the ESC is waterproof (most are not).
An ESC that costs you more will generally give you better control, a lot more features, adjustability and overall quality and longevity.                                                 
Okay, lets move onto motors. Which one do we buy?


The first thing we should do before we race out and buy a new motor, is to check the actual size and measurements of our RC Vehicles motor space. There are various motor sizes available for different types of RC Vehicles. If you check your RC Vehicle specifications, they will normally specify what size motor your RC Vehicle is designed for.

The most common motor size used in RC Vehicles is often called the 540. 

The 540  motor size is often used in many lighter 1/10 size RC Vehicles, with the larger 550 or 1/8 sized motors used in heavier 1/10 and 1/8 scale RC Vehicles. Larger size RC Vehicles use even larger size motors, and your smaller size RC Vehicle generally uses 370 or 380 size motors.

Not only are there differences in the length and the diameter of the motor, but there are also differences in the motor shaft diameter. The most common shaft size is 1/8" (3,175mm). Many larger motors use a 5mm shaft.

The diameter of the shaft directly influences on the selection of gears available. 

The mounting hole positions in each motor are also dependant on the motor size. It is because of all these factors that, it is very important to check what size motor fits your RC Vehicle.

Another thing to consider is whether it is a brushed or brushless motor. If you are changing from a brushed to a brushless motor, don't forget you will need a brushless ESC.

Motors are available sensored or sensorless. The difference is; sensored motors have sensors inside the motor that register the position of the rotor. Sensored motors are more responsive from low rpm and give a more precise feel. Sensored motors are used more in competition racing than sensorless motors. Sensorless motors are cheaper to buy and are used more in RTR (Ready To Run) RC Vehicles and general hobby use.

An ESC needs to be compatible with your motor, as some ESC's can only power sensorless motors, while some ESC's only work with sensored motors. 

The power of a motor is indicated in "kv" or "turns" and sometimes both.

A motors kv means its RPM per volt of electricity, e.g.: 3000kv. The higher the kv the more power the motor has.

The turn number, e.g.: 8.5T or 13.5T, refers to the number of times the wire in the motor is wrapped around the stator. To make it easier to understand - just remember,

The fewer the turns, the more power the motor produces.

But before I go..

What is the Stator? I hear you ask,

Both the Stator and the Rotor are parts of the electrical motor. The differences between the Rotor and the Stator are that the Rotor is the rotating part of the motor, and the Stator is the stationary part of the motor. We can talk more about this another time.

Now with all these turns and kv's it's easy to get confused....

It is important to remember that different RC Vehicles have different specifications. If your RC Vehicle is large and heavy it will require more torque, meaning that a heavy 1/8 vehicle for example needs a lower kv and a higher torque motor.

With any motor choice, it is important to have the right gearing.

If you are planning to change to a completely different motor from what you have been using, remember to change the gearing at the same time - and do follow the manufactures recommendations.

Keep in mind, when choosing a higher power motor - will also shorten the runtime on one charge and produce more heat.

Make sure you do your homework before purchasing a new ESC or Motor.

Well that's it guys and gals, that's the basic information you need to hopefully guide you in the right direction when purchasing an ESC or Motor for your RC Vehicle. 

We hope you find this information helpful, Happy RC-ing From the Team @ Aussie Hobbies.