RC Car and Truck Component Guide

By: John Sly - April 6th, 2020

I know when I first got into playing with my RC car it was a ton of fun until I broke my first part. Then I had to try to find replacement parts and describe my issues to forums without really knowing the right words for the broken parts. There are also a lot of different components and different applications of the same parts. This guide will hopefully help you out along the way. It has a focus on electric cars, because that's what I know, but I'd like to keep adding to this over time so that it's got everything.

RC Types

There are a lot of RC types, but I think these cover the major categories:

Street / Touring / Drifting: These all vary slightly but have very similar builds. These cars are built to be driven on flat surfaces like pavement, asphalt or sometimes carpet. They are intended to be lower to the ground and are not suited for off-road driving. Tires are typically rubber and are designed for 4WD for drifting.



Buggy / Truggy: These are typically a cross between an on-road and off-road vehicle. They are still typically built with speed in mind, but have a better ground clearance, and larger shocks to handle rougher terrain.

Crawlers: These are built primarily for off-road use. With higher ground clearances and special features like locking differentials, they’re typically seen climbing obstacles that look unclimbable.

Power Sources

On top of the classification of the body, just as important is the power source. Depending on the power source, your internal components will typically revolve around this. Every type of RC car can have any type of power source.

Electric: These run on batteries. Batteries today tend to provide good acceleration and torque. The downside is, the run times are limited and recharging batteries takes a lot longer than draining them.

Nitro: These are built more like the cars you drive on a daily basis. The run on a special fuel that then powers an engine. They have a lot of moving parts that can get hot and require a bit of fine tuning, but make a great sound when you run them.

The Electronics

There is a never ending evolution of RC components, so consider this a living document!

Radio TX

The radio is what makes it “RC”. For most RC Vehicles, this is the gun style radio controller. Typically with a trigger control for the throttle and a wheel on the side for steering. These can come equipped with additional channels, but the basic unit has two channels, one for steering and one for the throttle. TX are the transmitted signals.

Radio RX

This is where your radio signals are received. RX is the Received signals. These will typically draw power from your ESC or in some cases directly from the battery. Each channel will relay a designated signal from your Radio TX. You’ll connect your servo and your ESC into your RX.

The Servo

A servo is a motor that can rotate X degrees. In the case of RC servos, they typically rotate up to 180 degrees. These will control your steering. They receive their signal from the ESC as well as their power. Depending on the type of RC vehicle you have you might want an ESC with more power to keep the wheels turned.

The ESC or Electric Speed Controller

The ESC is what translates the signal from your RX and sends the proper amount of power to your motor. There are two primary types of ESCs, and lots of specialized types beyond that. Brushed and Brushless are to two primary types.

Brushless ESC: These have three wires that connect to the motor and send a pulse and rotates the motor.

Brushed ESC: These have two wires that connect to a DC motor.

Motors

These are typically the power house of your RC vehicle and it was mentioned above, these come in two different flavors, brushed and brushless. I won’t get overly technical because I might get it wrong but...

Brushless: These operate on three poles, hence the three wires that connect to your motor. The drive the motor by sending a magnetic pulse that causes the motor to rotate. If your motor is moving backwards, then you only need to switch two of the wires.

Brushed: These operate on a more basic level and can be fed direct DC power to move, where a brushless motor requires an ESC to move. The downside is these can wear out over time as contact inside the motor must be maintained via the brushes.

Gearbox

This is where the fun starts and you differentiate a hobby grade RC car from a cheap toy. To translate your motor movement to your wheels, you’ll have a gear box. In addition to driving your wheels, it also changes the rotation.

Your motor will have a gear directly attached to it with a certain diameter. This will then connect to another gear that goes to your wheels. Different gear ratios will contribute to different fine tuned speeds. One rotation of the motor will not be the same as one rotation of the wheels.

These can become even more complex as you start to work with two speed gear boxes that can adjust the gearing while in motion.

Differentials

I’m not a car person, so this took some learning when I first needed to deal with these. From the gearbox, you’ll have a drive shaft. This will be a long rod that’ll connect your gearbox to a box in the front and back of your car (if you have 4WD). This will have a large gear with multiple smaller gears in it.

The first thing this does is rotate the spinning force from the drive shaft 90 degrees so it can be sent to the wheels.

Inside of the differential gear will be four smaller gears that allow for slippage. You can see this by holding on wheel in place and spinning the other wheel. The fact the one wheel can be held in place while the other spins is because of the differential. When driving, any time you are turning, the outside wheel will need to rotate faster.

A locking differential will prevent this from happening, forcing the tires to spin at the same rate and not allow for slippage. This useful if you have three tires on the ground and one in the air. Instead of the tire in the air spinning while its counterpart is rooted in place between two rocks, it will force the stuck tire to try to keep spinning and get itself out.

Suspension

Working our way out we come to the suspension. This is what gives your wheels some bounce and keeps the car from shaking apart when you drive it on anything but a perfect flat surface. The two primary types of suspensions are independent and solid axle.

Independent Suspension: This is where each wheel moves freely on its own suspension. Vehciles intended for speed typically have independent suspension. As the car hits a bump or a dip, the individual wheel can adjust for it.

Solid Axle Suspension: This is what you typically see on crawlers. This allows the wheels to move together to conform more to the terrain. This will almost look like your vehicle is twisting. At lower speeds, it gives a higher range of movement and keeps both tires on the ground.

Wheels and Tires

The easiest place to start because all RC Cars and Trucks have wheels. When purchasing a set of tires it’s easy to look for something identical, but if you’re looking to change it up, then try to match your current tire diagram.

Material: Most tires are rubber, but not all of them

Internal Material: a lot of tires have foam inserts, but again, not all of them

Tire Diameter: check the diameter of the rims and the tire, they’ll affect how your vehicle handles.

Width: You don’t want something too wide that when it turns, it hits your vehicle and rubs.

Mount: This is the size of the hex and the mounting hole. If these don’t match your current tire, then it definitely won’t fit your vehicle.

Offset: This is the offset from the width. Some wider tires will have an offset so that you can use larger tires without them running into the side of your vehicle.

This is a living document that I’d love to continue to update. If you have any suggestions, please let us know!