How to Build an RC Rock Crawler on a Budget

If you’re here wondering how to build an RC rock crawler on a budget, then you’re in the right place!

This is a project that can be as challenging as it is rewarding. It took me a few iterations to arrive at this step-by-step guide, so you can rest assured that you will get a working RC crawler if you follow these instructions to the letter.

Before we begin, you should know that this project requires some tools. Ensure you use the right tools and materials for the chassis for a successful build.

How to Build an RC Crawler in Four Steps

Step 1: Get an appropriate base.

Building a base for an RC crawler is too complicated a process, so we’ll use a pre-made base to build the chassis.

For this part of the build, I recommend either the Axial Wraith or the Axial AX-10 Deadbolt, which are widely available and the best fit for rock crawling and perhaps a bit of trailing. These trucks use the same axles, shocks, and transmissions, so either one will do.

Axial Wraith features a 4-wheel driveshaft with a splined slider and screw shaft that help create a positive lock on the output shaft. It has a four-link suspension, oil-filled shocks with silicone diaphragms and bushings, and 2.2-inch ripsaw wheels. It’s one of the most attractive bases for 1:10 crawlers since it creates a pretty impressive 1:1 scale appearance.

The Axial AX-10 is just as good a choice for a crawler base. Like the Wraith, it has such impressive crawling abilities that it’s dubbed the “go-anywhere” crawler base. Also, like the Wraith, it comes with a splined driveshaft and a 4-link suspension. However, it is slightly cheaper and features an adjustable battery tray.

Keep in mind the RC crawler we’re building is not designed for competitive rock crawling. At best, it provides the agility to crawl on rocks like the best of them while retaining the speed and stability you may need when racing against friends.

All the mechanical parts of the truck are useful in this build. The only component we are constructing from scratch is the chassis.

Step 2: Get the parts and materials needed.

After securing the Axial Wraith or AX-10, your next mission is to gather some simple parts and materials from your local hardware stores.

The parts you’ll need are:

• Two large plastic cutting boards (Derlin) measuring ½ inches thick – These will form lightweight yet durable chassis plates.
• Eight 1-inch long screws and eight 2-inch long screws – The screws hold the chassis plates together firmly.
• Matching hex drivers – You need the right hex drivers to screw together the chassis plates.
• Axial Wraith center transmission – Ideally, it should come with a gear cover with axles and a motor plate. Even though you can buy axles separately, you can also use the axles included on the Traxxas slash after you’ve drilled the bottom out.
• Electronics – The set of electronics needed to run the RC crawler must include brushed or brushless speed control, a motor, a transmitter and receiver set, a servo (as big as you can get), and a battery (can be Lithium polymer or nickel metal hydride).
• Four shocks with long travel – The shocks included in the Axial bases are sufficient for this project. Otherwise, it doesn’t really matter whether you use plastic or aluminum shocks.
• Four bead lock wheels
• Four rock-crawling tires
• Assembly screws – They should come included with the axles and extra parts. If you have to buy them separately, ensure you get compatible screws from your local hardware store. 

Step 3: Gather your tools

The entire build can be completed using very basic tools. The plastic cutting boards (Derlin) are fairly easy to cut and drill, but they become tougher and harder to manipulate once braced and assembled.

The tools you will need for this project are:

• A coping saw – The Irwin Tools ProTouch is my personal favorite for this project. It utilizes a high-speed steel blade that cuts cleanly without leaving jagged edges. However, my favorite bit about it is the highly ergonomic handle, which feels very comfortable no matter how good you are with a saw.
• A cordless drill – Any old cordless drill will do, but if you can’t afford a DeWalt, this Craftsman cordless drill/driver kit is a heck of a bargain. It’s got a keyless chuck, a 2-speed gearbox, and an LED light for improved visibility. I use the drill to put the screws in most of the way since the plastic can be tough. It saves my wrists from endless screwing.
• Sandpaper – I recommend having a sanding block as well, but it’s optional. What you should have is some 60-grit and 150-grit sandpaper to smooth out the chassis after it’s been cut and assembled.
• Drill bits – Here’s a pro tip: get drill bits that are slightly smaller than the diameter of the screw shafts. This leaves just enough room for the threads of the screws to bite into the plastic for a secure hold.
• Hex drivers – Assembling and disassembling the RC crawler will need a few hex drivers of different sizes. For this specific project, you will need three sizes: 1.5mm, 2mm, and 2.5mm. You’ll need the hex drivers to tighten the screws by hand.

Step 4: Designing, cutting, drilling, and assembling the chassis

The final step of construction is the most important one. First, you need to understand what makes a successful rock crawler chassis. I’ve done the research for you and narrowed it down to two things: ground clearance and chassis flexibility.

So, the two attributes your chassis must have are:

• Adequate ground clearance – Rock crawlers need loads of GC to handle their terrain with ease.
• Low center of gravity – Keeping the COG low ensures that the wheels have enough contact and grip.

Cutting the Delrin plastic is not easy by hand. Furthermore, you can’t cut it with just any saw because most high-speed tools will melt the plastic. If you must use anything other than a coping saw, get a slow band or reciprocating saw.

Assembling the chassis requires the correct placement of the batteries and electronics. Mounting the battery lower allows you to use a high-capacity battery, but placing it in front of the transmission case requires a bit of rewiring to get it to move forward and backward normally.

Mount the servo on one side and your battery on the other. If you need a secondary battery, it is possible to mount a 1:16 scale 2200mah 2-cell lipo up front.

Finally, use small screws to mount the electronics bay on the chassis. Delrin is a food-grade plastic, so it doesn’t receive adhesives well. As such, screws are the best way to fasten the electronics bay in place.

Once you’re done assembling all the components, your RC rock crawler is ready for its first test run!