Review: Injora Rock Tarantula Chassis Conversion Kit for the TRX-4M

Review: Injora Rock Tarantula Chassis Conversion Kit for the TRX-4M

It’s hard to make a good thing even better. The Traxxas TRX-4M is one of my favorite small-scale crawler/trail models, and since buying my first last year, I’ve been in love with the performance and versatility that this 1/18-scale machine wields. Perfectly content with swapping out bodies and applying custom scale bits to these machines, I’ve never felt the need to convert it into anything other than a trail truck or scale rock crawler.

That all changed until Injora’s Rock Tarantula Chassis Conversion Kit arrived on my doorstep as a review item. Before long, I sacrificed a TRX-4M Bronco for donor parts as I launched into this rig revamp.

What’s Included:

The Rock Tarantula Chassis Conversion Kit is a kit after all, so much assembly is required. The kit arrives in a bag with most of the parts needed to complete the conversion. The nylon tube-frame sections, body panels, LED light bar, Y-connectors (for the light bar), and assembly hardware are all packaged in separate bags to avoid a mess of parts spilling onto your workspace.

Also included are instructions, which become helpful when connecting cross-braces and other structural elements of the chassis. It needs to be noted that you will need a TRX-4M to complete the conversion project. Most of the TRX-4 is used for the Rock Tarantula build, except for the chassis rails, cross-members, and battery strap.


Putting the pieces of this rock-crawling chassis together was a painless experience. There were a few screw holes that needed to be bored larger, and I ran into an over-torquing issue with one of the screws, causing the surrounding nylon to split, but other than that, it was smooth sailing. I wish a coarser-threaded screw were used to provide more bite and a better indication of snugness when assembling the frame.

With the tube frame assembled, it’s time to mount it to the chassis plate of the TRX-4M and connect suspension links, shocks, and the driveline. This is where I hit pause on my build after looking at what my donor rig had to offer. While “mostly” stock, the TRX-4M that would be used did have a few upgrades in the form of brass portal covers. I decided to throw a few more goodies at it before wrapping up the project, namely Injora’s 59mm Aluminum-bodied Shocks ($24.98) and their 180 Pro Motor with an Aluminum-bodied Transmission Case and Steel Low-speed Gears ($39.99).

I’m running most of these components in other vehicles and love the performance of the motor and suspension. The low-speed gears were new to me at the time, but I figured they’d be a significant upgrade, thanks in part to the performance of the 180 Pro Motor. Once those remaining parts arrived, it was time to dig in.

Marrying the TRX-4M bits to the Rock Tarantula cage was quite easy. I experienced an alignment issue with one set of mounting screws, but that was the only issue I ran into during this process. Attaching the body panels was the final step I knocked out with ease. Again, some coarse-thread screws would be a great addition to this kit, even for the body panels.


Now the real fun begins. Before attaching the body panels, I took this refreshed machine for a quick spin around my basement and up a treacherous path to the top of “Throw Pillow Mountain.” The TRX-4M was fun before, but this chassis kit seriously levels up the enjoyment. Before long, I was headed outdoors to see how this reconfigured rig would handle my front yard crawler course.

Like a knife through butter, this TRX-4M with the Rock Tarantula Chassis Kit quickly conquered any obstacle in its way. Similar in performance to other 1/10-scale rock buggies, this little rig was almost unstoppable. While there were a few hang-ups, they were few and far between. I got a major thrill from driving this rig and am happy to have performed this conversion.

What’s the Verdict?

Do you love a crawling experience that can challenge your technical driving skills but still want a compact and portable machine? If so, Injora’s Rock Tarantula Chassis Conversion Kit is a perfect fit. Easy to assemble and incredibly capable, I highly recommend this kit for anyone who wants to change the driving experience on their TRX-4M. I’m considering building another with even more upgrades.

Where to Buy Injora’s Rock Tarantula Chassis Conversion Kit