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Special Project: Bigfoot TRX 4x4x4

Special Project: Bigfoot TRX 4x4x4

When you are constantly building and upgrading your vehicles, it’s inevitable that you end up with a box of spare parts, and if you are like me, you keep them organized in some way, for me it is by brand. That’s how I ended up with a big ’ole box of Traxxas parts. Keeping things organized allows me to quickly dig through the box for what I need. I’m sure there are much better ways to organize parts but this is how I do it and it worked for my Legos as a kid so I figured why not do the same with my RC parts?

While I was digging through my Traxxas box, I noticed that I had what looked like the foundation for a “spare parts” TRX4 build. I instantly had the urge to complete it. Having previously built rigs that featured all the available TRX4 bodies Traxxas offered, I wanted to make something different. I have to say that as a kid the one truck that stands out and ultimately got me hooked on monster trucks was the iconic Bigfoot #1.

OG Monster

If you grew up in the 80s, you’ll know that Bigfoot was the original monster truck. It made its debut at a time way before events such as Monster Jam even existed. And to a little boy growing up during that time, it was (and still is) an amazing sight to behold. Originally created as a way to promote his 4×4 shop, Bob Chandler, continually modified the truck from 1974 through the 80s. The highly modified F-250 Ford pick-up is probably one of the most famous trucks in vehicular history.
In 1981 Chandler drove Bigfoot up and over a couple of junk cars, just for fun, to see if he could do it. Well, needless to say, the truck drove right over the top of the cars, and the rest is history. Branding our monster truck loving minds with the ultimate image of what a monster truck is meant to do, Bigfoot #1 was also the first monster truck to drive over cars for an audience in 1982. That’s how it’s done! Interestingly, Bigfoot #1 has evolved over the decades and has seen 18 different tire and wheel combinations. That’s sounding like what we do to our RC trucks. Speaking of RC trucks, let’s get back to the build.
TRX 4X4X4

I searched around my workshop for a Traxxas Stampede Bigfoot body that I knew I had but was afraid to put on the Stampede knowing it would just get thrashed. Traxxas made the licensed version of the Bigfoot Classic on a Stampede platform, which is a very popular RTR kit for the company. After locating the body, I did a little research and found out that replica Bigfoot wheels were also available from Traxxas. I got them ordered up from traxxas.com and began sorting out how I should get the build going.
As with all custom projects, things rarely go smoothly. I loosely assembled a rolling TRX4 chassis from my parts bin to give myself a foundation to start with. From what I understand, the real-life Bigfoot #1 had four-wheel steering (4WS) incorporated into it back in 1979 and Bigfoot was billed a 4x4x4. I’ll call my creation the TRX4x4x4. So to make things more complicated and difficult for myself, I used two steer axles so I could give it Bigfoot #1’s realistic 4-wheel steering action.

Kit Bashing

Realizing that the wheelbase of the Stampede Bigfoot body is much shorter than that of the TRX4, I realized some serious kit bashing was required to get the job done. I took some measurements and broke out the Dremel and drilled and moved the shock towers and various other parts around to get things closer to fit the body better. The most challenging part of this was that the links were all too long, so with the help of a lathe and die set, I turned down and re-threaded the link so I could get the correct wheelbase.

At this point, the chassis was mocked up but I didn’t have body mounts, a battery tray or any of the electronics installed yet. I decided to test fit the body on the chassis to see what else I may need to modify before sourcing and installing the aforementioned items. Having a pre-painted and pre-drilled body proved challenging to fit, so back into the parts bin I went for some body mounts. I found old Slash body mounts that I could cut up and attach to the chassis. Lots of cutting, grinding and epoxying later, landed me in a good position to get the body mounted. Now I knew what kind of room I was working with for the electronics.
While rummaging through the parts bin, I found an old Slash On Board Audio (OBA) unit and one speaker so I was set on using that as well. The Traxxas OBA set up uses the Slash body to help amplify the sound and with the Bigfoot body mounted, I had just enough room to mount the speaker on the battery tray and have it resonate off the body. The OBA module was attached across the front shock tower for ease of adjustment.
Roadblock

Since I had a steering axle in the rear, I needed to get a servo back there to actuate it so back in the bin I went. I came up with a TRX4 servo mount left over from one of the long arm conversions and a pair of Traxxas E-Revo 2.0 servos that would work great as well as two Traxxas Micro Shift Servos, one for two-speed transmission and the other one was for the front diff. The rear axle already had a locker in it but the front had the linkage to engage and disengage it so I hooked up the linkage, did some more trimming with the Dremel and the physical part of the steering both front and rear was done.
With an assembled chassis with electronics and body mounted, I hit a roadblock with no way to get the rear steering to function. This is when my TRX4x4x4 project went on the dreaded shelf of “never done projects.”
There it sat for almost four months until I stumbled on a forum where someone had 4WS on their Traxxas TRX4. 15 minutes and $32 later, I too had the Bastens QuadSteer 4-Wheel Steering Control Module on the way from bastens.com. I was excited to get things going on the project again. The nice thing about the Bastens QuadSteer module is that you can use a factory Traxxas transmitter’s toggle switch to change and select the kind of steering you want, front, rear, crab or front and rear opposite. On a crawler, this would be very useful but on this Bigfoot it was 100% for realism and the cool factor.

A Traxxas On Board Audio set up from a Slash was installed to give the Bigfoot monstrous sounds.

Realistic engine sounds from the Traxxas OBA speaker resonates off the body to help amplify the sound.

Remnant pieces of Techflex loom does wonders to tame wild wire nests.

Completion

With my version of Bigfoot built and functioning, I was left with a birds nest of wires from the Traxxas BEC, four servos, the OBA set up, the QuadSteer box with Y-connectors and a bunch of adapters that I stuffed into the TRX receiver box. I took the next few days to clean up shorten and loom all the wiring for a much cleaner installation. I used Techflex Flexo PET loom that I’ve kept scraps of from having done multiple 1:1 engine swaps and custom harnesses for racecars that I’ve worked on. The remnant of Techflex loom does wonders to hide wild wire nests.

Crushing Time

With everything tucked away and plugged in, it was time to crush some vehicles. Lacking any alternatives, I took out one of my Traxxas 4TEC 2.0’s to act as the sacrificial crusher car. With the OBA cranked up, Bigfoot TRX4x4x4 was fired up, loud as can be and raring to go. The heavily modified TRX4 based monster truck did its job, cruising over the 4TEC 2.0 as if it were a parking lot speed bump. All four wheels could steer in any number of configurable ways. I couldn’t be more pleased with this project that began life in a parts bin.

Final Thoughts

In summary, this was a really fun build and I’m sure it will get plenty of attention at the park or act as a conversation piece on the shelf. The Traxxas On Board Audio sounds awesome, the licensed Bigfoot body immediately brings me back to my childhood, the bouncy nature of the tires and short wheelbase make it fun to drive over things and the 4 wheel steering is the icing on the cake of this classic style Bigfoot TRX4x4x4. If you want a Traxxas Bigfoot but don’t have a big box of Traxxas parts to dig into, the company’s ready to run Stampede-based Bigfoot No.1 may be right up your alley.

Text by Leigh Guarnieri and RCCA Staff
Images by Leigh Guarnieri

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Updated: May 18, 2021 — 10:55 AM

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