THE FOUNDATION – Starting A Scale Crawler Build Based On A GCM Racing CMAX 2 Chassis

If you could start a scale crawler build from ground up, which chassis would you go with? That’s a question that we pondered for a while and after spending some time in deep meditative thought, we finally figured out a direction to go in. If you’ve ever been at an Ultimate Scale Truck Expo (USTE) event, you’ll know how cool super scale trucks are. To that end, we decided to build our very own “doll house” build by using an ultra realistic foundation from GCM Racing.

When it comes to scale truck chassis, GCM Racing has been pumping them out since 2007. When it comes to satisfaction and function, there’s nothing like the experience that comes from building a GCM chassis. Well, that’s what we found out when tackling our latest crawler build from the popular brand. With designs made for specific truck setups and bodies, it’s no surprise that 2021 showcased another new design from GCM Racing.

CMAX 2 from GCM came from almost half a year of constant design and prototyping, with new suspension geometry and setup, which includes all new axles and body mounting options. With the proven fitment of the long

chassis called CMAX (2016), GCM redesigned the majority of the rails and other components to have the same great long chassis fitment, but with simple bolt-and-go link suspension and refreshed geometry.

The CMAX 2’s ladder frame design is manufactured in Canada with billet 6061-T6 aluminum blanks that are filled between the rails with in-house machined cross members and mounts. The girth of the new CMAX2 chassis design makes a setup tough as Chuck Norris, and simple assembly is as sweet as maple syrup.

When combined with GCM’s all-new Nylon-12 ST2 axles, the CMAX 2 offers competition-level anti-squat geometry in the rear, as well as a weight balance that holds center of gravity as low as possible for trail driving stability. The chassis also boasts all steel drivetrain components that keep it powered with four wheels of off road fun for the long haul.

The transmission comes with the required pinion gear, all hardware, and full ball bearings, as well as a dust sealed case design and super low 53:1 final drive ratio. Ready for epic climbs and side hills? The LRT2 Tcase comes with 11% overdrive already built into the front axle output, so the turns are correct, and drag is limited.

CMAX 2 has all the characteristics of a realistic scale truck, which is precisely why we chose this chassis to embark our build on. It has a completely flat rear frame for box or interior fitment, a super low center section that allows for interior seat mounting, and engine bay-ready motor placement for all our planned under the hood details.

The CMAX 2 kit we are centering our build on is sizes for a Jeep JKU body. We opted to add GCM’s machined all-aluminum bumper set for proper protection and its scale looks. The rear JK Angle Bumper has all the right lines to match our future rig’s daily driver-weekend warrior look and includes a socket for a trailer hitch. Up front, the bumper includes a couple of different threaded winch mount holes, and six LED light sockets for 5mm lights to keep the trails lit up at night.

We populated the chassis with an ultra compact Castle Creations Mamba Micro X2 ESC and sensored brushless motor combination. We also installed a Reefs RC 422HD v2 servo for smooth and powerful steering. Connected up front on the bumper is an RC4WD WARN winch for proper pulling with a realistic look. A Spektrum receiver also sits in the chassis ready and waiting to guide this rig over trails when its completed.

If you’re looking to build your own crawler based on this chassis, you’ll be glad to know that the CMAX 2’s flexible setup options include two wheelbases, 313mm and 323mm, and two steering servo mount positions to match the chosen bodywork. GCM Racing has designed tons of skid plates, side trays, battery, bumper, and body mount files available through the GCM Builder’s Group on patreon.com/gcmracing. This useful website provides direct fit parts that you can 3D print at home.
The customization options from GCM’s CMAX 2 chassis level are astonishing and we found that the quality of the components is second to none. With the chassis mocked up, we’re excited to get this rig ready for a future USTE event. Stay tuned to see our next steps for this scale crawler build.

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Text by Leigh Guarnieri and Chris Robinson
Images by Jerry Tsai