Building a Custom RC Rock Crawler

Building Better With Bender

May. 30, 2006 By Pete Bach

For several years, as Radio Controlled Rock crawling was evolving, there was only one choice in how you created your own rig. That choice was to modify your existing rc truck. There were several platforms to start from like the Clod Buster and TXT-1 but you had to bear through pain staking work and much trial and error. When finished, you had created an average performing rig. As many of us old timers struggled through the modification process in the early days, there were a few guys out there that looked in from the outside and laughed at our drill presses, ban saws and Dremel Tools. They worked in or owned their own machine shops with CNC Machines, Water Jet Tools and other high dollar lathes. They began drawing up sketches of every rc crawling part that they could think of and let their precision machines do the rest. One of these visionaries, Brad Dumont, owner and operator of Bender Customs, in Denver, Colorado, was one of those guys who saw the future of rc rock crawling and tapped into it at the right time.

Bender Customs produces some of the finest custom RC parts around and they specialize in rock crawling. Starting off designing products for the Scale 2.2 Class, Bender Customs made a huge impact on the sport and now owns the market for chassis sales in the small arena. The SW2 chassis is seen at every competition from coast to coast and Brad, or “Bender” as he is known as, recently dominated the 2.2 Class in the Colorado Points Series, with a victory over a six month competitive event, of course, using his own chassis.

Follow along while we build a custom crawler, using the Bender SW2 chassis and some other trick parts that Bender builds himself!

One of the main ingredients in a 2.2 shaft driven truck is the use of TLT-1 axles. Perhaps the simplest way to find the axles is to buy a brand new Tamiya TLT-1 Rock Buster Kit and rob the parts to build the axles for your project. The fun begins here, as you can see that building an axle for a radio controlled crawler is no different than that of a full scale Dana type axle.

The differential carriers contain spider gears that need to be locked. There are no lockers or spools for most rc applications so the hard core guys that want front and rear spooled diffs choose to use JB Weld, cold weld epoxy, to do the job. Pack it up with the JB and let it cure over night. Nothing to it……and you’ll never break one of these babies!

After the JB has cured, short work is made of buttoning up the entire axle assembly, consisting of the carriers, axle shafts, bearings, ring and pinions, stub shafts, steering knuckles and axle housings. One great thing about using a complete TLT-1 kit is that you’ll have all the hardware you need, including nuts, bolts, screws, etc, etc, etc. At this point, you’ll want to install the optional Bender Customs Upper Link Mounts. The link mounts are a must in our opinion! Not only do they mount the upper links, they also allow the steering servo to ride above the diff housing in the front. If you choose to run four wheel steering, you can mount up a rear servo exactly like the front. For this ride, we chose to mount our electronic speed controler on the rear upper link mount and are happy with two wheel steer. This axle is ready for installation and action!

Next in line is to get the Traxxas Stampede transmission built so it can be ready for installation in a later step. The “Pede” tranny is a simple unit with three main gears, one of which also contains differential spider gears. These also must be locked with our trusty JB Weld. Once locked, the three main gears in the tranny, the top gear, diff gear and idler gear all mate up together by shafts riding on silky smooth bearings. Don’t go cheap and use brass bushings!!!!!! Two plastic casings sandwich the gears together and provide decent reduction. A 55 Turn Lathe motor from Integy is a common unit used to power these rigs and provides excellent torque, combined with a low tooth count pinion gear. The motor attaches directly to the transmission as you can see. Set the tranny aside for now.

Taxxas provides many of the parts used on the Bender based rig and the T-Maxx lends its turnbuckles to this 2.2 crawler. The 109mm turnbuckles are actually used as lower suspension links in this project and work well. They are stout units that hold up to big, sharp rocks and huge amounts of torque and twist. The upper links are supplied in the TLT-1 kit if you chose to buy it. You can also cut, drill and tap your own aluminum rod links….but why complicate things? It’s time to link your axles up to that shiny new Bender Customs Chassis. The TLT kit uses nice little link stay mounts that bolt onto the axles and retain the link rod end. On this project, we chose not to use the included rod ends that were in the kit in favor of the more durable Traxxas rod ends. Screw on the rod ends and bolt the links up to the axles, followed by the other ends to the chassis. The Bender Customs chassis is completely predrilled for the correct suspension geometry and mounting points.

Shock choice is easy. Again, Traxxas was called upon for parts and Maxx XXL shocks are used in a Bender build. They provide just the right ride height and the correct suspension travel needed for flexing over big rocks. Another great part about the Bender chassis is the adjustability. There are multiple upper shock mounting locations, allowing endless suspension tuning. Mount them to your liking and you’ve got a rolling rig!

The Bender Customs SW2 chassis needs two cross braces at the top. Many choose to use the braces from the TLT kit, which also double as a mounting point for the shocks since they are already tapped. We used these braces but before mounting them in between the chassis plates, we decided it was time to slap the tranny into place. The transmission basically falls right into place, laying flat on the Delrin skid plate. Two large, included button head screws, secure the tranny in place. Now, put your cross braces in, and you’re almost finished!

Time to get power from the tranny, down to those axles! Once again, Traxxas steps up with their Stampede drive shafts and yokes. We recommend that the Traxxas steel output yokes are used rather than the plastics stockers. They are pricey but well worth it! One note: You will need to grind off a small flange on two of the yokes for fitment on the pinion shaft. Loc-Tite these moving parts and you won’t have to worry about them wiggling loose for a long time.

For this project, we wanted pure, competition winning performance so we used Proline Tires. The M2 rubber compound found in Proline tires are unbeatable on the rocks and the 2.2 Moabs fit the bill here. There are many choices of 2.2 wheels on the market and four chromed HPI wheels made their way onto this truck.

This crawler is ready to rock!!! Electronics are the last part of the installation and it is up to the builder on what he or she runs. There is plenty of mounting room for a receiver, ESC and servo(s). Bender Customs suggests that you run your 7.2 battery pack laying on top of your front servo. This is achieved by a small piece of Velcro to locate the pack, along with a loose fitting zip tie for security.

Why mount it there, you ask? Weight placement has a HUGE impact on the way a 2.2 rig performs on the rocks and with a heavy battery pack being mounted low and towards the front of the vehicle, it allows the rig to crawl up rock faces that you’d have to see to believe.

If the simplicity of building a 2.2 rock crawler wasn’t enough, Bender Customs was also innovative enough to make the SW2 chassis platform with the versatility to build a Super Crawler, Clod based rig or a 14 inch wheel based shaft driven, TXT-1 axled truck!!! There is nothing you can’t build off of this chassis!

Everyone should see one of these little rigs crawl…..and that’s just it…you will only see it. The 2.2 Bender Customs crawler is so quiet, you can barely hear it run, even if you’re standing right next to it. And…any one familiar with electric powered radio controlled vehicles knows that run time diminishes quickly. Not with these trucks! They are extremely efficient. You can expect, on average, one hour or more of run time, using a 7.2 Volt, 3000mah battery pack!!! Can you say hours of fun?!?!

You can see how easy it is now to build your own crawler and why there have been thousands of SW2 chassis sold. This particular crawler was built for Hobby Town USA, owners, Todd and Bernadette Noble. The red, white and blue, Proline Racing, Rock Pleaser body tops off and completes this Bender Customs 2.2 Rock Crawler. Building with Bender is Beautiful!!!! Newsletter
Join our Weekly Newsletter to get the latest off-road news, reviews, events, and alerts!