Ultimate RC Rock Crawling

Radio Control Car Action, Oct 2003 by Trujillo, Richard

THE TRUCK STOPS HERE

RC truck rock crawling is a growing sport in the U.S. A dedicated group of rock-crawling enthusiasts builds custom trucks to satisfy the need to earn "king of the hill" status, and it has become so popular that members of RC4WD.com and RCMT.net decided to host their first Ultimate RC Rock Crawling event in Southern California. Tamiya USA, Team Orion, Team Lost and RC4WD.com donated prizes for all the winners. Members came from all over Northern and Southern California to participate, and a few dudes even came all the way from Colorado to join in the fun. Let's check out the action.

They even came from colorado!

When I pulled up to the staging area for the rock crawl, I spotted a license plate from Colorado. I couldn't believe that someone actually drove from that far away just for some RC rock-crawling action! Twelve-year-old Ty Goedl made the 1,100-mile trek to California all the way from Ft. Collins, CO, with the help of his 18-year-old brother, Levi. Ty is a 7th grader from Cache La Poudre Junior High and is an avid RC'er. He lives with his family on more than 40 acres of land where he has built an RC rock-crawling course alongside his BMX track, small snowboard park and trampoline. Talk about having your own extreme Disneyland!

It took Ty and Levi about three days to drive to Call. Along the way, they stopped at a couple of skate parks, went swimming and, of course, a mini vacation away from the parents wouldn't be complete without a stop in Vegas.

Although Ty was one of the youngest participants, he had by far the biggest rock-crawling monster truck there. As you can see from the photos, Ty based his crawler on a Thunder Tech Racing Tremor conversion kit that he modified with much longer suspension links. His truck also features a couple of Hitec HiTorque steering servos, a Novak Super Rooster ESC and a 10-cell battery pack. With 40 acres of extreme land and permission to go on a road trip to Cali, it looks as if Ty and Levi have a couple of cool parents.

Rock-crawling truck setup tips

If you think you have to be an engineer to build one of these trucks, you're wrong. Here are a few simple tips that will help you to build your own rock crawler.

LOCK THE DIFFERENTIALS. This is the most important mod if you want to build successful rock crawler. Differentials are usually welcome on a truck, but for rock crawler, they're a detriment. When faced with an obstacle such as a rock, you often approach it at an angle so that your truck goes over it one wheel at a time. When the first wheel starts up the rock, the differential sends power to the opposite wheel which isn't under load. But with a locked diff, the first wheel maintains constant power, so it's able to get over the rock.

INSTALL SOFT, AGGRESSIVE TIRES. Tires with an aggressive tread pattern that can grip any surface are vital for rock-crawling success. Tires such as Pro-Line's Big Joe 40 Series are a good example of what you should look for. If the tires can't support the truck's weight without inserts, use the softest inserts that will do the job. If the tires themselves are rigid, spray them with WD-40 to soften them. If they flaten out, that's OK; they'll have max traction when rock crawling.

INSTALL STOCK MOTORS, AND GEAR FOR TORQUE. Rock crawling isn't a speed event but father a slow, calculated ascent. For unhurried, powerful starts over objects, torque is key; tons of rpm will just flip the truck onto its roof. You should also gear your truck low to achieve the same effect.

LOWER THE CENTER OF GRAVITY (CG). The need for a low CG may seem obvious, but moving every gram as low it can go will really make a difference. When a truck is rock crawling, it faces steep inclines. If most of its weight is high, the truck will roll over too easily.

ARTICULATION IS KEY. Independent-suspension trucks don't provide enough articulation for them to climb over steep rocks. A solid-axle truck with a 4-link suspension is the way to go. You want to set up the suspension as soft as you can to allow maximum axle articulation without unsettling the chassis.

How it works

There was a semiformal classification process and only a few informal rules. In the first class, Clod Busters and TXT-1s ran on a course set up with boulders that were about 2 feet in diameter. The rules were simple: make it through the 30-foot course as quickly as possible. Ten-second penalties were given if a truck touched the marker or if the driver had to touch his truck to get it unstuck or to flip it back onto all fours.

The second class was for Bruisers and Tamiya Cross Country (Pajero) chassis. The course was set up and timed in the same way as the course for the larger trucks was, but to match the much shorter suspension travel of the Cross Country chassis, the rocks were much smaller.

The competition

It's usually sunny in Southern California, but on that weekend, it decided to rain. The weather made the rocks a little slippery, but it didn't slow anyone down. In the Clod Buster/TXT-1 class, the competition was fierce. Some drivers carefully picked their way through the course, while others just bashed through. Hector Carries Jr. of Upland, CA, drove his 4-link, Jeep-body Clod Buster to finish third, and Hector Carries Sr. took second. Brian Jones showed them who was boss; he was crowned the first Ultimate Rock Crawling Champion in the Clod Buster/TXT-1 class.