There you are, kicked back at camp, relaxing, when you hear the sound of a 'wheeling rig coming over a nearby hill. However, the sound coming toward you is not the deep throb of a big V-8, but instead, something else, something weird. It's the subtle whirring of a pair of small electric motors. Then a little 1/10 scale-well, 4WD vehicle crests the hill. You watch as it picks its way down a rocky slope, mimicking the same challenging maneuvers done by real, fullsize trail rigs. What you're seeing is scale 'wheeling and rockcrawling.
Dirt race buggies and monster trucks are nothing new in the world of radio-controlled (RC) vehicles, but in recent years there has been an emergence of these little scale vehicles being used to simulate realistic trail and rock-competition action. Hobbyists take pieces of a stock RC truck kit and combine them with an aftermarket or home-fabricated chassis to build small rigs capable of conquering some pretty incredible slopes and rocky terrain.
A popular kit that is probably the most trail-worthy right out of the box is the Tamiya TXT-1. The kit comes set up with a four-link suspension, straight axles and a trick CNC-machined chassis. A Lexan body tops it off. | 
Nitro- (gas) powered trucks can play too, but they are generally designed more for higher speeds, rather than slow 'wheeling. Nitro trucks can be purchased with independent suspension or with straight axles. Note the Jeep CJ-8 body. | 
Here is an example of a tube-frame crawler based on the popular Tamiya Clod Buster kit. The gearboxes have been locked, geared down and attached to the custom chassis using a four-link setup. One motor on each gearbox provides the motivation. |
Racing buggies and stadium trucks typically are built with independent suspension. But, as in full-scale wheeling, the straight-axle models reign supreme for hard-core terrain. The forced articulation offered by a solid axle works best for climbing and crawling traction. Most of the 4WD kits offering the greatest capabilities and relatively large tires are marketed as monster trucks, but work very well when they're adapted to rough-terrain use.
Among a large selection of kits, there are two common RC models that are often used for building scale wheelers: the Tamiya TXT-1 and Tamiya Clod Buster monster trucks. Both kits use straight axles but differ in their motor/transmission mounting. The TXT-1 uses a transmission and two electric motors that are centrally mounted in the chassis. In this kit, each axle is connected to the transmission via a small driveshaft. This setup offers the more realistic configuration of the two trucks. The Clod Buster uses axles that are actually gearboxes. They consist of the axle portion, transmission gearing and the motor itself, all combined into one unit. This gearbox is then connected to the chassis via some form of linked suspension.
Much like a fullsize rig, a mini 4WD uses many of the same types of construction parts. Driveshafts, axles, rod ends and coilover shocks all add to the realism. | 
Available drivetrain parts include differential spools, tranny gears and stronger driveshafts. RC4WD supplies a wide variety of upgrades to allow you to build a more capable and bulletproof model. | 
There is a wide array of tires available that allows the mini-'wheeler to tackle any and all terrain. Crawler fans have also taken to custom siping and cutting tires for more flex and traction. |
Each of these trucks will allow you to build a 4WD with 6-inch-tall tires that you can run almost anywhere. Suddenly, your yard becomes a scale 'wheeling playground. The TXT-1 is probably the most trail-worthy chassis without resorting to aftermarket parts. The cheaper Clod Buster has the advantage of a lower center of gravity due to the gearbox design, but requires a custom or aftermarket chassis to bring out its real trail performance.
With the wide variety of chassis kits, rod ends, link parts, servo mounts and so on, the design possibilities are endless. Tires are available in aggressive treads, chevrons and even paddles for sand. Wheel choices include plastic and aluminum, and beadlock rims. Motor and gearing options can be set up in a variety of ways, whether you want to cover a lot of ground fast or slowly crawl your way across the landscape. Rear-steering capability can be added to reduce turning radius with locked axles. Tunable coilover oil shocks, of all things, also let you optimize your suspension travel, spring rate and damping.
RCGUY Engineering builds this economically priced aftermarket rockcrawling chassis. Add your Clod Buster axles and some oil-filled shocks and you've got a very competent rolling chassis. Top it off with your favorite Lexan body. | 
RC4WD manufactures aluminum beadlock wheels for many popular models. Bob Stewart, the designer, showed us how miniature beadlocks are used to secure tires to the wheels instead of having to glue them. This makes tire changes much more convenient. | 
Here is a comparison between a Clod Buster and TXT-1 axle. You can see the Clod axle (below) has an integrated transmission and the motor is mounted to the axle assembly. The TXT-1 axle is more realistic with a top-loading driveshaft, but requires a chassis-mounted transmission. |
When buying a 4WD RC kit, you'll typically need some other components and support gear to get it all up and running. A typical electric truck kit will also usually require you to purchase radio gear, a battery, a charger, an electronic speed control and a high-torque steering servo (a second one of these is required to add rear-steering capability).
Once you get your little rig built and start running trails, you'll quickly discover how much fun it is to competently overcome obstacles and learn to tune and tweak your rig just as you do your fullsize one. Already there have been several scale rockcrawling competitions in California, Arizona and Australia, and interest in parts availability is increasing in this arena. Upgrade parts are becoming more available and include aluminum knuckles and wheel hubs, differential spools and other gearing options.
Hard-core play does not come without consequences. If you play hard with your RC wheeler, it will suffer damage. Broken wheels, axles, links-all just like the rig you drive. The big difference is that should you break your little rig, you simply pick it up and carry it back to camp for some miniature repairs. Scale parts are also considerably cheaper as well. So during those lean times when you're saving to repair your trail rig, you can at least 'wheel with your RC rig-even if you have to replace its parts once in a while.