total guide to big air, The

Radio Control Car Action, Aug 2000

What drew you to this hobby? Twenty bucks says it was off-road action in general and jumping in particular. Jti!athe club; everybody likes to get air, and any time an activity allows people to leave the ground and return (relatively) safely, they will try to see how high they can go. Just look at motocross, dirt jumping, snowboarding, in-line skating and other-dare I say it-"extreme" sports: if it can be launched, people ate gonna go big. RC is no different; everybody likes to sky their stuff. And the cool thing is, you'll never get hurt no matter how hard you biff! To satisfy your (and our) need for big-air thrills, we built some trick trucks just for jumping, put together a few tips to help you get off the ground, and cut out of work early to stage a jump fest for the camera: hope you like it.

HPI RS4 MT

From the start we knew we would include an HPI VT in this article, but we couldn't decide which to build-nitro or electric. So we built both! Knowing the kind of big hits the truck would have to take, we thought the black-and-blue theme was appropriate.

MODIFICATIONS

Chassis. Stock plastic all the way here. with the addition of HPI's carbon-fiber upper brace. We set up the chassis for stick packs, since hard-wiring saddles in the field is a huge pain. We also installed a graphite rear shock tower on tap of the stock plastic tower to help avoid breakage in a tail-first landing (and it looks trick).

- Suspension. Like the Nitro MT, the RS4 MT got the boiled-arm treatment. HPI Super Shocks replace the plastic stockers, and a full set of aluminum hubs, hub carriers and rear bulkheads just about guarantees that suspension failure will not sideline this rig. Factory Team* titanium turnbuckles and RPM* ball cups enhance strength and keep the blue motif happening.

- Drive train. We fitted HPI universals front and rear, and Robinson Racing* Absolute gears replace the HPI originals. (There wasn't anything wrong with them, but hey, this is a project truck!) We also added HPI's heat-sink motor plate.

Electronics. A tiny Keyence* A-O1R reversing ESC feeds the juice of a Trinity 1700mAh stick pack to a Trinity Speed Gem Sapphire motor (that's a 17-turn for those of you who aren't Gem savvy).The ESC's 1980s-lookin' Day-Glo wires weren't jibing with the black-and-blue look, so we went for all blue wiring and even dyed the Deans* connector black. An Airtronics* 94537 servo and KO Propo* Mars radio control it all.

- Body, wheels and tires. Yet another truck with Agitator-for-Traxxas rims, but we dyed them blue this time. Team Losi * rubber gets this MT hooked up with step-pins all around, and an HPI Dodge body (minus interior shell) is the finishing touch.

DuraTrax Maximum MT

A lot of these Maximum trucks are running around, and we're sure they're getting jumped and taking some lumps. DuraTrax* has a line of parts to beef up your Max, and they happen to be perfect upgrades for our "Big Air" proJect. But we didn't stop with DuraTrax stuff, of course; check it out.

MODIFICATIONS

Chassis. We made a style upgrade with DuraTrax's optional purple chassis, but the stock wire chassis brace wasn't making it We installed a huge tie-rod brace that we took from an aftermarket Clod Buster chassis kit. You could make a similar brace by using aluminum tube over a threaded rod and a couple of Rocket City* ball ends. We bolted a Kyosho* fuel tank in the center of the chassis just for fun, and a Pro-Line* Chevy Silverado completes the package.

- Suspension. DuraTrax's "No breakage" guarantee on the Ma)es molded parts suggested we could leave the stock pieces in place, but after getting a look at the new optional purple aluminum suspension arms, we decided they were must-haves. The original shocks work great and probably could have handled the abuse we had planned, but we selected a set of long Tons* Big Bore fronts and extra-long rears because they have more travel. We built the shocks with 2-hole pistons and 45Wr oil with Traxxas black springs. We had to add about six 0-rings to the outside of the shaft to prevent the axle from hitting the outdrive when the truck bottoms out. Trinity shock standoffs space the tops of the shocks from the towers.

Drive train. The Danny and drive axles remained largely unchanged, but a Trinity* aluminum brake adapter and slipper plates have been added. DuraTrax's optional steel main gear is also a good idea, but we couldnt get one in time for the launch party, so we settled for the stock plastic unit

Electronics Futaba* gear was selected to control the truck. A Standard 148 servo takes care of the throttle, and a 9304 servo bolted to the chassis with Tinity servo mounts steers the Max A 3PDF radio system and DuraTrax 5-cell receiver battery complete the package.

. Engine. An O.S.* CV topped off with a DuraTrax heat-sink head replaces the stock Torq .12 engine, and the lame airplane-style muffler was tossed away in favor of a Paris* tuned pipe. A Kyosho header made the quick transition around the engine to keep the exhaust system in close to the chassis so the body would fit The pipe and header are held together with a GS Racing* coupler.