Tamiya TNX 5.2R | News | RC Car Magazine

The 1/8-scale racing truggies may be very popular at the moment, but the market for a four-wheel drive, two-speed, solid center differential monster truck has never gone away. Tamiya’s TNX fits right in with the Traxxas T-Maxxes, Revos and Savages in this monster truck segment, but this time Tamiya has loaded up the biiiig gun! The TNX 5.2R truck sets a new standard at Tamiya for power-to-weight ratio, with a ginormous .32 rotary start engine strapped down to the always fast, always lightweight Tamiya TNX ----- chassis. The result of this crazy combo is speed, power, wheelies and more speed. Sound like fun yet?

Suspension. Like the original TNX, the 5.2R truck features fully independent pivot-ball suspension at all four corners, with a single high-volume plastic threaded body oil shock. You can easily convert the TNX 5.2R to eight shocks, two per wheel, with the included mounting positions. The pivot ball suspension design allows for easy camber and track-width adjustments, as well as bind-free suspension action. Steel turnbuckles are included as well for quick adjustment.

Drivetrain. The 5.2R’s drivetrain has been beefed up, with full time four wheel drive. Metal dogbones transfer the power to all four wheels, while a steel spur gear with slipper clutch translates all of the insanely strong 5.2R’s power to the ground. A full set of metal shielded ball bearings smooths the drivetrain action, while an adjustable two-speed transmission offers excellent low-end acceleration along with fast high-end speeds.

Steering. A single Tamiya TP-S3010 servo with 90 oz./in. of torque steers the big truck easily via a dual bellcrank steering system. Silky smooth pivot ball steering knuckles take care of the rest, with steel steering turnbuckles controlling the front wheels. The TNX 5.2R’s suspension may not be the latest or craziest design you’ve seen, but it does simply work well on a variety of surfaces.

Chassis. Like the original, the 5.2R’s rolling chassis is very light, allowing the TNX truck to be propelled easily by any powerplant you strap in. The blue anodized, 2.5mm thick “duraluminum” chassis plate houses the center transmission, both front and rear bulkheads, center braces and a large capacity 150cc fuel tank with primer button.

RTR Gear. You get a lot inside the 5.2R’s box, including a pre-painted TNX body, 27mhz AM transmitter with built-in fail-safe inside the receiver, pre-glued “oval spike” tires, Tamiya’s electric “Handy Starter” rotary start mechanism (you supply the 7.2v stick pack to power it, however) and of course the 5.2R behemoth .32 engine. A full decal sheet, brief instructions and a large capacity air filter are included as well.

Performance Testing
We ran our TNX 5.2R everywhere, from the sand wash area behind our building to a baseball lot to Sun Valley’s KZ Speedway racetrack. Having seen Tamiya’s factory drivers Jimmy Jacobsen and David Jun whoop up with the TNX in the past, we’re well aware of its racing potential.
From the first break-in tank through the leaning-out process, it’s apparent that the 5.2R engine is a totally new beast. Previous TNX trucks were quick, but not this quick. The 5.2 engine spools quickly, snaps into its powerband, and rockets the TNX away like a potato from a potato gun. Tamiya sets the two-speed transmission just about perfectly at the factory, with a slightly early engagement that keeps engine revs in the meat of the 5.2R’s powerband. After a few quarts of fuel, we leaned the 5.2R engine out fully and had to hang-on to our britches.
Even at roughly nine and a half pounds, the TNX 5.2R truck feels light on its feet thanks to that .32 monstrosity perched in the bed. Acceleration is quick and snappy, making timing sections, jumps and any obstacle in its way only a quick trigger blip from long gone. And unlike the “truggies” some of us are driving, the TNX 5.2R’s solid center spool means full time four wheel drive regardless of the traction. Once tuned in, our TNX 5.2R performs wheelies on a whim, with enough yank to flip the truck backwards if you stay on throttle during its nose-high action. What a change from the original TNX with the small block engine! We bashed our TNX everywhere and did manage to break a front steering knuckle. The wreck was very mild, as was the weather—at the time, it was a frigid 50F (frigid for Southern California, at least!) and the truck’s plastics did seem slightly brittle. Once the weather warmed up, our truck was bulletproof once again.
Handling is respectable, though our TNX feels slightly bouncy with the stock spring/shock oil setup. Although the light shock oil gives the truck forgiving handling when bashing, it’s not ideal for racing or prepared surfaces. Steering is excellent (the included Tamiya steering servo serves up 90+oz/in of torque!), as is braking on dirt surfaces. We simply had a great time running and bashing our TNX 5.2R around, and had even more fun trying to keep the front wheels down during acceleration and radar testing. Lean the 5.2R engine out, and hang on for dear life.

What Did We Like?
Power, power, and more power! The 5.2R engine, which is a .32ci big-block, powers the TNX so effortlessly that it seems unfair. On pavement during acceleration runs, we literally could not keep the front end down—it wanted to wheelie everywhere. This kind of punchy, torque-happy performance will be welcomed by everyone from backyard bashers to point-and-shoot racers who like snappy throttle response. We also like the TNX’s rotary start mechanism, which is both lightweight and easy to use, as well as the Tamiya built-in fail-safe.

What Would We Change?
There isn’t much to gripe about, depending upon what you plan to do with the truck. The vast majority of guys will enjoy driving the TNX in their back yard. For the racers out there, you’ll want to upgrade to racing tires and a better transmitter/radio, though again this is less of a gripe (if Tamiya were to include these items, it would increase the price substantially) and more of a wish-list.

Conclusion
Tamiya’s TNX 5.2R is the TNX that both bashers and racers have been waiting for. It retains the original TNX’s lightweight chassis, but adds a totally new dimension in the form of crazy, stupid power that’s fun and useable. With an average street price of $480, the TNX falls smack in the middle average price range for trucks in this segment, and what you get will blow you away. Although the TNX does not offer some wildly innovative suspension or a bargain basement price tag, the 5.2R does bring Tamiya’s renown high quality and (now) high performance reputation with it. One yank of the throttle, and you’ll be grinning ear to ear. Whether bashing or racing, the TNX 5.2R dishes up extra servings of power, speed, and most of all, fun.o

THE FINAL CALL
Highs: 5.2R engine makes outrageous power, lightweight chassis, rotary start, built-in fail-safe inside receiver.
Lows: No rechargeable receiver pack, general-use tires don’t work well on the track, and the transmitter is a lightweight.
The Final Call: The fastest, quickest TNX ever; we expect to see many of these in “standard” monster-truck racing as well as in bashers’ back yards.

On The Other Hand…
Collin: The new 5.2R TNX was a very good move on Tamiya’s part, as it shows that they realize what is selling, and turned it into an all-in-one package. Which is exactly why the 5.2R comes loaded and ready-to-race right out of the box. The very adjustable pivot ball suspension takes the truck to a new level on the track, and the extremely lightweight design combined with the new power plant allows this thing to boogie! It stands a chance in both backyards as well as tracks all over.

Zero to 100 feet: 3.49 seconds
Zero to top speed: 6.68 seconds
Stalker ATS verified Top Speed: 35.53 mph

SOURCES
• Tamiya America, Inc., 2 Orion, Aliso Viejo, CA 92656-4200 • (949) 362-2240; fax (949) 362-2250
• Byron Originals, Inc., P.O. Box 279, Ida Grove, IA 51445 • (712) 364-3165; fax (712) 364-3901