Even the most affordable hobby-grade trucks aren’t what you’d call “cheap,” and that goes double if you want to make the leap to a 4WD machine. And so, we’re pretty intrigued by Arrma’s new Granite 4X4. For less than $250, Arrma lets you hit the dirt with an all-new design that includes all the running gear to get you going, including a 7-cell battery. It’s a good-looking rig, and is well equipped with oil-filled shocks, a full set of ball bearings, and 12-turn brushed power. Let’s see how much bang we get for the 250 bucks.
The shocks’ 12mm bores hold plenty of oil, and shaft protectors are incorporated into the spring perches.
Simplified Oil-Shock Suspension
The Granite features fixed links for the camber and toe as a means of cutting costs, and make for a simpler setup, but the Arrma engineers seem to have done their homework and gotten the geometry spot-on. The composite shocks are large 12mm units, resulting in plush landings and a nice floaty feel over rough terrain. The front shocks feature stiffer front springs to keep the jump takeoffs level and nose landings safe. And unlike every other shock out there, the spring perches are threaded onto the shock shafts, so they can’t pop off. “So how do the springs get on there?” They slide over the tops of the shock bodies, that’s how.
A single-pad slipper clutch prevents drivetrain overloading and protects the plastic ring and pinion gears.
The gasket- and O-ring sealed diffs use planetary gears instead of bevel-gear internals.
Shaft-Driven 4WD
The Granite’s 4WD system features a slipper-clutch-equipped center shaft driving a pair of differentials like virtually every other 4X4 truck, but there are a few unique details. The center shaft telescopes, which allows the motor/transmission module to be removed, and also allows the chassis to flex without bowing the shaft. The differentials contain steel, straight-cut planetary gears for strength, but the ring and pinion gears are plastic instead of metal as most other trucks use. The plastic gears should be fine with the stock power system, but keep an eye on the gears if you upgrade to a brushless power system (or like a tight slipper-clutch setting). Telescoping universal joints reach out to the wheels, which grab 14mm drive hexes to resist stripping (compared to the usual 12mm hexes).
The 12T motor gets an extra wrap of steel around its can to boost torque.
12-Turn Brushed Power
The Granite comes out of the box with a powerful 12-turn brushed 550 motor for awesome torque and speed. The included speed control is the Arrma Mega Waterproof 35A that provides a constant 6V output to the receiver and a 176ºF thermal overload protection to keep it from overheating. There is an easily accessible jumper system on the top of the unit that allow you to switch from NiMH to LiPo as well as enable/disable reverse.
The dBoots Fortress tires are glued up to wheels with beefy 14mm hexes to resist stripping.
The 35-amp speed control is installed as part of an “electronics module” with the servo and receiver.
The chassis’ modular design makes it easy to work on. The motor and transmission, for example, come out as a unit.
Arrma supplies a Tactic TTX300 radio system that looks basic, but it’s surprisingly capable, with dual-rate steering, adjustable endpoints, and a multimode third channel.
Modular Tub Chassis
The Granite’s chassis features a fully modular design, allowing you to remove the electronics and the power systems with relative ease. Even with the components removed, the chassis has very little flex to it, which allows the suspension and tires to do the jobs they are supposed to do. The chassis includes raised debris guards around the front and sides to help keep gunk out. The chassis also features a nearly completely flat bottom, which helps the truck skim over obstacles without getting hung up.
Also Available in Short-Course Flavor
The Arrma Senton 4X4 is spec’d out just like the Granite, just slightly stretched to accommodate standard short-course dimensions. You also get specialty bumpers and nerf bars to help you hang with the competition. The Senton even provides you with all the same RTR running gear and modular chassis design that works so well on the Granite.
Behind the wheel
With the exception of four AAs for the Tactic transmitter, Arrma supplies everything you need to get rolling with the Granite 4X4. That includes a charger, which will keep you waiting three hours for each juice-up but is still an improvement over the eight- to 10-hour charge times of most other wall warts. Still, a fast-charger will likely be the first upgrade for most Granite buyers. Powered up and ready for action, the Granite is geared for torque and takes off with gusto before maxxing out at about 20mph. The slipper clutch is set just tight enough to slip for a moment when launching, which prevent wheelies but protects the plastic ring and pinion gears. Swap the supplied NiMH pack for a 2S LiPo and exchange the 14T pinion for an optional 17T, and Arrma claims 30mph top speeds are possible. I’m sure that with the punchier batteries and the larger optional pinion, the 30mph mark will be a reasonably easy target to hit. No matter what I did with the Granite, the truck remained extremely well planted. I tried what I could to upset the chassis, but the suspension soaked up everything I could throw at it. The truck jumped evenly, landed softly, threw dirt, and kept on rolling. There are no adjustments to caster, camber, or shock location, leaving very little for a tinkerer to change (or a noob to mess up), but the factory settings are fine. The Granite is a big-tire 4WD monster truck; it’s not like there’s some great secret to make them handle for fun-running. The truck had very good traction on asphalt due to the sticky dBoots rubber, and there was plenty of body roll when cornering—no swaybars here! I expected the Granite to roll onto its lid, but before the truck would go over, the rubber would give way with enough slip to keep the shiny side up. The tires also gripped well on grass, dirt, concrete—just about any surface they touched. Monster 4X4s like the Granite encourage hard driving that leads to wrecks, but the Arrma machine bounced and cartwheeled without popping any parts. And it’s frugal with battery power; I got about 25 minutes of run time before I noticed a dip in power. If you go LiPo when it’s time to grow your battery stash and get a 4000 or 5000mAh battery, the Granite should go nearly an hour per charger with more power and punch to boot.
Final Word
The Granite 4X4 appears to be another well-executed Arrma machine. Someone wanting a rugged basher truck to stunt with and beat the snot out of would be very satisfied with the likes of this vehicle. For the price, you can’t beat the ruggedness. It doesn’t have adjustable links, three diffs, brushless power, etc., but what it does have is a fun platform to build from if you choose—or you can just leave it alone and run it until the tires come off. The price and the ease of servicing the internals mixed with the strength of the components make this a strong contender in the RTR basher market.
The post RC Reviews: AARMA GRANITE 4X4 appeared first on RC Car Action.
