The secret’s out, ARRMA‘s new Nero monster truck is here…and RC Car Action drives it first! This wild ride packs a super-sized 1/8 scale footprint, a new 6S-rated power system, and the “Diff Brain” we’ve all been been waiting to see–three locking differentials that you control from the transmitter to activate Blast, Wheelie, Drift, and Climb modes. It’s an impressive machine–read on and see for yourself!

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In the world of RC cars and trucks as well as full-size vehicles, new models are released with far greater frequency than the platforms you’ll find behind the body panels. Examine any new car or truck and chances are you’ll find a familiar chassis, suspension arms, and other components. Not so with ARRMA’s latest—the Nero monster truck is entirely new from bumper to bumper, and not just in terms of every part being new. The entire truck represents new design concepts for ARRMA, including a move to inboard suspension, “Diff Brain” locking differentials, and a wild-looking chassis that backs up its sci-fi styling with serious strength. The all-new design, combined with a potent 6S-rated power system, is aimed at delivering a highly versatile, high-performance driving experience that can literally shift into Drift, Wheelie, Climb, and “Blast” modes as easily as turning a dial. Sounds like fun, right? RC Car Action is the first to drive the all-new Nero, so let’s get to it.

Inside the Diff Brain

The Nero’s signature feature is “Diff Brain,” which allows the front, center, and rear differentials to be locked and unlocked remotely, via the transmitter. The clever design integrates a micro servo into each of the three gearboxes rather than using linkages, and a yoke mounted directly to the servo slides a collar with six locking pins into or out of each diff to lock or unlock the differential. Normally this would require a 5-channel radio (one channel each for steering and throttle, plus three channels for the three diff servos), but the Nero uses a single channel to operate all three diff servos. This is done via the Diff Brain module, which plugs into the receiver’s channel-3 port.

4 Diff Modes

The Nero’s Tactic TTX300 is preset with four differential configurations, each selected by turning the Diff Brain control dial. They are set in this sequence:

Blast Mode: All diffs unlocked

The Blast mode offers the best all-around handling, with a truggy-like driving experience.

Wheelie Mode: Center diff locked

If a car with an open center diff starts to wheelie, the differential diverts power to the front wheels, which brings the front end back down. With the center diff locked, the rear wheels never bleed off power to the front end, so you can lift the front end high.

Drift Mode: Center and rear diffs locked

With the center and rear diffs locked, you can keep the rear wheels spinning full bore without the diffs shunting power disproportionately between the right and left rear wheels or the front and rear end. While the front end steers, the rear end is free to hang out and slide.

Climb Mode: All diffs locked

There’s a reason trail trucks always have locked front and rear diffs (or skip them all together): There’s nothing better for scaling obstacles. It’s the worst for high-speed handling, but when you need to go slow and pick your way through difficult terrain, this is the way to do it.

If you want to save yourself $100, you can also get the Nero without the Diff Brain feature. You’ll still get the Diff-Brain-ready transmitter, and the differentials and gearboxes arrive ready to accept the Diff Brain servos and diff-locking bits. ARRMA will offer the required servos, control unit, and mechanicals for Diff Brain capability separately, and the Nero manual covers installation.

Vertical-Plate Chassis with Sci-Fi Style

If you think an RC vehicle should look just as good with the body off as it does with the body on, you’ll love the Nero. You’ll find a pair of 3mm vertical aluminum plates at its heart, but the cockpit-like roll cage, substantial side pods, and “nose guard” are what gives the Nero its stealth-fighter-meets-Batmobile look. And while stylized, it is functional; all that plastic protects the electronics, and the side pods hold the batteries. Removing the chassis lower cover reveals substantial aluminum motor and transmission mounts that also brace the chassis, and the plastic bulkheads that enclose the front and rear gearboxes and form the chassis’ ends are impressively complex feats of injection molding.

Inboard Laydown-Shock Suspension

Long, stand-up shocks are typical for virtually every independent-suspension RC off-roader, so it’s always a standout feature when any model bucks the trend. The Nero is one of very few to eschew the stand-up standard in favor of laydown shocks mounted in the chassis. Long pushrods reach up from the lower suspension arms and through the upper arms to reach ball bearing-mounted rockers, which transfer suspension movement to the red-anodized aluminum shocks. The dampers are robustly built with nutted pistons, bleeder-equipped caps and 4mm shafts. And even though the shocks are out of harm’s way up in the chassis, ARRMA still specs rubber boots to protect the shafts. Expect long life between rebuilds. At the ends of the suspension arms, you’ll find pivot balls to set camber and rear toe, with aluminum retainers to dial out play. The setup offers lots of smooth travel and is soft overall for maximum bump-eating capability.

All-Metal Drivetrain

Lest there be any doubt as to the Nero’s ability to handle the full 22.2-volt jolt from a 6S LiPo battery setup, ARRMA has spec’d a full-metal shaft-drive system from the motor on out. The steel ring and pinion gears are joined by aluminum and steel telescoping shafts, with the same construction used for the diff-to-wheel power transfer. Simplicity is also part of durability, and the Nero only has one more gear mesh than a typical 1/8-scale layout, which is as simple as it gets. Instead of having the spur gear wrap the center differential, the spur gear shares its shaft with an input gear that then drives the center diff’s ring gear. This achieves an appropriate gear ratio for the Nero’s 3.8-inch tires, and also allows a slipper clutch to be fitted—it’s a heavy-duty three-pad unit.

NEW BLX200 POWER SYSTEM

The Nero gets ARRMA’s most powerful brushless system, which combines a 2000Kv sensorless motor with a 150-amp speed control to deliver a claimed top speed of 60+mph on 6S LiPo. While ARRMA’s previous 6S-rated vehicles used Deans-style plugs, the Nero’s fan-cooled controller gets a pair of more robust XT90 connectors on the ends of its 10-gauge wires. Inside the plug’s plastic jacket, you’ll find 4.5mm gold-plated bullets, all the better to cope with big amps. The motor is ruggedly built too, with a deeply finned, machined-aluminum case, 4-pole rotor, 5mm shaft, and rubber-booted wire exit. The power system doesn’t have a ton of adjustability, but it does have the essentials—which most users probably still won’t mess with. But for the record, you get six brake-strength settings, low-voltage detection on/off, and a reverse lockout option. You’ll need to supply your own batteries. The Nero requires two 2S or 3S packs with XT90 connectors, and ARRMA recommends a minimum capacity of 5000mAh. We tested the truck with a pair of Duratrax DTXC2004 Onyx 3S packs.

PERFORMANCE

Getting the Nero ready for action only requires you to fire in the not-included transmitter batteries and a pair of packs for the car—a couple of Duratrax 3S 5400mAh LiPos, in this case. The battery trays open with a push button, so there are no clips to hassle with, and foam spacers accommodate a variety of pack sizes. Gearing was left stock with the installed 15-tooth pinion, but there’s also a 17-tooth gear in the box for speed-running to more than 60mph. Testing began with all diffs unlocked (Blast mode), and the Nero showed off the incredible power expected of a big monster truck running 22.2 volts worth of LiPo juice. The Nero easily lights up all four tires and “mohawks” the Sand Scorpion rubber as it tears off with roost trailing from all four tires. The suspension is highly active and does a good job of keeping the chassis composed as the tires pump furiously through rough terrain. That soft suspension does contribute to body roll when cornering, but the truck’s wide footprint and the inboard suspension’s low center of gravity make it less roly-poly than you’d expect a monster truck to be. In the air, the Nero is easy to level out thanks to those big gyroscopes (the tires) at each corner and the power system’s instant torque delivery. If you’ve got the skills to perform backflips and front flips, the Nero has the throttle and braking snap you need to do so. As an all-around dirt thrasher, the Nero is a wild ride and a lot of fun, with all the dirt-hurling power you could ever want. In fact, you’ll do most driving at partial throttle because 6S is just a ridiculous amount of speed and power.

Like other 6S monsters we’ve driven, the Nero is easier to drive on 4S, which is also easier on your battery budget. But if you’ve got room for the Nero to stretch its legs on 6S, go for it—and hold on tight. With the Nero’s monster-truck chops confirmed in Blast mode, we turned our attention to the other Diff Brain settings. Clicking to each setting at the transmitter seamlessly shifts the diffs in or out of lock, and you don’t need to stop; just avoid shifting while the drivetrain is under load or at full throttle. Wheelie mode locks the center diff to prevent it from unloading to the front wheels as they lift. The setting works, but to be fair, it’s not like the Nero needs help doing wheelies on 6S since it has the power delivery of a top-fuel funny car. Shifting to Drift mode locks the center and rear diffs, and makes it easy to hang the back end out for extra-long slides. This works better in dirt than on pavement since the Nero isn’t rolling rock-hard drift tires, but if you want to grind the tires into dust with a blacktop sideways session, go for it. The final setting is Climb mode, which locks all three diffs for maximum traction. This mode makes the truck a handful for driving at speed, but that’s not what it’s meant for. Instead, the Climb setting is designed to prevent diff unloading when a wheel is in the air while traversing difficult terrain, or when a wheel has minimum traction in conditions that require all four tires to keep pulling—such as slogging through mud or climbing a steep grade. The Nero’s sensorless power system isn’t ideal for the precise low-speed throttle control that true crawling requires, but it’s far more capable than any open-diff truck will be in those conditions. And if you’re like us, you’ll be more inclined to power-blast your way over obstacles rather than crawl.

THE VERDICT

ARRMA’s onto something with the Nero. We’ve seen locking diffs on trail-oriented vehicles before, but building the functionality into a high-horsepower monster truck (and adding a lockable center diff to the mix) more fully exploits the potential of radio-lockable differentials. Flipping the transmitter’s Diff Brain switch instantly transforms the Nero’s handling, and makes a truck that’s already a good all-rounder into an even more versatile machine. Unsurprisingly, a vehicle as large and feature packed as the Nero doesn’t come cheap, but it also comes without skimps— you’re getting a lot of metal, plastic, technology, and performance here. And a lot of fun.

SPECS

Item no.: ARAD71BB

Price: $800 (with Diff Brain); $700 (minus Diff Brain servos and control unit)

Length: 21.9 in. (555mm)

Width: 17.8 in. (452mm)

Wheelbase: 14.9 in. (378mm)

Drivetrain: 4WD Shaft

Power system: BLX 150-amp speed control with 2000Kv sensorless 4-pole motor

Requires: Two 2S or 3S LiPo batteries with XT90 connector