HPI BAJA 5B FLUX

Jul 29, 2013 No Comments by

PHOTOS JOEL NAVARRO

1/5-SCALE 2WD DUNE BUGGY | RTR

A big buggy with even bigger power!


When HPI Racing released its first Baja 5B buggy in 2006, they revolutionized a segment in RC that had never before been pushed to the forefront of both technology and availability. Up until that point, large-scale RC represented a small niche with cars from small-market brands overseas that had little domestic exposure; not only was the Baja a staple on hobby shop shelves and supported by a full stock of replacement parts, but its long and narrow single-seat dune buggy profile was something that the class had never seen before. Despite the Baja's reliable and powerful gasoline engine, it didn't take long for aftermarket companies to tinker with electric-powered conversions, and with Castle Creations already powering many of HPI's brushless-powered Flux line of cars, it seemed only a matter of time before the Baja 5B was converted into the industry's first electric-powered ⅕-scale. In a very Dr. Frankenstein-like way, HPI created a monster — how does 10 horsepower and 60mph sound?


VEHICLE SPECS

  • Item no. 107684

  • Scale: 1/5

  • Price: $1,380

  • Weight, as tested: 23.6 lb. (10705g)

  • CHASSIS

  • Aluminum monocoque

  • SUSPENSION

  • Type: Lower H-arm/upper A-arm

  • Inboard camber link positions (F/R): 1/1

  • Outboard camber-link positions (F/R): 1/1

  • Shock positions, towers (F/R): 1/1

  • Shock positions, arms (F/R): 1/1

  • Shocks: Threaded aluminum coilover shocks

  • DRIVETRAIN

  • Type/ratio: Gear-driven 2WD, 9.77:1

  • Spur gear/pinion: 57/14, Mod 1.5-pitch

  • Slipper clutch: None

  • Differential: Oil-filled bevel gear viscous torque differential

  • Driveshafts: Steel dogbones

  • Bearings: Rubber sealed

  • WHEELS & TIRES

  • Wheels: HPI Super Star, black

  • Tires (F/R): HPI Dirt Buster Rib, M Compound/HPI Dirt Buster

  • Block, S Compound

  • Inserts: Molded

  • ELECTRONICS

  • Transmitter: HPI Racing TF-20 2.4GHz

  • Receiver: HPI Racing RF-20 2.4GHz

  • Speed control: Castle Creations Mamba XL2

  • Motor: Castle Creations 2028–480Kv

  • Steering servo: HPI Racing SFL-11MG

TEST EQUIPMENT

  • Battery: MaxAmps 6500mAh 4S Baja Flux Pair ($400, not included)

TRUCK-DERIVED DRIVETRAIN

Look at those teeth! The Baja Flux's Mod-1 pinion and spur gears equate to 25.4-pitch.

Just like the traditional 1/10-scale buggies that are dwarfed by the Baja's monstrous footprint, this big buggy uses a traditional 3-gear transmission that's borrowed from its gasoline stablemates — even down to its 2.4:1 internal ratio. The alloy case of HPI's oil-tuned Viscous Torque Differential is crammed full of hardened metal gears to supply the appropriate power to each of the Baja Flux's rear tires under loads of duress. With drivetrain abuse a paramount concern when fitting such brutal brushless horsepower, the Baja Flux is fitted with rubber, boot-wrapped ‘Super Heavy Duty’ 9mm driveshafts, along with correspondingly larger drive axles and diff shafts.

CASTLE CREATIONS PROPULSION

That's not a 12-oz. 7-Up stuck down there – the monstrous Neu-Castle 2028 pumps out 480Kv of power, more than enough on two 4S packs.

THE NEU-CASTLE 2028–480KV MOTOR IS NEARLY THE SIZE OF A SODA CAN. IT COMES HARD-WIRED TO CASTLE'S MAMBA XL2 ESC TO HARNESS THE POWER OF UP TO AN 8S OR TWO 4S LIPO PACKS FOR A TOTAL OF 29.6 VOLTS OF POWER

Located deep within the Baja Flux's chassis, the Neu-Castle 2028–480Kv motor is nearly the size of a soda can. It comes hard-wired to Castle's Mamba XL2 ESC to harness the power of up to an 8S or two 4S LiPo packs for a total of 29.6 volts of power, like the pair of MaxAmps 6500mAh packs that I installed. With nearly 10 horse-power available at the flick of a trigger, it's comforting to know that HPI Racing chose the TF-20 2.4 GHz radio with fail safe, and the high-torque SFL-11MG all-metal-geared servo with aluminum servo arm, for the ultimate in directional control. With no fuel tank sticking out of the left side, the Baja Flux is wrapped with a new body and adorned with HPI's Dirt Buster tires on beadlock wheels with softer S-compound rubber in the rear for added grip.

RIGID TUNNEL CHASSIS

A slot in the battery box's lid allows the wires to pass through.

The Flux borrows its aluminum monocoque chassis from the gasoline-burning Bajas, which forms a narrow but sturdy platform onto which the rest of the buggy is built. Converting the car to hold the brushless motor required a remarkably few new metal brackets and an adjustable motor mount, leaving plenty of room for a large battery box that protects up to two 4S LiPo packs with no tools needed — just flip the swiveling locks to free the lid and batteries that lie beneath. The tubed roll cage should look familiar as well, providing both extra protection for the car's innards as well as adding significant scale appeal.


The front suspension uses a pivot ball setup for smooth steering and easy caster adjustments.

HPI Racing's TF-20U transmitter is all business. It does have trim and dual rate knobs, along with servo reversing switches, but its main purpose is to provide glitch-free control for a very fast (and very heavy) buggy. Powered by just 4 AAs, it's a light and comfort able controller with which to command the Baja Flux for long driving sessions.

LONG-TRAVEL SUSPENSION

A rear skidplate protects the buggy when blasting over rocks and desert terrain.

Check out the suspension setup at both the front and rear of the Baja Flux — it looks just like a 1/10-scale racing buggy, just much bigger. With beefy suspension arms swinging on huge 6mm hingepins and shocks that are nearly seven-inches long, there's plenty of travel to soak up whoops and ruts that would swallow a smaller car. With this big buggy comes big adjustment options, including rear camber links, threaded tie-rods, interchangeable rear toe-in spacers in the three-piece rear hubs, and sliding front upper A-arms that use clips to accurately change caster (with changeable bump-steer via spacers on the steering knuckles, naturally). Even the threaded 20mm VVC/HD shocks are externally adjustable, with 3-piece pistons that offer five different valving settings without disassembly.


BEHIND THE WHEEL

I COULD MANIPULATE THE BAJA'S ATTITUDE IN THE AIR WITH A COMBINATION OF THROTTLE, BRAKE, AND STEERING INPUTS TO DO WHATEVER I WANTED IT TO DO

If driving the Baja Flux doesn't get your blood pumping, you should visit a doctor immediately. The Castle Creations brushless system is infinitely more manageable at low speeds than the gasoline engine, which has to wait for the clutch to engage, and even at a low rpm, cogging is all but unnoticeable. Once you squeeze your fist, however, the Baja Flux's once-docile demeanor erupts in a rush of electrons and tire spin that chews up real estate at an alarming rate. The rush continues all the way up freeway speeds if you can manage to keep the car moving in a straight line, which requires a delicate touch and nerves of titanium, and leaves behind a rooster tail of dirt, rocks, and other hard objects with which you do not want to be blasted. There's instant torque avail able at any speed that will light up the tires and rocket the car forward like a top fuel dragster without the roar of the engine; in fact, the howl of the brushless system makes it more terrifying.

When operating the car using the intelligent matter located between one's ears, there's a lot to praise when describing the car's handling traits. Steering is light and direct, with impressive maneuverability given the buggy's length and weight. The stock HPI Dirt Buster tires work remarkably well on a variety of non-asphalt surfaces, offering enough control to navigate tight corners and induce controllable high-speed drifts aided by the buggy's sure-footed stability. The lack of a high-stall clutch makes it easy to wind and weave through corners and climb hills, and the included servo did a fantastic job of guiding the Baja Flux's direction wherever I chose to point it. Despite the car's incredible inertia, I never once felt even the slightest bit out of control of the Baja Flux unless I chose to be.

With such enormous suspension travel, the Baja Flux skipped across the top of large ruts like a full-size desert racer blitzing the whoops of the Baja desert — fitting, right? That same solid suspension came in handy when launching the Baja skyward, and I was amazed at how controllable the chassis was while airborne. Much like a 1/10-scale 2WD buggy, I could manipulate the Baja's attitude in the air with a combination of throttle, brake, and steering inputs to do whatever I wanted it to do — whether it was to land flat on the downside of the landing or throw the most terrifying whips I've ever completed with a radio control vehicle.

+

  • Brutal acceleration

  • Hair-raising top speed

  • Agile and controllable handling

  • Tons of adjustment

  • Top-shelf included equipment

  • Requires lots of running room to realize potential

  • Body and skidplate collects plenty of debris

  • Though tool-free, battery box makes for cumbersome pack changes

Final word

If my backyard was a racetrack the size of Rhode Island, the Baja Flux would forever be my favorite RC car. While I admire the sound, realism, and run time of the gasoline engine, the controllably explosive torque of the Castle Creations system improves the Baja platform's driving experience at all speeds, with the added convenience of Plug-N-Play ease of use that only electric power can provide. The chassis is sorted perfectly for off-road performance, fitted with premium-level equipment, and wrapped into an attractive overall package that begs to get dirty. It may take up more room in your truck when getting to and from your favorite off-road site, but it's totally worth it.

SOURCES

Performance Tests

About the author

Associate Editor Since receiving my first hobby-grade RC car as a holiday present from my father nearly 20 years ago, I've been fortunate enough to meet more people and experience more opportunities through the adventures I've had in the RC industry than I would've ever imagined. I've done it all - from working at a hobby shop, to being a factory sponsored racer, to working for some of the biggest brands in the industry. I've enjoyed each and every one of the dozens of kits I've built, hundreds of events I've attended, and thousands of laps that I've logged at race tracks around the world, and my passion is to share those experiences with other hobbyists so that they may find fulfillment in their own RC careers.
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