That’s cool . . . and different! That’s been the general reaction to the new Vaterra Twin Hammers. And, while Horizon Hobby announced the entire Vatarra brand all at once with multiple vehicles, both on- and off-road, most would agree that the Twin Hammers stole the show. This off-roader is modeled after an Ultra4 “race car” that would compete in the already legendary King of the Hammers off-road race. What’s cool about Ultra4 is that it’s still very much grassroots racing in many respects and a single best setup has yet to be defined. The lineup is likely to include a few machines with innovative fully independent suspensions and numerous more traditional rigs with solid axles front and rear and, a growing number that mix the new with the tried and true. The latter use independent front suspension and solid rear axles. This combination makes sense since the King of the Hammers race blends fast-paced desert racing with metal-bending rock crawling. That’s the exact sort of adventure the Vaterra Twin Hammers was made to handle. Check it out and discovery if this rig is right for you.
DID YOU KNOW?
King of the Hammers, known as KOH, started seven years ago in 2007 with only 13 particpants. The race takes place at Johnson Valley OHV (Off-Highway Vehicle) area in California. The area is managed by the U.S. Department of the Interior, Bureau of Land Management. There are many named trails in Johnson Valley, but the more famous ones are Sledgehammer, Jackhammer and Claw Hammer.
> Full assembled and RTR
> Remotely operated 2-speed transmission
> Solid rear axle with locked differential
> Independent front suspension with inboard shocks
> Aluminum shocks
> Included 2.4GHz radio system
> Brushed 540 motor
> 2000 mAh 2S LiPo battery with charger
> Waterproof electronics
> 1.9 Race Claws tires
The chassis of the Twin Hammers is a simple design that consists of a shallow, smooth molded composite plastic main tub–made to glide over rocks–and a molded plastic cage. The cage is an integral part and not just a cosmetic bolt on. The overall material and build quality is excellent. The rear of the tub raises up to accommodate the rear 4-link suspension. To help increase ground clearance, the sides of the chassis are angled up a few degrees.
The battery tray sits behind the rear shocks and is protected and a bit hidden by the rear cage. The tray is designed to accommodate the included 2000 mAh LiPo battery and larger packs such as Dynamite’s 4000 mAh. Behind the battery tray is the hard-to-miss functional spare tire.
DID YOU KNOW?
Horizon Hobby’s Brent Redlin was the main designer of the Twin Hammers. He received help from Senior Project Manager Richard Trujillo who has been sneaking off into the desert to play with scale crawlers before the segment was invented. Brent has also designed the Losi Comp Crawler, Losi Night Crawler, Losi 5IVE-T and Losi Mini-Sprint.
It’s hard to miss and impossible to argue against the fact that the Twin Hammers has an impressive suspension design. And while it certainly looks impressive, as soon as you start flexing the suspension, you’ll quickly realize that Vaterra is onto something. The rear suspension is a 4-link design and the front is independent–not your typical rock crawler setup.
The underside of the lower front arms is smooth, which, like the chassis, helps the Twin Hammers slide over obstacles. A close look at the front arms and hubs reveals that the suspension arms are mounted higher than usual on the outer hubs in an effort to increase ground clearance–pretty clever! The upper camber links are adjustable, as are the push rods that connect the arms to the cantilevers for the inboard shocks. Vaterra reported to RC Truck Stop that the shocks are the same units found on the Losi Night Crawler. The shocks feature aluminum bodies, 2-piece plastic/aluminum caps, bottom-loading cartridges and are exceptionally smooth. Pre-load is adjusted with clamping collars.
The rear suspension is silky smooth (even more so than the front), but it’s a more traditional design compared to the front. The plastic lower links of the 4-link design are trailing arm or beam style and similar to what you’d see on a desert truck. The lower arms feature substantial triangulation which prevents unwanted side-to-side axle movement. The upper links are fixed length and also plastic. The pivot balls in all of the links, however, are chromed metal. The inner mounts for the upper links are moveable and feature two mounting positions. The shock towers are tall, removable and anchor into the chassis tub and cage. The two upper shock mounting locations are offered. Optional sway bars are offered for the front and rear.
DID YOU KNOW?
Seven out of ten of the 2013 King of the Hammers top qualifiers used race cars with independent front suspensions and solid rear axles–just like Vaterra’s Twin Hammers.
I could talk about universal front axles, sealed bearings, sealed front gear differential, the straight rear axle, but the shining star of the Twin Hammers’ drivetrain has got to be its 2-speed transmission. High or low gear selection is done remotely via the transmitter. This, even more so than the suspension, is what enables the Twin Hammers to be both high speed desert racer and go-slow crawler. A mini servo actuates the 2-speed. The stock spur is 78-tooth and the pinion a 28-tooth, and the gearing is 48-pitch. Gearing can be changed with TLR (Team Losi Racing) spur gears. Internal low gear ratio 4.05:1 and the high gear ratio is 2.27:1. The final drive ratio in low gear ratio is 32.26:1 and 18.09:1 in high gear. Richard Trujillo, Senior Project Manager at Horizon Hobby, explained that those ratios are final drive ratios as they include the ring and pinion ratio. It’s also worth noting that the center transmission features an aluminum motor mount and dual disk adjustable slipper.
As was previously mentioned, the front axles are universal axles which are more durable and perform better than dog bone axles. Universals are a nice and often unexpected feature on a ready-to-run. The driveshafts features captured universal ends that are extremely unlikely to pop apart.
The solid rear axle comes locked, but the front differential comes coated with thick grease. The front differential is sealed so silicone fluid can be added. Richard states that 500,000wt silicone seems to be the favorite choice for fluid thus far. Vatarra also offers an optional locker piece (item no. VTR332000) if you believe you’re going to spend most of your time on the rocks.
The wheels connect via plastic “standard” 12mm hexes.
The Twin Hammers comes equipped with a Spektrum DX3E 3-channel 2.4GHz radio system that offers the needed adjustability for proper 3-channel operation without having to go with a “computerized” and more expensive model. There is no digital readout, and features such as end points, steering rate and the trims are adjusted via small dials. The DX3E is matched with a waterproof receiver, and like other Spektrum transmistters, only four AA batteries are needed for power.
A Dynamite LiPo Tazer 12-turn Waterproof Speed Control handles power duties and offers three modes–Forward/Reverse with Smart Brake (default setting), Forward Only with Brake and Crawler Mode. As the name indicates, the speed control is waterproof like the receiver. It also features over-voltage, thermal and stall protection. The built-in BEC delivers 5.6 volts and 1 amp max. The previously mentioned Smart Brake prevents instantaneous changes of direction which would likely take a toll on the drivetrain. The Crawler Mode is just the opposite. The speed control connects to a Dynamite 15-turn brushed motor.
DID YOU KNOW?
RC’ers can’t leave well enough alone. Okay, you probably knew that. Not wanting to leave well enough alone ourselves, we wondered what brushless setups would be best for the Twin Hammers, so we went to those in the know. Kevin Wilson, Vaterra Brand Manager, said a popular setup has been 3100 Kv brushless motors matched 3S. He states that he personally uses a 2800 Kv setup with 3S and adds that because of the Twin Hammer’s low ratio, it’s tough to get really high speeds. According to Kevin, with a 3100 Kv setup and 3S you’ll see about 22 mph–pretty quick for a rig like this.
Rounding out the waterproof electronics gear is a 625WP Metal Gear Servo WP. In addition to being able to survive a dunking, the servo features a partial metal case. An addition servo operates the 2-speed.
Vaterra makes the Twin Hammers truly ready to run and includes a Dynamite 2-cell 2000mAh LiPo and a LiPo charger. The charger is a basic, no-frills unit that can charge up to 3S LiPo packs, albeit at a slow rate.
Tires, Wheels & Body
The 1.9″ Race Claws tires are molded in the Blue or “B” compound which is the same soft and sticky rubber used for the popular Losi 2.2 Rock Claws tires. Since the Twin Hammers is built for multipurpose use–it has to go fast and crawl–Vaterra matched the tires with traditional foams.The molded plastic wheels are true bead locks with aluminum rings. The spare included is a fully functional spare.
The Twin Hammers has a pre-painted, multi-piece body that attaches to the roll cage with 2mm screws. As I’m sure you see for yourself, the hood and roof panels have molded in light buckets. Overall, the body isn’t too flashy which will appeal to some and leave others wanting more.
DID YOU KNOW?
Brian Miller, Vaterra Category Manager, came up with the Vaterra moniker. VA meaning “go” Terra meaning earth. The brand is focused on adventure and intertwining full-size motor sports with scale RC. The brand’s tagline is “Adventure Driven” is described as a shared passion for motor sports and RC.
When we test, we test. The RC Truck Stop review sample has seen a lot of miles. I’ve taken it on rocks, sand, scale comp trail setups and backyard bashed the daylights out of the thing. It’s a capable crawler in many scenarios and the tires are noticeably, well, great, but there is torque twist. That plush suspension twists when trying to climb up many ledges. When the rear tires start to get bound up, the power starts to follow the path of least resistance and rear suspension starts to squat to one side. With so much suspension travel, the torque twist is significant. Vaterra’s optional sway bars should go a long way towards improving the Twin Hammers’ crawling capabilities. When I first started driving the Twin Hammers, the front differential seemed pretty firm, but during the first run, the grease stopped doing the trick and the front became a completely open diff. I foresee some silicone fluid in the Twin Hammers’ future.
RC Madness in Enfield, CT has a long sand drag strip. On terrain such as sand and loose dirt, the Twin Hammers does great. Again, the tires shine bright as they provide plenty of grip and being able to switch into high gear makes the off-roader pretty versatile. It certainly isn’t a one-trick pony. Usually sand is just about the worse thing you can subject a vehicle to, but the sand hasn’t caused any accelerated wear, and the high gear helped the Twin Hammers scoot along at a respectable speed.
Fairly early on, I noticed an intermittent hesitation when going from reverse back to forward. Eventually this became more frequent and the lack of throttle response presented itself whether I was going from forward to reverse or vice versa. Then the hesitation got even worse and the Twin Hammers would lose all throttle and needed to be turned off and back on to resume functioning. I presumed the speed control’s Smart Brake feature was malfunctioning, but took a chance and tried binding a different Spektrum transmitter to the receiver. Surprisingly, the radio swap seemed to solve the problem and the Twin Hammers has been working perfectly since. Speaking of the electronics, when cruising along, the servo seemed a decent match for the Twin Hammers, but when having to get into some King of the Hammers type action, the servo’s relatively slow speed led to some not-so missed lines. The servo is waterproof and Vaterra should be applauded for that, but servo will need to get replaced.
DID YOU KNOW?
John Reynolds won the first King of the Hammers in 2007, and Shannon Campbell is the only driver with more than one first-place victory–2008 and 2011.
While the Twin Hammers doesn’t have the speed to get really huge air, it is a great jumper. It lands like someone placed a down pillow under it. It just plops down so softly. The suspension setup that helps it land so well also helps it go full speed over some pretty rough terrain. With its smooth undercarriage and plush suspension, it takes a lot to get the Twin Hammers out of shape. High speed cornering can lead to some dramatic rolls, but the same sway bars that would help tame torque twist on the rocks will help keep all four tires planted in the turns.
Running on the mostly-dirt scale trails at RC Madness was so much fun that it was hard to put the transmitter. Here, I was amazed at how capable the little rig was. It was really in its element and fun to drive. It climbs dirt hills, scrambles over rocks and cruises right along when needed.
At some point during testing (and we do a lot of testing), the rear drivetrain stopped functioning properly. Unnoticed in the field, the left rear wheel wasn’t getting power. While I suspected the locker in the center of the axle blew out, it turned out to be the plastic 12mm hex. The drive pin completely spun in the hex. On the other side, the hex was also torn up and the pin snapped in half. Surprisingly, the left side was still working. Needless to say, I replaced the plastic hexes with aluminum pieces and dug around in my parts bin until I found a pin thin enough to fit–the Twin Force uses a surprisingly thin drive pin.
DID YOU KNOW?
The Vaterra team chose to go with 1.9″ tires because they believed the 1.9 scaler segment was taking off and that the overall size of the vehicle with the smaller tires also seemed to fit the adventure message as you could easily take this rig with you anywhere you wanted. They felt that the 2.2-size tended to be a little bulky to carry around.
The design and parts quality of the Twin Hammers is excellent. While the vehicle falls under Horizon Hobby’s new Vaterra lineup, it is clearly of the same caliber as the Losi and Team Losi Racing vehicles. The included electronics, however, don’t seem to be on par with the rest of the package. The LiPo and charger are more than adequate (the battery is pretty nice actually), but the radio system, servo and speed control could be better. The plastic hexes are another item that doesn’t seem to be on the same level as the rest of the vehicle. The drive pins are thinner than I’d like to see, but they would likely never fail if paired with aluminum hexes. Overall, the aforementioned design and parts quality of the vehicle itself more than make up for the electronics. The Twin Hammers is hardly the first RTR to get/need an electronics upgrade (it is, however, the first radio I’ve needed to replace to finishing testing). What the Twin Hammers does get high marks for is being an original concept. This is no me-too product and it definitely accomplishes Horizon Hobby’s goal of engaging real world motor sports with an adventure theme. Quite frankly, the Twin Hammers is one of the coolest additions to the hobby we have seen in a long time, we recommend it to anyone with an interest in off-road RC and we can’t wait to the platform take off.
> The fit, finish and overall quality of the materials is great
> Well executed design–2-speed and suspension are awesome
> Solid overall performance with lots of potential
> Electronics not as good as rest of vehicle
> Plastic hexes failed
> Body is a little bland (totally subjective)
About the Author: Matt has over 25 years of experience in RC and has worked professionally in media for over a decade. Matt enjoys everything from racing to rock crawling to bashing, and he believes RC should be all about having fun. Matt is as at home covering a world championship in an exotic country as he is showing a new hobbyist how to set gear mesh. His desire to share the hobby with as many people as possible inspired him to create RC Truck Stop and RCTruckStop.com.