Top Speed: unverified
> It’s a solid axle monster truck
> Includes speed control and motors (albeit mild motors)
> Cool chassis design
> Narrow tires are out of proportion
TAMIYA KEEPS IT REAL WITH A NEW SOLID AXLE MONSTER
What you’re looking at is the TXT-2 Agrios–4WD, scale, electric, solid-axle monster truck. It’s the latest release in Tamiya’s well-loved line of “real” monster trucks. If you’re a regular here at RC Truck Stop, this release probably isn’t news to you. And, if you’re a solid-axle monster truck aficionado, this truck has probably been a long time coming. In fact, a TXT-2 was in such high demand that someone actually took the initiative to start an online petition to persuade Tamiya to pull the trigger and update its TXT platform. I don’t know if Tamiya caught wind of the call for a new truck, but what was once just wishful thinking is now here and ready for action.
> 1/10 scale
> 4WD shaft-driven drivetrain
> Solid axles with open gear differentials
> 4-link suspension with eight shocks
> Plastic chassis reenforced with aluminum tubes and side plates
> Addition ball bearings included for complete ball bearings
> Plastic transmission gears and metal axle gears
> Includes electronic speed control
> Included 540 sealed motors
> Clear Lexan body with Agrios theme decals
> Axle mounted steering servo
> Chassis and axle bumpers
The TXT-2 mixes scale looks with a durable, practical design that is distinctly Tamiya. Materials used include aluminum, a whole lot of metal screws and a variety of different blend composite plastics. The end result is actually pretty innovative. Technically, the chassis is a TVP (Twin Vertical Plate) design. The TVP configuration was made famous by HPI’s Savage line and now seen on a good number of monster trucks and rock crawlers. Tamiya did, however, do things a little different than you’d typically see. Each side of the chassis has a molded plastic section that looks like the side of a tube frame (just like a real monster truck), but hidden in each of these plastic side plastic pieces are two (that’s two per side) long (they go the whole length of the chassis) 8 mm thick aluminum tubes. The aluminum tubes are anodized black and blend right in. If that wasn’t enough, 2 mm thick aluminum plates get bolted behind each side. The black anodized plates end up looking like sponsor plates found on a real monster truck (even more so when decals are added). The suspension links and transmission mount to big aluminum side plates.
DID YOU KNOW?
One of Tamiya’s most famous vehicles, of which there are many, is the Clod Buster which was its first solid axle monster truck. It was released in 1987. In 1999, the Juggernaut was next and quickly followed in 2000 by the Juggernaut 2 that addressed its infamous bevel gear issue. The TXT-1 was released in 2002.
The chassis is capped off at each end with braces and bumpers (the axles also feature large bumpers) and has a large squared off battery box suitable for LiPos. Tamiya makes mounting electronics, such as the speed control and receiver, easy by providing two plastic top plates. The top plates have a nice diamond plate pattern molded in and the plate above the motors can accommodate two fans. The end result, when everything is all pieced together, is both heavy duty and, well, heavy. While this is supposed to be the objective part of the review, I do have to say the design is pretty darn cool and fun to build.
Unlike the chassis, the TXT-2’s suspension is pretty simple. Each solid axle is connected to the chassis via a 4-link setup. The links are aluminum with plastic rod ends. The upper links are triangulated (narrower at the axle mounting location) to help prevent unwanted side-to-side movement of the axles. It’s worth noting that the upper links also attach to the axles with a vertical mount, so washers can be added to tune anti-squat characteristics. The front and rear suspensions are essentially identical.
DID YOU KNOW?
The TXT-1, the TXT-2’s predecessor, used a cantilever setup for the shocks. The Juggernaut and the revised Juggernaut 2 used leaf springs. Interestingly, the Clod Buster, the oldest of Tamiya’s big monsters, has a shock and spring setup that is most similar to the new TXT-2–eight coil-over shocks. The Clod’s shocks, however, were friction units with no real damping.
The TXT-2 uses eight fluid-filled plastic shocks. As is typical of Tamiya shocks, the dampers are plenty smooth. Tamiya includes somewhat thin oil (they call it their “soft” oil) that works out to be a good match for the included shock pistons, springs and the weight of the big truck. The shocks have plastic caps with bladders and the O-ring seals (two per shock) mount in the bottom of the shock body. Tamiya offers very cool aluminum upgrade shocks that feature properly functioning reservoirs with secondary floating pistons.
Unlike the TXT-1, the lower arms do not have provisions (holes) for sway bars. The rod ends are the same part, so while the TXT-1 lower arms are shorter (by 2 mm), they called for plastic spacers to lengthen them to 99 mm. One 1 mm spacer went on each end between the tube arm and rod end, so they should be fine to use of the TXT-2 (if you can source the parts). That’s a mouth full and just means you could use TXT-1 lower arms and sway bars if you wanted to.
For those unfamiliar with RC monster truck lingo, the TXT-2 is a shafty, which means it has driveshafts going from a chassis-mounted transmission to the axles. Its forefather, the Clod Buster is, in complete contrast, a MOA (Motor On Axle) truck. On the Clod, each axle has its own motor that drives the axle directly, so no driveshafts. The big upside of the shafty design is that is far more realistic. The downside is torque twist where all those inline spinning parts influence handling.
The TXT-2 has a pretty substantial transmission (it’s a carry over from the TXT-1) and it’s the first thing the instructions call for you to assemble, so right off the bat you get a good feeling for what this truck is all about. There is no slipper clutch to protect the gears, but like many other Tamiya models, the plastic gears have a whole lot of surface area and can take far more power and abuse than the stock “silver can” motors can dish out. Those motors (more on those in the Electronics Section) mount side by side to a 2 mm-thick stamped aluminum motor plate (not exactly super beefy, but at least it’s not plastic). Those previously mentioned wide gears are all plastic and the transmission is fully ball bearing supported. Actually, while the instructions state metal bushings are used in three locations, our kit included full ball bearings, so the bushings hit the trash. I loaded the gears with synthetic Teflon-based lubricant. The grease I use is slick, but not so tacky that it actually causes drag.
DID YOU KNOW?
The TXT in TXT-1 and TXT-2 stands for Tamiya eXtreme Truck. The TXT-1 was the first in the family to not have 4-wheel steering. Tamiya does, however, include all the needed parts for 4-wheel steering.
Tamiya includes two 19-tooth .6 module pitch pinions (the TXT-1 used 15-tooth pinions) that mate to a 40-tooth spur gear that is cushioned by three rubber O-rings (instead of the spacer used on the TXT-1) that slide on the gear shaft first. As previously mentioned, the gears are wider than typically seen (read: strong) and the O-rings should help absorb some jolts. And, if all of that wasn’t enough, Tamiya includes another set of transmission gears as spares (Thank you, Tamiya).
With the exception of different mounting pieces, the axles are essentially the same as used on the Juggernaut 2 (which were beefed up version of the Juggernaut 2 axles) and are essentially the same as the TXT-1 (there are some part number variations). The design is classic monster truck in that it replicates the extremely heavy-duty top loader style axles. Unlike the transmission, the axles use all metal gears, but like the transmission there are a lot of them. Each axle has a gear differential that is well sealed enough to pack with different greases (silicone fluid will seep out) to tune handling. Just keep in mind that running too thick of a grease will mostly just make the truck take even wider turns. I used the same slick grease I used in the transmission. The uprights are the same as used on the Clod Buster and the outer axles are also splined to accept matching splined brass 12 mm hexes. The wheel adapters are the same as the TXT-1, so wheels and tire combos made for the Clod and such are a go if you want to change things up.
It’s a kit, so the electronics list is short. That’s okay because most RC kits don’t come with any electronics. Tamiya, however, includes a speed control as it generously does with many of its sport kits (this speed control is easily a $60+ added value). The TEU-106 BK is built to run dual motors off a single battery. Speaking of the battery, the speed control has a built-in low voltage cutoff. An aluminum heat sink helps keep the unit cool, and heat and over current protection do their part in help keep you from wrecking it. The BEC delivers 6V/2A to the steering servo. Reverse can also be locked out, which is a nice feature, but unlikely to be employed on a truck like this. Maximum continuous current is rated at 150 amps and for up to 7.2V batteries. I ignored the battery limit rating and risked the extra 0.2 volts by running a nice ProTek 7.4 7000 mAh LiPo. The hard-cased battery easily fits and 7000 mAh is one big gas tank.
What would a Tamiya sport kit be without at least one silver can motor? The TXT-2, as you know by now, has two. They are Mabuchi Motor RS-540SH sealed can motors with preinstalled power leads with bullet connectors. These motors are a simple as it gets, but they are reliable and relatively maintenance free.
Tires, Wheels & Body
While the vast majority of potential TXT-2 purchasers won’t think anything of it, the tires included are narrower than previously seen on Tamiya monsters. The tires, original seen on Tamiya’s nitro-powered TNX, are, in fact, 25 mm narrower than TXT-1 tires. Since real monster truck meats are 66 inches tall and 43 inches wide, the TXT-1 tires were very realistically proportioned. RC monster truck purists will not appreciate the skinny kicks, but that crowd would also probably swap the TXT-1 tires for a set of soft aftermarket tires such as RC4WD Rumbles anyway. So, it actually makes sense that Tamiya include a tire that is better for everyone else. And, if the tires being too skinny is the downside, the upside is that these tires are in every other way a better tire. The undisclosed compound is softer and traction is worlds better than the TXT-1 tire. The tires are pliable enough to require foam inserts. Tires that are stiff enough to not require foam inserts for support were cool in the ’80s, but we can do better now.
The gray plastic wheels are a one-piece plastic design with a faux headlock treatment. I like the styling, some people don’t. It’s completely subjective.
When the TXT-2 was unveiled, almost as many people who grumbled about the narrow tires, also whined (truth hurts, sorry) about the body. While the Agrios theme may not be to my liking, the body is awesome (subjective comment, I know). It’s a clear Lexan shell molded out of 1.2 mm thick material, so it’s strong without being too heavy. By accident or on purpose, it is styled almost identically to the desert truck (Trophy Truck) style bodies we have been seeing pop up on some monster trucks such as Bigfoot 18 and 19 since 2011. I decided to make good use of this body style and paint it bright orange (Tamiya PS7) like the Speed Energy sponsored Bigfoot 19. Our friends over at Digital Designed made the vinyl logos, and the end result is the coolest one-color paint job I have ever done. You can get the exact same decal set I used from Digital Designed for a pretty modest price.
This is the part of the review I really like–actually testing it. I anticipated two things before running the TXT-2–that it would be slow due to its weight and silver can motors and have bad torque twist thanks to the lack of sway bars. Drumroll, please. I was wrong on both accounts. With the ProTek LiPo installed, the truck had nice acceleration and a respectable top speed. On level pavement (probably the most boring place to drive the TXT-2), the top speed was reading between 19 and 21 mph (this top speed has been called into question and we agree, but we do not believe it is too far off). That’s not exactly a land speed record, but it is far from disappointing. I’m sure I’ll eventually upgrade to a mild brushless setup, but I’m in no rush. What about that other worrisome issue? Torque twist can absolutely ruin handling, but the TXT-2 isn’t nearly as plagued with the problem as I thought it would be. In fact, I’d say it isn’t a problem at all. Torque twist is there, but not enough to be an issue. If you grab full throttle from a standstill, the left front tires slightly lifts, but there is no loss of control. So, out of the gate, I was pretty happy with the TXT-2. It makes a great first impression. The big truck was a lot of fun blasting around on grass, dirt and pavement.
DID YOU KNOW?
Tamiya, founded in 1946, was original a sawmill company. A sawmill? In 1948, wooden models ships were offered, and in 1953 the sawmill was closed and Tamiya went on to be a model company.
After doing what most TXT-2 owners will do–bashing it around the yard–for a few days, I did what most won’t do–I took it to a local RC monster truck race. Along with a couple of my “race trucks,” I headed up to RC Madness in Enfield, CT to race with the RCMTC-NY guys. I did this mostly to get even more testing in (sorry, but one lap around a smooth softball infield for photos doesn’t constitute a real test) and to see what the hardcore guys thought of the TXT-2 in person. The truck handled the track very well and raised many eyebrows. Did it win any side-by-side races? No (actually, it was close enough to win a few when other drivers bobbled, but it didn’t beat any of the full-race trucks in clean races). When it comes to power, these guys use about as much moderation as a fat guy at an all-you-can-eat buffet. The bone stock TXT-2 was out gunned, but everyone noted how well it jumped and generally took to the track. A few of the guys took the wheel and they came away with the same thing I had–the TXT-2 makes a great first impression. I had a blast driving over the jumps and crush cars and besides the obvious speed disadvantage, I though the steering needed some work as tight, hairpin turns were not its strong suit. But, more power might help swing the rear end around, as would different tires. So, I wouldn’t be looking to be making any big modifications until after power and tire swaps were done. Of course, the racers noted the “too narrow” tires, but loved the body. Getting back to the performance, at one point, I was asked if the truck was still stock, which is another good indicator that the TXT-2 is for real. When I said it was box stock, a veteran racer quickly pointed out that its racing performance was extremely better than a stock Clod Buster.
The TXT-2 has seen a lot of use since returning from the track. I have a few ramps for bashing that are all about two times higher than the ramps it had previously seen action on. I couldn’t even begin to guess how many times this truck has now been airborne, but it’s a lot. During one run, I heard the drivetrain start to make a racket as the truck lost power and rolled to a stop. I feared the worst and figured I toasted the transmission. Wrong again. Both driveshafts came loose as set screws back outed. I had used the included thread lock, but it didn’t hold. No worries. In about five minutes, I had the truck back in action after I cleaned off the set screws and applied a different thread-locking compound. I’ll keep an eye on those. That wasn’t the only repair I had to perform. After a full speed collision with an immovable object where one tire took the brunt of the impact, a steering links pulled out of a rod end. It could have reinstalled the rod end, but it would likely just pull right back out, so I used one of the spares that came with the kit (Thank you, Tamiya). Again, the repair took about five minutes.
After about a month of testing from start to finish, I can say that I am quite pleased with the performance of the TXT-2. I do admit that I now want some more speed, but isn’t that how it goes with any RC? Put enough miles on just about any RC and you’ll want it to be faster. And, what was What it lacks in speed, it makes up for in predictable handling.
If we acknowledge that RC companies don’t design, manufacture, market, distribute and support a vehicle just for little ol’ individual us (you do realize that, right?), we can appreciate that Tamiya has a pretty tough task on its hands when developing and releasing a truck like the TXT-2. It simply isn’t easy to create a truck that appeals to the average RC customer with desires typically leaning more towards performance and still live up to the scale expectations of the RC monster truck aficionados. This is complicated by the fact that neither group really embraces compromise. But compromise is inevitable, and that is exactly what the TXT-2 is to some extent. Compromise isn’t a negative, it’s a reality. All of this is really just the longwinded way to say whether you’re just looking for a cool basher or you’re a dedicated monster truck racer, the TXT-2 will put a smile on your face. It’s an enjoyable build, a cool design and fun-times-ten to drive. I will eventually–keyword is eventually–swap out the tires, but I would likely do the same even if it had the tires found on its predecessors. I’ll probably eventually (there’s that word again) toss in some more power, but I think I’ll go with a single mild brushless motor. Point is I’m going to have some fun with this truck and I’m in no rush to makes changes. The TXT-2 is fun right out of the box.