DuraTrax Maximum ST & MT Pro
DuraTrax’s Maximum ST claimed the number-one spot in our RTR nitro-truck shootout back In the October 1999 issue of Car Action, despite the fact that It was equipped with a horrid little expansion-chamber muffler and extension– tube exhaust combo. As many of you know (and for those who don’t), I’ve always recommended against this setup because it robs you of power and causes heat buildup.
Well, DuraTrax has not only upgraded the exhaust system to a power-adding and cooler-running tuned system, but it has also added a whole lot of other things and given the Maximum ST a “Pro” suffix. Oh, yes; Its turf-banging brother, the Maximum MT, has also been given the Pro treatment and just as much cool hop-up stuff, Including oversize i-scale shocks fit for doing overtime monster service. I tested both!
* Chassis. The Pro Series uses a tub-style chassis manufactured of anodized 6061 T-6 aluminum (2mm) that supplies more than adequate stiffness for the ST and MT. Tub chassis formed of high-quality aluminum have a long and proven competition record. Remember that years back, Team Associated drivers actually pre
ferred the aluminum-tub chassis and moved away from carbon fiber. When the “Team” car was introduced, it featured an aluminum tub that was, by the way, substantially thinner than the ones found on these DuraTrax trucks (just a bit of history).
Both vehicles have 27 degrees of front-end kick-up and rear braces that run to the top of the gear case. I guess my only gripe about the chassis is that the mounting holes are not countersunk and that protruding round-head screws, vulnerable to being damaged, are used throughout. Not a real biggie, but countersinking would have been nice. The engine– mounting holes are slotted, so I guess gear-ratio options from DuraTrax are in the future, but not presently available, I’m told. The receiver is mounted on a thin (again, 2mm) aluminum upper radio plate that also captures the onboard battery pack with a piece of foam sandwiched between.
* Drive train. Right off the bat, the first thing you notice about the drive train on these two trucks is the 2-speed tranny. Now, I know what you’re probably saying: “A 2-speed on an off-road vehicle?” I admit it does sound a bit dubious but, so far, once we had them adjusted correctly, I never had a problem with them jamming because of dirt. Shift points are adjustable, and with the combination of the 2-speed and the tuned-pipe-equipped Torq .16 engine, these Pro Series trucks are fast-very fast.
The tranny looks very durable and consists of: a one-piece metal layshaft/input gear unit; metal idler gear and composite differential ring gear, with all internal differential beveled gears being metal. Gear thickness throughout is 9mm, and all are supported by ball bearings on both ends. As I said, things look quite robust inside this diff case. The 2-speed ratios are: first gear-3.47:1; second gear-2.53:1; final drive for the gearbox3.25:1. Metal half shafts use output-cup/dogbone drives inboard and universals outboard. The U-joints are of very good quality and exhibit almost no play. Power is transferred from the Torq .16 to the drive train via a 3-shoe composite clutch.
* Suspension and steering. The lower A-arms and other chassis components are made of what DuraTrax calls “StressTech” plastic. This stuff is pretty rugged and even survived when a radar speed run that went “awry”-that is … I mean, that went “a-right”-into a concrete aqueduct. Steve Pond was driving-not me; OK? The impact bent a hinge pin and pulled it out of the arm mount, but nothing broke. Steel turn– buckles make camber adjustments easy, and all hub carriers and steering blocks are made of anodized aluminum. Inner and outer axle ball bearings are found on both trucks. I’d like to point out that DuraTrax did not just add big wheels to the ST and then call it the MT. Not only are larger, 14-scale-style- shocks found on the MT, but its A-arms are also 16 inch longer than the ST’s. Both trucks use threaded aluminum shock bodies for easy preload adjustment via knurled collars.
* Engine and accessories. Both trucks include DuraTrax’s pull-start Torq .16 engine. The engine features a rotary carburetor with lowand high-end needles as well as true ABS construction and a machined heat-sink head. My biggest dislike about the original Maximum series was the use of a little expansion-chamber can muffler and skinny exhaust tube. This combination robs you of power and causes heat-yuck! The Pro Series adds the header and tuned-pipe system you see here-hallelujah! That spells more power with cooler running.
* Body, wheels and tires. DuraTrax includes factory-finished bodies with all the Maximum trucks, “regular” and Pro alike. The ST wears a sleek racing-style body while the MT model includes separate, injection-molded, chrome-plated detail parts including a light bar and bumpers. The MT body does the “shimmy” when the truck is being run; I’d like to see better-supported body posts.
As for the rolling stock, both Pros include chrome, 2.2-inch wheels with chevron tires, but the MT’s rubber is noticeably larger for a true monster stance.
Nothing can ruin the enjoyment of a nitro-powered vehicle faster than a cranky engine. The Torq .16 may be the most reliable engine to have ever been put in a ready-to-run vehicle. We had three Maximum vehicles come through our office, and every engine started up right away and kept running. I even ran the engine with a ridiculously rich high-end needle setting-slow and sloppy, as the expression goes-with no battery connected to the glow plug. Even then, the engine idled and accelerated from idle without stalling. This is a testament to the excellent design of the twin-needle carburetor.
Remember I said these trucks were fast? Well, how does 43mph sound for the MT? I’d say 43mph for a monster truck is smokin’, and I wouldn’t have believed it myself if I wasn’t behind the wheel for the radar testing. Since both trucks have the same gearing, you can expect a slightly lower top speed from the ST because of its slightly smaller-diameter tires. Because of these smaller tires, which effectively give a lower ratio and better acceleration, we got the ST to pull the front wheels a few times when it shifted into second gear. I like these trucks. Suspension travel and shock action are very smooth and made both easy to drive. Like almost any other 2WD vehicle, both understeer under hard acceleration, and turning tightly has to be coordinated with the proper application of throttle and brake. The brake worked well, by the way-well enough to lock up the wheels at the end of the speed runs but not well enough for daydreamer Steve to avoid the wall.
I do have one steering dislike: I found the stock steering servo a bit on the limp side for the large-wheel MT version. The tires on the MT are in the standard monster-truck, chevron-tread style and work exactly as you’d expect. On the other hand, I found the tire choice for the ST a bit perplexing. The tires are a smaller version of monster– truck, chevron-type tread designs-the same as are found on the original, non-Pro Maximum. I find this DuraTrax choice curious; why did it put all these great options on the Pro ST and then stop short at the tires? We know how huge a difference tires can make. It’s kind of like ordering a hot Corvette with all the options and then asking the dealer to supply it with temporary spares on all four corners. Though not on a par with an all-out race truck, I think the ST pro is far more capable than its chevron tires.
The Torq .16, with its very good carb, really helps out a lot when you’re driving. The good idle and very good throttle response really make the Pro trucks respond well in the turns and short straights. This carb is so good that it even had a reliable idle and decent throttle response when I tried to get it too quiet with a super-rich, sloppy, high-end needle setting. This carb kept the engine going and going and going. DuraTrax-kind of like Duracell in this respect.
It’s obvious that DuraTrax has put a lot of time and effort into the development of these ready-to-run trucks. Moreover, I think they offer a whole lot of value, considering all the stuff that’s loaded onto them-from the smoothly functioning anodized shocks to the close– tolerance steel universal drives. But the first and best reason I recommend these trucks to you is the engine. In general, the engine has never really been the big selling point with ready-to-run nitro vehicles; it is now. We had three samples of the DuraTrax trucks– two MTs and one ST-and right out of the box, the engine on every one started and kept running. I think most would agree that in this nitro game, that’s a most important feature.
The MT will bang and bash with the best of them, and given enough runway, will out-drag them all in a straight run. With some off-road, stadium-truck front and rear tires mounted on the ST, you may do better than you expect at your local track. You might not beat the hottest Associated and Losi trucks out there, but if you’re a smooth, practiced driver who stays on the track and out of the woods, maybe you will. One competition fact is for certain, in my humble opinion: the DuraTrax ST Pro and MT Pro are top competitors in the nitro-powered, ready-to-run truck market.
Copyright Air Age Publishing Aug 2001
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