1/10-SCALE NITRO by Bob Hastings
SUPPOSE THAT YOU TOOK THE NEW TRX 2.5-POWERED T-MAXX and removed its 4WD, 2-sped and reverse gearing; what would you have? You’d have the 2WD Traxxas SportMaxx, which costs about 100 bucks less than a T-Maxx and is a full pound leaner. Although the lower cost is instantly attractive to anyone who wants to get into the Maxx craze, its lighter weight will appeal to race enthusiasts. Has Traxxas created the perfect entry-level Maxx, or is this the turnkey racer that competitors have been yearning for? Quite possibly, it’s both; only a closer look will tell.
CHASSIS. The SportMaxx has a 3mm chassis that’s identical to that of the recently revamped T-Maxx. The thicker, stronger and stiffer blue-anodized, 6o6i stamped-aluminum plate shows the cutouts for the old Maxx’s bottom exhaust exit, and it’s ready to accommodate the reverse-shift servo if you want to install that option. Composite, ladder-style braces provide additional longitudinal stiffness to the chassis.
DRIVE TRAIN. The SportMaxx uses the same 20/72 clutch-bell and slipper– equipped spur combination as the T-Maxx as well as its enclosed transmission case. Instead of the clutches and gears that make up the T-Maxx’s reversing 2-speed, Traxxas installed a very simple, efficient, singlespeed, forward-only tranny. The 3-gear unit is supported by bearings (a full 23 in the drive train), and it weighs significantly less than its older sibling: 113 grams versus 204 grams. Less weight means a better power-to-weight ratio and a reduction in the rotating mass of the drive[ine. A 37mm fiber disc pad provides rear-wheel braking, and the front U-joint will accommodate future 4WD plans.
A telescoping, heavy-duty, plastic drive shaft delivers power to the rear planetary– gear differential The hardened– steel ring and pinion gears were designed to withstand the power of the TRX 2.5 and the rigors of off-road abuse. Sliding universals take the torque to the rear wheels, and the plastic sliders allow greater suspension travel over dogbones and fixed-length universals.
SUSPENSION AND STEERING. Traxxas uses the WideMaxx suspension in the SportMaxx as it does in the new T-Maxx. It’s an inch wider than the previous one and is significantly beefier. The eight plastic-body, coil-over Ultra shocks are fluid damped; they have three upper mounting positions on the shock tower and four positions on the lower suspension arm. Pivot balls allow camber and track-width adjustments, and clip-type spacers allow 4, 7, or ici degrees of caster angle. Strong 3.5mm turnbuckles allow front and rear toe adjustments, and a bush ing-supported bellcrank with a heavy-duty Traxxas 2055 servo is used for steering.
ENGINE AND ACCESSORIES. I’ve run a few gallons of nitro through previous test vehicles equipped with the TRX 2.5 engine, and it’s now a favorite of mine. Once you’ve completed the ABC powerplant’s recommended break-in procedure, you’re rewarded with reliable idling and ballistic revving with smooth throttle transition at all rpm. The 2-needle, composite slide carb is easy to tune and prevents fuel from boiling in the intake (as may occur with a hot aluminum-body carb).
The 2.5cc engine’s “tuned” air filter looks similar to a hot-rod’s highvelocity stack; its conical design optimizes airflow to the carb. Its other features include a knife-edged, machined connecting rod; an oversize cast-aluminum heat-sink head with protective top; a lightweight piston with a longer connecting rod; and an integrated-pilot-shaft (IPS) crank with a large-diameter port. The composite tuned pipe was created specifically for the 2.5, and it looks like those on competition motocross bikes.
The SportMaxx also includes the revamped “smart” EZ-Start 2 that is stronger, more reliable and easier to use. The wand-type controller fully encloses the starter battery, and new circuitry senses whether the starter motor is drawing too much current (because of a flooded engine, for example) and will shut the system down to prevent it from being damaged. Other features are an elastomer “cush” drive to protect the starter gears from damage and LEDs that indicate motor and glow-plug status.
BODY, WHEELS AND TIRES. Although its styling is similar to previous Maxx designs, the six-color ProGraphix paint schemes and body are new. The shell is precut and drilled. and you have the choice of blue, red, green and silver for a main body color. You can also opt for a body with a clear center section so you’ll be able to personalize it. If you have a tough time deciding on a color, visit Traxxas.com; its interactive color selector lets you virtually “paint” a body online to see how your finished color scheme would look. As well as the attractive new scheme, the most notable style change is the large, molded sill between the front and rear fender wells. This makes the body look more aggressive and adds rigidity, too.
The SportMaxx’s wheel treatment immediately differentiates it from its 4WD siblings. The one-piece nylon rims have five tapered spokes and a metallic finish; a raised ridge on the outer portion of each spoke further enhances the style. In a return engagement from the Maxx fleet, Traxxas’ multipurpose Maxx Terra tires deliver a nice mix of traction and good overall wear with their chevron pattern.
The first thing you’ll notice is how smoothly the drive train operates. Since the SportMaxx doesn’t have an internal clutch transmission and a lot of rotating mass, there’s none of the clutch snatch that’s often encountered with the T-Maxx. (This is the tendency for the clutches to alternately grab and release when engine rpm nudges the engagement point.)
Power from the free-revving TRX 2.5 accelerates the truck with ease and spools it up to its 30.4mph top speed in short fashion. There’s definitely enough reserve power to gear up the SportMaxx for more speed, especially when you consider that although the T-Maxx is heavier, it can top Oomph with the same TRX 2.5 engine.
If you drive the SportMaxx as if it’s a big 2WD stadium truck, you’ll be amazed at how well it handles. Unlike the T-Maxx, which has the benefit of its front wheels to pull it out of a corner, the SportMaxx experiences a good deal of on-power push. I found it easiest to apply a little brake before turns to plant the front end and to help pivot the rear; as soon as the corner is established, I smoothly roll on the throttle to blast out the other side. If you use too much power when you exit a turn, the TRX 2.5 can easily loop the truck, but its throttle response is so linear that it will make even the biggest hacks look smooth!
Running across a surface that has any traction lets the SportMaxx really show off its lighter chassis and enormous power. Even if it’s already rolling, a clamp on the throttle immediately lifts the front end in a very gratifying, bumper-scraping wheelie. Go to clamp from a standstill, and the SportMaxx flipped right onto its roof.
Without the pull from the front wheels, this truck doesn’t have the low-speed climbing prowess of the T-Maxx; that isn’t meant as a knock as much as it is an observation (like me saying that I didn’t like the hamburger because it didn’t come with cheese). If you’re into climbing, you’ll probably want to look into the 4WD upgrade. If big speed and tall ground clearance will satisfy your off-road needs, you’ll find this truck amazing. The SportMaxx’s disc brake is a hefty 37mm in diameter; since it only has to stop the rear wheels, the stock servo can easily lock the rears if you apply too much brake pressure. A benefit of the rear-only brakes is that you can’t mistakenly endo the truck if you brake too abruptly.
Who is the SportMaxx for? Anyone who’s looking for a big monster that’s a blast to drive will certainly find it a worthwhile investment. If you’re a current-generation?-Maxx owner who has been toying with the idea of upgrading it to TRX 2.5 status, skip the conversions and move on over to the SportMaxx. It’s a welcome arrival for those who have found that the higher admission price of the T-Maxx was outside their grasp.
Competitors who like to customize their racers will undoubtedly enjoy starting with a trimmed-down race machine. The truck su its a variety of purposes, and it will appeal to many folks for different reasons. Before the others catch on, though, I suggest that you be the first at the hobby shop to grab one.
(888) 872-9972; traxxas.com.
Copyright Air Age Publishing Feb 2003
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