Team Losi Triple-X Brian Kinwald Edition 2

Radio Control Car Action, Apr 2004 by Sams, Jason

WAIT; THAT CAN'T BE RIGHT. HAS IT REALLY BEEN FIVE YEARS since Team Losi introduced the Triple-X buggy? Whe the third-generation X-car debuted, it was nothing short of an off-road revolution, and it remains fresh to this day, but that hasn't stopped Team Losi from looking for ways to go faster. With the release of the Brian Kinwald Edition 2 version of the groundbreaking buggy, it looks as if the R&D guys have done just that. Just like the original "BK" Triple-X, the "BK2" is loaded with all of Losi's factory options. But there are slaso some drive-train and supension tweaks that are much less obvious to the eye but stand to make a big impression on the track. Keep reding, and all will be made clear ...

KIT FEATURES

CHASSIS. Like the Kinwald-edition buggies that precede it, the BK2's chassis is molded of graphite-plastic composite for reduced weight and maximum rigidity. The shape is classic Triple-X with raised sides that increase cornering clearance. Although the main chassis is the same, a new molded front pivot mount, rear pivot plate and aluminum rear pivot mount have been added to accommodate the new VLA (Variable Length Arms) suspension package (more on that later). All the new molded parts as well as the battery strap are made of graphite composite, and since the stuff is slightly conductive, battery-insulation tape is also provided to prevent the cells from shorting on the sills of the chassis' battery tray.

DRIVE TRAIN. The BK2's drive train is all new from the drive axles up. The 3-gear transmission has a smaller differential (46 teeth, compared to the original Triple-X's 51), an aluminum top shaft with integrated i8T top gear and a new and higher internal drive ratio of 2.56:1 for quicker acceleration. The differential has some new internal features too, including a diffadjusting screw with two thrust-bearing seals to help keep dirt out (the original Triple-X had one seal butted up against the head of the screw), longer outdrives (to reduce binding caused between the dogbones and outdrives) and a stronger square-cross-section diff spring that will endure much more use before it wears out. The diff's smaller diameter and correspondingly more compact transmission case lower the BK2's center of gravity, but not low enough for Team Losi. To completely slam the CG, the tranny case protrudes through the rear pivot plate and actually hangs about imm below the chassis (don't worry; a molded-in skidplate protects the exposed tranny). The smaller diff and lowered tranny also let the motor sit closer to the gearbox, thus reducing the car's polar moment of inertia. According to Team Losi, this greatly improves forward traction and speed on bumpy sections of a track. The BK2's dual-pad slipper-clutch will also help out on bumpy and/or slick tracks, and it's the same as the previous Kinwald car with the exception of its spur gear: it's one of Losi's new Kevlar models.

One of the BK2's most significant new features is its management of "friction dynamics," to use Team Losi's term. The BK2's MIP CVDs are significantly shorter and mate with longer diff outdrives. The new geometry reduces the distance the CVD's dogbones move inside the outdrives during suspension articulation ("dogbone plunge" is the term Losi uses). With reduced dogbone plunge, the BK2's suspension travel is smoother and the drag-braking effect of plunge friction is reduced. Speaking of friction reduction-Teflon-shielded ball bearings keep all the spinning stuff spinning smoothly. Say that five times fast.

SUSPENSION AND STEERING. The BK2's key suspension features are its variable length arms. Each suspension arm has two outer hinge pinholes that match a pair of hinge-pin bores in each hub carrier. If you use the outboard hole, you increase the arm's effective length, and vice versa when you use the inboard hole. The BK2's width doesn't change, but the effect on the suspension action can be dramatic. There are new shock and swaybar position options as well, all designed to give the car an aggressive feel. The arms and the rear shock tower are molded graphite; the front tower is 1/8-inch G-10 and proven tough by five years of competition. The Triple-X pioneered the "leading camber link" concept and the use of vertical ball studs for roll-center adjustment, and in "BK" trim, the turnbuckles are titanium. Threaded, hard-anodized shock bodies are also familiar BK touches, but their anodized-aluminum adjusting nuts with O-ring "grabbers" are new to the BK2 (and much easier to twist than the old nylon nuts). Titanium-nitride shock shafts are another classic BK feature, but Team Losi didn't stop at the shafts with the BK2. The hinge pins are also titanium nitride; that's a first. It makes sense; ti-nitride's scuff-resistance and slipperiness are most beneficial to shocks but also important for hinge pins. An aluminum rear pivot block is another new BK2 piece and it steps up the car's durability factor (the style points don't hurt either).

The BK2 uses a dual-bellcrank, ball-bearing steering system with an adjustable servo-saver-all pretty standard stuff, except for the bellcrank pivot post's angle; they're tilted backward to match the angle of the steering arms' kingpins. This removes bump-steer and contributes to the Triple-X's laser-precise steering.