CEN Fun Factor MT and BG
Behind the wheel with CEN’s bashworthy, nitro 4WD off-roaders
“Fun Factor,” eh? With a name like that, CEN makes an up-front promise that its nitro-powered BG and MT (which, unsurprisingly, stand for “buggy” and “monster truck”) will be, um. enjoyable to drive. The BG and MT chassis and drive trains are identical and share all of their parts with the 2WD Fun Factor Rally and Stadium Trucks reviewed in our March 2000 issue. The MT and BG are both full of features: shaft-driven four-wheel drive, .16 pull-start engine, bail-bearing drive train and pivot-ball suspension are just a few of the highlights. I’m glad to see all the high-zoot stuff in there, but that’s no guarantee of a high fun factor for the Fun Factor buggy and truck (although it certainly helps). I crashed and bashed both machines to see how well they could make time fly; here’s how they did.
Chassis. The Fun Factor chassis is constructed of nitro RC’s most basic element: 2mm aluminum plate. The stuff is purple-anodized and stamped with deeply radiused sides that almost qualify the chassis as a tub and make a stiff platform for the rest of the Fun Factor’s (FF) components. The chassis’ nose is stamped separately to provide a generous 30 degrees of kick-up and is attached via screws that thread into steel inserts in the nose plate. A broad upper deck secures the steering servo and suspends the fuel tank, and a short rear brace supports the spur-gear bearing block and rear brake assembly.
Most of the chassis’ right side is taken up by a very roomy and well-sealed radio box. A body clip keeps it closed, and the lid accepts the on/off switch and antenna. By unplugging the steering and throttle servos and removing the radio box’s mounting screws, the radio system can be removed intact.
Drive brain. CEN followed the standard nitro-tech playbook pretty closely and equipped the FF with front and rear bevel-gear differentials, a plastic spur gear, a fiberglass brake disc, cam-actuated steel brake caliper, dogbone-type rear axles and 12mm drive hexes. Unexpected touches include universal front drive axles (copied from MIPs CVD design) and sealed bearings for all the main drive train’s rotating parts.
A two-shoe dutch and 47-tooth spur gear equip both the MT and BG, and CEN wisely specs two different clutch bells to suit each car. The MT gets a 13-tooth clutch bell to compensate for its tall tires, and the BG sports a 16-tooth unit to better spin its smaller treads.
Suspension and steering. Like a little T-Maxx, the FFs’ suspensions eliminate lower H-arms, upper camber links and hinge-pin-held hub carriers in favor of a full pivot-ball setup with upper and lower A-arms. The widetrack MT’s arms are long enough for the upper units to wrap around the shocks, simultaneously stiffening the arms and protecting the shocks from potentially shaft-bending impacts. The narrower BG’s arms aren’t long enough to perform the same feat, but they are thick and appear strong nonetheless.
Both FF machines cleverly use identical hub carriers for the front and rear suspensions. The discshaped carriers hold on to the suspension’s pivot balls with plastic-padded aluminum retainers and operate smoothly. For steering duty, bellcrank arms are screwed to the front carriers to mate with the steering links. To keep the rear carriers from flopping around on the suspension arms, plastic bosses replace the bellcrank arms, and steel rods are installed as toe-in links. Since the rods are threaded, toe-in can be adjusted in any amount.
Plastic-body, fluid-damped shocks suspend the FF chassis and seem to operate as well as other brands’ plastic shocks, but aluminum upper and lower sealed caps make the CEN units a bit more stylish than the black-on-black variety. Spare pistons are included, and the shocks are filled with fluid at the factory. As built, they’re a bit underdamped, but the spring rates feel about right.
A pair of steering bellcranks with a spring-loaded, cam-type servo-saver is joined to the upside-down steering servo via a threaded rod and ball joints, so no Z-bend linkages are used. The servo-saver’s tension is adjustable-albeit with some difficulty, since it’s buried under the upper deck-and is factory-set on the soft side of the adjustment range-all the better for the type of abusive play that machines like the FFs are subjected to.
Engine and accessories. CEN’s own NT-16 engine is standard issue for both FFs, and it’s a pretty good little mill. In addition to the always welcome extra displacement (16 instead of the usual .12), the NT uses a 2-needle carburetor for full mixture adjustability. Unfortunately, the low-end needle is tough to reach because the radio box obstructs it, but the slotted high-end needle can be easily set with a screwdriver, even with the body on. A pull-starter is no surprise, and the machined heat-sink head should cool effectively. A foamelement air cleaner is also included.
The FF’s unconventional engine placement requires a 180degree header, and the CEN unit is a little rough-looking but perfectly functional. A plastic, tuned-style pipe with dual tips and a recessed pressure fitting finishes off the exhaust system.
Body, wheels and tires. Both FF machines have what CEN calls “P&D” bodies, which stands for “painted and decorated.” The bodies are also trimmed (albeit crudely) and mounted at the factory. The MT gets a conservative red paint scheme with a rhinoceros motif, and the BG sports a zebra-stripe shell that simultaneously evokes television artifact “Daktari,” Fruit Stripe gum and anything Cher wore in the ’70s.
Monster-style chevron tires grace the Ws 22-inch rims, and the BG gets block-tread rubber on its narrower 2.2-inch hoops. The rubber is stiff enough to forego foam inserts-a good thing, since none are included. The white wheels have a tasteful hole-pattern design that is stylish and allows the included hex wrenches to pass through the wheels to the suspension pivot balls for easy camber adjustments.
My first runs with the BG and MT were supposed to be simple straight-line passes for top-speed radar testing, but they turned into all-afternoon street-punishment sessions. The CEN NT-16s started easily and ran reliably after a brief break-in and proper carburetor setting. After clicking off a 36mph best run for the MT and 31mph for the BG (that’s the difference smaller tires make), fellow editor Derek Buono helped me put a hurt on the CEN machines. As the top-speed numbers suggest, there was plenty of play-around power on tap, thanks no doubt to the .16 displacement. The little BG wasn’t as fast as the MT, but it took off much more quickly and had plenty of torque to light up the tires. Unless we kept both cars pinned until their engines revved out and the W’s speed edge could materialize, we’d swear the BG was faster because it’s so quick off the line. Though it isn’t slow, the MT just can’t spin up its big tires as quickly.
Unsurprisingly, the BG also outhandles the MT, but neither could be described as great handlers. Underdamped shocks create a lot of chassis sway, and hard turns cause them to lift the inside front wheel (but to their credit, neither FF flipped). It isn’t the fast way around a vacant lot, but these aren’t racing machines, and their hyperactive suspensions make the FFs fun to watch. Unfortunately, the light damping also makes it easy to bottom out the chassis, and a few tanks’ worth of curb-hopping gave the FFs a lot of hard knocks. Nothing broke, but I always wince when I hear the metal-to-pavement slap of a chassis bottoming out. After a thorough pounding, the only damage (outside of scuffs and scrapes) was a bent toe-link on the MT after a string of high-speed cartwheels. The bent link added about 10 degrees of toe-in, which meant the car had to be driven just about sideways to track straight, but the problem was easily (and literally) straightened out in 10 seconds with a pair of pliers.
So nothing broke, but how about the brakes? The FF’s single– disc setup effectively hauled the cars down to a stop. The brake got a greater workout from the MT’s taller tires, but it could still lock the wheels after first scrubbing a little speed.
There’s a lot to like about the CEN Fun Factor 4WDs, but the Mirage III transmitter casts a pall of cheapness that the FF chassis and NT-16 engines don’t deserve. Likewise, the dubious body graphics (and for that matter, the less-than-awesome packaging) may divert hobbyists from what are some pretty cool off-road vehicles. As a reader of RC Car Action, you’re smarter than that, and just as a flashy body and slick marketing wouldn’t fool you into buying a lame kit, I don’t think you’ll let the Fun Factors’ goofy graphics and sub-par transmitter blind you to the merits of the chassis. For a bargain price, you get a strong and reliable engine with tuned-type exhaust, a full-time shaft-driven 4WD system with sealed ball bearings and full pivot-ball suspension (found on much more expensive vehicles such as the Traxxas T-Maxx and the latest 1/8-scale competition buggies). These highs easily outweigh the lows. The too-soft damping is fixed with a $3 bottle of shock fluid; if you don’t like the bodies, they’ll be trashed soon enough; and given the FFs’ low cost, the Mirage III radio is practically “free,” so you won’t feel bad replacing it-or, you could just use it and keep 75 bucks in your pocket because it works just fine.
Of the two Fun Factors, I think the MT is the star; the monstertruck look is always a draw, and the MT’s higher top speed and wider stance make it a more attractive off-road play package. I like it so much, in fact, that my next project will be based on the Fun Factor. With a fresh body, revamped radio, dialed-in damping, a few style mods and a new name-I’m thinking “Fear Factor”we’ll see what the CEN 4WD truck platform can really do.
CEN/GENKA TRADING CORP.
1800 East Miraloma Ave., Ste. F, Placentia, CA 92870; (714) 792-1923.
4105 Fieldstone Rd., Champaign, IL 61821; (217) 355-9511;
Copyright Air Age Publishing Sep 2001
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