Schumacher fusion R12
SCHUMACHER IS KNOWN FOR ITS COMPETITION electric cars and over-powered nitro trucks, but a true nitro racing sedan has not been part of the lineup-until now, that is. The Fusion R12 pairs Schumacher’s on-road prowess (proven by the success of the Axis and Mission series) with a unique drive-train layout to deliver an exciting and innovative nitro sedan that has been generating positive buzz since its A-main debut at the 2003 Winter Nats. Should we believe the hype?
CHASSIS. The R12 is partially assembled by Schumacher and pops out of its window box with the main chassis and drive-train parts installed. The main chassis plate is made of 3mm, 6082 aluminum sheet and has a large flywheel opening as well as cutouts for the differentials, 2-speed gears and throttle servo that help these components sit lower in the chassis. A slender graphite top deck joins the front and rear gearboxes and aluminum layshaft bulkheads as it snakes between the servos, the fuel tank and the engine. The top deck is narrow, but the plate graphite is 2.5mm thick, and seven screws squeeze it against the chassis; the car is definitely stiff.
A roomy radio box holds the receiver and its battery with room to spare and also encloses the switch harness. Five screws clamp the box shut, just about guaranteeing that dirt and fuel won’t get in. The servos are attached to mounts molded on the box, so all the electronic gear can be removed as one unit; four screws hold everything in the chassis.
DRIVE TRAIN. Here’s where the R12 is truly innovative. Most belt-driven nitro tourers use three belts to get power to the wheels. Schumacher gets the job done with two; a 7mm belt does the heavy work of connecting the layshaft pulley to the rear differential, then a 3.5mm belt wraps the front and rear differentials. The belt actually passes between the engine’s flywheel and crankcase (thanks to a spacer machined into the flywheel), and a pair of adjustable pinch rollers sets the belt’s tension just before it meets the front diff. As expected, a full set of ball bearings is standard.
Both differentials are ball units, and each holds 12, 2.5mm carbide diff balls. Schumacher’s “blade” universal-joint axles take power out to the wheels. The “blade” is a plastic yoke that slips over the drive pins in the dogbone end of the axle. The yoke contacts the aluminum outdrives instead of the pins, and this reduces friction and wear.
The R12’s 2-speed transmission is as unique as its two-belt drive system. The external shift mechanism uses a machined, hard-anodized aluminum carrier block to hold two crescent-shape drive dogs: one for shifting, another for engine braking. The transmission’s second drive dog engages later than the shift dog, and it stays engaged after you clip the throttle, thereby using the engine’s drag as a supplemental brake. As with the shift dog, the brake dog’s engagement point can be adjusted by means of a setscrew. You can lock out the engine-braking function entirely or set it so the engine brakes the car as long as the clutch is engaged.
The R12’s primary braking force comes from a 2.5 vented-graphite brake rotor tucked behind the 2-speed. Steel caliper plates grab the rotor, and they’re very well supported by an aluminum bulkhead. It should be a powerful setup; we’ll see on the track.
ENGINE ANDACCESSORIES. The R12 doesn’t include an engine, but everything you’ll need to bolt in a rear-exhaust small-block is in the box. A specialized aluminum flywheel provides front drive-belt clearance and holds a 4-shoe setup with a waist-style spring. The clutch bell is steel and is threaded for quick pinion changes. Thick, machined-aluminum engine mounts look as though they can handle anything short of a hemi, and a complete exhaust system with a round-port 180-degree manifold and an aluminum dual-chamber pipe is standard. I only wish the pipe had a pressure fitting; instead, the pressure line is simply forced into a hole in the pipe.
The R12’s fuel tank has a forward-facing lid for fast fill-ups and a cap-mounted pressure fitting to reduce fuel foaming. It’s a little bigger than the ROAR-required 75cc, though; to reduce the tank’s volume, a “correction bung” is supplied and must be installed inside the tank.
SUSPENSION AND STEERING. Schumacher’s well-proven lower
A-arm/upper wishbone suspension is right at home on the R12. The upper arms use steel turnbuckles to set camber, and the arms can be slid up to 4mm for caster adjustments. Droop screws in the lower arms are used to set ride height, and the suspension-arm mounting blocks can be positioned for zero or 2 degrees of arm sweep-in (in the rear) or sweep-out (up front). Rear anti-squat is adjusted by stacking washers under the forward arm mount, and front and rear toe-in are adjustable via thick steel turn-buckles.
Threaded, aluminum-body shocks are mounted on the R12’s short graphite shock towers. Preload is easily adjusted with knurled aluminum collars that use 0-ring grippers to hold their settings. The shocks use bottom-loaded seals and foam inserts for volume compensation, and Schumacher’s Vari-Tune pistons permit damping adjustments without shock fluid changes. Each piston is actually two halves nested together. By rotating the upper half, more or fewer piston holes can be selected. It works, but it’s a messy job, since you have to remove the seal cartridge to get at the pistons.
BODY, WHEELS AND TIRES. Like most competition sedans, the Fusion R12 does not include a body. I tested the car with a Protoform Dodge Stratus 2.1 body, but Schumacher supplied a Frewer DTM Touring shell for photos -looks good! Wheels and tires are included with the R12; you get white dish wheels and blue-compound slicks, which are very firm. I put them aside for playing around and shod the R12 with TakeOff TF-series foams instead. The TF sneakers are a new line for Schumacher, and the foams will be offered in 31-, 34-, 37-, 40- and 43-shore compounds, and in 26, 28 and 30mm-wide versions. I installed 37-shore, 30mm rear tires and 40-shore, 26mm front tires as suggested by Schumacher.
Copyright Air Age Publishing Aug 2003
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