Honda Innovation - 2003 FourTrax Rincon

9/1/2003 6:04:00 PM

From its unassuming beginnings in 1948, Honda has been defined by creative thinking. Everything that wears a Honda logo comes from a heritage so deeply rooted in innovation that standing still is the same as going backward. Which is why-from the first 1970 ATC90 to the 2003 FourTrax Rincon--more advancements in ATV technology have come from Honda than anyone else.

Honda ATVs have always been about smart solutions to tough problems. That sort of fresh thinking goes deeper than flashy technology. It transcends any simplistic bigger-equals-better mentality. Much deeper Honda's ATV engineering is based on the premise that the truly great ideas are the ones that stand up to a full day's work. That's why Honda ATV engineers tackle the challenges of research and development firsthand. They ask questions. They understand what customers expect a product to do, perhaps better than the customers themselves. Staying ahead of the curve with ATV engineering that's as functional as it is innovative isn't easy. It's just the Honda Way. What follows is a compendium of landmark Honda innovations that have shaped the development of the All-Terrain Vehicle.

Automotive-style Automatic Transmission

A first in the ATV world, the Rincon incorporates a true automotive-style automatic transmission to route power from the engine through a hydraulic torque converter to drive to three forward gears and reverse. An electronic control unit (ECU) takes data regarding throttle opening, vehicle speed, engine speed, gear selector position, brake application and engine oil temperature to determine the optimum gear selection. And because the Honda automatic transmission shifts electronically, there are no unsightly and trouble-prone vacuum lines. Plus, the system provides true engine braking, unlike the belt-drive systems used on other brands of ATVs. In addition, the Honda automatic transmission is fully sealed and impervious to external contamination. Since the transmission uses multi-filtered engine oil as hydraulic fluid, this design simplifies maintenance and ensures an adequate fluid supply under all operating conditions.

Independent Rear Suspension

As another notable Honda first, the Rincon features an independent rear suspension with lightweight forged aluminum components to provide plenty of sophisticated, well-controlled wheel travel. This double-wishbone design incorporates forged aluminum knuckles and upper/lower A-arms that are not only strong but also yield a significant savings in unsprung weight. The rear knuckle pivots feature lightweight metal bushings in place of conventional ball joints and radius arms, thereby eliminating toe-in as the rear suspension travels through its stroke. This elegantly simple design maintains rear wheel alignment and further reduces unsprung weight, contributing to the Rincon's responsive handling. Also, lightweight single-tube gas-charged rear shocks and a stabilizer bar deliver plush, well-controlled damping through the Rincon's exceptional 8.0 inches of rear wheel travel. As an added bonus, the lack of a rear final drive case adds to the Rincon's laudable ground clearance for even better maneuverability.

Longitudinal Engine/Driveline

Though Honda's circle of engineering is comprised of interdependent components, ingenuity often radiates outward from a single bit of bright-think that makes a host of seemingly unrelated advancements possible.

Perhaps the most illustrative example of this is the powerful efficiency of Honda's longitudinal engine and driveline layout introduced on the 1995 Foreman® 400, and currently found in the Foreman 450, Recon®, Rancher™, Rubicon™ and Rincon models. It's an optimal system sending power to the wheels in the most efficient manner: straight lines. The longitudinal layout has many advantages: a lower center of gravity, low seat height, increased ground clearance, lighter weight and fewer moving parts than traditional engine driveline systems.

First, the big picture. By aligning its crankshaft with the vehicle's direction of travel, the longitudinal layout creates a lighter, simpler, elegantly efficient way of sending power to an ATV's drive wheels. This simplicity may be best seen in the driveline: Using 45 percent fewer parts, the Foreman 400 4x4 transmission, for example, weighs 41 percent less than the more conventional design used in Honda's legendary FourTrax 300 4x4, and delivers power to the wheels with 5 percent more efficiency.

Honda's longitudinal engine also rides low enough in the frame to optimize ground clearance and define a low seat height, a difficult accomplishment in ATV design. Ordinarily, increasing ground clearance to avoid hang-ups such as rocks and stumps would raise the entire vehicle. But raising the entire vehicle also raises its center of mass. That compromises handling, especially when traversing inclines, an unacceptable situation to Honda engineers.

The solution is Honda's shorter, overhead valve (OHV) engine design. Using pushrod valve actuation, this OHV design carries its camshaft down in the crankcase rather than up in the cylinder head to reduce engine height. The room that would have been taken up by an overhead cam is put to better use, lowering center of mass, lowering seat height and increasing ground clearance. A counter-rotating balance shaft makes the rubber-mounted engine smooth enough to allow the use of a lighter frame than would otherwise be necessary

Because Honda also wanted to maintain the power characteristics of an overhead-cam engine, namely the ability to rev higher than typical pushrod engines. Traditional steel pushrods would not work so lighter pushrods were necessary. Honda engineers set their sights on aluminum to create a lighter, quieter, higher-revving valve train. Aluminum pushrods expand at the same rate of aluminum cylinder and cylinder head, making for more consistent tappet clearance and a quieter engine than with stainless steel pushrods.

However, aluminum can wear faster and bend more easily than steel. A conventional welded steel cap on an aluminum pushrod created a brittle joint. Honda's solution was to develop a new aluminum alloy pushrod material. Using a unique pushrod end shape, Honda engineers came up with a revolutionary design by attaching a steel ball to the end of this alloy pushrod. The results? Two tiny steel bearings and spark of electricity cleared the way for the most extraordinary, versatile ATV design on earth. And the bright thinking in Honda ATVs goes on from there.

Torque-sensing Differential

The Rancher, Rubicon and Rincon 4x4s use a clutchless front differential system that automatically sends power to whichever front wheel has the most grip. By virtually eliminating torque steer, the new system drastically reduces the effort necessary to initiate a turn.

Electric Shift Program™ (ESP™)

Combining the control of a manual gearbox with the convenience of an automatic transmission, the ESP system lets riders shift up or down with the push of a button while an electric motor disengages the clutch, shifts the gearbox and re-engages the clutch. An onboard electronic control unit controls the speed of each shift perfectly after considering engine rpm and countershaft speed, as well as shift drum and shift spindle angles.

To maintain a smooth ride, ESP won't let the gearbox go into first or reverse at engine speeds above 3000 rpm. To ensure adequate control on hills, ESP electronics won't approve a shift to neutral at speeds greater than 2 mph.

Hondamatic™ Transmission

One of the most ingenious drive systems on wheels, the Hondamatic transmission introduced on the 2001 Rubicon creates a compact, quiet, maintenance-free package capable of transmitting engine power with up to 98 percent operating efficiency. Mounted parallel to the crankshaft, the Hondamatic system's engine-driven hydraulic pump drives a variable-capacity hydraulic motor, producing continuously variable torque output with true engine braking. An ingenious set of pump and motor pistons work with a motor-side swash plate to continuously change motor-side hydraulic capacity. The result is a smooth, seamless flow of power, perfectly matched to operating conditions. A dash-mounted knob selects either D1 for maximum performance or D2 for maximum torque. A third position puts the Hondamatic in Honda's exclusive ESP mode, allowing the rider to "shift" via two buttons on the Rubicon's left handlebar.

Radial ATV Tires (Sport ATVs)

An industry first on the 1988 FourTrax 250R and currently offered on the TRX400EX. True radial design allows a tread pattern with bigger knobs that get a better grip on the dirt for improved straight-line acceleration and cornering traction.

Snorkel Air Intake

To keep dirt, water, sand, mud and other indigestibles out of the engine's inlet tract, all Honda ATVs route incoming atmosphere to the reusable air filter via free-flowing ducting.

Vacuum-piston Carburetor

Work or play, mixing an ATV's air and fuel accurately and efficiently at all speeds is extremely tough duty. So Honda started using vacuum-piston carburetors on the FourTrax 300 series in 1988. The carburetor's vacuum-controlled piston equalizes venturi vacuum for smooth acceleration under different conditions. An auxiliary starter pump on the carburetor body injects extra fuel into the carburetor to ease starting under sub-zero conditions.

Electrically Heated Carburetor

The ATV-mounted carburetor integral electric heater system improves driveability and ensures smooth operation in cold conditions. This feature is found on the Rincon, Foreman ES/S and the Rancher series.

Rear Disc Brake

The Rincon comes equipped with Honda's first rear disc ATV brake. Located upstream of the differential, this configuration reduces unsprung weight, and increases ground clearance and wheel travel. The Rincon's rear brake also uses a Collet-type caliper--a first on an ATV--for improved maintenance.

Shaft Drive

Fully sealed shaft drive systems on Honda multi-purpose models deliver power to the wheels with maximum efficiency and minimum maintenance.


Hot or cold. Wet or dry. Honda engineers have put untold hours of development into exactly what it takes to start an ATV engine thousands of times under the most demanding conditions so you never have to worry about it.

Eccentric Axle Adjusters

O-ring chain-drive systems on Honda's sport ATV models carry the rear axle in an eccentric mounting system that is rotated to maintain proper tension and perfect rear wheel alignment.

Sealed, Easy-access Maintenance-free Batteries

The sealed design of Honda's ATV batteries give owners one less thing to worry about, and they're easy to get at when it's time for a new one.