2001 Honda Odyssey -- Chassis

OVERVIEW
Honda engineers set three primary goals when developing the Odyssey chassis: First, they wanted it to perform like a car; specifically, superior ride, handling, maneuverability and braking. Second, in keeping with their goal of providing car-like comfort, they designed the chassis to minimize NVI-I (noise, vibration and harshness). Finally, Honda engineers wanted to design and package the Odyssey chassis components so as to take up a minimum of space, leaving the maximum amount of room for passengers and cargo.

The following list highlights the engineering features of the Odyssey chassis:

Enhanced Ride and Handling

• Low center of gravity and wide track add to stability
• 16-inch wheels and 215/65 R16 M+S tires
• 4-wheel independent suspension: front suspension is a low spring-rate strut type and the rear suspension uses double wishbone links
• Negative-offset steering axis

Enhanced Braking Performance

• Electronic Brake Distribution system (EBD) optimizes braking force in response to vehicle load
• 4-wheel anti-lock braking system (ABS)
• Electronic Traction Control System (TCS) (EX only) prevents wheel spin on slippery roads and surfaces with a split coefficient of friction
• 11.8-inch ventilated front disc brakes
• 10-inch rear drum brakes

Minimize NVH

• Floating front subframe isolates engine vibration
• Fluid-filled and electronically controlled engine mounts absorb engine vibration over a wide range of engine speeds

Packaging Efficiency and Operability

• Low floor
• Wide cargo compartment
• Compact rear suspension design maximizes rear cargo space
• Pedal-type parking brake
• Spare-tire compartment under passenger-compartment floor
• Lightweight plastic resin, 20-gal. fuel tank located in front of the rear suspension
• 2000-pound towing capacity (3500 with towing package)

CLASS-LEADING RIDE AND HANDLING
In order to create the best-riding and best-handling minivan in its class, Honda engineers designed the Odyssey body and frame so that it would have a high degree of bending and torsional rigidity, then added a 4-wheel independent suspension system. The four-wheel independent suspension offers enhanced ride and handling benefits and better isolation from road noise and vibration.

INDEPENDENT FRONT SUSPENSION
The Odyssey's independent front suspension is a MacPherson strut-type, with a large, forged lower wishbone arm that helps to feed suspension loads into the frame over a wide area. This, in turn, helps to minimize the transmission of road noise and vibration to the body and frame and also adds additional. strength of the system.

The Odyssey's ride over rough roads benefits from the front suspension's low-rate, long-travel springs, which soak up bumps and road distur-bances more effectively. The addition-al space these springs require is read-ily available in the Odyssey's front end, thanks -to its large front sub-frame and crush-zone area.

In order to enhance its handling and stability, the Odyssey's front suspen-sion is designed so that the inside front wheel will assume a slight toe-out attitude when cornering, and both front wheels will assume a toe-out attitude when braking. A bush-ing, built into the front, inner pivot of the lower, front suspension arm, pro-vides the necessary compliance. The result is quicker, more linear steering response and enhanced straight-line braking stability.

DOUBLE WISHBONE REAR SUSPENSION
The Odyssey also provides the ride and handling advantages of a double wishbone rear suspension. Since Honda engineers wanted the Odyssey to have a wide, low and flat cargo floor, the rear-suspension components needed to fit into the space available under the floor, while providing superior ride and handling characteristics. In order to accomplish this, they eliminated the long, vertical upright that normally connects the upper and lower transverse links to the hub and wheel, and connected the various suspension links directly to the bearing carrier/hub assembly. Next, because the springs and shock absorbers take up a majority of verti-cal space in the rear suspension, Honda engineers specified a wider, lower spring to take up less vertical space and moved the rear shock absorber to a new location outside the spring pack, then angled it to better fit under the floor. As a result, the Odyssey rear suspension sits lower and takes up less space, and the body can also sit lower on the suspension. This lowers the vehicle's center of gravity, which improves handling and stability.

A large rubber compliance bushing, built into the leading-link pivot where it anchors to the body, helps to absorb impact forces from sharp pavement breaks and bumps.

A small degree of toe-in compliance has been built into the rear suspen-sion transverse links, where they pivot at the wheel carrier. Any side pressure that may result from corner-ing, off-camber road or crosswind, causes the outside wheel to assume a slightly toe-in attitude. The resulting steer-effect helps to counter the roll-induced steer effect of the side force, so the Odyssey tracks straighter under these conditions.

The static rear roll center height is 148 mm (5.8 in.) Rear suspension travel is 220 mm (8.7 in.).

ENHANCED STABILITY UNDER A VARIETY OF DRIVING CONDITIONS*
In addition to the precise control and inherent stability of its 4-wheel independent suspension, front-wheel-drive layout and 16-inch wheels, Honda engineers incorporated several additional features into the Odyssey chassis to enhance its stability under a variety of driving conditions, including a high static stability factor, negative-offset scrub radius steering, a brake-actuated electronic Traction Control System (TCS) (on EX models), a 4-wheel anti-lock braking system (ABS) and an Electronic Brake Distribution system (EBD).

HIGH STATIC STABILITY FACTOR
The Odyssey boasts what Honda engineers call a high static stability factor, meaning its relatively low center of gravity, long wheelbase (118.1 in.) and wide track (66.1 in., fr./66.2 in., rr.), combine to give it a greater resistance to pitch and roll forces, such as crosswinds and off-camber roads. As a result, the Odyssey tracks straighter, with less need for steering correction. It also corners flatter and is less prone to nose dive under heavy braking.

NEGATIVE STEERING OFFSET
The steering system incorporates a negative-offset scrub radius, which helps maintain straight-line control on road surfaces with differing traction coefficients; for example, a typical carpool lane when one tire is on the road shoulder and the other is on the pavement.

ENHANCED BRAKING STABILITY FROM ABS AND ELECTRONIC BRAKE DISTRIBUTION SYSTEM (EBD)
The Odyssey braking system uses 11.8-inch front ventilated disc brakes and 10-inch rear drums. Power-assist is provided by twin-vacuum servo units that provide a firm, progressive feel without a resultant high pedal effort. In addition, the pedal ratio between the force applied by the driver's leg and the resistance of the hydraulic system has been matched to provide the driver with the optimum balance of force and control.

A pedal-type parking brake, under the left side of the instrument panel, is used instead of a lever-type, which, if mounted between the driver's and passenger's seat, would interfere with the walk-through area.

An anti-lock braking system (ABS) is standard on the Odyssey. The Odyssey ABS system is a four-sensor, three-channel system with a speed sensor located at each wheel. There is a separate channel for each front wheel and the rear wheels share a common third channel. This is a "select-low" system, meaning the system controls both rear-wheel slave cylinders together.

When the driver applies maximum brake pressure and impending wheel lockup is detected, the sensors send a signal to an electronic control module (ECM). The ECM processes the information, then signals the ABS system to momentarily reduce, then reapply, full brake pressure at the appropriate wheel(s). If impending wheel lockup occurs when brake pressure is reapplied, the cycle is repeated. This allows the tires to maintain maximum braking traction without locking.

Since a large vehicle like the Odyssey has a higher center of gravity than an automobile, the braking system is more sensitive to the placement and amount of cargo. For example, during hard braking, when lightly loaded, there is more of a tendency for rear-brake lockup to occur, while plenty of traction is still available for braking at the front, wheels. In order to minimize the onset of rear brake ABS engagement, the Odyssey has an Electronic Brake Distribution system (EBD). When the ~rear-wheel ABS sensors detect incipient lockup, EBD signals an additional ABS solenoid to reduce braking force to the rear wheels, thereby maximizing braking force.

TRACTION CONTROL SYSTEM (TCS) HELPS MAINTAIN TRACTION UNDER VARYING ROAD
Odyssey EX models incorporate an electronic Traction Control System (TCS). TCS uses the ABS sensors and software to detect front-wheel slippage when power is applied. When slippage is detected in one or both wheels, it activates the brake calipers at the appropriate wheel until it stops slipping. The system is very effective in providing traction and stability on slippery surfaces, such as ice or snow, and helps maintain stability on surfaces with a split coefficient of friction; for example, when only one wheel is on ice and the other is on dry pavement.

WHEELS AND TIRES
The Odyssey features 16-inch wheels and tires. (In the class, only the Chrysler Town and Country offers wheels and tires this large as an option.) The Odyssey EX model has alloy wheels and the Odyssey LX has steel wheels with full wheel covers.

VIBRATION-REDUCING ENGINE-MOUNTING SYSTEM
In addition to its low-vibration 60-degree V-6 engine, the Odyssey uses a special subframe and engine-mounting system to further reduce vibration. The subframe is mounted to the mainframe rails, using rubber insulators. The engine-mount brackets and dynamic-damper brackets that mount the engine to the subframe are made of cast aluminum. Cast aluminum brackets are more resistant to vibration than stamped-steel brackets. Vibration absorption is further enhanced by two rubber bushing mounts, a passive fluid-filled engine mount and an electronically controlled fluid-filled mount.

The electronically controlled rear engine mount is designed to damp low-frequency, high-load vibrations such as those that occur when the engine is idling in gear and the air conditioning is on. The mount contains two fluid chambers separated by a barrel-type valve. At low engine speeds, the valve is open so the full volume of both chambers can damp the vibration. As engine rpm increases, an electronic control unit commands a vacuum actuator to close the valve; taking one of the chambers out of the system and making the mount firmer so that it more effectively damps road and driving vibration.