2003 Honda Pilot -- Chassis
5/16/2002 5:29:58 PM
The Pilot was designed to deliver a confident, secure and fun driving experience with outstanding isolation of undesirable noise, vibration and harshness (NVH) for exceptional comfort in all driving conditions. Its chassis also provides the foundation for the Pilot's capabilities as a people and cargo hauler, 4500-pound towing platform and off-road vehicle.
The Pilot boasts the widest wheel track in its class - 66.3-inches in front and 66.5-inches in the rear - for improved handling stability, ride comfort and interior space. Chassis components were designed to provide for well-controlled body motions with ride and handling characteristics that are balanced and secure. The use of fully isolated front and rear suspension subframes enhances the Pilot's outstanding noise, vibration and harshness controls to provide a ride that is quiet as well as safe and secure.
The Pilot employs a strut-type front suspension that provides a generous 7.3 inches of wheel travel (4.3-inches in compression, 3.0-inches in rebound). Separate load paths to the unit body are provided for the coil spring and the shock absorber to reduce road noise. A solid 0.9-inch stabilizer bar is linked directly to the strut via ball-joint connections to reduce body roll during cornering maneuvers, a critical factor in minimizing the "head toss" tendency that is associated with many taller vehicles and SUVs.
The lower control arm bushings are designed to provide a stabilizing toe-out steering effect when loaded during braking or cornering. The L-shaped arm allows a very tight steering lock for good low-speed maneuverability.
A welded-steel subframe secured to the unit body's longitudinal rails supports the Pilot's engine, transaxle, transfer case, steering gear and front suspension. The front of the subframe assembly is constructed of tubular steel for maximum stiffness with minimal weight penalties and features four tuned rubber mounts to isolate the subframe from the main body structure. A stiffener located under each subframe attachment fastener helps stabilize the assembly, thereby sharpening handling and braking performance. A stiffener plate bolted across the subframe under the transfer case greatly increases the assembly's rigidity.
Two dynamic damper units and one mass damper are strategically positioned to counteract noise and vibration, while two fluid-filled engine mounts reduce the transmission of engine noise and vibration to passenger compartment. The steering gear mounts are made of heat-resistant rubber to provide good vibration isolation, the firm retention necessary for sensitive on-center-steering feel.
The Pilot's rear suspension is a compact, multi-link trailing arm layout for excellent ride and handling, minimum weight and optimum packaging. Wheel travel is a generous 4.9 inches in compression and 3.3-inches in rebound. The three links that position each rear wheel laterally run between the knuckle assembly and the subframe. A trailing arm also runs from the unit body to each rear knuckle. Coil springs seat on the lowermost lateral link and anchor against the unit body directly behind each axle shaft. Shock absorbers positioned ahead of the drive shafts run from a low point on each knuckle to a secure attachment point on the unit body. Steering knuckles are an "in-wheel" design to optimize suspension geometry and packaging efficiency. Bushing compliance provides a modest toe-in effect in response to substantial cornering and braking loads to enhance overall stability. A solid 0.8-inch stabilizer bar helps reduce body motion during cornering. A new urethane bump stop is applied to the rear suspension for improved ride quality.
The rear subframe, which supports most of the rear suspension and the rear axle drive unit, is made of high-strength steel for high stiffness and minimal weight. The shape of the rear subframe is equally important - it must accommodate the drivetrain components for the VTM-4 four-wheel drive system and the multi-link rear suspension, and still allow for the versatility of the third-row seat and flat cargo floor. For excellent ride and handling characteristics, the subframe attaches to the unit body at four widely spaced, rubber-isolated, mounting points. Rear-suspension components, especially the springs and shock absorbers, are as compact as possible to facilitate a wide, flat, load floor and to leave room for both a spare tire and a full-size fuel tank. The rear axle drive unit is mounted to the subframe by means of rubber isolators to block road and powertrain noise and vibration from the passenger compartment. A tuned dynamic damper attached to the drive unit cancels propeller-shaft and drive-shaft vibration.
The Pilot's rack-and-pinion steering system is tuned for quick, linear, car-like response and sensitive feel - and the torque-sensing power steering assist is high for parking maneuvers and low at highway speeds. The system uses heat-resistant rubber mount bushings, high-pressure die cast aluminum gear housings, a low friction material rack guide for good on-center feel and a damper valve to reduce steering wheel vibration.
Wheels and Tires
To assure both a comfortable and controlled ride, Honda engineers used computer-aided design to create tread and internal tire construction characteristics that provide a high level of comfort, and wear resistance while also achieving outstanding all-weather handling and low noise.
A 70-series tire was selected to provide optimum comfort for all passengers. Tires are 235/70R 16 104S radials mounted on 16 x 6_ inch wheels. The LX rides on styled steel wheels, while EX models feature cast alloy wheels. The compact spare is carried under the rear load floor and can be lowered by turning a hidden hex-head bolt with the provided lug-nut wrench. The hex-head bolt is located under a cover conveniently located in the rear hatch trim area. This arrangement guarantees the security of the spare and keeps it readily accessible without disturbing luggage or cargo carried onboard.
Room is provided to stow a flat or a full-size spare in the compact spare's location. Corrosion and failure of spare tire retention equipment, a common problem in some competitor SUVs, is avoided by use of stainless steel and polymer materials eliminating high-mileage failure.
The Pilot features large capacity brake components consistent with its use as a people and cargo hauler, and as a towing platform. Employing four-wheel disc brakes and four-channel anti-lock brakes, the Pilot's brakes are tuned for stable, linear and progressive braking forces. For optimum performance with widely varying loads, Pilot has Electronic Brake Distribution system (EBD) technology. EBD monitors braking force and adjusts front-to-rear brake effort to achieve maximum braking performance and stability. At the rear, a select-low braking strategy is used to help maintain directional stability in slippery driving. In the event one rear wheel verges on lock-up, triggering a pressure modulation at that wheel, brake pressure is also diminished at the adjoining wheel to help preserve the rear axle's lateral stability.
Extra-large brake rotors and calipers provide the capacity necessary for short stopping distances and excellent fade resistance, even with a heavy load. The vented front rotors are 11.8 inches in diameter and 1.1-inches thick. Solid drum-in-disc rear rotors are 12.3 inches in diameter and 0.43 inches thick. A drum-type parking brake mechanism is positioned within the inner portion of the rear rotor. Parking brakes are both set and released by stepping on a pedal located on the left side of the driver's foot well, freeing space in the console area. The tandem-type vacuum booster consists of two 9-inch diameter booster chambers.
Anti-Lock Braking System (ABS)
The Pilot's Anti-Lock Braking system (ABS) has four sensing and activating channels to detect a wheel on the verge of lock up. In the event this occurs, brake pressure is held and then reduced to permit that wheel to regain traction before full braking resumes. The front suspension geometry has a very small scrub radius to help maintain dynamic stability even when one front wheel is braking harder than the other because of uneven traction conditions.
The 19.2-gallon, saddle-shaped fuel tank is molded of high-density polyethylene for low weight, freedom from corrosion and impact resistance. It is positioned ahead of the rear wheels and over the propeller shaft to help guard against collision damage. Corners of the tank are rounded and the inside of the tank is baffled to diminish the likelihood of sloshing-fuel noise. The polyethylene filler pipe and fuel lines are light, not susceptible to corrosion and resistant to fuel vapor losses. A high-efficiency fuel pump is housed inside the fuel tank. The fuel-filter is a lifetime design that never needs replacement.
The Pilot complies with all evaporative emissions, on-board diagnostics and refueling vapor recovery requirements. The fuel vapor canister and filter are rubber mounted for noise isolation and protected against rock and debris damage by a deflection shield.
The Honda Pilot has a towing capacity of 4,500 pounds for boats and 3,500 pounds for trailers. A heavier load is acceptable with boats because their pointed bow shapes impose less aerodynamic drag on the towing vehicle than a slab-faced, square-cornered trailer.
Honda engineers conducted extensive research on the towing needs of the typical SUV buyer, including customer clinics in Los Angles and Chicago, and a survey of households with SUVs. They found that, on average, 32 percent of SUV buyers use their vehicle for towing with 18 percent towing more than four times. They also found that only about ten percent of total vehicle miles traveled by the typical SUV customer involve towing activity, and that boat towing is the most common use at 46 percent.
While conventional towing capacity figures boast a high maximum tow rating, even though some sacrifice of passengers and cargo may be necessary to suitably accommodate maximum loads, the Pilot's 3,500/4,500-pound rating is calculated to include up to four passengers and their cargo.
To help ensure that customers will be able to move a maximum rated load up a grade from rest (such as pulling a loaded boat trailer up a launch ramp), engineers sought out some of the most challenging entry roads and launch ramps in the country. Testing verifies the Pilot's ability to handle a 17-degree (31-percent) grade on mountain roads approaching Lake Cumberland in southern Kentucky and a 15-degree (27-percent) grade at 5,280-foot elevation at Lake Tahoe.
A note in the Pilot's owner's manual suggests reducing gross combined weight 2-percent for every 1,000 feet of elevation. At sea level, the Pilot can tow a 4,500-pound boat and four passengers up an 18-degree (32-percent) slope.
In support of safe towing, the Pilot's tow hitch and other hardware are factory engineered for dealer installation. The dealer-installed trailer hitch is a Class III receiver-type design that bolts on with no drilling, cutting or bumper-cover modifications. An external transmission cooler and separate power-steering fluid cooler is also included along with a harness to provide electrical power to trailer lights that plug into a connector provided at the rear of the vehicle.