Honda Civic -- Chassis

Overview
Honda has always been at the leading edge in suspension technology. Early on, the engineers realized that to accomplish the goals of a short front end and a more spacious passenger compartment and trunk, both front and rear suspensions on the 2001 Civic would have to be new designs. In addition, a unique new flat floor would help provide interior room and provide the foundation not only for the new chassis, but helping meet safety objectives as well.

So with a clean sheet of paper, the engineers targeted a comfortable and precise driving experience. The result is a smoother, suppler ride, with minimal body roll in the corners, providing the precision driving experience Civic owners have come to expect and demand.

MacPherson Strut Front Suspension
To reduce the overall length of the 2001 Civic, the engineers studied all components. One way to reduce length was to create a new front suspension system. The engineers then developed a state-of-the-art MacPherson Strut design. Changing the front suspension system also provided the engineers with the space they needed to relocate the steering gearbox.

  • The 2001 Civic has a high-mounted steering gearbox. This arrangement uses 43-percent longer, high-mounted tie rods to steer the vehicle and provide improved toe control (the amount the tires angle in toward the body) when compared to conventional MacPherson strut or double wishbone front suspension systems. In addition, this new steering system allows the Civic to track smoothly through corners.
  • A combination of the rigid chassis and refined suspension geometry increases the front tire contact with the ground so the 2001 Civic feels stable on the road, particularly during lane change maneuvers.
  • The front suspension uses Honda's progressive valve gas-filled shock absorbers that effectively absorb the ruts and bumps in the road, providing a smooth, comfortable ride.
  • Spring rates for front compliance bushings were reduced 24 percent for smoother ride.

Double Wishbone Rear Suspension
The new rear suspension is more compact than its predecessor. This compact, triangular rear suspension requires less space because there is no trailing arm alongside the fuel tank.

  • This design enabled the engineers to move the exhaust pre-chamber from the cabin floor to the rear area. In turn, that enabled them to create the first flat "tunnel-less" floor in the interior, and yielded a wider trunk.
  • This suspension design moves the back tires rearward in order to reduce the shock from the road surface for a smoother, more comfortable ride.
  • The rear suspension provides secure tire-to-ground contact by enhancing the rigidity of the body and bearings for smooth and stable handling.
  • Spring rates for rear compliance bushings have been reduced by 15 percent, again contributing to a smoother ride.

Well-Balanced Roll Center
To help ensure precise and stable handling, the Civic suspension geometry has been designed with a well-balanced roll center. The suspension roll center is 85.7 mm above ground level in front and 156.7 mm above ground level in the rear.

Wheels and Tires
The 2001 Civic models have larger diameter wheels and tires and EX models now have a larger 15 inch tire compared to last year's 14 inch tire. The tires feature new materials and refined construction technology. These tires provide better fuel economy by reducing rolling resistance, while also enhancing wet and dry handling and traction when driving in snow.

Power Steering
The steering ratio has been changed from 17.5:1 to a quicker 14.5:1 for a more nimble steering response. In addition, the 2001 Civic uses a variable load power steering pump. In comparison to the number of revolutions of a conventional power steering pump, a linear injection volume is achieved with a relief valve, which adjusts the necessary power assist through oil quantity control. Due to the variable type pump cam, unnecessary oil injections in the 900 rpm and higher range are eliminated, resulting in a 0.5 percent improvement in fuel economy.

Braking
The front discs have been increased from 9.5 inches to 10.3 inches in diameter on Civic DX and LX trim levels (the EX already had the larger diameter front discs).

Three-Channel Anti-lock Braking System (ABS)
ABS is standard on 2001 Civic EX models. It continues to be a four-sensor, three-channel system with a speed sensor located at each wheel.

ABS enhances steering control during hard braking. Speed sensors at each wheel send signals to the ABS control module. When the system detects impending wheel lockup, it first holds, then reduces hydraulic pressure to the affected wheel, letting it regain traction before full braking resumes. The ABS function is also highly effective on split-friction surfaces in which the wheels on one side of the vehicle have significantly less traction than those on the other side.

With this four-sensor, three-channel system, it apportions braking power to the front wheels independently and to the rear wheels in tandem. This enhances the driver's ability to maintain steering control during hard stops on slick road surfaces.

Flat Floor
An integral part of the new Civic is its unique flat floor. The challenge presented by a flat floor is reduced rigidity (because a flat sheet flexes more readily than a formed one). To overcome this tendency, the new Civic has a "tunnel side frame" with a large, flat, cross-section replacing the usual tunnel structure. This improves torsional rigidity and makes the body stronger.

  • In the previous Civic, the rear side frame had a curved shape using a rear "outrigger" to connect it to the side sill. On the 2001 Civic, the side sill and rear side frame are straighter, which made the overall connection between the two more direct and rigid.
  • The new rear suspension design also allows for a straighter rear side frame.

Fuel Tank
The 2001 Civic features a new blow-molded plastic fuel tank that increases capacity and reduces emissions. This design allows for a more complex shape so it can be molded around other components, optimizing fuel tank capacity while allowing interior and trunk space to be increased.

  • Fuel tank capacity is increased to 13.2 gallons from 11.9 gallons.
  • Up to one third of all vehicle emissions occur while the vehicle is parked, including gasoline evaporating into the atmosphere. The 2001 Civic counters this by adopting a returnless fuel supply system that effectively seals the tank to reduce vapor loss. This helps improve the thoroughness of the evaporative system, which also lowers the standing emissions levels.
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