2015 Honda Fit - Chassis

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Overview
Significant changes were made to the 2015 Fit's chassis to dramatically improve all aspects of ride quality, handling, steering feel and noise. The foundation of these changes is a lighter but more rigid platform with an emphasis on the rigidity of suspension mounting points for improved lateral stiffness. Newly designed front and rear suspension with revised geometry and damper settings plus sprung- and unsprung- weight reductions were also employed to improve ride quality. Steering feel was improved with a new electric power steering (EPS) system with increased rigidity for a solid, accurate steering feel. Braking was also addressed with optimal tuning for a more linear brake feel. The numerous changes result in a smooth and agile ride-and-handling character.

Key Chassis Changes

  • Increased rigidity and reduced weight
  • Front and rear roll center height changes
  • New strut-type front suspension
  • New front subframe structure
  • New high-rigidity H-type torsion beam rear suspension
  • New rear damper design
  • New EPS system

Front Suspension
The new front suspension has been redesigned and tuned to improve the shock absorption characteristics of the Fit. Used for the first time on the Fit, a new link between the suspension and stabilizer bar reduces friction to provide more linear operation. The suspension's high-speed damping is improved with the use of a blow-off valve to decrease damping at higher speeds by extending the oil passage. This allows the suspension to act more quickly and therefore allows the wheels to track the road better when surface gets rough.

Geometric changes that help the new Fit's handling and stability include a lower front roll center and an increased caster trail. To promote steering self-aligning torque while also improving feel and feedback, caster trail was increased to 0.31 in.

The newly designed truss-structure front subframe is stronger but also 4.4 pounds lighter. Similar benefits were obtained with the use of high-strength material and new designs of the lower arm, bushing and the new stabilizer bar with a larger outside diameter increasing from 0.85 in. to 0.95 in., but lighter as it is now hollow instead of solid.

The front suspension lower arm bush rate has been reduced to promote a slight longitudinal movement of the front wheel to absorb impact when hitting irregularities on the road. The result is improved suspension comfort.

Rear Suspension
Receiving a similar blow-off valve to improve high-speed damping as the front suspension, the Fit's innovative rear dampers utilize a new dual-path mounting system. This method separates regular damping load, which is fed into the upper shock mount bushing, from higher-impact bound stopper load, which is fed more directly into the body. The design allows more freedom to tune the shock bushing characteristics to improve ride quality and handling. The rear dampers are also mounted with less rearward inclination to allow them to better track road surface changes.

For increased agility through better roll steer characteristics, the rear roll center height was raised and roll stiffness increased through more rigid suspension components.

Increased strength and lighter weight were obtained through the redesign of several components. These include reducing the length of the trailing arm and lighter but stiffer rear wheel unit bearings. The adoption of a new lighter weight, high-rigidity, double-wall H-type torsion beam helps to improve handling by decreasing lateral force toe-out and reduces weight by eliminating the need for a separate stabilizer bar.

The rear trailing arm bush design has been modified to reduce initial play. The result is improved response to inputs for increased road-holding performance.

Steering
To provide a high-quality steering feel that is both refined and sporty, the Fit's EPS system received many improvements. Increased rigidity afforded by solid mountings and a larger-diameter column shaft improve steering linearity and reduced vibration for a more direct and positive steering feel. A new EPS torque sensor uses both steering angle and rate signals to provide a smoother, more linear initiation of steering assist at all speeds, further enhancing the feeling of accuracy and refinement. It also improves steering self-centering from full steering lock in condition.

When compared to the operation of a conventional hydraulic pump power steering system, the Fit's simpler and lightweight EPS increases efficiency because it does not draw continuous power directly from the engine. Other advantages of electric power-assisted steering include its simplicity and compactness (no hydraulic system is needed to power it) and its lower power consumption, which helps improve fuel efficiency.

New to the 2015 Fit is a driver-assistive Motion-Adaptive EPS. Using vehicle speed and steering angle data, Motion-Adaptive EPS works with Honda's Vehicle Stability Assist (VSA®) to detect instability in slippery road conditions both during cornering and under braking and automatically initiates steering force that prompts the driver to steer in the correct direction. For more information see the Safety and Driver Assistance section.

Wheels and Tires
The new dynamically styled Fit LX trim rides on 15-inch wheels with full covers in a cross motif, geometric style that complements the body design. The 15-inch wheels are shod with all-season 185/60 R15 tires. On the EX and EX-L fresh and sporty 16-inch alloy wheels with a high-contrast multi-spoke design provide an even higher level of visual sophistication. The 16-inch wheels come with all-season 185/55 R16 tires. A T135/80 D15 compact spare is located in the under-trunk storage space.

Braking System
The 2015 Fit features 10.3-inch ventilated front discs and 7.9-inch rear drum brakes. The standard 4-channel anti-lock brake system (ABS) and Electronic Brake Distribution (EBD) enhance stopping performance by adjusting front-to-rear brake pressure according to vehicle load distribution for optimum brake balance at all times. Sensors at each wheel send signals to the control module, which can modulate braking pressure based on individual wheel speed, optimizing brake pressure balance on all four wheels.

For 2015, the Fit's front brake calipers were redesigned to increase rigidity and the brake booster has a higher ratio—both measures to improve initial brake response. Also, the Fit's braking system now incorporates Hill Start Assist, which helps prevent the vehicle from rolling backwards when the driver switches from the brake pedal to the accelerator pedal while stopped on a hill. For more information on Hill Start Assist see the Safety and Driver Assistance section.

Chassis Features

Suspension and Chassis

LX

EX

EX-L

MacPherson Strut Front Suspension

Torsion-Beam Rear Suspension

Stabilizer Bar (mm, front)

25.4

25.4

25.4

Electric Power-Assisted Rack-and-Pinion Steering (EPS)

Steering Wheel Turns, Lock-to-Lock

2.51

2.51

2.51

Steering Ratio

13.06

13.06

13.06

Turning Diameter, Curb-to-Curb (ft)

34.1

34.1

34.1

Power-Assisted Ventilated Front Disc/Rear Drum Brakes (in, front/rear)

10.3 / 7.9

10.3 / 7.9

10.3 / 7.9

Wheels

15" w/full covers

16" alloy

16" alloy

All-Season Tires

185 / 60 R15 84T

185 / 55 R16 83H

185 / 55 R16 83H

Compact Spare Tire

T135 / 80 D15 99M

T135 / 80 D15 99M

T135 / 80 D15 99M

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