2006 Mazda MX-5 Miata Craftsmanship and Crearure Comfort Details
CRAFTSMANSHIP AND CREATURE COMFORTS
To maximize the immediacy of the driver-vehicle interface, in addition to static attributes, the MX-5 development team placed special emphasis on dynamic aspects of craftsmanship.
Dynamic Craftsmanship
The fit of the driver to the car and its controls is a critical aspect of any enjoyable lightweight sports car. State of the art analysis tools were employed to assure that all drivers ranging from 150 cm (4 ft, 11 in) to 186 cm (6 ft, 1 in) in stature could realize a comfortable seating position.
Legroom and headroom are increased by 10 mm (0.4 in) and 17 mm (0.7 in) respectively to accommodate 95-percentile US males. Fore-and-aft adjustment is increased by 50 mm (2.0 in) over the previous MX-5. Another improvement is the addition of a steering wheel adjuster offering 32 mm (1.3 in) of vertical movement.
To perfect the location and orientation angle of the steering wheel, a driving simulator was employed. Eight sensors attached to the driver’s arms facilitated analysis of myoelectric activity during routine control movements. This information enabled engineers to fine-tune the steering to achieve a comfortable steering effort. Other measurements of manipulative ellipsoid made with the assistance of Hiroshima University faculty members allowed plotting operating-force ellipsoids quantifying the force and motion needed to activate the shift lever. This body of knowledge was instrumental in finding the driver’s “sweet spot,” or in other words, the point where the minimum effort and the least amount of motion was needed to turn the steering wheel and move the shift lever.
Further ergonomic studies revealed that the height difference between the driver’s shoulder and the top of the shift knob has a major influence over the amount of force that can be comfortably applied. This resulted in positioning the MX-5 shift lever fairly high to minimize the magnitude of grip required at the side of the knob. The knob was shaped to yield a uniform pressure no matter how the knob is gripped.
To improve heel-and-toe operation of the brake and throttle, the height difference between those two pedals has been reduced by 5 mm (0.2 in) and pad surfaces are larger. The dead pedal has been moved a bit closer to the clutch pedal to make its position more comfortable.
By polling customers, the development team learned that the surface feel, grip of controls, and their shape were critically important parameters. Leather wrapping the steering wheel helps reduce its slipperiness. Increasing the friction between the hands and the wheel significantly reduces the necessary grip force. But too much friction lowers the grip needed to the point the wheel feels sticky and over-sensitive to hand motion. So the leather used for the MX-5’s wheel and its exterior coating were very carefully selected. A glove equipped with pressure sensors revealed that most of the grip for steering wheel movements comes from palm and middle-finger pressure. This study led to a thicker layer of soft urethane padding and an egg-shaped cross-section for the rim, imparting a natural feel that is valued feature of Mazda sports cars. Simple toggle switches were added for cruise-control and audio-system functions.
The MX-5’s bucket seats are configured with spring-type cushion suspension to insulate the occupants from road vibration, reinforcements to make the upper and lower structure of the seat sufficiently stiff, and support springs firm enough to resist movement of the occupant’s center of gravity during cornering, braking, and accelerating. Compared to the second-generation MX-5, the vertical movement of the center of pressure against the seat back is cut in half. While the driver’s shoulder is free to move without restraint, the seat back provides ample under-arm torso support. The front of the seat is soft enough to permit easy pedal operation and firm enough for good thigh support. The seat-belt guide imparts a sense of oneness between the driver and car by its ease of use.
Strides in outward visibility were achieved by positioning the windshield 3-degrees more upright and by locating their bases 90 mm (3.5 in) closer to the occupants. This results in forward visibility, when looking towards the near-side windshield pillar, that’s 4 degrees wider than before. Which substantially aids locating the apex of the curve during cornering maneuvers.
Research at Mazda’s Yokohama Technical Center allowed coordination of engine sounds with the MX-5’s acceleration rate. A five-axis system—using linear, harmonic, calm, quiet, and deep indexes—was created for an evaluation panel to log their auditory impressions. Goals established were enhancing harmonic characteristics through intake and exhaust tuning, emphasizing the calm dimension by reducing high-frequency engine noise, swelling the linear aspect with reduced rumble noise, and minimizing the boom and harsh sounds at low rpm. An ArtemiS software package from HEAD acoustic allowed the panel to compare audio data by listening through head phones. A map of the car’s “voice” was created by plotting engine rpm (horizontal axis) versus sound frequency (vertical axis) with color traces indicating the intensity of the sound.
As part of this examination, the MX-5’s engines were tuned and engineered to deliver sounds consistent with JInba Ittai priorities the way a conductor directs an orchestra performing a complex musical score. The three distinct sources of noise—mechanical engine components, the intake system, and the exhaust system—were treated like the brass, woodwind, and percussion sections of an orchestra to create a harmonious voice which greatly enhances both the MX-5’s vitality and its car-to-driver (rider and horse) bond.
From idle to 5,000 rpm, the tuned lengths of the intake manifold runners play the dominant melody. Since the mechanical ruckus of the engine is subdued by a very stiff cylinder block and a well supported crankshaft, the harmony of the equal-length runners sings sweetly with an intensity roughly proportional to the throttle opening. Exhaust tones supplement the intake refrain below 3,000 rpm, after which the car is moving forward quickly enough that the exhaust contributions to the sound track are lost to the wind.
The MX-5’s Variable Induction System (VIS) is another key orchestral instrument. A valve in the intake manifold remains closed between 3,250 and 5,000 rpm to maximize torque and to maintain the equal-runner-length harmony mentioned above. Above 5,000 rpm, the valve opens to shorten runner length, thereby maximizing the engine’s output all the way to the 6,700 rpm redline. In this condition, intake runners are UNEQUAL length which generates a throaty rumble sound with the throttle floored and the tachometer climbing.
To enrich these engine notes and to add to the MX-5’s aggressive-sounding character, one wall of the intake manifold plenum chamber is tuned to resonate at 500 Hz much like tympani filling in the orchestra’s low tones.
Static Craftsmanship
The latest advancements in manufacturing technology facilitate many high-quality, finely crafted static attributes. Front bumper guards are injection molded using glass-reinforced plastic instead of steel to minimize the space required for this component. That, in turn, left room for a dramatic headlamp design and a specially curved hood opening. The guard is fitted by ultrasonic welding instead of by conventional screw attachments.
The windshield frame has a one-piece design that increases strength while producing a smooth, flowing outer surface. Sun visors nest neatly in recesses formed into the horizontal portion of the frame.
To minimize or eliminate interior gaps, the passenger-side air bag cover is seamless and a tight interface is provided between the center stack and console.
Door armrests are covered with a soft rubber material. The rigidity of the door structure was tuned to provide a pleasant closing sound.
Amber gauge illumination sets the tone for interior illumination. Audio controls, climate controls, steering-wheel-mounted switches, the Activematic shift gate, and power window switches are all illuminated with light of the same color and intensity. Black dials with a white needle improve visibility, and the needles jump when the ignition is switched on, giving a lively feel to starting up. Switch and vent register vane motion has been tuned for a high-quality sensation. Some interior trim has a matte aluminum finish for a very refined look. Many plastic interior parts have textured surfaces (when viewed under a microscope) to disperse incident light, yielding a higher quality appearance from all angles during various lighting conditions.
The new Z-fold soft top is easy to raise and lower from the driver’s seat by means of a single, central latchhandle. (Dual latch handles were previously fitted.) Hidden assist springs preserve a neat appearance. The top structure is a weight-savings design requiring no cover in the lowered position because support bows are hidden from sight. A roof drip molding above the side windows and weatherstrips with a minimum number of joints help keep rain water from infiltrating the interior. High-speed vibration of the top is discouraged by a new reinforcement at the top of the rigid glass rear window opening. The soft top is available made of cloth or vinyl.
For a cleaner and sleeker appearance, the rear window of the Sheet Molding Compound (SMC) hard top meets the deck surface and no molding is used between the glass and hard top. Rear latches that hold the top to the body are a lighter-sectioned, more elegant design. The inside of this top has a molded liner and seals that resemble the trim of a closed coupe. A safety lever is provided at each inside latch position to signal when the latch is fully engaged.
An engine cover hides unsightly hoses from view, suppresses injector noise, and provides a neatly integrated underhood appearance.
Special visual touches are the radically rounded hood opening, oval exterior motif, heavy-thread upholstery stitching, and well designed instruments that twitch slightly when the ignition key is turned.
Deep-Seated Comfort
To make the MX-5 as pleasurable as possible and enjoyable to drive on a daily basis, comfort-related details received special attention.
Wind in the hair is one thing but cockpit turbulence and buffeting isn’t fun on long drives. Small quarter windows block drafts between the windshield pillars and door mirrors into the cockpit. A newly designed aero board located between the seat back hoops is taller than before and perforated to slow down reverse-flow air that rushes into the cockpit. Mesh construction helps to reduce weight.
Even though the climate control system is smaller than before to facilitate a more rearward engine location, a highly efficient design allows it to do a better job maintaining cabin comfort with the top down or up. The addition of two HVAC registers helps direct air flow towards the waists and thighs. A total of seven climate-control modes are provided to cover every possible circumstance. In the new vent-waist mode, cool air can be directed not only towards the upper body but also towards the thighs, to alleviate heat from the sun on summer days with the top down. And in the new foot-waist mode, warm air is circulated through the foot wells and the waist-level outlets to keep lower body areas warm in winter, greatly extending the top-down season.
Audio equipment varies by market. In Europe , AM and FM radio is standard. A six-disc changer and Bose premium sound is available in high-grade models. In addition to AM and FM reception, the standard North-America and Japan MX-5 includes CD play capability with the Bose equipment offered as an option. For Australia , the standard fitment is AM/FM stereo radio with a six-disc CD player and six speakers. Bose equipment with seven speakers unit is standard on high grade models.
Rear speakers are mounted in the rear trim next to the top-inboard corners of the seats for optimum audio performance, especially with the top down (availability depends on the model). Full range and tweeter speakers are mounted in the door panels. Bose premium systems also have a full-range speaker mounted atop the dash to enhance audio imaging.
Equalization can be tailored to open or closed driving thanks to a switch that informs the head unit of the car’s configuration. A cabin-mounted microphone allows a new Bose AudioPilot system to compensate for ambient noise. The sound field and phase characteristics are prioritized slightly in the driver’s favor. The standard system has a vehicle-speed-sensitive volume switching feature that is operated manually.
2006 Mazda MX-5 Overview2006 Mazda MX-5 Chassis Details
2006 Mazda MX-5 Exterior/Interior Details
2006 Mazda MX-5 Safety, Security Environmental Details
2006 Mazda MX-5 Special Features
2006 Mazda MX-5 Specifications
