MX-5(1989～)
Chapter3:Tough decisions in pursuit of "Jinba Ittai"
Demand for improved safety finally drove the original lightweight sports cars of the 1970s to extinction. Achieving the required safety performance while keeping vehicle weight down was just as challenging for the MX-5’s developers. Computer analysis, which had been nonexistent in the 1970s, played a key role in the revival of the lightweight sports car. It is no coincidence that the MX-5 program manager was an expert in vehicle body engineering. By fully utilizing the latest computer analysis technologies, the team managed to build a light and rigid body which met modern safety requirements.
As Japan has a rainy season each year, there are relatively few convertibles on the roads. However, Mazda’s development team chose to remain faithful to the “Jinba Ittai” concept and purposefully picked a manually operated soft top. They also rejected proposals for a 2+2 seat layout in order to concentrate on a pure two-seat roadster. These and other difficult decisions ensured the MX-5 would be as light as possible.
A linear driving feel
The team narrowed down the possible engine choices to a 4-cylinder 16-valve 1.6-liter inline DOHC engine. They decided to stick to natural aspiration, without any turbo or supercharger. The MX-5’s Jinba Ittai-infused fun-to-drive character was realized by neither a surprisingly high output nor advanced engine control technologies.
While keeping mechanical losses and engine resistance as low as possible, the team achieved a smooth engine power curve and linear acceleration up to the rev limit; characteristics that provide an exhilarating experience for the driver.
In order to ensure adequate feedback when changing gears, engineers created a “powerplant frame” to rigidly connect the transmission and differential. It significantly enhanced the performance feel and became an essential technical element in the evolution of the MX-5.
For the suspension system, the development team chose a double wishbone setup for all four wheels, due to its superior dynamic characteristics. Despite the extra complexity this involved, the engineers never thought of compromising in their pursuit of the best possible sports car. The suspension is another reflection of the engineers’ dedication to “Jinba Ittai.”