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 Samurai attack on
the Ferrari horses... |
Prepare to discard all your favourite notions about Japanese sport cars. Step one: realize
that Japanese sport cars are not necessarily lightweight runabouts like the Toyota MR2 and
Honda CRX, or on the other hand, luxurious GTs like the Nissan 300ZX, the Toyota Supra and
the Mitsubishi Starion. Step two: stop looking only to Europe for the latest in high
performance technology. Step three: admit that Japanese cars are joining the 150-mph,
0-to-60-in-six-second ranks.
Now that you are up to speed, we have one final shocker. You would not have to sell your
sister into slavery to buy the machine responsible for this revolution in the sport-car market.
The super car that supposed to fulfil such a demand and be the replacement of the 300ZX
(Z31 type) called MID 4, courtesy of Nissan .... Given Nissan's long history of sport car
production, it's hardly surprising that it would be the first Japanese marker to offer
a take-no-prisoner model.
MID4 Prototype 1985
The MID4 was armed with a full load of performance technology. Four-wheel drive,
four-wheel steering, anti-lock brakes, a four-cam, four-valve V-6 mounted amidships,
and low-slug, two passenger body was all part of the program.
With such equipment, the MID4 could easily wear a Ferrari prancing horse or a Porsche crest.
The Nissan logo that is stamped into its tail instead is particularly attractive, for
it ensures that the MID4 will have everyday reliability and price that would not require
collaboration with an investment banker.
The responsibility of creating the MID4 was given to a team of designers headed by
Shinichiro Sakurai in the spring of 1984. Sakurai was a well known Japanese car
enthusiasts as the designer of the Nissan Skyline sport coupes, which have been so
successful in the domestic market over the past fifteen years. The progress of Sakurai's team
was amazingly rapid, that the first four prototypes were completed by March 1985. After
the first four, six second generation were built, and these were said to be very close
to what's planned for the final production model.
| Sakurai did not skimp on the MID4's design. For optimum handling, he chose a
mid engine location. To improve the high speed stability of the mid-engine layout,
as well as to project a high-tech image, he specified four wheel drive. Naturally,
anti-lock brakes and a four-valve engine were deemed essential for a car of this class.
One the basic checklist was established, Sakurai's team chipped in several other
sophisticated refinements to bolster the MID4's sporting, high tech profile.
The engine, for example, is an evolution of the fuel-injected, 3.0-liter V6 that powered
the Maxima and 300ZX (Z31). For MID4 duty, it had all new all-new heads with four valves
per cylinder, actuated by belt-driven double overhead camshafts and hydraulic bucket tappets.
Such features already describe a distinguished powerplant, but the MID4's engine had
additional refinements.
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The intake cams were regulated by a hydraulically actuated and electronically controlled
mechanism that varied the valve timing with rpm. The intake manifold had two unequal-length
runners for each cylinder to improve breathing throughout the rpm band.
The MID4 heralded a new era for car enthusiasts
Each cylinder had its own ignition coil mounted above a long-life, platinum tipped spark
plug. Each spark plug was affixed by a piezoelectric detonator sensor that helped the
engine-control computer determine the optimum ignition timing for each cylinder. Finally
the MID4 had a drive-by-wire system instead of a mechanical connection between the
accelerator pedal and the throttle plate. A sensor on the accelerator signalled the
driver's desire for a change in power output to engine-control computer. The computer
than modulated the throttle opening, ignition timing, or fuel delivery (or combination
of these elements) to produce the smoothest and most efficient power change that the
driving conditions permitted.
Nissan had no depth of experience to call on for the design of the MID4's chassis, but
that did not stop the design team from specifying a very complex system of delivering
power from the mid-mounted, transverse engine to all four wheels. Maxima transmission
mounted in line with and to left of the V6.
| Spur gears transferred the output from the
transmission to a planetary-gear centre differential located behind the engine and
transmission assembly. This device than split the power and sent one third of it to the
front axle and two third to the rear, the two outputs being carried by the coaxial shafts
extended to the right of the centre differential.
The inner shaft runner straight to the rear axle differential, but the power from
the front axle travelled a more circuitous path: from the outer coaxial shaft, to a
spur-gear set, along a second output shaft, through a set of bevel gears, along a short,
solid driveshaft, through a longer tubular driveshaft, and finally trough the front
differential to the front wheels. A viscous coupling located on a second output shaft
limiting the speed difference between the front and the rear axles.
The design of this intricate driveline was subcontracted to Styer-Daimler-Puch in Austria
in order to save time and to take advantage of Styer's four wheel drive experience.
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The front/rear torque split of 33/67 percent was selected to complement the MID4's 40/60
front/rear weight distribution and provide the neutral handling that Sakurai wanted.
Although the viscous coupling automatically prevented large speed differences between
the front and the rear wheels, a limited slip differential is also used in back, ensuring
firm traction under acceleration and promoting straight line stability.
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An emphasis on stability is evident in much of the MID4's design. Sakurai did not want
a car whose performance can be appreciated only by experienced drivers, and the MID4's
suspension was designed accordingly. Unlike several recent high-performances Japanese
cars the MID4 rode on struts all around. Although such a layout is generally regarded
as low on the sophistication scale, Sakurai's design team incorporated many detail
refinements to improve the struts' operation.
In front, the struts were angled sharply inward and located by very long control arms.
This configuration was possible because the MID4 forward compartment housed only a radiator
and few other pieces of hardware. The front suspension geometry produced good camber and
toe curves, as well as low hoodline. The dumpers were gas pressurized had external
reservoirs and could be adjusted from the cockpit to any of three settings. In the rear,
each strut were located by a semi-trailing control arm and lateral link.
This layout caused the rear tires to toe in as the suspension bushing defected under
cornering of braking loads. Normally there would be undesirable toe-out during acceleration,
but the bushings were shaped asymmetrically to be stiffer under acceleration, resulting in
little actual toe-out.
Nissan's HICAS system also contributed to secure handling, which produced a limited form
of four wheel steering. HICAS (High Capacity Active Control Suspension) that was already
production on the Skyline in Japan. On MID4, the system was incorporated in rear suspension's
lateral links, which are anchored in hydraulic cylinder behind the powertrain assembly.
Hydraulic pressure was provided by the power-steering pump, and that sensed the MID4's speed
and steering-wheel angle. As speed and cornering force increased, the rear wheels steered
toward the centre of the corner a maximum of 0.5 degree, thus improving stability. The
rack-and-pinon system that steered the front wheels was power-assisted largely in the order
to provide the hydraulic pressure for the HICAS system.
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Full load of performance technology
Sakurai's penchant for the safe and secure chassis dynamic also mandated an antilock
braking system, which operated in conjunction with single-piston callipers and large
ventilated rotors.
A conventional stamped steel unit construction chassis held all these parts together.
Except for the steel roof and engine compartment cover, all of the MID4's body panels
were fibreglass.
A change of body materials gave Nissan the perfect opportunity to modify the MID4's
styling, which was its weakest feature. There were too many echoes of other mid-engine
sport cars in the MID4's lines. While the various elements did hang together reasonably
well, the overall effect was neither contemporary nor particularly stunning.
| The interior worked as well as it looked, provided one fits the package. The
cockpit was entirely behind the front wheels, allowing the foot wells to be full
and wide and nonadjustable steering wheel to be nicely positioned.
A full set of
round gauges were housed in a simple binnacle directly in front of the driver and
the rest of the dash is clean and smooth. The climate controls and the radio were
housed in the centre console. All surfaces were tastefully finished in leather.
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The MID4 heralded a new era for car enthusiasts. It was certainly the first
Japanese foray into the realm of truly sophisticated sport cars, but it would
have hardly been the last.
Sz.S.
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