Road impressions

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Mazda RX-7

Mazda makes no bones about it; the brand new version of its successful 2 + 2 sports coupe RX-7 was designed from the start for the American market. When you consider that of the 470,000 units to have rolled off the production lines in Hiroshima since 1978, 360,000 have been destined for Stateside consumption, Mazda’s preoccupa­tion with the tastes of Uncle Sam’s children begins to make sound economic sense. The good news for European customers, how­ever, is that a total revision of the car has resulted in some very worthwhile improve­ments, even if the old £11,499 price is likely to have risen quite considerably by the time the newcomer finds its way onto the UK market after February 1986.

From driving experience in both Japan and America, in a variety of specifications, we can say that the new RX-7 is a whole lot better than its predecessor, whose only real claim to advanced technology was its con­tinued use of the rotary engine. Bar the same company’s Luce 929, the RX-7 is still the only car in the world to use this type of powerplant, yet the Japanese are confident it is perfectly capable of matching conven­tional piston engines in performance, fuel economy and longevity. On the latter point the company claims owner reports in excess of 150,000 miles, while the new RX-7’s type 13B unit has a new design of apex seal said to prolong life further while enhancing torque and economy. Compared with the original UK RX-7’s 12A engine, the new 2.6-litre equivalent produces 35 bhp more (150 at 6,500 rpm) and is torquier (134 lb ft at 3,000). Other improvements include a 14% lighter rotor, a reduction in water jacket capacity to provide 20% faster warm­up and a new variable-intake porting system in which a smoother spread of power is achieved by staggering input timing. Where the 12A relied on two twin-stage Nippon four-barrel carburettors, the 13B uses Nippon Denso fuel injection based on Bosch L-Jetronic patents.

If the engine has been brought up to date, so has the remainder of the RX-7. After years of minor criticism, gone is the vague recirculating ball steering and in its place is a crisp rack and pinion design which has variable assistance controlled by electronics available as an option. Ventilated disc brakes are fitted all round, the fronts working in conjunction with powerful four-piston calipers. Mazda’s engineers, led by project head Akio Uchiyama, couldn’t quite bring themselves to go the whole hog with ABS and 4WD, but we understand both systems are in the production pipeline and are currently undergoing development testing. The same applies to the triple rotor engine, for which RX-7’s engine bay has plenty of room.

It is in the suspension department that the greatest changes are to be found. Uchiyama has retained the familiar MacPherson strut and bottom wishbone system at the front, yet has now used aluminium in places to save weight, while the car’s piece de resistance is to be found aft. Out has gone the unsophisticated but well located live rear axle and in its stead is an entirely new independent set-up codenamed DTSS for Dynamic Tracking Suspension System. In Japan the idea of four-wheel steering (4WS) is all the rage and while Mazda hasn’t quite gone that far on RX-7 it has come up with something approaching that philosophy. In essence the new system is based around trailing arms and MacPherson struts but each rear hub is mounted on a triaxial floating mounting comprising one ball joint and two rear bushes, one of which is pre-loaded. In response to high lateral-G inputs (over the 0.4 mark) the outer rear wheel ceases to toe out and automatically adopts a small measure of toe-in to increase understeer and enhance stability. The system is designed to operate whenever the car undergoes a de­stabilising manoeuvre, such as braking, accelerating, hard cornering or sudden lane changing.

A further refinement is a Camber Control Mechanism (CCM) which is designed to give the more compact system the same behavioural characteristics as a pure double wishbone set-up by maintaining desired camber angles. The icing on the cake is Auto Adjusting Suspension (AAS), which is available as an optional extra. It comprises a system of electronic sensors which monitor variables such as braking, acceleration, vehicle speed, steering angle and latetal-G to calculate the degree of damping required. There are three modes: Normal, Firm and Very Firm, with a driver selector giving a choice between Firm or Sport. Above 50 mph the front dampers automatically assume a Firm mode while in Sport all four dampers are Firm. Very Firm is activated by strong destabilising forces and functions automatically, depending on lateral-G.

One look at the RX-7 is sufficient to cause great confusion with products from Porsche. Despite Uchiyama’s assertion that aero­dynamic and practical considerations, plus a desire to retain the B post treatment from the original car, made the greatest influence on the new model’s styling it is quite clear that Mazda evolved the sleek shape to echo known Porsche customer tastes. The result is something we found grew on us, to the point where the hitherto handsome old car suddenly began to look decidedly lacking in harmony.

In test sessions at Mazda’s Miyoshi Global Handling Circuit, and California’s doomed Riverside International Raceway, plus during a brief spell on roads from Newport Beach to Riverside, the RX-7 displayed remarkably low wind noise characteristics and a superb ride, even on rough and broken surfaces, while as one would suspect the European specification cars handle markedly better thanks to firmer damping which dramatically lessens a tendency to roll oversteer evident on the US specification versions. At Riverside we saw a regular indicated 120 mph before the banked Turn Nine in the Euro cars and as ever the rotary power unit proved more than eager to rev way beyond its 6,700 rpm warning buzzer, although we weren’t over-impressed with its torque beneath 4,000 rpm. It weighs in a fair bit heavier than the older car, mainly because of its upmarket upgrading, but possesses a satisfying feeling of solidity and is a much more refined vehicle than its fore­runner.

The UK specification has yet to be settled but Mazda is working hard to keep the price below £14,000 to place the car firmly in Porsche 924S/944 territory. UK won’t get the 180 bhp Turbo, nor will it get ABS or power steering but from our long lead opportunity we’d definitely advise potential Porsche buyers to wait a few more months and try RX-7 for themselves before making a final decision. – D.J.T.

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