NSU Ro 80
|NSU Ro 80|
|Manufacturer||NSU Motorenwerke (1967–1969)
Audi NSU Auto Union AG (1969–1977)
|Body and chassis|
|Body style||4-door sedan|
|Engine||995 cc two-rotor Wankel engine, 115 PS (85 kW; 113 hp)|
|Transmission||3-speed Fichtel & Sachs all-synchromesh manual connected with automatic clutch and F & S torque converter|
|Wheelbase||2,860 mm (112.6 in)|
|Length||4,780 mm (188.2 in)|
|Width||1,760 mm (69.3 in)|
|Height||1,410 mm (55.5 in)|
|Curb weight||1,251–1,292 kg (2,759–2,848 lb)|
Noted for innovative, aerodynamic styling by Claus Luthe and a technologically advanced powertrain, the Ro 80 featured a 84 kW (113 bhp), 995 cc twin-rotor Wankel engine driving the front wheels through a semi-automatic transmission with an innovative vacuum system.
Other technological features of the Ro80, aside from the powertrain, were the four wheel ATE Dunlop disc brakes, which for some time were generally only featured on expensive sports or luxury saloon cars. The front brakes were mounted inboard, reducing the unsprung weight. The suspension was independent on all four wheels, with MacPherson struts at the front and semi-trailing arm suspension at the rear, both of which are space-saving designs commonly used today. Power assisted ZF rack and pinion steering was used, again foreshadowing more recent designs.
The car featured an automatic clutch which was commonly described as a three-speed semi-automatic gearbox: there was no clutch pedal, but instead, on top of the gear stick, an electric switch that operated a vacuum system which disengaged the clutch. The gear lever itself then could be moved through a standard 'H pattern' gate.
The styling, by Claus Luthe who was head of design at NSU and later BMW, was considered very modern at the time; the Ro 80 has been part of many gallery exhibits of modern industrial design. The large glass area foreshadowed 1970s designs such as Citroën's. The shape was also slippery, with a drag coefficient of 0.355 (very good for the era). This allowed for a top speed of 112 mph (180 km/h). Indeed, comparisons have been drawn between the design of the Ro80 and the aerodynamic 1982 Audi 100 built in the same factory some 15 years later.
Interior trim combined cloth covered seats with PVC headlining and a carpeted floor. Leather seats were a factory option, although rarely specified.
The company's limited resources focused on improving the reliability of the rotary engine, with much attention given to the material used for the rotor tips that sealed the combustion chambers. A feature of the engine was its willingness to rev quickly and quietly to damagingly high engine speeds, but it was precisely at these high speeds that damage to key engine components occurred: all Ro80s came with a rev counter, but cars produced after 1971 also came with an "acoustical signal" that warned the driver when the engine was rotating too fast.
In most respect the Ro80 changed very little during its ten years in production. From September 1969 the rectangular headlights were replaced with twin halogen units, and air extractor vents appeared on the C-pillar behind the doors. In August 1970 a slightly reshaped plastic grill replaced the metal grill of the early cars, and a minimal facelift in May 1975 saw the final cars getting enlarged rear lights and rubber inserts in the bumpers which increased the car's overall length by 15 mm to 4795 mm.
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The car developed an early reputation for unreliability. The Ro80 engine in particular suffered from construction faults, among many other problems, and some early cars required a rebuilt engine before 50,000 kilometres (31,000 mi), with problems arising as early as 24,000 kilometres (15,000 mi). The three-piece rotor tip seals were made out of the same material. The design fault caused the center section to have higher abrasion at cold starts than the corner pieces and the tip seals could push together, allowing the gas to blow past. With a changed tip seal design this was temporarily solved and with a tip seal center piece made of Ferrotic, the problem was entirely resolved. The fact that the rotary engine design was inherently thirsty (typically 13-16 l/100 km) and a poor understanding of the Wankel engine by dealers and mechanics did not help this situation. By the 1970 model year, most of the reliability issues had been resolved, but a necessarily generous warranty policy and damage to the car's reputation had undermined NSU's financial situation irreparably. NSU was acquired by Volkswagen in 1969, and merged with Auto Union to create the modern day Audi company as it is known today.
Alternative Power Source
In the UK, owners left with cars with seized engines that were going nowhere were provided with a solution by the Hurley Engineering Company. They supplied a torque converter adapter plate and other fittings so that a Ford Essex V4 engine could be fitted in the space left by a removed rotary engine. It was the only engine short enough to fit in the vacated space without modification to the body work. Depending on which Ford model it came from, the engine was available with front or rear sump wells, crank pulley or timing case mounted cooling fan, two capacities and a low compression version for using low grade fuel. In terms of smoothness and refinement, the V4 and the rotary were like chalk and cheese compared to the turbine quality of the rotary engine, but what the V4 did provide was dependability, an increase in torque and an improvement in fuel consumption. Later the Ford V6 was tried but needed body modifications, was thirsty and didn't quite have the right handling balance.
Series production began in October 1967 and the last examples came off the production line in April 1977.
During 1968, the first full year of production, 5,986 cars were produced, increasing to 7,811 in 1969 and falling slightly to 7,200 in 1970. After this output declined, to about 3,000 - 4,000 per year for the next three years. The relative thirst of the rotary engine told against the car after the savage fuel price rises accompanying the oil crisis of 1973, and between 1974 and 1976 annual production came in well below 2,000 units. In total 37,398 Ro80s were produced during the ten-year production run.
- Citroën GS Birotor
- Citroën M35
- NSU Spider – the world's first Wankel engined production car
- Mazda Cosmo
|Wikimedia Commons has media related to NSU Ro80.|
- "Autocar Road Test NSU Ro80 1,990 c.c. (nominal): German five-seater touring car with twin-rotor Wankel engine and front-sheel-drive. Rather poor petrol and oil consumption. Superb road-holding and stability. Power steering light with excellent "feel". Fine visibility and well-placed controls. Selective automatic transmission gives three wide performance ranges. Very advanced and pleasant car to drive.". Autocar. 128. (nbr 3755): 11–16. February 1968.
- Oswald, Werner (2001). Deutsche Autos 1945-1990, volume 4 (in German). Motorbuch Verlag. p. 403. ISBN 3-613-02131-5.
- "NSU". der-wankelmotor.de (in German). Retrieved 16 September 2010.
- "Die Gasdichtung des Wankelmotors". der-wankelmotor.de (in German). Retrieved 16 September 2010.