NSU Ro 80

NSU Ro 80
Overview
Manufacturer	NSU Motorenwerke (1967–1969) Audi NSU Auto Union AG (1969–1977)
Production	1967–1977
Assembly	Germany: Neckarsulm
Designer	Claus Luthe
Body and chassis
Class	Executive car
Body style	4-door sedan
Layout	FF layout
Powertrain
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
Dimensions
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)
Chronology
Predecessor	NSU Spider

The NSU Ro 80 is a four-door, front-engine sedan manufactured and marketed by the West German firm NSU from 1967 until 1977.

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.

The Ro 80 was voted Car of the Year for 1968^[1] and 37,398 units were manufactured over a ten-year production run, all in a single generation.

Running gear

Other technological features of the Ro 80, 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.

Transmission

The car featured an automatic clutch which was commonly described as a three-speed semi-automatic gearbox: there was no clutch pedal, but instead, touching the gear lever knob operated an internal 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.

Styling

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.

NSU Ro 80 club meeting in Antwerp, 1993

The basic wedge profile of this 1967 design was much emulated in subsequent decades.

NSU Ro 80, IAA-Modell, Museum Autovision, Altlußheim, Germany

Interior

Interior trim combined cloth covered seats with PVC headlining and a carpeted floor.^[2] Leather seats were a factory option, although rarely specified.

Evolution

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 Ro 80s 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.^[3]

In most respect the Ro 80 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.^[3]

Unreliability

The car developed an early reputation for unreliability. The Ro 80 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.^[4][5] 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.^[6]

Commercial

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.^[3]

See also

• Comotor
• Citroën GS Birotor
• Citroën M35
• NSU Spider – the world's first Wankel engined production car
• Mazda Cosmo

References

Wikimedia Commons has media related to NSU Ro80.