Audi's all-wheel wonder turns 30

The original Quattro coupe turned the world of rallying on its ear and earned Audi a whole new global reputation. Photo / Supplied

Porsche family member Ferdinand Piech was the chief technical director of a project to develop an all-wheel-drive Audi back in the 1970s.

Piech had a degree in mechanical engineering from a Swiss university. He graduated in 1962 and went to work for Porsche from 1963 and 1971. He worked on the Porsche 906 and 917 race cars.

In 1972 he went to Audi, where he helped develop the Audi 80 and 100 sedans. Five years later, he began working on what would become the Audi Quattro.

He and his engineers knew that a car that distributes engine power to all four wheels is capable of withstanding higher lateral forces than one with rear- or front-drive. Therefore, its traction and cornering power are superior.

The engine Piech built for the prototype Audi was a turbocharged five-cylinder in-line unit.

He got the idea for such an engine after working on a turbodiesel five-cylinder unit for Mercedes-Benz. An in-line six-cylinder engine was too long for the Quattro prototype, based on a two-door VW Santana/Passat. So Piech built a five-cylinder petrol unit, using the earlier Mercedes-Benz diesel as a template.

That's roughly when the Audi catchphrase "vorsprung durch technik" - "advancement through technology" - was born. Piech was said to have coined it. It's been part of Audi since 1980, when the Quattro was unveiled at the Geneva motor show. The coupe was to turn the world of rallying on its ear and earn Audi a whole new global reputation.

Now Audi is celebrating the Quattro's 30th birthday. But back to the mid-1970s and Piech's development work with Audi. How much performance can front-wheel drive develop?

That was the question in 1976-77 during test drives in the snow in Sweden. The camouflaged Audi prototypes with their 125kW five-cylinder engines put in a worthy performance. But they were left standing when pitted against the 55kW Iltis military off-road vehicle.

The solution was obvious: a sporty Audi car with permanent all-wheel drive and plenty of engine power.

The project got off the ground in the early part of 1977 as "Development Order 262". It was masterminded by technical director Piech, project manager Walter Treser, and chassis chief Jorg Bensinger and codenamed "A1".

The prototype was a modified first-generation Audi 80 coupe with a slightly elongated wheelbase and five-cylinder turbocharged engine. The rear suspension was a second McPherson front suspension layout, rotated through 180 degrees.

In January 1978, trials began in deep snow in Austria. The prototype quickly showed how effective it was. But there was a hitch. The wife of Volkswagen development director Ernst Fiala had been driving another A1 prototype in city traffic in Vienna. She complained that the car felt "tense" on tight bends: "The car 'hops'," she said.

On bends, the front wheels took a slightly larger arc than the rear wheels, because the A1's axles were rigidly connected. The wheels needed to rotate faster.

Audi's developers focused on two objectives: the all-wheel drive was to be permanent, and it had to function without a separate transfer case and second propshaft at the front.

What followed was the "eureka" moment. Audi's transmission design chief Franz Tengler hit upon an idea as simple as it was practical: a 26.3cm long, hollow-drilled secondary shaft in the transmission, through which the power flowed in two directions.

From its rear end, the shaft drove the cage of the manually lockable centre differential. The differential transmitted 50 per cent of the power via the propshaft to the rear axle, which had its own differential lock.

The other half of the drive torque was transferred to the front axle's differential along an output shaft rotating inside the hollow secondary shaft.

The hollow shaft permitted all-wheel drive that was virtually tension-free, light, compact and efficient. The vital breakthrough was that the Quattro principle was no longer merely suitable for slow all-terrain vehicles and trucks, but also for fast passenger cars, and furthermore for volume-produced models.

All that remained was the name. One suggestion was "Carat", an acronym of the German for "Coupe All-Wheel Drive Turbo." Project manager Treser came up with "Quattro".

Said the then design chief Hartmut Warku of the name: "We wanted to symbolise a car that stands firmly on the ground. It was meant to put the emphasis on what it was capable of doing, not on what it looked like."

At Geneva, the white two-door car stood on an elevated turntable in the middle of an indoor skating rink close to the Geneva showground. It weighed 1300kg. Its 2.1-litre five-cylinder engine delivered 147kW and 285Nm of torque, helping it to sprint from zero to 100km/h in just over seven seconds and on to a top speed of 220km/h.

Production of the Quattro began at Ingolstadt at the end of 1980. Audi had initially planned to build only 400 units to enable the competition car to obtain homologation for the World Rally Championship.

But the revolutionary drive concept and its dynamic performance captivated the public from the very first day, and Audi had difficulty keeping up with demand.

The Sport Quattro with shorter overall length and wheelbase appeared in 1984, as the homologation model of the new rally car. Its lighter materials reduced overall weight, and its new four-valve turbocharged engine with an aluminum engine block delivered 225kW.

Over time Audi improved the car inside and out. The most important technical change came in 1987. The engine had been bumped up to 2.2 litres but the Quattro now featured the Torsen differential; the worm gear replaced the manual differential lock. The name Torsen was a contraction of the two words torque and sensing.

The transmission distributed power continuously but instantly diverted up to 75 per cent of torque to whichever pair of wheels achieved better grip. Thanks to the Torsen differential, which only locks up under load, the anti-lock brake system remained permanently available.

When production ended in May 1991, Audi had built 11,452 Quattros, 224 of which were Sport versions.