In 1932 German manufacturers Audi, DKW, Horch and Wanderer joined forces to form Auto Union. The main goal of this joint venture was to get a better position in the market and offer some real resistance to Mercedes-Benz. Although all four continued to produce cars under their own name, they shared technology and a four-ring badge on the radiator. When Mercedes-Benz announced their intent to enter Grand Prix racing in 1934, Auto Union could of course not stay behind, especially considering the huge support offered by the German government. With no real racing experience at hand this was easier said than done. They eventually employed the services of Dr. Ferdinand Porsche and Adolf Rosenberg, who were already in the process of building a new Grand Prix car.
Porsche had previously been employed by Austro Daimler and Mercedes-Benz for whom he designed the highly successful S-Type racing car. Almost a decade earlier Rosenberg had successfully raced a mid-engined car and he convinced Porsche to follow that route for their new Grand Prix racer. They felt there were several major benefits of this layout. Firstly there would be considerably more weight on the rear axle, which should improve traction. Another advantage was that a prop-shaft running through the driver’s compartment was no longer required. This meant that the driver could sit considerably lower in the car, lowering the centre of gravity and also the wind resistance.
The location of the engine was just the first of many unconventional design elements of the Porsche/Auto Union Grand Prix car. Even though Porsche was restricted to a maximum weight of 750 kg, he opted for a sixteen cylinder engine, keeping the mass down by using exotic alloys for the block and head. The cylinders were angled at 45 degrees, leaving just enough space for the intake manifold, which fed from the rear of the engine by a huge Rootes-Type Supercharger. Porsche opted for a simple and lightweight valvetrain consisting of a central camshaft, operating the valves to push-rods and rockers. In its first version, displacing just under 4.4 litres, the V16 engine produced 295 bhp at just 4500 rpm.
Dubbed the Auto Union Type A, the revolutionary mid-engined Grand Prix car made a very high profile debut at Avus in May of 1934. The new Mercedes-Benz cars were also present, but a problem discovered in practice forced them to withdraw. Auto Union driver Hans Stuck took the lead during the very wet first lap and had built up a one minute lead after just one lap. Behind him two Alfas fought for second and eventually for the lead when Stuck was forced to retire with a clutch failure. August Momberger was the only surviving Auto Union driver and he crossed the line in third, which was quite a disappointment after Stuck’s superb first lap, but there clearly was plenty of potential in the Auto Union GP car.
In the next few races, Auto Union’s debut performance was put in perspective by the now fully functioning Mercedes-Benz W25s and the all-star driving team. Only Stuck could match them and scored Auto Union’s first major victory at the all important German Grand Prix at the Nürburgring. The unusual layout of the Auto Union suited hillclimbs particularly well and Stuck won four of them in 1934. To bridge the gap with Mercedes-Benz, Archille Varzi was lured from Alfa Romeo / Scuderia Ferrari to join Stuck and the highly talented and young Bernd Rosemeyer. They were given the modified Type B to drive, which featured a larger, more powerful version of the V16 engine and torsion bar springs at the rear in place of the semi-elliptic leaf spring.
Varzi celebrated his Auto Union debut with a win in the Tunis GP, although still with the Type A. At the Type B’s debut, Stuck again excelled, but lost valuable when a tyre burst at 290 km/h. He was certainly not the only with the tyre problems and it became painstakingly clear that tyre technology was not able to cope with the increased power and speed at all. Fagioli eventually won the race with the latest version of the W25, which featured a 3.7 litre straight eight engine with twin cams and four valves per cylinder. Throughout the season the talented drivers struggled to keep up with the W25s and only when all the Mercedes-Benz racers failed at the Italian Grand Prix could Stuck add Grand Prix victory to Auto Union’s tally.
After the disappointing 1935 season, Porsche threw all caution to the wind and increased the V16’s displacement to just over six litres; boosting the power to a staggering 520 bhp for the Type C. Although this was an obvious improvement, it also made the Auto Unions even more difficult to control. At the time and for years to come the tricky handling was attributed to the engine’s location, but as Cooper proved two decades later there was nothing wrong with that. The unpredictability of the front and rear suspension contributed greatly to the Auto Union’s bad reputation. Only Rosemeyer and to a lesser extent Stuck could get to grasps with the Type C and at the occasions that he did, he was unstoppable.
It goes without saying that Mercedes-Benz did also improve the W25 for 1936, increasing the displacement of the eight cylinder engine to 4.7 litre. Varzi scored a controversial win in the Tripoli Grand Prix after his team mate Stuck was asked to slow down to let him by. Before the race the German government had asked for an Italian winner in the country’s colony as a sign of good will towards the Axis ally. Rosemeyer first took a victory in the Eiffelrennen at the Nürburgring and then repeated that feat on the same track during the German Grand Prix. With wins in the Swiss and Italian Grands Prix, he racked up enough to be crowned champion. Stuck made Auto Union’s success complete by finishing second.
With Porsche now engaged in Adolf Hitler’s Volkswagen scheme, there were little changes made to the Type C for the 1937 season. Determined to set things straight Mercedes worked hard over the winter and debuted the further refined W125, which featured a DeDion type rear suspension and a 575 bhp version of the eight cylinder engine. Although they still managed to win some minor races Rosemeyer and Stuck struggled against the mighty Mercedes-Benz. For 1938 the rules were changed heavily and the successful Type C was rendered obsolete. Porsche was replaced by Prof. Eberan von Eberhorst and work was started on the Type D. After Porsche’s departure there was a second major blow early in 1938 when Rosemeyer fatally crashed during a record attempt with a modified Type C Streamliner on the Autobahn.
Although it took many years to sink in, Porsche and Rosenberg had shown the first sign of things to come with their mid-engined Auto Unions. Since the 1960s this layout has become the norm for single seater and sportscar racing around the world. The revolution might have started much sooner if the War had intervened. Today only very few examples of the V16 Auto Unions remain with most of them fallen victim to racing incidents and later War-time aggression.
Sadly none of the Type A Auto Unions have survived. Using drawings provided by Audi, British experts Crosthwaithe and Gardiner have created a perfect replica for a prominent Belgian collector in the 1990s. Still in full running order, it is seen here during the 2009 Goodwood Festival of Speed where 75 years of the Silver Arrow was celebrated.
Source: Ultimate Car Page