THE Auto Union racing car was built in two basic forms, the 16-cylinder C-type which can through the 1934-1937 Grand Prix Formula and the 12-cylinder D-type which ran in 1938 and 1939 to the Formula of those years. It is the D-type Auto Union which concerns us this month. The Formula put a limit of 3,000 c.c. (3-litres) on supercharged engines and Dr. Porsche and the Auto Union engineers settled on a V12-cylinder layout for this capacity, while the concept of the whole car was basically similar to the original P-wagen design of 1933. The driver sat ahead of the engine, while the engine itself was ahead of the rear axle, with the 5-speed gearbox protruding out behind the rear axle. The chassis was of the ladder-type, made up of large-diameter steel tubing with similar tubular cross-members, while front suspension was of the Porsche trailing-arm system with transverse torsion bars. At the rear a de Dion layout was used with longitudinal torsion bars. The C-type Auto Union had taken the forward-mounted driver / mid-engine concept to extremes with the result that the cars were not easy to drive and were very prone to extreme over-steer, or “tail-happiness”, curbed only by the brilliant driving of the likes of Bernd Rosemeyer. With the D-type attempts were made to provide a more orthodox handling car, still retaining the mid-engine layout, and to this end the fuel was carried in pontoon tanks so that the driving position could be moved more rearwards than on the C-type.
For the years 1938 and 1939 Prof. Robert Eberan von Eberhorst took over from Professor Ferdinand Porsche, and was responsible for the development of the D-type. The V12 engine ran to 7,000 r.p.m. and developed something like 500 b.h.p. on a special alcohol fuel and it was potentially much faster round circuits than the previous V16 Auto Union. Unfortunately Rosemeyer was killed while attempting records on the Frankfurt-Darmstadt Autobahn at the beginning of 1938 so he never got to drive the D-type. He had been the main strength of the Auto Union team and his loss put the team at enormous disadvantage to the rival Mercedes-Benz team. However, they recruited Tazio Nuvolari into the team and once he had adjusted himself to the mid-engine concept he was very successful with the D-type Auto Union, winning the 1938 Donington Park Grand Prix and also the very last race in which Auto Union competed, at Belgrade on September 3rd, 1939.
After the war the Auto Union factories were in the East Zone of Germany and the racing team was never re-formed and all the cars and material from the racing department were assumed to have been destroyed in the bombing of Zwickau and Chemnitz. For many years the only Auto Union racing car known to exist was a C-type in chassis form on display in the Deutsche Museum in Munich, until in the late sixties and early seventies mutterings were heard about a D-type Auto Union in Czechoslovakia. It is this particular car with which we are concerned this month.
Auto Union D-type 1938/39
Chassis No. 4
Engine No. “July 1939”
A lot of people knew about this D-type Auto Union in Czechoslovakia and one or two people had seen a fuzzy photograph of it, but no-one had actually seen it. During the early 1970s Tom Wheatcroft was hard on the trail of it, for his Donington Collection, and arranged for a friend to visit Czechoslovakia and see the car. A lot of “cloak-and-dagger” stuff was involved but eventually this man returned to England, having actually seen the car, and confirmed that it was indeed a V12-cylinder 3-litre Auto Union Grand Prix car. Unbeknown to Wheatcroft, another collector living in Germany was also on to the scent, and while Wheatcroft’s contacts were about to settle the deal the news came through that Count Hubertus Donhof had acquired the car.
In 1974 Marlboro organised an old car and old driver re-union at the Dijon-Prenois circuit, in conjunction with the French Grand Prix organisers, and Count Dunhof brought his “prize” along for as all to see. It was a very original looking 1938 D-type Auto Union, though it did not run, but nonetheless it was a very exciting static exhibit in the paddock. Baron de Graffenried, who was organizing the re-union for Marlboro, invited along Professor Eberan von Eberhorst and H. P. Muller, who was one of the drivers in the 1939 team and it gave a lot of people a lot of pleasure to see an Auto Union for the first time and to see von Eberhorst and Hermann Muller with it.
There was much talk of the Porsche firm becoming involved with rebuilding the engine and gearbox, the crankshaft being a very complicated built-up affair with roller bearings for big ends and mains. However, rumours had suggested that there were no internals in the engine or gearbox, and this proved to be so, which made the Porsche task of such magnitude that Donhof lost interest. After a time it became known that the car could be bought, not so much “for a price” but by “the right person” in Donhof’s eyes. Eventually this turned out to be an American collector by the name of Kerry Payne and he had the car transported to Antique Automobiles of Baston, Lincolnshire with the instructions to “see what could be done to make it a runner”. It subsequently transpired that the car had been built up at the end of the 1938 season for exhibition purposes, which explained why there were no moving parts inside the engine or gearbox. Everything else was complete, the chassis, steering, suspension, brakes, bodywork and so on were all original and in good condition.
Some involved and complicated dealing took place, the details of which do not encourage close scrutiny, and a complete Auto Union engine appeared in Lincolnshire, having been discovered behind the Iron Curtain. This was a 1939 engine, with two-stage supercharging as against the single-stage on the 1938 engine, but otherwise was identical to the “exhibition” engine. Apart from a few carburettor parts and the odd oil and water pipe being missing this second engine was in full working order and it was installed in the 1938 chassis. At the time one of the current old-car magazines ran a fatuous story that this 1939 engine had been found in a shed near Donington Park! The story said that it was a spare engine left behind when the Auto Union team returned to Germany after winning the 1938 Donington Grand Prix. As the two-stage supercharging layout did not appear until 1939 this would have meant that Auto Union had taken an experimental engine with them to Donington Park in 1938, and one can just imagine them leaving it behind.
There was nothing to do about the 5-speed gearbox, as it was merely an empty shell, but by remarkable good fortune a modern Hewland racing gearbox and final drive unit was almost interchangeable. Professor Porsche was always years ahead in his thinking and his 1934-39 racing trans-axle unit sired the gearbox unit on the Volkswagen. Mike Hewland’s first essay into a racing gearbox for a mid-engined car was to use a Volkswagen unit turned upside down and mounted behind the rear axle instead of ahead of it, just like an Auto Union. All the subsequent Hewland gearboxes stemmed from the Volkswagen, so it is no surprise that the current Formula One Hewland gearbox looks very similar to a 1938 Auto Union gearbox, nor that it fits in the same space. Antique Automobiles got the car working, with its 1939 engine driving through the modern Hewland gearbox and Colin Crabbe demonstrated it at one of the Historic car meetings at the Nurburgring
Before Kerry Payne took possession of the car another momentous happening took place, in Latvia this time, when there was an old-car gathering and a 1937 V16 Auto Union C-type appeared, having been languishing in a Museum in Moscow. Deciding he had to acquire the V16 car, Payne offered the D-type for sale and Neil Corner bought it, selling his 1937 Mercedes-Benz W125 and Tipo B “monoposto” Alfa Romeo to a Japanese collector in order to raise the money. Before he took delivery of the Auto Union it was driven by Phil Hill for a feature in Road & Track, but there wad a nasty hang inside the engine and water came out of the exhaust pipes. Corner gave the car to Crossthwaite and Gardner who embarked on a monumental rebuild of the whole thing, stripping everything down to the basic components. The bang at Donington Park had been a connecting rod breaking so a new one had to be made, along with a set of pistons, valves, guides and many more parts. After some two years work the engine was rebuilt, as was the entire chassis, suspension, brakes, steering and so on. Bv the middle of 1982 it was all back together again and looking magnificent. Some test running was done at Goodwood and Silverstone and Corner planned to race it at the VSCC meeting at Silverstone in July, but one of the Bosch magnetos for the twelve plugs gave trouble so the car could only be seen as a static exhibit. It is still fitted with the Hewland gearbox / differential unit, but Corner recently acquired the complete and original gearbox for the car. While this D-type Auto Union has yet to he raced in an Historic event, it is a fine thing to see in the paddock after all the years that some of us thought we would never see an Auto Union again. When it appears in the 1983 season of Historic racing by the VSCC it should be an occasion not to he missed. — D.S.J.
Footnote: The C-type V16 cylinder chassis that languished in the Munich museum since 1937 was retrieved by Audi-VW and totally rebuilt at the NSU factory at Neckarsulm. It has been put into full working order, even to the engine being bench-tested and the complete car tested on a rolling-road. In 1980 it gave a demonstration at the Nurburgring Historic meeting and in 1982 was demonstrated at the Laguna Seca Historic meeting in California, by courtesy of Audi VW.