Rudolf Uhlenhaut: Mercedes' unsung F1 engineering genius

Humiliated, Mercedes withdrew from racing before the season was over and began making plans for 1937, plans which were to be brought to fruition by Rudolf Uhlenhaut.

In 1984 he told me, “When I joined the racing team I was made technical manager at first and later, technical director. I knew Alfred Neubauer, of course, but I had had no dealings with him up to that point. He organised the team and I handled the technical side he didn’t mess with me and I didn’t mess with him, so we got along well.

“My immediate boss was Fritz Nallinger. Max Sailer remained as nominal head of the department, but he had been responsible for the 1936 season, so he didn’t dare challenge me! I was responsible for building, developing and running the cars.

“The problem in 1936 (and before, for that matter) was that Mercedes Benz had nobody in the racing department who could drive the cars, they had to rely on what the racing drivers said and they had no technical knowledge. So, the entire department was reorganised and I was put in charge. I was just 30, which was very young for such a job and I was very surprised to get it.”

Within days of his appointment Uhlenhaut found himself at the Nürburgring with Rudolf Caracciola, Manfred von Brauchitsch and three grand prix cars, a 1935 model and two 1936 machines. After two days of testing the drivers departed for the Swiss GP at Bern, having made numerous suggestions regarding the cars’ springing.

Left to his own devices “with just a handful of mechanics and no Neubauer”, Rudi decided to see how the racers handled for himself, so he set off round the ‘Ring in the 1935 car, with its swing rear axle, and then a 1936 car, which had a de Dion rear.

“During the four or five years I’d been working on passenger cars we often drove them on the Nürburgring and we always drove them as fast as we could. I found out that driving a racing car was not much different from a passenger car at high speed.” He makes it all sound so easy, but at this point we should bear in mind that we are talking about the old Nürburgring here 17.6 miles (both the Nord and Sudschliefe were then in use) of the most demanding circuit ever built; and that the passenger cars he mentions were the 170 (1.7-litre) saloons. The 1936 GP Mercedes W25 had a 4.7-litre supercharged engine delivering 450 bhp, which was a tad more than that of the 170. Clearly, Uhlenhaut was a driver of exceptional skill with an analytical mind to match.

“My first impressions were of quite simple faults that any engineer could have found. First of all, the frame on both cars was much too weak it bent and vibrated on rough roads. Also, at that time our design department had the idea that the damping of the axle had to be very stiff, so they incorporated both hydraulic and friction dampers. This meant that there was very little movement of the axle against the frame; much of the springing was done in the frame itself. That was completely wrong and the car jumped all over the place because the wheels couldn’t follow the road surface. On one occasion I lost a rear wheel at top speed on the straight. The chassis was so stiff that nothing happened it was just like driving a motorcycle with a sidecar!”

Having discovered at first hand what was wrong with the cars, over the winter Uhlenhaut developed the fabulous W125. Now regarded as one of the all-time great Grand Prix machines, this retained the W25’s straight-eight, supercharged engine, but the capacity was increased to 5.7 litres, which produced a remarkable 580 bhp as a rule and well over 600 when necessary. A new, longer chassis made of oval tubes was suspended on wishbone and coil springs at the front and a de Dion system at the rear.

In March 1937, Mercedes took a W125 to Monza for testing, along with a 1936 car and Uhlenhaut made a point of driving both, largely because Caracciola, von Brauchitsch and Lang had little that was constructive to say about them. Mercedes also took along their new recruit, Dick Seaman, who had established himself as the very best English driver after a sensational 1936 season in his 10-year-old Delage. Dick got off to a bad start by crashing the W25 heavily and Uhlenhaut had his first taste of the Englishman’s honesty.

“He said that the crash was entirely his fault and that was quite remarkable – he would always tell you exactly what happened and blame himself if necessary. Other drivers had a tendency to blame the car, but he was very honest in this way.”

As Seaman spoke no German at this stage, he and Uhlenhaut quickly established a fine rapport in English and as the season progressed Rudi was astonished to find that Dick had a real grasp of the technical side. “In those days the drivers knew very little, but he was very knowledgeable, developed a good understanding with him and we used to talk a lot about technical details. I listened to his ideas and they were often quite useful.”

“He had proved that he could lap almost as fast as his drivers”

The W125 proved to be a winner first time out, at Tripoli, where Hermann Lang scored the first of a hat-trick of wins. Mercedes didn’t have it all its own way that year, however, for Bernd Rosemeyer (who had won the 1936 European Championship in only his second season of motor racing) was still on great form with the C-type Auto Union, which remained virtually unchanged from its 1936 specification.

It was Rudolf Caracciola who won the title in ‘37 though, for the W125 provided him with four of its seven victories and carried him to the crown. And for a man who had barely seen a racing car one year previously, Uhlenhaut had proved himself to be an engineer of remarkable flair. Alarmed by the power and speed of the Silver Arrows, the powers-that be brought in a new GP Formula for 1938. “We had a choice of using a 4.5 litre unsupercharged engine or a 3-litre supercharged unit,” recalled Rudi. “With our considerable experience of supercharging, we decided to go for the latter. Our 3-litre V12 was, in detail, the same as the previous straight-eight, with cylinders, crankshaft and con-rods built in the same way, but smaller, naturally. The chassis was also similar, but shorter.”

Once again Mercedes took the cars to Monza for pre-season testing and Uhlenhaut did many laps to satisfy himself with their performance. By now he had proved that he could lap almost as fast as his drivers, which certainly kept them on their toes.

The new 3-litre cars were highly successful, and Caracciola won his third European Championship in 1938 and the following year it was the turn of the very gifted Hermann Lang to take the tide.

Tired of seeing their Alfas and Maseratis constantly beaten by the Mercedes and Auto Unions, the Italians decided that their Tripoli Grand Prix (with its large amounts of prize money) would be for supercharged 1.5-litre cars in 1939. Bravely, Mercedes called their bluff and Uhlenhaut and his men secretly set to work in secret on the W165. Eight months later they stunned the Italians and everyone else by arriving at Tripoli with two jewel-like, supercharged V8s and, in the race, Lang and Caracciola simply blew the opposition into the desert sand. Hitler’s war brought everything to a tragic halt in September, 1939 and Uhlenhaut spent most of it designing and developing cylinder heads for the Daimler-Benz 603 aircraft engine. When hostilities ceased he ran a small transport business, his battered trucks fuelled by methane gas, before returning to Mercedes in 1948, as the company dragged itself out of the bomb-ravaged rubble that had been the factories at Unterturkheim.

In the early ’50s Fritz Nallinger, Uhlenhaut and Alfred Neubauer turned their thoughts to Grand Prix racing once again, but wisely decided to wait until 1954 and the new 2.5-litre formula. Meanwhile, they were impressed by the way Jaguar had created the new C-type sports racer from production components and decided to go the same route, Nallinger suggesting they use their new 300 saloon as a basis.

Uhlenhaut had had a big hand in the 300 and happily set about conjuring up a sports-racer from it. Designated the W194, this became one of the all-time greats, the 300SL, and it caused a sensation when it first appeared in 1952. Mercedes had inclined the six-cylinder engine of the 300 at an angle of 50 degrees in a very light spaceframe chassis with wishbones and coil springs at the front and swing axles and coil springs at the rear. The chassis was covered with a sleek body and doors that opened upwards, the legendary ‘gullwings’.

Neubauer did not waste time with minor races to check out the new cars, but threw them straight into one of the toughest events in the world, the Mille Miglia. They finished second (Karl Kling) and fourth (Rudolf Caracciola), and were only beaten by an heroic performance from Giovanni Bracco in a 3-litre Ferrari. Their next race was Le Mans, and they finished first and second. Mercedes were back.

A year later the go-ahead was given for the design of a new Grand Prix car, the W196, under the direction of Hans Scherenberg. Uhlenhaut ran the experimental department and, as before, had considerable influence on the design.

The return of Mercedes-Benz immediately passed into legend, the beautiful streamliners scoring a stunning one-two victory in the 1954 French GP at Reims. Driven by 1951 World Champion Juan Manuel Fangio, Karl Kling and Hans Herrmann, the W196s were simply sensational, their remarkable speed and staying power leaving the opposition broken in their wake. Remarkably, they themselves were left for dead in the next race, the British GP at Silverstone, where Froilan Gonzalez ran away from them in his Ferrari. From then on, however, the Silver Arrows were almost unbeatable and Juan Fangio was World Champion in 1954 with four wins for Mercedes and two with Maserati. In 1955 he was joined by Stirling Moss and once again the Mercedes were virtually on its own, winning five of the six races that season and Fangio was champion again.

The W196 was followed by the W196S, a three-litre sports racing version of the GP car known as the 300SLR. Again, Uhlenhaut’s contribution to its design was considerable and it won three of the four Manufacturers’ Championship races. Mercedes entered in 1955 and would surely have won the fourth Le Mans had the cars not been withdrawn following the terrible accident involving Pierre Levegh, whose 300SLR so tragically crashed into the crowd. At the age of 49, Uhlenhaut continued to test the racing Mercedes himself, and once again proved to be almost as fast as the aces. Stories that he had lapped the Nürburgring faster than Caracciola, Lang, Fangio and Moss were wide of the mark but, in truth, he was only seconds away.

As Stirling Moss recalls, “He was an extremely competent driver you had to be very sure of yourself before you complained that a car was no good, because he could get into it and show you that it was perfectly all right!” While he clearly enjoyed his prowess at the wheel, Rudi never considered becoming a racing driver, being more interested in technical matters. He came up with devices ranging from the sublime to the faintly ridiculous. The air brake used at Le Mans in 1955 was a great success, making the 300SLR more than a match for the D-type Jaguar with its Dunlop discs, and the 300SL powered racing car transporter was a superbly practical machine that also garnered tremendous publicity for Mercedes. Sadly, it was broken up some years ago, despite the firm’s passion for retaining its vehicles.

Faintly ridiculous was the ‘wastepaper dispenser’, a grille designed to be fitted to the front of the W196s after newspapers and other debris fouled the radiators of many cars in the 1954 Spanish GP. This was never used, no doubt largely because it would have thrown the rubbish straight into the drivers’ faces!

It was a nice try, though, and indicative of his fertile brain. “Nothing was impossible for Rudi,” says Moss. “I always felt that if I had asked for square wheels, either they would have been fitted the next day or he would have looked it up in a big, black book and said, ‘We tried that in 1936 and there was too much vibration!”

When Mercedes withdrew from racing at the end of 1955 Uhlenhaut returned to the development of passenger cars as head of research, where he stayed until his retirement in 1972. However, there was one more sports car to come from his team, and that was the fabulous C111.

First shown at Frankfurt in 1969, this mid-engined, gull-winged coupe stole the show and despite all protestations that it was purely an experimental machine, the wealthy were soon writing Mercedes blank cheques in the hope of getting one. They were all disappointed, for it never went into production and the prototypes all ended up in the museum collection at Unterturkheim.

Uhlenhaut told me that the C111-2, with its 350 bhp four-rotor engine, was his favourite car of all, and one unforgettable day in 1982 he took me for a run in it. He was then 75 years old, but he seemed to lose a good 50 of them as we strapped ourselves in. Once free of town traffic and on country roads he knew really well he let rip, and the Mercedes sang through the curves and hills in a 60km ride that took my breath away. The car was always beautifully positioned on the road and in the right gear. Rudi sitting back, relaxed and happy as a sandboy.

Uhlenhaut died on May 8, 1989, and Stirling Moss remembers him as “a lovely man, a very happy, very human individual. I look back on him with fond memories.”

Although he was always the first to stress that all his achievements at Mercedes were as part of a team, there is no doubt that he was an exceptional man who left an indelible mark on the history of the motor car and Mercedes-Benz in particular.