The cars racing in the 1955 motor sport season

Nov 30, 2009
The following Mercedes-Benz cars were entered in races in the 1955 season:
  • W 196 R Grand Prix racing car
  • 300 SLR (W 196 S) racing sports car
  • 300 SLR coupe
  • 300 SL sports car
  • Mercedes-Benz racing car transporter
The W 196 R Grand Prix racing car
In the last races of the 1954 season in particular, the W 196 R had revealed quite a few weaknesses and was therefore thoroughly revised during the winter break. Racing car connoisseur Louis Sugahara: “Even after the start of the 1955 season, the cars continued to be modified between races.” Alongside the chassis with a 2350-millimeter long wheelbase, a medium-length chassis (140 millimeters shorter) and the short Monaco version with a wheelbase length of 2150 millimeters were created. In its second season, the racing car had shed some 70 kilograms and put on another
22 kW in output. The W 196 R’s engine now developed 213 kW at 8400 rpm and gave the car a top speed of around 300 km/h. A conspicuous feature was the air scoop on the engine hood – the result of modified intake manifolds and a reliable item to distinguish the car from the 1954 version.
However, Rudolf Uhlenhaut, Chief Engineer and Technical Director of the motor sport department, did not change the successful basic design of the Grand Prix car. As in 1954, two bodywork versions were used, a fully streamlined car for maximum speed on high-speed circuits and the classic monoposto, a monocoque with uncovered wheels, better suited for twisting circuits. For while the Formula One regulations clearly specified the engines to be used – either a supercharged 750 cc unit or a naturally aspirated 2.5 liter unit, they made no restrictions concerning the shape of the bodywork.
As early as 1954, it had been realized that the advantages and disadvantages of the streamlined car had to be taken into account in race tactics. In the W 196 R’s first race, the French Grand Prix in Reims, Mercedes-Benz clinched a superior double victory with aerodynamically optimized cars but no sooner than the next race, the British Grand Prix in Silverstone, the streamlined bodywork demonstrated its weakness in that precise steering through corners was made difficult by the covered wheels. The monoposto had its premiere in the German Grand Prix on the Nürburgring.
Underneath the bodywork, both versions were identical. The eight-cylinder in-line engine with a displacement of 2496 cc transmitted its power via a centrally arranged output shaft. This layout reduced the vibrations of the engine whose output was boosted from initially 189 kW to 213 kW during the two years in which it was used. The mechanical direct injection system, with which Mercedes-Benz had been experimenting as early as before World War II, had meanwhile reached maturity and was fitted to the new engine. Another new feature was desmodromic valve control by means of rocker arms for opening and closing the valves – a design which, among other things, made the engine insensitive to great engine speed variations. First and foremost, however, desmodromic valve control increased the gas flow by over 40 percent as compared to conventional cam-and-spring control. The improved cylinder charge raised the power-to-swept-volume ratio of the eight-cylinder in-line engine consisting of two sequential four-cylinder units and installed in the car at an angle of
35 degrees.
The car’s backbone was a space frame, a design Rudolf Uhlenhaut had used – highly successfully – for several cars ever since the 300 SL prototype. Notwithstanding its high level of torsional stiffness, the frame of the W 196 R weighed in at a mere 36 kilograms. The 16” wheels were independently suspended from double wishbones at the front and mounted to a swing axle with low center of gravity at the rear. The initial idea of giving the car four-wheel drive was abandoned when the W 196 R proved to be superior to its competitors with rear-wheel drive alone.
For the 1955 season, several detail features of the car were revised. The intake manifold was modified, new wheelbase lengths were added and engine output was boosted. Whereas the 1954 season had seen streamlined cars at the start, it was the open monoposto with three different wheelbase lengths that dominated the scene in 1955. Since the Grand Prix races in Germany, France, Spain and Switzerland were canceled after the accident in Le Mans, the Italian Grand Prix was the only race in which the streamlined versions lined up at the start in 1955.
In 1954 the W 196 R clinched five victories, two second and three third places. And although four races were canceled in 1955, the Silver Arrows recorded six victories, five second places and one third place, thereby underlining their superiority. Louis Sugahara: “In a way, 1954 can be seen as a test stage before the cars were perfected in 1955.”
One exception in the configuration of the W 196 R for 1955 was made in setting up three cars for the Grand Prix of Buenos Aires on January 30. Instead of the 2496 cc engine of the Formula One car, the engine from the 300 SLR (2982 cc) was installed - under a hood with a conspicuous bulge to accommodate the new unit – for this formula-free race.
The 300 SLR (W 196 S) racing sports car
The victories of the 300 SL in 1952 had shown that Mercedes-Benz was competitive again on an international scale in sports car racing as well. Setting their sights on the 1955 world championship title for brands, the designers came up with a new racing sports car, notably incorporating experience gained in the design of the W 196 R Grand Prix Silver Arrow. The 300 SLR may have resembled the 300 SL in terms of its looks, but underneath its bodywork it boasted Formula One engineering. This was also reflected by the internal model designation – W 196 S – for the racing sports car, derived from the W 196 R formula monoposto.
For the sports cars, there was no such thing as a displacement limited to 2.5 liters in naturally aspirated engines, as was the case in Formula One. Continuing the tradition of the 300 SL, which was powered by the three-liter six-cylinder engine from the Mercedes-Benz 300, Rudolf Uhlenhaut gave the new racing sports car an engine with a displacement of almost three liters. This eight-cylinder engine was installed in its compartment at an even steeper angle than in the racing car to make a particularly flat front end possible.
While the configuration of the racing sports car engine – two engine blocks, each with four cylinders, a shared crankcase and centrally arranged output shaft – was reminiscent of the racing car engine, the new engine had been cast out of an aluminum alloy for the first time. For the Grand Prix cars, by contrast, the racing department had opted for a special approach in that the engines were made up of steel plates. With desmodromic valve control and direct injection of the fuel by means of a Bosch pump, the 300 SLR shared proven engineering features with the racing cars.
The front suspension of the racing sports car consisted of double wishbones connected to horizontally mounted torsion bar springs and telescopic shock absorbers. The negative-camber rear wheels were mounted to a single-joint swing axle. Interior drum brakes were used to decelerate the 300 SLR. The lightweight space frame, basically the same as in the 300 SL, carried an aerodynamically optimized bodywork made of a light magnesium alloy in the 300 SLR. Newly developed features of the roadster were movable flaps behind the cockpit for use as an air brake – a forerunner of which had already been tested in the 300 SL coupe.
The racing sports car had a top speed of well over 300 km/h, engine output between 213 kW and 221 kW and a weight of roughly 830 kilograms, thus being clearly heavier than the Grand Prix car.
The 300 SLR coupe
The 300 SLR racing sports car had originally been meant to be a coupe but the drivers had voted in favor of a roadster, first and foremost because of the noise levels they expected inside the car in racing. In spite of this, two coupes were set up additionally in 1955 under the auspices of Rudolf Uhlenhaut. In their design, the 300 SLR Gullwings were very similar to the 300 SL sports cars. The coupes were to be entered in the Carrera Panamericana but the long-distance race in South America was no longer staged from 1955 onward.
However, the Gullwing with three-liter eight-cylinder engine was extensively used for testing. Among other things, Alfred Neubauer gave a 300 SLR Gullwing to Wolfgang Graf Berghe von Trips, specifically signed on for the Tourist Trophy in Northern Ireland, to drive all the way from Stuttgart to Dundrod prior to the race. In this way, von Trips was to familiarize himself with the car. In the race itself, however, he drove a roadster. The racing department also used the coupe for practice sessions prior to the Swedish Grand Prix in Kristianstad and prior to the Targa Florio in Sicily, without entering the Gullwings in the races themselves. Like the spider which was tried out in the Mille Miglia and in Le Mans, the coupe was part of the racing department’s enormous fleet.
At a later stage, one of the two coupe was registered for operation on normal roads and served as Rudolf Uhlenhaut’s company car – and as the “Uhlenhaut Coupé” it became almost as famous as the 300 SLR entered in races.
The 300 SL sports car
Launched in March 1952, the Mercedes-Benz 300 SL (W 194) sports car designed by Rudolf Uhlenhaut was a sensation. Based on the 300 (W 186) passenger car model, the coupe with its characteristic gullwing doors had initially been conceived as a thoroughbred racing sports car but then transformed into the W 198 sports car whose large-scale production began in 1954. The car’s 125 kW engine and four-speed transmission were taken from the Mercedes-Benz 300. To make the sports car competitive, Uhlenhaut designed an extremely light space frame and an aerodynamically highly efficient bodywork.
The unconventional structure with a frame made of steel tube triangles forced the designer to come up with an equally unconventional door design. Since the frame completely enclosed the cockpit up to engine hood level, Uhlenhaut was unable to fit normal doors and instead created the car’s characteristic gullwing doors. At a later stage, the entrance was enlarged at the lower end, and the production 300 SL coupe was also given this lower entrance, but the doors hinged at the roof frame, earning the coupe the name “Gullwing” in the United States, were retained for the 300 SL coupe as its hallmark.
As early as in its first year, the 300 SL emerged victorious in the Le Mans 24 Hours, the race in Bern, the Sports Car Anniversary Grand Prix on the Nürburgring and the Carrera Panamericana. In 1953, Rudolf Uhlenhaut designed a further developed version of the sports car for racing, a modified 300 SL with chassis number 11, which was to gain a certain amount of fame as a prototype but remained nothing more than a development stage between racing sports car and production car.
It was only in the production version that the 300 SL was used for racing again. Successes of the W 198 in long-distance races and rallies rounded off the record year 1955 for the racing department. In the Mille Miglia, three 300 SL scored a triple victory in their category; Werner Engel won the European Touring Car Championship at the wheel of a 300 SL, Armando Zampiero clinched the Italian Sports Car Champion’s title and Paul O’Shea secured the American Sports Car Championship for himself.
The production version of the Mercedes-Benz 300 SL was built from 1954 until 1957 as a coupe and from 1957 until 1963 as a roadster.
The Mercedes-Benz racing car transporter
Wherever the Silver Arrows showed up, the blue Daimler-Benz racing car transporter was never far away. This unique vehicle, built as a one-off in 1954, continued to turn heads throughout the 1955 season. Its sole purpose was to provide lightning-quick special-purpose transportation between the plant and the race track, should one of the race cars require some last-minute modification, for example, or if one of the Silver Arrows was involved in an accident and had to be repaired as quickly as possible prior to the next race. In such circumstances, the high-speed blue transporter would be on hand to make a dash across Europe with its precious silver cargo on its back. Otherwise, transportation of vehicles, tools and equipment for the pits was handled by a fleet of heavy-duty trucks.
The racing car transporter was made up of various production components and specially manufactured parts. The chassis of the Mercedes-Benz 300 S was complemented by a forward cab which owed its flowing lines among other things to components from the 180 model. From the cab through to the fully streamlined rear end, the transporter appeared as an integrated whole, showing little of the customary separation between cab and load platform.
The high-speed car transporter was powered by the three-liter six-cylinder engine which also did service in the 300 SL. With an output of 146 kW and torque of
253 Newton meters at 4750 rpm, the 6.75-meter long transporter had a top speed of 170 km/h.
After its active service, the transporter was first sent on a tour of motor shows and exhibitions, then used for testing and finally scrapped in 1967. It did not make a return to the roads again until 2001, when after seven years of meticulous work the former Mercedes-Benz AG unveiled an identical replica version of the racing car transporter. The Mercedes-Benz Museum placed the relevant order with MIKA in Mölln, in the north of Germany, in 1993. Since there were no blueprints, the racing car transporter had to be reconstructed piece by piece on the basis of photographs and other documents. It took almost 6,000 working hours to create the detailed replica. But the effort was worth it, if the interest generated by the blue vehicle’s appearances at classic car events is anything to go by – for here the looks of amazement are no different from those of 50 years ago.