The 300 SL racing sports coupé is an important link in the racing history of Mercedes-Benz. As first sports car of the brand after the Second World War in 1952, and very successful to boot, it put new life into motor sports before Silver Arrows again were sent into the fray in 1954.
When the Second World War came to an end, Mercedes-Benz’s first concern was reconstruction – it was only after 1950 that Neubauer’s racing department began thinking about competing again. A first attempt was the participation of the last pre-war Silver Arrow W 154 in two races in Argentina. Hermann Lang, Karl Kling and Argentinean Juan Manuel Fangio put up a good fight in Buenos Aires, but the performance of swift but heavy cars no longer sufficed to score victories. The 1.5-litre W 165 racing car was never reactivated.
The parameters for future activities in motor sports were outlined during the all-important Mercedes-Benz management meeting on June 15, 1951, the gist being that top-flight racing and sports cars were the way to go. New racing cars would have to wait until 1954, however. The company’s coffers were empty; the Formula One regulations applicable at the time would expire at the end of the year, and the interim solution for 1952 and 1953, corresponding to the contemporary Formula 2 with two-litre displacement, did not comply with the brand’s profile and product range.
But a sports car took shape quickly after Alfred Neubauer and Prince Wilhelm von Urach, deputy of Chief Engineer Rudolf Uhlenhaut, had reported about the Le Mans 24 Hours they had watched, also in June that year. The concept of the winning car, a Jaguar XK120C, was convincing: a light frame, a light body, as many standard components as possible. Such a car, Nallinger pointed out, could be set up on the basis of the Mercedes-Benz 300, the saloon with which the Stuttgart enterprise had been steering a middle course between prestige thinking and post-war austerity since April 1951.
In just nine months the Mercedes-Benz 300 SL – the very first SL – was created; the letters stand for “Sport – Light”. The racing sports coupé was presented to the press on 12 March 1952, and demonstrated the following day on the Stuttgart – Heilbronn motorway. The team in charge of concept development and design was led by Rudolf Uhlenhaut. It comprehended the likes of Wolf-Dieter Bensinger, Franz Roller, Manfred Lorscheidt and Ludwig Kraus. The majestic Mercedes-Benz 300 saloon contributed the SL’s suspension, slightly modified and made lighter, double wishbones at the front, a swing axle at the rear, and telescopic hydraulic shock absorbers and coil springs all round. The additional torsion bars on the saloon’s rear axle were dispensed with. As to the track, the team opted for a compromise between the two extremes of wide (reducing the negative consequences of camber changes brought about by the swing axle) and narrow (keeping the frontal area small). Because of their lighter weight and their good-natured way of dealing with the negative consequences of the swing axle, 15-inch wheels, initially bolted on as on the production car but later fastened with central locks (of the knock-off type), were preferred to bigger units that might have led to higher mileages and lower temperatures. The 300’s brakes (drum diameter 260 millimetres) were carried over as well, their width enlarged to 90 millimetres.
A large number of parts adopted from the Mercedes-Benz 300
The 300’s four-speed transmission remained almost untouched, while its 265-kilogram high six-cylinder in-line engine was subject to a number of modifications. Three Solex downdraft carburettors and a “sharper” camshaft raised its output from 115 hp (85 kW) to 175 hp (129 kW) at 5200 rpm. To achieve the aforementioned smaller frontal area and to lower the centre of gravity, the engine was installed in the supporting structure at an angle of 50 degrees to the left. This would have severely obstructed access to the spark plugs. So they were relocated from the block to the cylinder head, with corresponding changes to both.
The tubular space frame as supporting structure, constructed by Franz Roller and his team to Uhlenhaut’s specifications, was a filigree latticework of a large number of triangles, absorbing tensile and compression forces. Tests comparing it to the W 154’s ladder-type frame with its oval tubes showed that it had about the same stiffness but, at 50 kilograms, was 20 kilograms lighter. Apart from acting as the SL’s backbone, the space frame also supported its body.
To ensure maximum stability, the space frame reached high up at the sides. This design necessitated the use of the legendary gullwing doors with entry from above across the broad vehicle sides. Initially the doors’ lower edge was at the level of the waistline, apart from chassis number six that first appeared at the model’s Mille Miglia racing premiere in early May 1952. From the Le Mans 24 Hours in mid-June onward, the doors extended into the sides of the aluminium bodies. The 300 SL’s bodywork, too, was a design masterpiece with its smooth plainness and the narrow roof structure, as borne out by a drag coefficient as low as Cd = 0.25. Its oval grille resembled the W 154’s, harking back on the great pre-war tradition. The first two bodies were made by skilled panel-beaters on a wooden form in the Untertürkheim works, the others – seven had been envisaged in September 1951 – at the Sindelfingen testing department.
On 3 May 1952 the 300 SL took the start at the Mille Miglia. Karl Kling and Hans Klenk took second place in the thousand mile race. Rudolf Caracciola finished fourth. It was not a victory yet, but Mercedes-Benz was the only brand that could boast two cars among the first five finishers. At the Bern Prize for Sports Cars on 18 May the 300 SL managed a triple win: Karl Kling crossed the finish line ahead of Hermann Lang and Fritz Riess. The race in Bern was overshadowed by the severe accident of Rudolf Caracciola, which put an end to his racing career.
A double victory in the renowned 24 Hours of Le Mans underscored not only the performance of the gullwing car but its durability too: the team of Lang/Riess finished first ahead of Helfrich/Niedermayr. At the Grand Prix Jubilee for Sports Cars on the Nürburgring in August, the 300 SL competed in a new form: four coupés had been converted to roadsters, and one of them took the start with a shorter wheelbase and narrower track. The fours cars triumphantly crossed the finish line in the order Hermann Lang, Karl Kling, Fritz Riess and Theo Helfrich.
But the double victory of Karl Kling/Hans Klenk and Hermann Lang/Erwin Grupp in the Carrera Panamericana caused an even bigger stir: In November 1952 the German drivers captured the title in the race in faraway South America. The exotic flair of the long-distance event is underscored by the collision of team Kling/Klenk with a vulture that crashed through their windscreen. After that the 300 SL the continued the race with a protective grille in front of the glass.
Mercedes-Benz 300 SL (W 194)
– Entered in racing: 1952/53
– Engine: six-cylinder in-line four-stroke petrol engine
– Displacement: 2996 cc
– Output: 175 hp (129 kW)
– Top speed: 240 km/h
Source: Daimler AG