Guide: Return of the Silver Arrow - a Historical & Technical Appraisal of the Mercedes-Benz W194 300 SL
Background
Mercedes and Benz both enjoyed significant success as separate firms during the early days of motor racing.
Their merger in 1926 created an industrial behemoth.
When Adolf Hitler’s Nazi party came to power in 1933, substantial government funds were diverted to both Mercedes-Benz and rival Grand Prix manufacturer, Auto Union.
The result was absolute domination of the sport from 1934 until the outbreak of World War 2; Germany’s nationalistic approach left conventionally funded Italian, French, British and American teams unable to compete on equal terms.
Six years after hostilities ended, Mercedes executives agreed the firm should return to top flight motor racing.
The decision was made in June 1951. However, as the new two-litre un-supercharged Formula 1 regulations did not reflect the firm’s technical aspirations, a sports car programme for the 1952 season was sanctioned instead.
Since 1947, Ferrari had established itself as the dominant force in this class of racing. In addition to the red cars from Maranello, Mercedes’ big budget machine would be pitched against an exceptional field of models from Jaguar, Aston Martin and Alfa Romeo plus specialist firms like Gordini, Cunningham and Allard.
Given type number W194, the new 300 SL (Sport Leicht) used an array of mechanical parts sourced from the W186 300-series that had been introduced in April 1951.
Mercedes’ first W194 prototype was running by November 1951 and, in March 1952, the finished W194 was shown to the press. The car went on to make its competition debut at the Mille Miglia road race around Italy on May 4th.
Chassis
At the W194’s core was a brand new tubular steel spaceframe chassis that weighed just 70kg.
Distinctive Gullwing doors were required for the neat aluminium body because of two large bulkheads that ran down each flank. The bulkheads provided extra torsional rigidity, but resulted in very high sills, hence the need for Gullwing as opposed to conventional doors.
The 300 SL had a wheelbase of 2400mm. Front track was narrower than the back (1381mm and 1445mm respectively).
By canting the engine at a 50° angle, Mercedes were able to give the car a very low profile and exceptional aerodynamic efficiency.
Front suspension was via unequal length wishbones while the rear swing axle was imported from the W186.
Coil sprung telescopic dampers were fitted all round along with finned hydraulic drum brakes.
5 x 15-inch Rudge centre lock wheels were originally shod with Englebert and later Continental tyres.
A huge fuel tank was located behind the rear axle. How full it was had a major impact on handling.
Furthermore, the rear swing axle was joined only at the differential and not the wheels themselves which led to potentially extreme changes in camber on imperfect road surfaces.
Engine / Transmission
The Type M194 single overhead camshaft Straight 6 engine fitted to the SL was a modified version of the standard W186 300-series unit.
As per the original, it featured a cast-iron block, light aluminium alloy two valve head and displaced 2996cc thanks to a bore and stroke of 85mm and 88mm respectively.
Because the engine was canted at 50°, the spark plugs had to be repositioned from the block to the cylinder head.
The SL version also featured a high lift camshaft and three Solex downdraught carburettors. Compression was increased from 6.4:1 on the W186 to 8.0:1.
Peak output was 175bhp at 5200rpm and 207lb-ft at 4600rpm.
Early examples used wet-sump lubrication to save weight, however, this was soon changed to a racier dry-sump arrangement.
Mercedes’ existing W186 four-speed gearbox was installed, but uprated with a separate oil pump.
Bodywork
Bodywork was designed and fabricated in-house at the Sindelfingen works with the exception of the first two prototypes that were manufactured at Unterturkheim.
The lightweight fully enveloped bodywork was typical of early 1950s German design. It featured soft curves, short overhangs and little in the way of superfluous decoration.
Exposed headlights were mounted either side of a primary nose intake complete with 15-bar grille and three-pointed star.
Surprisingly, engine cooling vents were absent from both the hood and flanks.
To improve aerodynamics, the cockpit was made as narrow as possible. Visibility was excellent thanks to the slim pillars.
Interior
Once over the wide sills, the driver was confronted with a wood-rimmed four-spoke steering wheel and body coloured metal dash.
Dials for road and engine speed were housed in separate cowls directly behind the steering wheel.
Supplementary gauges for oil pressure, oil temperature, water temperature and fuel were mounted alongside the steering column. A clock was positioned in the centre of the dash along with a variety of toggle switches.
Aside from some basic door trim and two cloth bucket seats with tartan-patterned centres, there was no upholstery to speak of.
Weight / Performance
Although performance figures were never published, the 1130kg Gullwing was estimated to have a top speed of around 155mph.
Depending on the axle ratio, a 0-62mph time of around 5.5 seconds would likely have been possible.
Production
Of the first ten W194s originally built, nine were completed with closed Gullwing bodywork and one was a Spyder. Three of the Gullwings were subsequently transformed to Spyders mid-season.
A uniquely configured eleventh W194 300SL was assembled over the winter of 1952-1953 to serve as a development mule for the subsequent W198 300 SL Gullwing production car.
Production Changes
At the 1952 Le Mans (june 14th / 15th), the W194s arrived with newly extended doors that cut into the sides of the bodywork. During practice, the T-car ran with an experimental roof-mounted airbrake that was ultimately deemed unsafe by the organisers and removed on safety grounds.
The W194 Spyder made its debut at the Nurburgring (August 8th) and ran a new side-exiting exhaust that emerged from a cut-out on the right-hand sill. One of the cars on hand at the Nurburgring (chassis 010) also featured a shorter 2200mm wheelbase.
In addition, a T-car that appeared at the Nurburgring ran with a Roots-type blower that drew and then compressed the fuel from three sidedraught carburettors mounted directly onto the casing. Dubbed the 300 SLK, peak output was 230bhp, but the Type M197 Kompressor motor was never raced.
At the Carrera Panemericana (November 19th to 23rd) all three cars ran with bored out 3.1-litre engines.
Competition History
Mercedes’ 1952 campaign focused on five big races: the Mille Miglia, the Swiss Grand Prix support race for Sports cars at Bremgarten, the Le Mans 24 Hours, the German Grand Prix support race for Sports cars at the Nurburgring and the Carrera Panamericana.
Three W194s were entered for the Mille Miglia which got underway on May 4th. The lead entry of Karl Kling / Hans Klenk was in with a shout of victory until a wheel came loose late on which handed the win to Ferrari. Kling / Klenk nevertheless crossed the line second and team-mates Rudolf Caracciola / Paul Kurrle were fourth. The Hermann Lang / Erwin Grupp entry crashed out.
Two weeks later, Bremgarten hosted an 18 lap race for Sports cars and Mercedes entered four W198s. Once the pole-starting Ferrari had retired Mercedes were able to take first (Kling), second (Lang) and third (Fritz Riess). Unfortunately, the race was marred by a career-ending crash that left Rudolf Caracciola severely injured after he ploughed into a tree at high speed.
Three new Gullwings were then entered for the 1952 Le Mans 24 Hours which took place over the weekend of June 14th and 15th. Grid positions were dictated by engine size which meant the Mercedes lined up ninth (Theo Helfrich / Helmut Niedermayr), tenth (Lang / Riess) and eleventh (Kling / Klenk).
While the Kling / Klenk entry retired just after midnight, the cars of Lang / Riess and Helfrich / Niedermayr finished first and second following Pierre Levegh’s late retirement from the lead having driven his Talbot-Lago single-handedly for 23 hours.
Against limited opposition Mercedes ran four W194s in new Spyder trim at the Nurburgring German Grand Prix support race on August 8th. Kling took pole for the 10 lap race followed by team-mate Lang and Robert Manzon’s works Gordini T15S. Riess and Helfrich started fourth and fifth. Predictably, when Manzon retired the race turned into a Mercedes benefit: Lang took the win, Kling was second, Riess third and Helfrich fourth.
Three W194s were then on hand for the season-ending Carrera Panamericana (November 19th to 23rd): a brace of Coupes for Kling / Klenk and Lang / Grupp and a Spyder for John Fitch / Eugen Geiger.
Although the Fitch / Geiger entry was disqualified for having received outside assistance after a mechanic touched his car on the penultimate stage, Kling / Klenk took another famous win for the W194 with a time just over 35 minutes faster than their team-mates Lang / Grupp in the sister Gullwing.
The result in Mexico capped a remarkable season for the W194 on Mercedes’ return to frontline competition.
Text copyright: Supercar Nostalgia
Photo copyright: Mercedes-Benz - https://www.mercedes-benz.com
