Mercedes-Benz 300SL

After being a dominant force in Grand Prix racing before World War II, the engineers at Mercedes-Benz must have found the late Forties to be a humiliating  period. Their nation was a shambles, devastated by the fall down of the Nazi regime with which their cars had been so closely associated, fairly or unfairly, and, as other countries clawed their way out of the abyss, back toward normalcy, they were being left behind. Other, lesser brands were occupying winner’s circles that Mercedes-Benz engineers figured they owned.

Mercedes’ engineers collapse

But the draught in Mercedes-Benz motorsport fortunes would end soon after the Fifties started. Mercedes’ crack engineering corps finally got the approval to go racing, and, under the direction of Rudolph Uhlenhaut, who had been through the good times and the bad times with the company, they jumped  into the project with a vengeance.

The post-war Mercedes-Benz, no longer the  favorite of Der Fuehrer, had vastly fewer forces to bring to bear on its racing program than it had in its Thirties heyday. Instead of designing an engine from scratch, Uhlenhaut’s work was to prepare the M-B luxury car engine for racing applications. On the face of it, the job was daunting.

There was nothing especially bad about the in-line 6 cylinder, but there wasn’t much especially good regarding  it either. Its valves were operated by a single overhead cam, not the dual overhead cams of the competitor Jaguar XK engine. Though it displaced just 2996 cubic centimeters (183 cubic inches), it was tall, lengthy, and heavy–in other words just fine for Mercedes-Benz limousines and sedans, but marginal, at best, for sports car racing.

Engine revamped

Dealt this mediocre hand, Uhlenhaut and his crew went to work on the engine and almost quickly were able to wring 175 horsepower from it–certainly not top-of-the-charts but at least encouraging. Still, Uhlenhaut knew that he and his band had been ingenious that the new racer was not going anywhere, both literally and figuratively.

With a boat anchor for an engine, Mercedes engineers knew the body structure and chassis had to be extremely light for their car to even have a chance of being competitive, so they put together a skeleton so light it might have come from a dirigible had it been made of aluminum rather than steel.  The Mercedes-Benz 300SL‘s space frame was constructed of narrow-diameter steel tubing, instead of thick-section frame rails. To provide the torsional rigidity necessary for racing with this construction method, Uhlenhaut’s engineers specified a wide, girder-like assembly across what, in a traditional car, would have been the lower half of the doors.

This structure required the use of the top-hinged, upwardly swinging “gull-wing” doors and resulted in a sill width that was challenging to all but the most agile. Since Uhlenhaut was going racing and had no intentions to offer the 300SL as a production car,  that was fine by him.

Similarly, the Mercedes-Benz staff dealt with the stretched  height of the 3-liter engine by canting it at a 45-degree angle. Doing so permitted  the hoodline to be kept aerodynamically low.

Secret was back suspension

Uhlenhaut’s engineering ace in the hole was an independent back suspension. Many racing cars,and not a few passenger cars, by 1952, were fitted with an independent front suspension. Since that end of the car didn’t involve the transmission of power from engine to wheels, the shift from a beam axle to an independent set-up could be made moderately easily. But designing a workable independent back suspension that could accommodate power delivery while handling all the forces that were applied to racing tire/wheel combinations was a conundrum. Most of the successful road racers of the era used a DeDion or live axle  set-up.

It’s not Mercedes-Benz.The rear suspension the Mercedes-Benz engineers designed wasn’t particularly sophisticated in modern periods. In fact, it was in some ways like the suspension that got the Chevrolet Corvair in so much trouble with Ralph Nader in the 1960’s. It utilized swing axles, located by trailing arms, with coils as the springing medium.  However, this was in 1952, not 1964, and these were racing cars, so the rear suspension proved to be a handling boon.

Wearing simple aluminum bodies and simple nomenclature, a team of 300SLs was prepared for the 1952 sports racing season. (300 stood for the model from which it was  obtained and SL connoted Sport Leicht.) Right out of the box,  the car took a second at the Mille Miglia, falling to a Ferrari on that brand’s  home turf. It was a favorable beginning, but it didn’t begin to tell the tale.

Racing successes pile up

In rapid succession, 300SL ripped off victories in the the 24 Hours of Le Mans, Swiss Grand Prix, the German Grand Prix, and the Carrera Panamericana. It was an unprecedented series of  triumphs  and gave notice to all the world that Mercedes-Benz was again a force to contend with.

But certainly not on the race track.

Its point made in that legendary 1952-53 season, Mercedes decided to drop out of “factory” racing. And that might well have been the end of the 300SL had it not been for Max Hoffman, the New York-based entrepreneur.

A one-time foreigner himself, Hoffman never met an unfamiliar car he didn’t like or at least wanted to sell. He took one look at the 300SL gleaming on its stand at the New York Auto Show, and he guaranteed Mercedes-Benz executives he would buy 1,000 units if they would create  a production version.

The challenge is acknowledged

Thus challenged, Mercedes-Benz could barely say no. Uhlenhaut was sent back to the drawing board to “productionize” his brainchild, while  Walter Hacker and Karl Wilfert were given the task of turning its aluminum racer body into something the factory could build in volume.

Sensing the production car would have, to a large extent,  more weight, Uhlenhaut redesigned the cylinder head and specified Bosch mechanical fuel injection, which upped horsepower considerably. In stock trim the engine  supplied about 240 horsepower at 4,800 rpm.

The new body-style, complete with a mammoth three-pointed star in the grille and  chrome bumpers, was both handsome and aerodynamic enough to allow a 140-mile per hour top speed. It was unquestionably the fastest production vehicle of its day.

In comparison, its handling was not up to modern standards, but one has to keep in mind,   it was shod with extremely narrow, bias-ply tires.  Armed  with a set of modern tires, tuned to its stiff chassis, it might well surprise doubters with its prowess.

It  definitely surprised and delighted all doubters during its 1954-57 production fun. A total of 1,400 300SLs were  created, a sadly small number for one of the greatest sports racing production cars the world has ever known.

—© Studio One Networks—

Tagged with: luxury car • Mercedes-Benz

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