FAST TIMES
The glamorous supercars of Mercedes-Benz, 1926-1939. PART I: S, SS, SSK and SSKL
Article Graham Robson
Images Daimler Archives
Just for once, let me invite you to put away your wallets and ignore your outstanding debts. Waft your way back to the 1920s and 1930s instead, assume that you have a lot of money, and see what supercars from Mercedes-Benz you could have had in that period. But in those days, you couldn’t expect to saunter into a glossy showroom, inspect a demonstrator model, and pick up your new machine the following day; it could take six months and you would definitely have to make a decision about coachwork along the way before a new supercar could be yours.
In the beginning
This story really starts in 1924 when Ferdinand Porsche – yes, that Porsche – arrived at Daimler. About the same time, the two constituent companies – Daimler and Benz – signed their “Agreement of Mutual Interest,” which moved on to become a full merger in 1926.
The most exciting Mercedes-Benz products of the late 1920s were the supercharged 6-cylinder models, all of which evolved from a 1924 design that Porsche had engineered immediately after his appointment, the original rated at 100 horsepower without the supercharger; 140 horsepower with it engaged. It is interesting to note, however, that although derivatives of this big engine and its related chassis were on sale until 1933, Porsche himself left Mercedes-Benz in 1929 after a blazing disagreement over policy, after which all technical responsibility was handed over to Hans Nibel.
Although the archetypical Type 24/100/140 was most emphatically not a racing car, and did not even have a chassis specifically intended for sports-car use, all the technical quality and potential were there for everyone to see. Indeed, its long-stroke 6,242cc engine hid a light-alloy cylinder block, overhead valves and an overhead camshaft that operated the valves through the medium of finger followers, all of which set the pattern and general layout of many other Mercedes-Benz engines that would follow in the next generation.
From the original basis of the 24/100/140 model, with its massive channel-section chassis frame, its I-section front axle suspended on half-elliptic leaf springs and with cantilever suspension of the back axle, a new series of Mercedes-Benz sports cars came to be developed and put on sale. Each seemed to be faster, more powerful and more expensive than its predecessor. It is also true to say that the company always had more than half an eye on the motorsport potential of these cars.
The first obvious upgrade was to make a new car smaller and lighter while at the same time making the engine more powerful. The result, first seen in 1926 (the year of the merger) was the Type 24/110/160 or K-Type – where K stood for Kurz – German for “Short.” This, incidentally, was still something of a relative term, for the new car’s wheelbase was still an impressive 11 feet 2 inches (439cm), and its fully equipped rolling chassis (without bodywork) still weighed in at nearly 3,400 pounds (1,542kg). With the supercharger engaged, up to 160 horsepower was claimed – for short periods – and delivered a top speed close to 100 mph.
What made this car instantly recognizable at the time – and legendary in the years that followed – was its exhaust system. At a time when almost every road car in the world had exhaust piping that was tucked discreetly under the chassis frame, on the K-model and its successors the pipes were routed proudly out through the side of the hood before being collected into a single tail-pipe, which then disappeared under the body sills. In most cases, these pipes were built of flexible corrugated metal, plated and highly polished. Because of the porting arrangements of the big 6-cylinder engine, there were three such pipes of rather massive dimensions. In every way, this was a car for the proud and extroverted owner: The styling spelled “power.”
S-Type 1926-1930
That, however, was just the start, for in 1927 the K-model was supplanted by the S-model, which was also rather ponderously known as the Type 26/120/180. Although a brief glance at that model name indicates that the engine was not only enlarged (to 6,789cc), but more powerful than ever, the main advance being to the chassis design. The S – for “Sporting,” no doubt – benefited from an entirely new low chassis frame in which the rear end of the side members was swept high over the line of the back axle, and in which half-elliptic leaf springs were underslung. There were additional crossmembers to brace the frame and the engine was moved back by about 12 inches (30cm) in the frame itself.
In spite of all this chassis development, however, the design still suffered from poor brakes, which proved to be its weakest feature in the sport-car races for which it was intended – its acceleration and straight-line speed were of the best, but its stopping power was not. The S-model, incidentally, was seen as having better brakes than the earlier K-Type, which must have been truly terrifying.
The new model was not only fast, but also very flexible, for it could crawl along in top gear at walking pace yet (with supercharger engaged) it could almost top the 100 mph mark. Incidentally, the factory-prepared racing models with higher compression ratios, and using special fuels, turned out at least 220 horsepower: It was in a car of that type that Otto Merz won the German Grand Prix of 1927. Only 149 S-model cars were ever made.
SS-Type 1928-1934
More, however, was yet to come, as Porsche (before he left) and then his successors at Mercedes-Benz indulged in a bit of carefree one-up-manship. In 1928, the new SS-model appeared, this having an official rating of 27/140/200, extracted from an engine which had once again been enlarged – to 7,069cc – and in the same season there was an even more specialized derivative called the “SS” (or 27/170/225), which showed that the engine had been yet further boosted for its new application.
That was the limit of capacity that could be gained in this engine, but it was certainly not the last time that even more power could be squeezed out of it. In some forms, the supercharged version of the 7.1-liter engine could be pushed up to 300 horsepower and beyond for truly short-endurance motorsport purposes.
The SS of 1928, thereafter, remained the company’s supercar in residence for five years, until 1933, yet sales were tiny – only 114 such cars were ever produced – which meant that each one was assembled slowly and carefully by dedicated craftsmen.
SSK-Type 1927-1932
SSKL-Type 1927-1932
No matter, for the company really intended the SS to form the basis of the SSK and of an even more specialized and (in road-car terms) entirely impractical car called the SSKL. Both those types were intended purely for use in motorsport; both were the epitome – the ultimate expression (in Mercedes-Benz's eyes) – of what a true sports car should be.
The secret of their construction was encapsulated in the letters K and L. K, as noted, was short for Kurz, meaning that the chassis frames had been shortened yet again, this time from a wheelbase of 134 inches (439cm) to one of only 116 inches (375cm), while L stood for Leicht (or Lightweight), meaning that the car had been extensively lightened.
Both cars, therefore, were considerably shorter than the SS, and this was always perfectly obvious from a glance at the bodies supplied – usually very stark open two-seater sports bodies with exposed spare wheels on the tail – and because every style tended to be dominated by the expanse of hood that was needed to cover the lengthy supercharged engine. Only 33 SSKs were built.
Because Porsche had stormed out of Stuttgart in 1929, it was his successor (and erstwhile colleague) Hans Nibel who takes most of the credit for the evolution of the simply extraordinary SSKL-model. To Nibel, it seems, there were only two ways in which the design could be improved without making radical, costly and time-absorbing changes: He could either consider increasing the engine’s power output yet again, and/or he could try to lighten the chassis.
Because there was no further capacity available in the engine block, the power increases he and the works team required would have to come from the use of the aptly named elephant blower, for this was the largest of the entire family of superchargers ever to be matched to this engine. This monster, along with changes to camshafts and other moving parts, allowed at least 300 horsepower to be available in extremis. Officially, therefore, an SSKL was a 27/170/300 model. However, in fairness one should point out that it was an unsupercharged 170-horsepower machine that the SSKL operated much of the time.
The engine changes were not obvious at a glance unless an observer knew all about the different sizes of superchargers that Mercedes-Benz was using, but the alterations applied to the chassis frame most certainly were. To reduce the car’s weight as much of possible (and remember, please, that the SSKL was a works racecar of which only a handful were ever built), Nibel resorted to the age-old method of punching holes into every significant chassis member. This pared up to 250 pounds (113kg) off the weight, but must have affected the frame’s stiffness considerably and certainly had an adverse effect on the road-holding. Although the car was still a winner in the right hands, it could not possibly have pleased the orthodox engineering brains inside the company. It also begs the question that in S, SS and SSK form, the design must have been over-heavy all the time.
The SSKL was so specialised that it could surely never have been a true production machine and, as far as is known, no private sales were ever made.
In the meantime, time had flown, Mercedes-Benz’s worldwide image had changed considerably, and it was time to phase in a new series of supercars. The 370-540 series, to be explored in the November-December issue of The Star, were on the horizon.