Brave New World

The 1934-1939 130, 150, & 170H were the first and only  rear-engined passenger cars ever built by Mercedes-Benz

Article Graham Robson

Images Daimler Archives

Certainly it isn’t often that Mercedes-Benz has made a big miscalculation, persisted with it, and then seen its failure headlined in public. But there was one such mistake – the first and hopefully the last: the innovative 1934 rear-engined 130H sedan. Or was this a case of simple misfortune? One fact is unassailable: once the 130H and its successors were swept away in 1939, any further idea of developing another rear-engined Mercedes-Benz road car was banished.

Even so, to get back to the beginning of that miscalculation, we have to dig back into the 1920s when the idea of developing the world’s first rear-engined production car had started circulating throughout Germany. Trying to catch up with the United States and Great Britain, the nations that then dominated the world’s automotive markets, German visionaries began to dabble with the idea of building a streamlined automobile, in which the bulky engine and transmission could be moved to the rear of the chassis, allowing the vehicle’s nose to be shortened. Not only that, but if there was no propeller shaft or transmission tunnel bisecting the body, then the passenger compartment could be enlarged. The technical team at Daimler – in the 1920s headed by Ferdinand Porsche – evaluated just such a design, but did not produce a prototype.

By 1930, however, facing the economic collapse that had engulfed Germany, Daimler determined to downsize and thereby reduce the price of their cars. Long-serving technical boss Hans Nibel was instructed to design Project W17, as the new car was initially coded. Coincidentally, (for no cooperation took place) Ferdinand Porsche began similar work at his own new independent consultancy in Stuttgart, and Hans Ledwinka initiated the first of his rear-engined designs at Tatra.

With the still-to-be-announced 170 sedan, and the massive new Grosser both ready to reach the public, Nibel, Max Wagner, and their team found time to think deeply, and to make their W17 a real trend-setter. By 1931 the first prototype was on the road. Several layouts were assessed before the final version emerged.

The W23 130H

In the beginning, there was to be a two-door/four-seater car, complete with a 1.2-liter flat-four “boxer” engine in the tail, but this produced only 25 horsepower, and was not considered commercial. To follow it up, a new layout, featuring a transversely-mounted four-cylinder engine, was also tried, and even an early prototype of the company’s pioneering diesel engine was also proposed, but the definitive 130H did not emerge for its first secret test runs until 1932-1933.

Nibel may have been influenced by the unsuccessful rear-engined streamlined Tropfenwagen (Rain-drop car) race cars with which Hans Rumpler had hoped to gain the company’s support in the 1920s, and it was this car’s basic layout which finally matured in the evolving W23, which was named 130H (the H standing for Heck, the German word for rear) by the time it reached the public. The launch came in February 1934 at the Berlin Motor Show, with sales beginning during the year.

Many British and American observers ignored the new 130H as a silly novelty from a country which was still struggling to find its economic feet. However, towards the end of that year Britain’s leading motor magazine, The Autocar, published a detailed study of the 130H. The article included an excellent cutaway drawing of the running gear by celebrated technical artist Max Millar.

In its own insular and rather patrician way, The Autocar reflected the views of many British engineers by summarizing as follows: “…the long-accepted sequence of components has been reversed, or at least very materially revised. Precisely what advantages are gained in a country such as ours by these changes, and, still more, the reaction of the ordinary car user to them, remain to be proved. … Here is a car entirely different in its whole construction and layout from any machine, big or little, which we produce….

“It is an attempt to meet the conditions obtaining in its own country, where many people require a car that shall be economical, yet will not be content with one that involves tedious travel over long distances….”

One must salute The Autocar at this point for getting to the very core of Mercedes-Benz’s thinking, especially as the magazine’s analysis of the car was so accurate. Although the company’s solution had been totally logical – there was to be a separate chassis, with a choice of different coachwork bolted to it – Stuttgart elected to use a sturdy backbone chassis frame (part tubular, part box section), which supported an independent front and rear suspension on simple cross-members.

For technical students, there was much to raise eyebrows, though we may be sure that Nibel’s team had given a lot of deep thought to the layout. At the front, suspension was by upper and lower full-width transverse leaf springs – which effectively provided transverse wishbones – while at the rear there was a swing axle, with suspension by large diameter coil springs. The backbone chassis also incorporated a pressed steel fork extension supporting the engine, which was mounted behind the line of the rear wheels.

The four-speed transmission was mounted in line with the engine and differential and ahead of the line of the rear wheels, with a long gear linkage leading forward via guides mounted on top of the chassis backbone. Rack and pinion steering was fitted just ahead of the line of the front wheels.

If all this was novel, the engine itself was quite conventional, for it was no more and no less than a water-cooled 26-horsepower, 1,308cc side-valve four-cylinder unit which just so happened to be a close relative of the existing “six” used in the latest Mercedes-Benz model, with which it shared the same bore, stroke, valve gear details and production machining lines.

The gearbox had four forward speeds – or rather, as Mercedes-Benz hoped its clientele would understand – three speeds and a semi-automatic overdrive top gear. According to The Autocar’s road test: “To engage the overtop, without the clutch pedal being touched, the gear lever is moved sideways and forward, the throttle is released momentarily, and a synchromesh action brings in the overtop without any further movement being necessary by the driver.”

Although this made for a very elegant and close-packed layout, the assembly included an engine-cooling fan located ahead of the engine – rather than at the rear close to the outside world, as one might expect. The radiator was positioned in front of that (but behind the rear seat, and sealed off from it), on top of the line of the rear wheels and the differential itself. One can only imagine the initial reaction of a seasoned mechanic, upon first opening the engine cover at the rear of the vehicle and seeing this somewhat eccentric arrangement.

Three versions of the 130H were initially produced – a two-door four-seater sedan, an open-top version, and a rare cabriolet, all constructed at the Sindelfingen plant on the outskirts of Stuttgart. Unhappily, demand was not as high as company planners had hoped. This was due to a combination of public reluctance to embrace the car’s totally novel features, the prices (which were significantly higher than those of obvious rivals), and the inescapable facts that the 130H was heavy, not very fast, and its handling suffered from rearward weight distribution.

Independent road tests showed that the top speed was at best 55 mph (even for the 1930s, that was considered somewhat sluggish), and that it could take up to 37 seconds to accelerate from rest to 50 mph. It was no wonder, therefore, that The Autocar, whose road test standards could be described as “diplomatic” on all occasions, included these little gems:

“It is a car which, for several reasons, does not lend itself well to the ordinary routine of test figures.…. the limit on first, the emergency ratio, is not above 10mph, and on second not more than 25mph, whilst direct drive allows speed up to about 48mph. Again, the geared-up ratio is not intended for low-speed acceleration.”

Even more significant however was the fact that throughout this test, not once was the car’s handling or road holding mentioned or described, and indeed it was not for some time afterwards that most people discovered why. The fact was that with at least two thirds of the car’s weight over the rear wheels, it was an over-steering beast in many cornering situations.

Even so, Mercedes-Benz tried very hard to market this new machine, and managed to sell almost 5,000 examples before discontinuing the 130H during 1936. To sell over 2,000 cars a year at this time in the company’s history was creditable enough (the new 170, for example, was selling more slowly than the 130H in the same period), but with the Sindelfingen plant already bursting at the seams, and with more prestigious new models like the 170V and the 230 on the horizon, some brutal decisions had to be made.

The W30 150H

This, however, was not the end of the pedigree, for even as the 130H was being manufactured, the company decided to dabble further and produce a two-seater sports roadster derivative. With a much-revised chassis layout again inspired by Hans Nibel and his associate Max Wagner, it got as far as the prototype stage, was first shown in 1935, but never went into series production.

Although photographs and drawings made this obvious, it was not always emphasized that the entire layout of the 150H’s chassis was different from that of the 130H. Although the basic backbone frame was retained, the position of the engine and transmission package had been moved forward to improve the weight distribution, which automatically meant that the cooling fan and cooling radiator could be re-positioned to the extreme rear of the car.  On the other hand, the fuel tank had to be moved up to the nose, effectively taking up all the otherwise useful luggage space. This, presumably, makes the 150H the world’s very first mid-engined sports car to reach the public, even though it never went into series production.

Not only that, but the engine was substantially re-designed, enlarged to 1,498cc, and given overhead camshaft valve gear. The result was that it produced 55 horsepower – which compared very well with the 26 horsepower of the 130H side-valve unit – and the sleeker, lower and sportier body allowed it to reach nearly 80mph.

This all looked very promising, except that to make any money from the 150H Mercedes-Benz would have had to hoist the selling price to 6,600 Reichsmarks, considerably more than the existing 170 sedan. And although this was never stressed, all hopes of developing the 150H into a successful and appealing competition car were stymied by the presence, in that same time span, of BMW’s sensational new Type 328 model.

The 150H project was abandoned gracefully after a mere handful of Sport Roadster prototypes had been constructed. Only one example is believed to survive today.

The W28 170H 

So was it the hope of building on the original 130H’s reputation, or a case of sheer stubbornness on the part of a company that was used to everlasting success, which caused the 170H of 1936 to go on sale? No matter, the fact is that as the 130H was discontinued, the 170H appeared to take over its market slot.

The technical, styling, and marketing links between the 170H and the previous 130H were clear, but the other connection with the newly launched 170V model – somewhat understated by the company – was more significant. This was that, to rectify the lack of performance from which the 130H had always suffered, the new 170H model was set to use the latest 38-horsepower 1,697cc side-valve power unit which was to power the 170V so very successfully right on into the 1950s.

At first glance, the 170H looked rather like the discontinued 130H, though there had been obvious and suitable changes made to modernize the styling. Under the skin, the tubular backbone chassis frame and the independent suspension had both been carried forward from the 130H to the 170H – and the new vehicle’s wheelbase had been increased by four inches to provide more space in the cabin – with the engine once again sitting in the extreme tail. Although both the engine and sloping back body style were virtually as before, there had been a major re-positioning of engine components, for the cooling radiator had been banished from its original position above the transaxle, and now had to live alongside the engine itself. As before, both a sedan and an open-top sedan were available, but Mercedes-Benz made no further attempt to market a roadster.

The larger engine made the 170H a much more practical machine, for it could now reach up to 68 mph on Germany’s new Autobahns. Additionally, it must be said that Mercedes-Benz tried strenuously to make the 170H a popular success. The problem, however, was that the new vehicle had to sell for 600 Reichsmarks more than the 170V saloon (which was a much more spacious four-seater than the somewhat close-coupled 170H), and it always had to fight an uphill battle against the public’s distrust of the unfamiliar mechanical layout and, frankly, against its 130H predecessor’s reputation for poor handling. The public voted with its pocketbook, keeping it tightly closed in the case of the 170H. In three years Mercedes-Benz sold a mere 1,507 examples – compared with 65,000 170Vs during the same period.

So in the end, which German car would finally succeed with a rear-engine layout? It was, of course, the postwar Volkswagen Beetle, and we all know what happened to that.

Images

The pioneering streamlined, rear-engined, swing-axle Rumpler vehicle of the 1920s influenced Hans Nibel and Max Wagner’s design for the 1934 Mercedes-Benz W23 130H.

The W23 130H employed a tubular backbone chassis, forked at the rear to accommodate the engine and four-speed transmission.

The front wheels were independently suspended with two transverse leaf springs; at the rear, the 130H used a swing axle with a single coil spring on either side. The four-cylinder in-line water-cooled engine produced 26 horsepower.

The W30 150H was first developed in 1933–1934 as a two-seater sports car for competition.

In July 1934 an experimental prototype won four gold medals in a 2,000-kilometer endurance race across Germany. Based on the 1.3-liter unit from the 130, the engine developed 55 horsepower, more than twice the original.

To improve weight distribution and handling, the engine and transmission were turned 180 degrees, so that the engine was in front of the rear axle. In effect, this created an early version of the mid-engine layout still in use today.

The W30 150H competition prototype served as the basis for the sleek W30 150H sports roadster, which caused a sensation at Berlin’s International Motor and Motorcycle Show in February 1935.

However, the unconventional two-seater did not make it into production.  The only known surviving example is now in the Mercedes-Benz Museum, Stuttgart.

The final rear-engined Mercedes-Benz of the decade, the redesigned, more powerful W28 170H, was revealed in February 1936 at the International Motor and Motorcycle Show, Berlin. Similar in overall appearance to the 130H that it replaced, the new vehicle’s wheelbase was increased by four inches to offer more cabin space. Unusually for the era, a cabin heater came as standard.

While careful chassis tuning resulted in much improved handling when measured against the awkward 130, the 170H’s road manners still took some getting used to.