The prototype R7 was designed by engineer Alfred Böning and built in 1934 . It is not only a very special motorcycle, he also has a very special history.
A special motorcycle
In publications after the Second World War also called himself the prototype BMW R 17 or R 5 . But the R7 was too different to have stood for one of these two models. In addition, the R17 was already on the market in the same year. If one sees the R 7 looks like a concept car , a motorcycle that subcutaneous "normal" technology has, because it only concerns the appearance. That will be exhibited at fairs and determine what style elements and which do not catch on the basis of the reactions of the public and press. But the R7 was just packed with new technology.
Chassis
The frame , which in a normal production models riveted plate frame was, was at the R7 a pressed steel bridge frame . In addition, the entire engine was encased in sheet metal and was first a telescopic fork used. The fuel tank was largely submerged between the panels, which could be opened at the sides to reach the electrical parts. For the driver there was a big, luxurious floating saddle arranged, and aluminum running boards. The speedometer was not at the wheel but in the headlight. It was a rotating blade as a long time would be applied in luxury cars. In the chrome cover above the tank was an oil pressure gauge and there was also the H-pattern hand circuit milled
Styling
The entire bodywork made with the smooth cylinder head covers for a sleek, well-groomed appearance, which was hardly seen anything of the art. The fit beautifully shaped fenders in the Art Deco style that was in vogue at that time. This also applied to the exhaust fish tail , of beautiful curves and lines was provided. The lack of a tubular frame (the engine hung in the bridge frame) the sleek appearance was reinforced. This was also a construction principle which was extremely rare and had not been applied by BMW. The rear fender was with wing nuts are loosened and then be folded in order to remove the rear easier. Yet still the bike had some characteristics of the rapid record equipment such as WR 750 , by Ernst Henne had ridden. On the other hand came some styling characteristics of the R 7 back in the R 17 and the R 5 later.
Engine
As mentioned above, a study model hypodermic often existing technology, such as the engine and gearbox . But the R7 was in that area at all so new and was probably intended as a prototype for a very exclusive and expensive motorcycle. The engine was developed by Leonhard Ischinger, with highly advanced technology. It was a 800 cc long-mounted boxer engine with overhead valves . The crankshaft was forged in one piece, there were open big end bearings used. The cylinders and cylinder heads were cast in one piece, whereby the head gasket was canceled. Head gasket could at that time still easily leak or rupture, often by the different expansion coefficients of cast iron cylinder and aluminum cylinder heads. The camshaft below the crankshaft, so that the push rods below the cylinder walked through. That led to a better positioning of the valves and the spark plug , but also for more ground clearance , because the cylinders were to be higher. Ultimately, this only from 1969 on production models ( / 5 series are used).
History
The R7 never came into production and was never even exhibited at fairs. The management of BMW was changed, the Second World War on the go, and BMW decided what to give less extreme sport models. The R 12 and R 17 from 1934 were given the telescopic fork. The R7 prototype does have ridden, as demonstrated by a test report from a journalist who made a test ride on an R 5. He saw the R7 driving and reported that in his report. Furthermore, there is very little published about this particular motorcycle. He disappeared in a coffin, even after some parts were torn off. He remained there until he was found in June 2005. The machine had seventy years do not stand well in the coffin. Rust and acid from the ruptured batteries had done their destructive work. BMW Classic, a business that deals with the history of the brand, the BMW Museum and the contacts with classic car clubs, nevertheless decided to restore the machine. During the restoration, it was also targeted search for the original documentation, such as drawings and the like, and they found it, what restoration considerably simplified. However, many parts had to be made completely new, because there were hardly used existing equipment. That made the restoration very expensive, but with the support of the parent company was not a problem. Meanwhile, the machine is ready to drive. The intention is that it is not a static museum piece, but the motorcycle will be driving to see in classic car meetings and other classic events
Fonte: Wikipédia
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The best bike BMW ever made?
The 1934 BMW ‘R7’ prototype is one of the most talked-about and best-loved motorcycles of the 1930s, yet it never left the factory, and was known only through a single, mysterious photo for over 70 years. The life story of this graceful machine is an untold tale of aesthetic movements, internal factory politics, and harsh commercial realities, in which this lovely motorcycle remained a ghostly ‘might have been’.
First conceived in 1933, the R7 began with a simple brief; create a wholly new motorcycle as ‘range leader’ to replace the R16, introduced in late 1928. The R16 used a chassis built from stamped-steel pressings (sometimes called the ‘Star’ frame), a cost reducer which eliminated the skilled labor necessary to weld or hearth-braze a tube frame. Previous BMW frames had a Bauhaus simplicity, while the pressed-steel ‘Star’ gained a shapely Art Deco flair. The new look begged an aesthetic question too compelling to ignore, given the general industrial trend towards Streamlined shapes on cars, airplanes, trains, and toasters. If the R16 whispered Art Deco, what would a total embrace look like?
The responsibility for this new machine likely fell to Alfred Böning, the designer of BMW motorcycle chassis from the 1930s onwards. While no names were attached to the curved frame and swooping mudguards of the R7, “it is perfectly clear the hand of an artist was involved”, according to Stefan Knittel, author of several books on BMWs. The prototype R7 is elegant, simple, and perfectly balanced – did Böning unleash a hidden flair for styling, or were BMW automotive ‘fender men’ called in for a bit of curvaceous appeal? In the early 1930s, individual designers were rarely celebrated, although a few ‘stars’ in the industrial design world were rising, like Raymond Loewy and Norman Bel Geddes. BMW first gave kudos to their ‘pencils’ with the 1940 Mille Miglia streamlined racing cars…in the 1980s! No surprise then that so little remains of the R7’s genesis.
While the styling was obviously radical for BMW, the engine and gearbox were equally innovative, a fact discovered only during restoration of the dismantled R7, in 2005. Likely drawn up by Leonhard Ischinger, BMW’s ‘engine man’ in the 1930s-50s, the engine bears a superficial resemblance to the rest of BMW range, but the crankcase and gearbox castings are one-offs, as are their internals. The cylinder heads and barrels are a single casting, as per aero-engine practice at the time; one less joint to leak. The unique crankcase was shaped to seamlessly fit the monococque chassis from which it hangs. The front forks are a BMW first in being fully telescopic, leading the rest of the motorcycle industry by several years. Internally, the camshaft is placed atop the crankshaft, and the gearbox uses a primary shaft separate from the gear cluster, which slows down the gear speed and helps reduce the notorious shaft-drive ‘clunk’ when shifting. These last two ideas appeared in BMW bikes in the 1950s, when Böning was finally able to incorporate them on production machines.
The R7 weighed in at 165kg (5kg lighter than the R16) with engine capacity 793cc, producing 35hp @ 5000rpm (2hp more than the R16), breathing through Amal-Fischer carburetors with accelerator pumps (!) and swill-pots to cure any fuel starvation while cornering. Thus the experimental model had seriously hot performance, being capable of over 90mph while looking sensational. Superbike, anyone?
When completed in 1934, the R7 wasn’t exhibited or press-released; it appears to have been shelved immediately.The first the world knew of the ‘Art Deco’ BMW was a magazine article on the new R5 model in 1936, which included a retouched side-view photo captioned “what could have been”. That solitary photo launched decades of mystique around the R7, giving rise to the Question: why on earth didn’t BMW manufacture this beautiful machine?
Complicated forces worked against the R7. While the prototype is a hand-fabricated one-off, actual production would require huge investment in tooling for the metal pressings, new castings for the engine, gearbox, and cylinders, plus setup for all the unique internal parts. With only a few hundred of their excellent R16 sold, recovering the tooling investment was unlikely. Also, BMW were aware that motorcyclists are very conservative consumers, and bikes which read as ‘design exercises’ in sheet metal were never successful: the Mars (Germany), the Ascot-Pullin (England), and the Majestic (France) all trod a similar path to the R7, being ‘ideal’ designs of innovation and great style, yet doomed to commercial failure. Motorcyclists of the Vintage period, dedicated gearheads all, wanted the fiery beating hearts of their mounts visible in all their complication; this remains our enduring delight.
Internal factory politics certainly played a hand as well. Rudolf Schleicher, chief of motorcycling at BMW, was convinced the ‘range leader’ should be a sporting motorcycle, not a luxury machine, and factory notes indicate his plan for a supercharged motorcycle for the public! The prototype of his blown roadster was seen in the BMW ISDT team of 1935, but such an ‘ultimate motorcycle’ was seriously impractical; “Every owner would need his own specialist mechanic, and BMW didn’t want private competition for their factory racing team,” notes Stefan Knittel. As it was, neither Blown nor Deco was produced, but the telescopic forks and curvaceous mudguards of the R7 did find their way onto the R17 model.
The R7 was dismantled, but never destroyed; it remained at the factory, strapped to a wooden palette in the factory basement, well known to BMW employees. It must have been dear to Alfred Böning’s heart, as he kept it close at hand until his retirement in the 1970s. By this time, BMW was re-collecting its history, with their famous ‘bowl’ museum opening in Munich for the 1972 Olympics. While a clamor arose in the 1980s to revive the R7, it wasn’t until 2005 the task was handed to two legendary restorers; Armin Frey undertook the mechanicals, while Hans Keckeisen massaged the sheet metal. The results are sensational.
The 1934 R7 prototype is an unquestioned design success - a graceful and beautiful study of flowing lines, curves, and feminine masses. Almost to a person, especially to non-motorcyclists, it is considered one of the most beautiful motorcycles ever made. As good as it is, the R7 is a total philosophical departure from what is best about BMW during its first 60 years; restraint. The extravagance expressed by the R7 is shockingly French - more Delahaye than Bauhaus.That the R7 was never serially produced makes complete sense, but 75 years on, she’s still a heartbreaker.
Fonte: Vintagent (This article was written for the 2011 Amelia Island Concours catalog by Stefan Knittel)
