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Motorcycle Investor mag

BMW /5 series

(by Ian Falloon, Mar 2022)

Ian Falloon looks at what now qualifies as a bargain classic

Times were tough for European motorcycle manufacturers during the 1960s. The Japanese already dominated the smaller capacity market and their success in Grand Prix racing enabled them to expand their horizons.

Although they concentrated on producing motorcycles over 250cc the survival of British and European manufacturers was threatened. Built with up-to-date machinery, these new mass-produced Japanese motorcycles offered class-leading performance, and were cheap and reliable.

While motorcycle sales sustained BMW early in the 1960s, by 1963 BMW’s new range of cars was more successful and profitable. Fortunately, in face of serious opposition, technical director Helmut Werner Bönsch managed to persuade BMW’s directors to sanction a pilot scheme to develop a replacement for the /2. With an internal designation of Type 246 this became the /5, a series of air-cooled boxer twins that would sustain BMW until 1996.

The new engine differed significantly in detail and execution to the previous /2 and was very automotive inspired. Instead of a pressed together roller bearing crank with the camshaft above, the crankshaft was a one-piece forged crankshaft type running in plain main bearings. The con-rods and bearings were straight out of the 1600cc BMW car. The single camshaft was now located below the crankshaft, and the pushrods below the cylinders, tidying the look of the engine.

The /5 was produced in three capacities; 500cc, 600cc, and 750cc, and each was ostensibly identical but for the capacity.

Compared to most other motorcycles of the day the R75/5 was a user-friendly machine. A 180 Watt auto style alternator powered the electrical system, a strong starter motor sat on top of the crankcase, and a fully enclosed shaft drive simply made life easy for those interested in high mileages.

Long before noise and emission regulations were enforced the /5 incorporated an integrated air filter and engine breather system. Also new for the R75/5 was a set of 32mm Bing constant vacuum carburettors.

Producing a modest 50 horsepower at 6200 rpm the four-speed R75/5 was still a respectable performer, capable of around 175 km/h.

With a “Featherbed” style frame, short swingarm, and telescopic front fork, the /5 chassis also represented a considerable departure from previous BMWs. Designer Von der Marwitz believed too much frame stiffness was detrimental for a street motorcycle, bolting the subframe onto the main frame section.

The long travel suspension gave a supremely plush ride for the day but the /5 never earned a reputation for sharp handling. Another area of criticism was the brakes. Although other Superbikes were moving to disc brakes, discs were untried on BMW motorcycles so the /5 had traditional drum brakes.

BMW R75/5

Even the Germans are prone to irrational behaviour and after two years BMW decided the R75/5 was too staid for the US market. Although they left the engine and chassis as before the fuel tank was downsized to 17 litres, chrome side panels added, and matching chrome plated side battery covers installed.

The 1972 R75/5 soon earned the nickname “Toaster” tank because of its similarity in appearance to the kitchen appliance. But not all markets greeted the “Toaster” fuel tank with unequivocal acclaim.

After sales stalled here in Australia the /5 was sold with the earlier-style larger tank as standard, and BMW Great Britain followed suit later in the year. Market resistance to the gaudy “Toaster” tank outside the US led to BMW returning to their more traditional conservative styling during 1973 but the chrome “Toaster” tank was still fitted to many US models.

With nearly 69,000 produced over four years, the /5 series re-established the BMW motorcycle tradition. Offering unparalleled touring comfort and reliability these are still viable useable motorcycles. Many spare parts are available, now remanufactured by BMW Mobile Tradition, and the /5 is one of the bargains of the classic bike world.