Windhoff Motorradenbau GmbH built motorcycles in Berlin, Germany, from 1924-1933. The factory was located at Bülowstrasse 106, Berlin W57, under the direction of factory owner Hans Windhoff.
Windhoff initially produced radiators for cars, trucks, and aircraft, setting up a factory with his brother Fritz in Rheine in 1902, then on his own in Berlin from 1907-24. In 1924 he entered the burgeoning German motorcycle market with a water-cooled two-stroke of 125cc. The engine was built under license from a design by Hugo Ruppe, whose ladepumpe (an extra piston used as a supercharger to compress the fuel/air mix) design was used most successfully by DKW in their Grand Prix racers. Windhoff had much racing success with these small two-strokes, although an experiment with enlarged two-stroke racers of 493cc and 517cc were less reliable.
In 1926, a totally new machine was designed; a dramatic and technically fascinating 746cc overhead camshaft, oil-cooled 4-cylinder. Only Granville Bradshaw (creator of the ABC motorcycle) had successfully used an oil-cooled engine in a motorcycle. The engine, designed by Ing. Dauben (who later joined Mercedes on the W144 - W146 racers) had no external oilways, making a very clean design. The engine finning acted as a giant radiator, with recirculating oil the cooling agent. The single overhead camshaft was driven by a train of gears at the front of the engine. No other 4-cylinder production motorcycle of the pre-War period had an overhead camshaft. The 63x60mm short-stroke engine produced 22 hp at 4,000rpm, which gave an 80 mph+ top speed.
The Windhoff chassis had no ‘frame’ to speak of, and the engine/gearbox unit was used as a stressed member, with the forks and rear subframe (4 parallel tubes) bolt directly onto it. The trailing-link forks use double leaf springs for damping, with no rear suspension; the rear frame tubes emerge straight out of the gearbox casting, and hold the final drive housing for the shaft drive, and rear hub and brake. Despite its massive appearance, the total weight of the machine was only 440 lbs. The price when new was 1,750DM, a bit more than the contemporary 750cc BMW R63 (1,600DM). Hans Windhoff designed a new machine for 1929, with a side valve flat-twin motor of 996cc, but the economic Crash of 1929 meant very few were produced. Windhoff struggled on with small two-stroke motorcycles of 298cc, with engines produced under license from Villiers. The company ceased operations by 1933.
Although both expensive and exclusive, four-cylinder motorcycles were not unknown in pre-war days - Henderson, Indian, Ariel and Nimbus being among the most successful - but few were as technologically advanced – or as imposing – as the German Windhoff. Introduced at the Berlin Show in 1927, the Windhoff Four must have seemed an unlikely departure for a firm hitherto associated mainly with two-stroke lightweights. Hans Windhoff's company was already established as a manufacturer of radiators for the automobile and aviation industries when it introduced its first motorcycle in 1924. The first Windhoffs were powered by an advanced Bekamo water-cooled two-stroke engine that incorporated a pumping cylinder, an arrangement used successfully by DKW throughout the 1930s. This efficient and powerful engine went into a straight-tube frame, somewhat reminiscent of a contemporary Francis-Barnett, and the range expanded to include models of 500cc and bigger.
Then came the sensational Four designed by Ing. Dauben, an automobile engineer who would later go on to work for Mercedes-Benz. Arguably the most advanced motorcycle design yet seen, the Windhoff Four bristled with innovation, for not only was its overhead-camshaft engine oil cooled, it also functioned at the motorcycle's frame. The crankcase and cylinder block were combined in a monumental alloy casting, to which the steering head was directly bolted, while four straight tubes supported the rear wheel. The latter was driven by shaft while the front was mounted in a leaf-sprung, trailing-link fork. Smoothly styled, with all its oil lines internal, Dauben's engine was an over-square design of 63x60mm bore/stroke that produced its maximum output of 22bhp at 4,000rpm. The unit was renowned for its smoothness and flexibility, enabling the Windhoff to be ridden at speeds as low as 6mph without snatch.
Such a complex motorcycle was necessarily expensive - the Windhoff was more costly than BMW's top-of-the-range 750cc twin - and at a time of economic depression was never likely to sell well. Taking a leaf out of his rival's book, Hans Windhoff introduced a BMW-like 996cc flat twin but that too was a casualty of those economically straightened times. Admitting defeat, Windhoff turned his back on the exotic and returned to making two-stroke lightweights, but this time using Villiers engines built under license. Sadly, this venture too was unsuccessful and Windhoff gave up motorcycle manufacture entirely in 1933.
Although ultimately a failure, Hans Windhoff's ambitious attempt to establish himself as a major motorcycle manufacturer resulted in one of the most remarkable motorcycles of the inter-war period.