Let's speak about motorcycles, which, next to the aircraft engines, was the supporting product at BMW. As a heritage, the M2B15 engine was delivered to the Victoria works to be installed for a chain-drive, and also for the belt-driven, almost unsellable Helios. The climate was right for the building of a completely new motorcycle, the R32.
It's not at all difficult to imagine what type of construction it would be. The boxer engine was turned (by 90°) so that finally, both cylinders would get an equal amount of air-flow. It was important, for the further course of the drive train, that this motorcycle had, quite quite common at that time, an unsprung rear-end. This making the typical cardan-drive installation more simple. Take a look at the relatively simple shaft and flange on the gearbox.
All together, after his GP-vehicle for Mercedes and his high- altitude engine, Max Friz delivered his third masterpiece. The R32 represented the basic construction-type for at least the next 50 years. It was needed now more than ever, because through the arrival of the engineer Martin Stolle, the (BMW)-engine was so much improved that from that time onwards they could do without deliveries from Munich.
Unfortunately at the same time, the Victoria engine had also become more powerful and there was the real danger that it would beat BMW in the racing sector. At least at this time, the freshly certified engineer Schleicher was there, who as a detail-designer, introduced overhead-valves into the R32, thus finally raising BMW above the anonymous masses. It now bears the name R37 and in contrast to the competition products (mostly English), all the moving parts, including the valve-drive, are protected from dust and from street dirt.