Legend has it that Irving accidentally placed a wrong side up tracing of the Vincent 500 motor on top of an equally sized drawing of the same motor in such a manner that it formed a V Twin. Moving it so that it would fit resulted in the 47.5° V twin which appeared in 1936. (The single leaned forward 23.75°.)
With 6.8:1 compression, it produced 45 bhp (34 kW).
The Vincent V-twin motorcycle incorporated a number of new and innovative ideas, some of which were more successful than others.
The Vincent HRD Series A Rapide was introduced in October 1936. Its frame incorporated motorcycling's first "cantilever" rear suspension, which was used on all Vincents produced from 1936 through 1955. Other innovations included foot gearchange instead of hand-operated gearlever, a four-speed gearbox instead of two or three, and a side stand.
Pneumatic forks were not to be a Vincent innovation, with both Phils believing girder forks were superior at the time. The Series-A had external oil lines and a separate gearbox.
The 998 cc Series A Rapide Vincent cost $600, produced 45 hp (34 kW), and was capable of 110 miles per hour.
The high horsepower meant that the gearbox and clutch did not cope well.