BROUGH SUPERIOR

800cc Straight Four -1931

The quest for the perfect four

Over the years, George Brough stubbornly tried to replace the traditional JAP V–twin power units on his Brough Superior motorcycles with four-cylinder engines, starting with a 60-degree V-four in 1927. Finally, he succeeded in 1931 with this astonishing and impressive 800cc with a four-cylinder automobile engine.

Twin Rear Wheels

Amazingly, this Brough prototype had twin rear wheels with a shaft final drive sandwiched between them. Along with the retention of the auto's reverse gear, this feature emphasized that this model was exclusively intended for sidecar use.

Disappointing Power Unit

In contrast with the Brough's traditionally impeccable finish, the engine, taken from the diminutive Austin Seven automobile, was a disappointing choice. Even though the new Brough Superior engine had been specially enlarged from 747 to 800cc, it was still a dismal little Hat-head four with a skinny two-bearing, unbalanced, "bent wire" crankshaft. It developed 23 hp – more than the auto version, but still not enough to attract devotees of the marque, who were used to something a little better – and only ten units of the Straight four were sold between 1931 and 1934. But at $240 for the machine alone ($282 with a sidecar), the Straight Four cost $15 more than the legendary V-twin SS100, guaranteed to exceed 100 mph and holder of the World speed record of 129 mph, established by Bert Le Vack at Arpajon in 1929.

SPECIFICATIONS

Engine: 800cc (58x76mm) water-cooled four-cylinder four-stroke, light-alloy cylinder head

Power Rating: 23 hp @ 4600 rpm

Valves: side

Fuel System: Amal carburetor

Transmission: 3-speed and reverse, shaft final drive

Suspension: Castle girder forks (front); rigid (rear)

Brakes: drum (front & rear)

Wheels: 3.25x19 inch (front); twin 3.00xl9 inch (rear)

Weight: 400 lb

This production-model Brough Superior Four no longer has its radiator faired into the nose of the fuel tank or the chromed fender.