Brough Superior SS100

In the company's advertising of the early 1920s the Brough Superior was hailed as the 'Rolls-Royce of motor cycles'; after the men from that famous marque's Crewe factory had examined the bike they had to concede that it did indeed live up to the title and they gave the Brough company permission to use the slogan. The motorcycle's performance was, however, quite different from that of the luxurious car to whose reputation it alluded. While the Rolls-Royce was more noted for its grace than its performance, the Brough could reach a genuine 100 mph, a speed that was thought to be far beyond the capabilities and safety limits of road bikes of this time.

The power unit of the first SS100 was a specially built, fifty degree vee-twin JAP of 988cc. What was most interesting about the engine was its valvegear which featured four separate little camshafts actuating the overhead valves through pushrods. The power output was claimed to be 45 bhp at
4500 rpm, with a really abundant supply of torque. Carburation was by a Wex, a B&B or a Binks unit, mounted on a T-shaped manifold in between the vee; sports models, however, had much more efficient breathing by way of twin Amal carburettors with long upright inlet tracts.

A four-plate clutch and three-speed Sturmey Archer gearbox were employed, the box giving speeds of 30, 65 and 100 mph in the three ratios, although the Brough could pull away from rest in top gear with just a little slipping of the sturdy clutch. Fuel consumption of the bike could drop to as little as 40mpg if all the performance was used, but a touring figure of between 50 and 55mpg was obtainable by most riders, who were content to let the SS100 purr along on a hint of throttle.

Early SS100s used a leading-link front fork of Harley-Davidson type, while the rear was completely rigid. The front design was chosen by George Brough as ideal for a high-speed bike, but it also dictated that if an effective front brake was fitted it would lock the forks in the fully extended position when applied with vigour. Needless to say, the internal expanding unit actually fitted was so weak as to be useless, so this problem never arose. On the other hand, the 8in rear brake was extremely powerful and much care was needed not to lock the back end up.

With the bike weighing a mere 340 lb with good ground clearance, it could be thought that the SS100 was ideal for country-lane riding, but the ponderously heavy steering and long wheelbase meant that it was much more suited to high-speed road work. The heavy steering also hampered town riding but that was more than made up for by the lusty engine that made light work of pottering along at low speeds in top gear.
Most of the big Broughs were very well equipped indeed, with small fly screens, rigid pannier cases (built exclusively for Brough by Brookes), Bon-niksen time and distance speedometers and an immaculate finish with a large nickelplated fuel tank topping off the looks.

In 1933, the SS100 was redesigned with a different JAP engine, a four-speed gearbox and various minor alterations. Then, two years later, a Matchless power unit was installed, but to connoisseurs of the marque neither of these later models rated as highly as the original, 100 mph 'Rolls-Royce of motor cycles.'

Specifications

(1933 model) engine Air-cooled, four stroke, JAP vee-twin-cylinder. 85-5 mm (3-36in) bore X 86 mm (3-38in) stroke = 988cc (60-27cu in). Maximum power 45bhp at 4500 rpm. Two valves per cylinder operated via pushrods and rockers by four camshafts. Single carburettor transmission
Three-speed gearbox. Chain drive to rear wheel frame
Single tube cradle suspension
Front - Friction-damper fork
Rear - Solid unsprung
brakes
Front - Drum
Rear - Drum
weight
340 lb (154kg) performance
Maximum speed 100 mph Fuel consumption approximately 45mpg

Source Super by Bikes Loure Caddell