Pre-unit construction

The term pre-unit particularly applies to BSA/Triumph's single- and twin-cylinder bikes after this firm adopted unit construction in the early 1960s.

With the exception of the Issigonis Mini family of cars, the practice in the automobile industry has also been to keep engine and gearbox oil separate.

The 1969 'Isolastic'-framed Norton Commando had its pre-unit engine, gearbox, and swingarm assembly bolted together on plates fixed to the frame via shimmed rubber bushes.

Among the Japanese manufacturers, Kawasaki produced a separate construction 650 cc vertical twin, inherited as a consequence of taking over Meguro in 1964.

These firms would build, say, the frame and fuel tank, but most of the other elements, such as engine, gearbox, brakes, electrics, controls and instruments were bought in from outside manufacturers such as JAP, Villiers and Lucas.