c1948 Triumph 5T 500cc 'Speed Twin' Motorcycle

Description

Triumph launched its Speed Twin 5T motorcycle at the 1937 British National Motorcycle Show. Made initially at its Coventry and later Meriden factories, it was a 500cc OHV vertical twin in a lightweight frame and became the first truly successful British parallel twin. Indeed, after World War II the Speed Twin was largely responsible for Triumph’s survival because, although a 500cc parallel twin was not revolutionary, the Speed Twin 5T model was lighter than many contemporary singles and with significantly more power and torque. Early models were only available in 'Amaranth red' with hand painted gold pinstripes to set off the paint. Based on a rigid frame from its single-cylinder bikes, the 5T’s sprung saddle was the only rear suspension, while there were girder forks up front. The two cylinders were fed by a single Amal Type 6 carburettor and many of its features such as the transmission and clutch were straight from the Triumph single. After the war, Triumph (now at Meriden after its Coventry factory was destroyed by enemy bombing) developed the Speed Twin with telescopic forks and optional sprung hub rear suspension. The headlamp and instrument area were tidied up in 1949 with the Edward Turner-designed nacelle, a feature retained until the end of the model line. In 1953, the generator and magneto were replaced with a Lucas alternator and battery/coil ignition system. The Speed Twin was also used by the UK Metropolitan Police Special Escort Group from 1952 until 1959. Further development led to the 1959 model 5TA, with a unit engine and gearbox construction and styling changes including an unpopular 'Bathtub' fairing, which became more and more abbreviated as the model developed before disappearing altogether for the last year of production in 1966.