Self-Changing Gears designed, built and licensed transmissions for various applications including light and heavy road vehicles, military, marine, and rail vehicles as well as motor racing cars.
Following the death of Walter Wilson in 1957, his son A.Gordon Wilson took over the running of the company until his retirement in 1965.
The original company Improved Gears Ltd was incorporated on 28 December 1928, and this later became Self-Changing Gears. The company moved a number of times in the early years, and in 1938 settled in premises at Lythalls Lane, Coventry. During the war, additional premises were used at Burbage, Leicestershire.
In 1935, J D Siddeley sold his interests in Armstrong-Siddeley motors (including Self-Changing Gears) to Hawker Aircraft forming Hawker-Siddeley. In 1951 Leyland Motors Ltd bought into the company, resulting in each party owning one-third of the company, and in 1957 Leyland bought-out Hawker-Siddeley's shares in the company, thereby gaining control.