He joined Ferrari in 1948, working under Aurelio Lampredi, followed by employment with Maserati (1953–1957), until the company dropped factory works racing. In 1958 he started his own company, known as Tec-Mec (Studio Tecnica Meccanica).
Tec-Mec, assisted by Giorgio Scarlatti, attempted at the tipo F/415 Formula One car, mostly based on the Maserati 250F, in which Colotti had been deeply involved. There was cooperation with Behra-Porsche (1959) and others such as Stirling Moss, who failed in his racing with Cooper T51, fitted with Colotti's, unfortunately rather unreliable, gearboxes. Colotti's cooperation with Alf Francis lead to the widely used in competition Colotti-Francis gearbox systems. With Wolfgang von Trips he designed the Trips-Colotti-Auto Union (TCA), and later their transmissions were used in Alfa Romeo 33 Stradale (1967).
The company is now called Colotti Trasmissioni and is run by his sons Marco and Paolo.