1931 AJS had been bought by the Matchless owners, the Colliers, in 1931.

1937/38 Name change to Associated Motor Cycles.

1937 Sunbeam had been bought in 1937 from Imperial Chemical Industries. AMC designed an all new range of Sunbeam motorcycles, maintaining the quality and engineering, but sold them to BSA in 1943.

In 1939 a 495cc AJS V4 was built to compete against the supercharged BMWs then dominating racing. The bike was a water-cooled and supercharged. In 1939 the dry-sump V4 was the first bike to lap the Ulster Grand Prix course at over 100 mph. It weighed 405 lb. Its top speed was 135mph. Then the Second World War intervened.

In 1941 Matchless introduced telescopic front forks called "Teledraulic" forks, considered by some to be the first major innovation in front suspension in 25 years.

WWII During the Second World War, Matchless manufactured 80,000 G3 and G3L models for the armed forces.

In 1946 Freddie Clarke joined AMC as Chief Development Engineer after a difference of opinion with Triumph.

In 1947 AMC absorbed Francis-Barnett, and in 1953 further extended the empire by soaking up Norton. Post-war landmarks start with the production of Matchless/AJS 350cc and 500cc singles, developed from the legendary war-time Matchless G3 produced for the Army. From 1948 competition models of the singles were produced which gave the company some memorable wins.

By 1956 they had eight models in their line up, but the number had dwindled in 1965. The G3L was the first to feature the "Teledraulic" front forks.

In 1949 the first Matchless/AJS vertical twin (500cc) was produced, later to be joined by 600cc and 650cc vertical twins in 1956 and 1959 respectively. On the racing front AMC were fielding the AJS Porcupine (500cc forward facing parallel twin), the AJS 7R (32 bhp, 350cc OHC single), the Matchless G50 (a 500cc variant of the 7R) and by 1951, the Matchless G45 (500cc vertical twin). The AJS Porcupine had been designed for supercharging, before the rules changed ending supercharged racing motorcycles, but even so, Les Graham won the 1949 World Championship on an unsupercharged AJS 500cc Porcupine.

In 1951 AJS development engineer Ike Hatch developed a 75.5 mm bore x 78 mm stroke, three valve head version of the 7R making 36 bhp. It was called the AJS 7R3, and was Ike's response to the Italian multi-cylinder racers. They did well enough in their first year, not as well the second. For 1954 Jack Williams, the works team manager, developed the bike further, lowering the engine in the frame, and making some tuning changes that gave 40 bhp @ 7800 rpm. It immediately won the first two rounds of the World Championship and took first at the Isle of Man TT. These were factory specials, but one has survived, and a second has been reconstructed from spares. In 1953 there was a Clubman range of Matchless/AJS 350cc and 500cc singles, and the production model Matchless G45 500 twin became available.

1953 Norton was bought by Associated Motor Cycles, by then consisting of the AJS, Matchless, James and Francis-Barnett marques, in 1953 after it became obvious that the Norton company was not doing well despite the success of the "Featherbed frame" used in racing bikes and the production 1952 Dominator 88.

After 1957 Norton models used the AMC gearbox.

AMC withdrew from the world of works and one-off road racing at the end of the 1954, with the death of Ike Hatch, and in the face of fierce competition from the other European bikes. Instead of works specials, AJS and Norton would make the production versions of the Manx Norton and the standard two valve AJS 7R, for privateers.

In 1958 the Matchless/AJS road bikes were joined by a 250cc and in 1960 by a 350cc for a lightweight series of singles.

In 1960 Bert Hopwood resigned from AMC and went to Meriden. That same year AMC posted a profit of a bit over 200,000 pounds, not so good compared with BSA's 3.5 million.

1961 Parent of seven subsidiaries manufacturing motor cycles, engine parts for aircraft, tool kits and small tools and fabricating engineers. Owned Matchless, AJS, Norton, Francis-Barnett, and James motorcycle brands. They posted a loss of £350,000.

1962 With the closure of the Norton plant at Birmingham in 1962 and the merger of Norton and Matchless production, the future was beginning to look rather bleak. In the sixties, with sales declining AMC made the commercial decision to focus on the Norton twins and the Matchless/AJS singles but they were not to be successful and the factory ceased production shortly afterwards.

Some models were "parts bin specials" put together at the request of the American dealers. The Americans were desert racing, so Berliners sent AMC an example custom bike using a Norton 750 motor in a G80CS frame, and asked them to build them some. This was the last Matchless motorcycle, the 748cc G15 which was also sold as the AJS Model 33' and as the Norton P11. The G15 was produced up until 1969. A Mk2 version was sold in Britain from 1964.

Matchless/AJS built predictable handling, comfortable, well-made, reliable and economical motorcycles, for their day. Unfortunately such attributes were not enough to keep them in business. Continuing poor sales led to AMC becoming part of a new company, called Norton-Villiers in 1966.

By the late 1960s, competition from Japan had driven the British motorcycle industry into a precipitous decline.

In 1966 AMC collapsed and was reformed as Norton-Villiers under Manganese Bronze.

1974 This only alleviated the problems briefly and Norton-Villiers eventually went into liquidation in 1974. Norton was reformed with financial assistance from the British government as Norton-Villiers-Triumph (NVT) actually incorporating the majority of the BSA motorcycle concerns but omitting the BSA name for Triumph. In part due to a labour dispute, NVT later went into receivership in 1974.