Norton Motorcycle Company - AMC

AMC

Despite, or perhaps because of, the racing successes Norton was in financial difficulty. Reynolds could not make many of the highly desired Featherbed frames and customers lost interest in buying machines with the older frames. In 1953 Norton sold out to Associated Motorcycles (AMC), who owned the brands AJS, Matchless, Francis-Barnett and James. In 1962 the Norton factory in Bracebridge Street, Birmingham was closed and production was moved to AMC's Woolwich factory in south-east London.

Under AMC ownership a much improved version of the Norton gearbox was developed, to be used on all the larger models of AJS, Matchless and Norton. Again, the major changes were for improved gear selection. In September 1955, a 600 cc Dominator 99 was launched. The 1946 to 1953 Long Stroke Manx Norton was 79.6 mm × 100 mm (3.1 in × 3.9 in) initially SOHC, the DOHC engine becoming available to favoured racers in 1949. The Short Stroke model (1953 to 1962) had bore and stroke of 86 mm × 85.6 mm (3.4 in × 3.4 in). It used a dry sump 499 cc single-cylinder motor, with two valves operated by bevel drive, shaft driven twin overhead camshafts. Compression ratio was 11:1. It had an Amal GP carburettor, and a Lucas racing magneto. The 1962 500 cc Manx Nortons produced 50 bhp (37 kW) at 6,780rpm, weighed 142 kg (313 lb), and had a top speed of 209 km/h (130 mph).

In 1960, a new version of the road-going Featherbed frame was developed in which the upper frame rails were bent inwards to reduce the width between the rider's knees for greater comfort. The move was also to accommodate the shorter rider as the wide frame made it difficult to reach the ground. This frame is known as the "slimline" frame; the earlier frames then became known as the "wideline".

The last Manx Nortons were sold in 1963. Even though Norton had pulled out of racing in 1954, the Manx had become the backbone of privateer racing, and even today are quite sought after.

On November 7, 1960 the first new 650cc Norton Manxman was launched for the American market only. By September 1961 the Norton 650SS appeared for the UK market, The 750cc (Atlas). By April 20, 1962 for the American market as they demanded more power, but the increases to the vertical twin engine's capacity caused a vibration problem at 5500 rpm. A 500cc vertical twin is smoother than a single-cylinder, but if the vertical twin's capacity is enlarged vibration increases. The 750 Norton Atlas proved too expensive and costs could not be reduced. Financial problems gathered.

There was an export bike primarily for use as a desert racer, sold up until 1969 as the Norton P11, AJS Model 33 and Matchless G15, which used the Norton Atlas engine in a modified Matchless G85CS scrambler frame with Norton wheels and front forks. This bike was reputed to vibrate less than the Featherbed frame model. AMC singles were also sold with Norton badging in this era.

Also during this period Norton developed a family of three similar smaller-capacity twin cylinder machines: first the Norton Jubilee 250 and then the Navigator 350 and the Electra 400, which had an electric starter. These models were Norton's first use of unit construction. The engine was an entirely new design by Bert Hopwood and the frame and running gear were from the Francis-Barnett range, also owned by AMC. These machines had a reputation for poor reliability.