Ariel first introduced the square-four engine in 1930. A pushrod 997cc Square Four 4G was introduced in 1936 developing 38hp and a claimed 100mph top speed. The rear suspension was redesigned in 1939 incorporating pivoted links to the rear wheel spindle. Post-war the Square Four used this suspension until production ended in 1958. After the war the 1000cc was continued and gradually uprated with telescopic front forks, improved cooling and an all-new aluminium engine. The final redesign came in 1954 and coded the 4G MkII; raised compression developed 42hp at 5800rpm and was a handsome machine. Lack of financing meant cessation in 1958. A book of contemporary road tests, specification and technical data, new model introductions, development, riders impressions, history, touring, technical articles on tuning, engine stripping, decoking. 136 pages, 350 illus. SB.
