Property of a deceased's estate
1939 Ariel 601cc Model 4F 'Square Four'
Registration no. HCR 526
Frame no. AX476
Engine no. EE469
Designed by the legendary Edward Turner, the Ariel Square Four was first shown at Olympia in 1930. Unique at the time of its introduction, the 'Squariel', as it was swiftly dubbed, featured a single block of four cylinders and twin geared-together crankshafts with pistons phased at 180 degrees. The crankcase was split horizontally, unusually for a motorcycle engine of the period, while the vertical valves were operated by a single overhead camshaft. A supercharged example was raced at the Isle of Man TT in 1931 without success, which was hardly surprising as its makers had envisaged the model as more of a luxury tourer than an out-and-out sports machine.
Although launched as a '500', the Squariel was soon enlarged to 601cc with an eye on the important sidecar market, this bigger version being made available for the 1932 model year. In 1937 a total redesign saw it re-emerge as the Model 4G, with 995cc overhead-valve engine, making the Squariel an even more enticing prospect for sidecarists. Designed by Frank Anstey, link-type plunger rear suspension became an option in 1939 but would not be offered again until 1946, when a telescopic front fork replaced the previous girder type. An exercise in weight shedding saw the cast-iron cylinder head and barrel replaced by alloy components for 1949, the revised model, now capable of 90mph-plus, being known as the Mark I. Introduced in 1953, the 'four pipe' MkII with redesigned cylinder head elevated the Square Four into the league of genuine 100mph motorcycles. Square Four production, along with that of all other Ariel four-strokes, ceased in 1959. To date, the innovative Ariel Square Four remains unique in motorcycling history; a true 'gentleman's motorcycle, this refined yet characterful machine retains an enthusiastic and loyal following, and is highly prized by discerning enthusiasts.
This Model 4F Square Four dates from 1939 and has the optional 'Anstey link' rear suspension, together with the additional options of valanced mudguards and a rear carrier. The machine had already been restored by a previous owner when it was purchased by the vendor in 2002. Accompanying documentation consists of four expired MoT certificates (most recent September 2003), old-style continuation logbook (issued 1976), purchase receipt (2002) and an original Owner's Guide (instruction book). Offered with V5C 'HCR 526' has not been used or run since acquisition in 2002 and will therefore require re-commissioning and the customary safety checks before returning to the road.