Norton Isolastic frame

The isolastic frame, designated by Norton as GlideRide, used a system of engine-to-frame mountings incorporating rubber bushes to isolate the vibration of the vertical twin engine from the frame and rider. The isolastic frame was developed for use with the Commando inclined engine, whilst the Featherbed frame continued in production for the Mercury with a softer-specification 650 cc vertical-engine until 1970.

Following the collapse of the old Norton parent-company AMC in 1966, a new business was structured to produce motorcycles using the name Norton Matchless Division, under a new parent company name of Norton Villiers Ltd.

Part of the changes involved creating a new design frame produced as previously by Reynolds Tubes in Tyseley, Birmingham, England, where the traditional Featherbed frame had been produced since the 1950s, shipped for assembly at the Matchless works in Woolwich, London.

In an attempt to reduce the worsening problem of engine vibration being transmitted through the frame, as the capacity of the engine increased to 750cc with the Norton Atlas, Norton Villiers decided to replace the Featherbed frame for their top model, and the Norton Commando was the result, although Norton-Matchless machines like the P11 continued to use conventional Matchless frames.

The innovative new design isolastic frame made it smoother through the use of rubber bushes to isolate the engine and swingarm from the frame, forks, and rider. As the rubber bushes deteriorated, however, the bike became prone to fishtailing in high-speed turns. Earlier models therefore required careful maintenance and adjustment of the clearance between frame and mounts using shims.

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Wikipedia