The unique variable-rate rubber all-independent suspension system of the new B.M.C. cars was developed at Bradford-on-Avon by Moulton Developments Ltd., under Mr. Alex Moulton. This company was founded three years ago at the instigation of Sir Leonard Lord to develop suspension and other components for B.M.C. vehicles under Moulton patents. It is an associate company of the B.M.C.
Each wheel is sprung by one rubber suspension unit acting at a high leverage to the suspension arm through special nylon-seated ball joints. The front units are mounted vertically in the sub-frame above the top wishbones while the rear units act on the trailing arms and are horizontally disposed in the rear sub-frame side-members to avoid encroaching on useful space. The Suspension Unit comprises inner and outer metal cones with a high-resilience natural rubber compound bonded between them. When the unit is deflected the rubber is subjected to combined compression and shear. Special shaping of the rubber cross-section, developed by extensive testing and photo-elastic study, has resulted in a compact and economical suspension unit. It is claimed that the special design of the rubber suspension unit with its uniform strain distribution throughout the rubber ensures a longer life than that of the normal steel springs hitherto used on conventional cars. No maintenance or lubrication is required.
The suspension ratings have been “tailored” to maintain good handling and ride characteristics throughout the exceptionally wide variation of load which results from having a full-sized body space in a very light vehicle. The inherent damping of the rubber not only allows exceptionally low damper settings but also cushions the high-frequency disturbances giving a high degree of shock isolation to all four occupants on rough roads.