The 4AB Roadster
Although virtually indistinguishable at a gallop, the 4AB began to show some external signs of differentiation from its predecessors. Notably, the radiator and shell were shortened, terminating at a neat valance at their base, whereas on previous models the shell had extended well below the bumper level of the car. Its wings were restyled to become more sweeping in appearance and the bonnet now had fixed sides with the top centrally hinged. The wheels received modest treatment with a change to the slotted disc type.
In the passenger compartment, Singer added a set of deeper, springed seat cushions and higher seat backs for added creature comfort.
The 1074 cc engine continued to power the 4AB and the chassis was essentially that of the 4A with additional stiffening at the front end. A massive box section cross member was added to carry what was really the most significant change to the Roadster series to date - the coil and wishbone independent front suspension units.
Steering was modified on the 4AB whereby a three piece track rod was adopted, with an idler shaft connecting to the steering box. This was done in order to create a symetrical layout conducive to fitting the car for either right or left hand drive. A forward mounted anti-roll bar was also added.
The other change of significance was the upgrade from an all mechanical to the hybrid Girling hydro-mechanical braking system.