The MGB throttle and choke controls connect the driver’s inputs to the carburettors via a system of cables, levers, and pick-up linkages. These components changed across production as the carburettor type, dashboard layout, and pedal arrangement evolved, making correct identification essential when ordering replacements.
Choke Cable
The choke cable runs from a pull knob on the dashboard to a lever mechanism on the carburettors that enriches the mixture for cold starting. Several different choke cables were used across production.
Chrome bumper cars from 1962 to 1969 used a round knob with a ‘C’ motif, while 1970 to 1974 chrome bumper cars and early rubber bumper cars to September 1976 used a round knob with a fan motif. From September 1976, a T-shaped knob was adopted. The cable grommet where it passes through the bulkhead also differs between chrome bumper and rubber bumper applications. A sticking or seized choke cable is a common complaint on cars that have not been regularly maintained, the inner cable corrodes within the outer sheath over time, particularly where moisture can enter at the bulkhead grommet.
Accelerator Cable
The accelerator cable connects the throttle pedal to the carburettor linkage and differs between chrome bumper manual, chrome bumper automatic, and rubber bumper applications. Chrome bumper cars with the 3-synchro gearbox used a different cable routing and guide arrangement from later 4-synchro cars. The cable guide, seal, and securing clips are available individually for cars where the cable itself is serviceable but the mounting hardware has deteriorated.
Linkage & Pedals
The carburettor linkage, the system of levers, pick-up arms, pins, and return springs that translates cable movement into synchronised throttle and choke operation across both carburettors, differs between HS4 and HIF4 installations. HIF4 cars use a bracket mounted to the inlet manifold and heatshield that carries both the choke and accelerator cable connections, and this bracket itself differs between chrome bumper and rubber bumper applications. The individual pick-up levers for accelerator and choke, the connecting pins, anti-rattle washers, split pins, and return springs are all available separately. The accelerator pedal changed several times during production.
Early 3-synchro cars used one type, 4-synchro chrome bumper cars another, and rubber bumper cars a further revised design, with a final change at September 1976. A rubber pedal pad is available as a modification for certain pedal types where the original did not include one, improving grip and foot comfort.
When replacing cables or linkage components, it is worth inspecting the full system from pedal to carburettor. Worn clevis pins, stretched return springs, and sloppy pick-up lever pivots all contribute to an imprecise throttle feel and can mask the benefit of a new cable. All the individual fixings, pins, washers, split pins, clips, and springs, are available separately for a thorough overhaul.