USA and later Canadian left-hand drive MGCs use a dual-circuit brake system with two separate Girling servo units, each providing vacuum assistance to one brake circuit. The front servo is mounted on a bracket on the right-hand side of the engine compartment adjacent to the oil filter, serving the front disc brakes. The rear servo is located at the right-hand rear of the engine compartment, serving the rear drum brakes. Both servos draw vacuum from the inlet manifold through a joint pressure failure switch, which activates a dashboard warning light if either circuit loses pressure.
This twin-servo arrangement is entirely different from the single-servo UK system and requires its own specific servo units, repair kits, mounting brackets, vacuum hoses, and pipe fittings. The dual-circuit system was a US federal safety requirement during the MGC's production period, and was also adopted for Canadian-market cars from August 1968.