The MGC uses Girling brakes throughout, not Lockheed as fitted to the contemporary MGB. This is a critical distinction that cannot be overstated: no brake components are interchangeable between the MGC and the MGB. The Girling system comprises 11-inch front discs with twin-piston callipers, 9-inch rear drums with wheel cylinders, and Girling Mark 2B vacuum servo assistance on all models. A conventional mechanically operated handbrake with cable actuation of the ratchet type is fitted to all cars.
Single-Circuit and Dual-Circuit Systems
The distinction between single-circuit and dual-circuit brake systems is the single most important consideration when ordering any brake hydraulic component for the MGC. Home-market and most export MGCs use a single-circuit brake hydraulic system, a single master cylinder feeds all four wheel brakes through a single hydraulic circuit, assisted by a single servo. USA-market cars, and all left-hand drive Canadian cars from August 1968, use a dual-circuit system with entirely separate front and rear hydraulic circuits, twin servos (one for the front brakes, one for the rear), and a tandem master cylinder. The pipe routing, adaptors, hoses, and brake light switch arrangements are completely different between the two systems.
When ordering any brake hydraulic component, the first step is to establish whether the car has single-circuit or dual-circuit brakes.
Servo Change Point
The brake servo changed during production on single-circuit cars. Cars up to approximately chassis number 1153 (not USA/Canada) used an early Girling servo with its own specific repair kit. From chassis number 1154 onwards, and on all USA and Canadian cars from the start of production, a revised Girling servo was fitted. An alternative Lockheed servo is available as a direct replacement for the later Girling unit, using its own repair kit, this provides a practical solution where a serviceable Girling servo is not available.
On dual-circuit North American cars, the twin servo arrangement uses front and rear units: the rear servo at the right-hand rear of the engine compartment serves the rear brakes, while the front servo on a bracket on the right-hand side of the engine bay adjacent to the oil filter serves the front brakes.
French and Benelux Market
Cars originally exported to France and the Benelux countries use the single-circuit brake system but with a separate transparent plastic brake fluid reservoir connected to the master cylinder by a hose, rather than the integral reservoir cap fitted to standard UK cars. This was a regional requirement for visual fluid level inspection.