All MGBs used 10-inch by 1.75-inch rear drums throughout the production run, with shoes operated hydraulically via wheel cylinders. The rear brakes are manually adjusted and do not self-adjust, shoes that have not been correctly set leave a disproportionate share of braking to the front discs, producing a front-heavy, unbalanced feel that no amount of front brake work will cure. Correct rear brake adjustment is one of the most effective and most overlooked improvements available on any MGB.
Drums & Inspection
Standard brake drums are available for both banjo and tube axle cars, the banjo axle was fitted to early Roadsters and GTs to approximately 1967, with the tube axle used from 1967 onwards. Red Dot slotted drums with internal grooves are available for improved heat dissipation. Aluminium drum covers in silver finish are available for a smarter appearance. Drum condition should always be inspected before fitting new shoes, shoes worn to the rivets will score the drum surface, and a scored drum cannot be corrected by new shoes alone.
Wheel Cylinders
Rear wheel cylinders are a common source of hydraulic leaks irrespective of mileage, as rubber seals deteriorate with age and inactivity regardless of use. Two specifications are used and correct identification before ordering is essential.
The standard Roadster and early GT used a 0.800-inch bore rear wheel cylinder. The MGB GT switched to a larger 7/8-inch bore unit from chassis GHD4-148083 on steel-wheeled cars and GHD4-142735 on wire-wheeled cars, correcting brake bias for the GT’s greater rear weight. The two units are physically distinguished by the position of the locating pin on the cylinder body, making incorrect fitment to the wrong backplate impossible by design. Both specifications are available in genuine OE and reproduction versions.
Seal kits in both specifications allow rebuilding. The circlip securing the wheel cylinder to the backplate is available alongside the specialist circlip fitting tool.
Shoes & Hardware
Brake shoes are available in standard reproduction and Mintex specifications. Brake shoe fitting kits for banjo and tube axle cars supply all springs and hardware for a complete overhaul. Individual springs are available for all positions, handbrake lever pull-off springs for banjo and tube axle types, adjuster end return spring, and left and right hand shoe pull-off springs. Steady pins, springs, cup washers, brake adjusters, handbrake levers, actuating lever gaiters, backplate bolts, self-locking nuts, and bleed screws are all available throughout.