The MGB GT V8 rear brakes use 10 inch diameter by 1.75 inch wide drums with leading-trailing shoe arrangement. The rear drum specification is shared with the contemporary four-cylinder MGB, the V8 places its primary braking emphasis on the front discs, with the rear drums providing the secondary braking effort and the handbrake function.
Brake Drums
Rear brake drums are cast iron with machined inner braking surfaces. Drums wear at their friction surface over time, developing increased internal diameter and possibly scoring. Drums should be measured at every brake service and renewed when above the maximum diameter specification, where deeply scored, or where heat-discoloured.
Brake Shoes
The leading-trailing shoe arrangement uses one shoe (leading) that the wheel rotation tends to push harder against the drum during forward braking, providing self-energising braking effort, and one shoe (trailing) that wheel rotation tends to push away from the drum, providing less braking effort. The arrangement gives uneven shoe wear (leading shoes wear faster) but provides directional consistency in braking effort whether the car is moving forward or reverse.
Wheel Cylinders
Each rear brake has a single double-piston wheel cylinder mounted at the top of the backplate, with the two pistons pushing the leading and trailing shoes apart against the drum. Wheel cylinders are subject to internal corrosion from moisture in the brake fluid and external corrosion at the cylinder body. Cylinder service kits include new pistons, seals and dust boots; complete replacement cylinders are available where corrosion is too advanced for service.
Springs and Hardware
Brake shoe return springs pull the shoes back against the wheel cylinder when the brake pedal is released. Hold-down springs and pins keep the shoes located against the backplate. Various small components, pivots, adjuster mechanisms, washers, make up the rear brake assembly. Complete spring and hardware kits are available alongside individual replacement parts.
MGOC Spares
MGOC Spares supplies V8 rear brake drums, shoes, wheel cylinders, springs and hardware kits for the MGB GT V8.