Tech Q&A: Spring 2005

By Kelvin Dodd

MGA Disc Brake Conversion

I have a 1958 MGA and would like to change the front brakes from drum to discs. I have wire wheels. What’s the best way to do this? Is there a kit available or can I do the conversion with stock MGA or MGB parts?

—Tony Colima

Moss brake caliper adapter plates (180-522) make converting a wire-wheel MGA to disc brakes easy using off-the-shelf components. To install disc brakes on these cars, MG redesigned the wheel hubs to accept brake rotors. New wire-wheel hubs for the disc brake cars are available (264-740, 264-750) and should be installed with new bearings and seals (125-500 [2], 125-400 [2], 120-600 [2]). The new brake rotors (182-180 [2]) are attached to the hubs with the following hardware: bolts (264-400 [8]), lockwashers (824-040 [8]), and nuts (310-075 [8]). Rebuilt MGB calipers (180-535, 180-545) are then installed on the brake caliper adapter plates with bolts and tab washers (320-135 [4], 181-670 [2]). Converting a steel-wheel car uses the same process, but the disc-brake wheel hubs are no longer in production and would have to be found used.

Ignition Proposition

The ignition switch on my 1973 MGB just failed. It appears that this switch is not available from Moss. How do I go about keeping the car original?

—Andy Jameson

This switch was discontinued in the ’70s. The factory supercession at the time was to supply the complete later lock assembly, which uses the smaller black switch but with separate bullet connectors instead of the normally supplied single multi-plug. A reproduction of this switch assembly is available (263-640 for your ’73) and would be an appropriate update for your car.