MG Car Repair: Locking brakes 79 midget, caliper pistons, brake master cylinder

Question
We have a 1979 Midget.  The brake master cylinder is new, After driving the vehicle a short distance, the brakes lock up and will only release after the car sits for an hour or so.  Any idea on what is happening and a fix?
Thanks,

Answer
Hi Dave,
There are several reasons that brakes can lock up and you must run a couple of simple tests to determine what the cause is.
First drive the car and duplicate the lock up and quickly jack up the front of the car and try to rotate each front tire. If both are locking up loosen the brake lines at the master cylinder to see if that frees up the brakes. If it does the master cylinder and/or the brake pedal is at fault. If it does not free up the brakes open a bleeder at either one of the calipers and if that only frees up one side then look to the flex line on the caliper as the fault. If opening a bleeder does not free up that wheel then you have either stuck brake pads or sticking caliper pistons on that caliper.
This is the method we used at the dealership and is a sure test.
Howard