I’ve replaced the master cylinder, all eight brake shoes, all wheel cylinders, all shoe springs, and all adjustments have been checked and double checked. I feel the problem is with my brake drums, and they are no longer manufactured.
Do you think my problem is the drums, and where can I purchase them?
Answer: Expecting an MG TD to stop on a dime is kind of like expecting an aircraft carrier to stop on a silver-dollar. Since you have the benefit of having similar cars with which to compare it, it’s likely that you really do have a problem.
There are really only three things that can go wrong with a brake drum. First, it can become contaminated with a substance such as grease, and this usually results in a shimmy when you apply the brakes. This is easily remedied with a thorough cleaning. Second, it can become warped, usually from heat, and this too usually results in some sort of vibration or pulsing upon application of the brakes. As long as the drum is still within tolerances it can be “cut” or “turned,” making it round again. Third, it can become too thin, usually from “cutting” or “turning” it too many times, and the result is an inability of the brake drum to dissipate heat faster than it is being generated. The result can be anything from “brake fade” to a complete loss of brakes. However, this generally only happens when the brakes are hot from repeated application.
Since you make no mention of your brakes performing in a sub-standard manner only when hot, I have to assume that it happens all the time. This leads me to believe that the problem may not be solved by replacing the drums. You’ve mentioned all of the parts of the brake system that have been replaced, but you omitted the one piece that can easily cause the symptom that you’re describing. That would be the rubber brake hose that goes from the hard brake line to the wheel cylinder on each wheel. These brake lines deteriorate with time and as they do, they become soft. When you step on the brake pedal, rather than transmitting all of the pressure to the brakes, they absorb some of this pressure by expanding. Not only does this result in less efficient brakes, it also results in an inconsistent “brake pedal feel.” The good news is that these hoses are easy to replace and readily available.
At the present time, the brake drums for your car are not available. Used drums do turn up occasionally in places such as ebay, but their condition will be unknown.