Brake adjustment affects pedal height- - - -not how much force the shoes apply to the drum. If a brake adjustment is slightly loose, there will be NO braking at all until both sets of shoes are firmly against the drum. One wheel locking up is usually the result of a hydraulic or a mechanical restriction to movement of the shoes. A collapsed flex line to a front brake, or a sticky wheel cylinder in the rear can cause one set of shoes to start braking before the other. Another problem that's often overlooked is a step worn in a backing plate that allows the shoes on one side to hang up momentarily and fail to contact the drum. Don't overlook the nitpicking details, but don't try to repeal the laws of physics! Slight differences in drum diameter that affect how much of the brake lining actually contacts the drum can result in uneven braking while new linings are "wearing-in" however.
Jerry
