Steelhead, as the shoes grab the drum they rock a little on their mountings, this causes the adjusting pawl to tighten up the adjustment. When you release the pedal the pawl ratchets back to the next notch until they are tight. If every thing is clean and lubed properly the reverse brake application is usually all that is necessary. Alternately pulling forward will insure that the pawls has indexed, it should not be necessary though to get an adjustment. Applying a dozen or so sharp stops in reverse should bring the shoes out to the drum. Once you have a full pedal you will know that they have reached full adjustment.
Brake fluid is non-compressible, think of it as a solid link back to the brake shoe. So if the linkage has to move the shoes a greater distance to contact the drum this calls for more pedal movement. As the clearance is reduced it requires less pedal movement, this is when you get a full pedal.
Denny Graham
Sandwich, IL
