Try adjusting those brakes
I wanted to comment on Philip Herrings 1987 GMC van with the sensitive brakes (May). I think one possible source that was overlooked is improperly adjusted brakes. The brakes usually adjust themselves when stopping in reverse, but after 20+ years of use it is not uncommon to have worn or loose springs and/or teeth worn off the adjuster star wheel. Furthermore, many people don’t know how to properly adjust brakes. There should always be a little bit of drag, about enough that it stops the wheel after 1/2 to 1 full turn after a good hard spin with the tire on. Rear brakes have a little more resistance with the rear axle and spider gears slowing the wheel.
Why leave some drag? Imagine I tied a rope around your waist and told you to run 50 yards. At the end of that 50 yards I am going to pull hard on that rope to stop you. Would you rather have the rope loose, or would you like me to keep some tension on that rope as you run? Tension will ensure that you come to a stop slowly, and not double over as I pull that rope. The same goes with brake shoes jerking the wheel to a stop when there is no drag. The drag should also be consistent throughout the revolution, no high or low spots.
Thank you for taking the time to share your thoughts with fellow Auto Restorer readers. The only thing I’ll add is that a slight drag on the brake shoes helps ensure that there is not a lot of clearance between the shoes and drums that would have to be taken up by some of the pedal stroke before the vehicle begins to stop. In other words, with too much clearance between the brake linings and drum it would take too much time between when the driver begins to depress the brake pedal and when the brakes actually begin stopping the vehicle. We expect and need near-instantaneous response when we begin pushing on the brake pedal.