It is a surge brake system. The best and easiest answer is get rid of that junk now. When your in the belly pull the steel hyd. lines too. Your axle spindles will give you problems too. They are way to small for new backing plates and brake assemblies. I found that the best solution, for me, was a new straight axle with hubs and brakes as a unit. The price is right, The lack of problems pays for itself. And, I am raised up about four inches for a safe ground clearance.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."