Rear leaf spring shackle issue

New SS springs were installed with Mancini racing's front hangers and new shackles. After installed, the lower RR shackle was pressed against the drop pan. I found here how to remedy that by raising the rear axle and using a pry bar to force it into compliance. Due to a trunk mounted battery, the exposed negative battery cable running under the drop pan was damaged. Fast forward, took the car to a show and parked after returning home. I just discovered that the same RR shackle did the same thing again; nearly severing the battery cable and pushed up the drop pan. Fortunately, its solid.
What can I do to stop this from happening again and any idea what's causing this?