im haveing the same problem, my shackles are slamming against my frame when flexed to hard, are my shackle mounts on my frame in the wrong position? they are new 4in lif springs that had been sitting in my back yard for a little bit to long and are real stiff, i havent wheeled with them yet but i have a feeling that they will just flattin out on the frame. ive been trying to break them in but i think that the softer they get the worse it will get. when under no load my pass side shackle is almost 90* strait up, my drivers side is about 75*.

please tell me what the deal is

your shackles arent positioned correctly, 90* is not ok for static height, you should be around a 45* angle....

you can move the shackle mount and test, however watch out, because hte fact they vary that much, might indicate a heavy load on one side, possibly no front spacer block if it was needed, or sagging springs