Originally Posted by
FBinNY
Don't know your particulars, but a SOP fix for sagging or weak coil springs was (still is?) to fit a study rubber balloon into the spring, and inflate it firm enough to add some lift. The coils braced the sides, and you ended up with a poor man's tunable, air ride suspension.
Also known as Air-Lift (tm), I used them on a wagon I used to own. Not because the springs sagged, but going to and from college and fully loaded, I wanted a level ride. I didn't want air shocks as the mounting points for them are small compared to the spring bases top and bottom. Worked fabulously. I ran separate air lines for each to improve roll stiffness, and I ran the air lines forward inside the lower trailing arm to the forward pivot, then a short jump to where I put the schrader valve, held in an existing frame hole, that way not a huge lengthening/shortening of running the line to the body just above the axle, as indicated in the instructions. The air bags were red flexible plastic, not as stretchy as rubber but far more durable and didn't need that much stretch. Oh, and ordered from the Sears catalog, back when there was a Sears and a catalog.