Before you spend $550 plus expensive shipping for a new spring, remove your old spring, carefully disassemble it and examine each leaf. Look for cracked or broken leaves, concentrating especially around the center bolt holes. That's usually where the spring leaves break. I have never seen a rear spring that wasn't savable by replacing one or two broken or fatigued leaves. The bottom four leaves take the most punishment, so the upper ones generally escape the need to be replaced. That's half the battle won right there! If you had a heavy sedan that had seen tortuous old country road use or had been used to carry heavy loads such as wood or coal or even junk metal, I could see the possible need to replace the fatigued rear spring. Unless your Sport Coupe suffered a similar fate and its rumble seat area carried heavy weight year after year, you may be able to save the bulk of the spring and only replace one or two leaves, easily saving you hundreds of dollars. Anyone with a stash of Model A parts probably has loose rear spring leaves lying around and could sell you what you need. Bert's Model A Center probably has hundreds of such loose leaves in storage. Or Sammy Guthrie at Arizona Model A in the Phoenix area. Readers here may be able to supply needed leaves, too.
Since you must remove the spring anyway to replace it, why not try to save it before ordering a new one? You might only need to replace one or two leaves. This would be a good opportunity to replace the bushings in the spring eyes and the perches (four total). If the shackles are worn, that could also result in a sagging rear end.
Once disassembled, concentrate on the bottom two or three leaves. Measure the distance from tip to tip and write that down. Put each leaf in a sturdy bench vise, centering them at the bolt hole in the middle. With one or two BIG boys helping, pull the end of the spring downwards to bend it. Remove the spring leaf and up end it in the vise so that the other side can be similarly pulled. Remove and measure again. Keep doing this until you have shortened the tip-to-tip distance two inches or so. Once the bottom four leaves have been similarly re-arched COLD, bevel the bottom tips at a 45 degree angle and grind out any indentations on top of the leaves caused by the leaves above digging in. Spray or brush on Slip-Plate, Lubriplate or a similar graphite base paste and re-assemble the spring with a NEW center bolt. Install the clamps. Once assembled, use a big C-clamp to protect against the spring leaves separating as you use a dedicated rear spring spreader to open up the spring for mounting on the rear axle. Or some guys like to install the rear spring in the crossmember and then lift the rear end up with a floor jack to attach it to the spring. Either way will work.
If you do all these things, you may be able to re-use most if not all of your old rear spring leaves, besides lubing them. And best of all, you have saved yourself several hundred dollars, as well as earned the satisfaction of making the repair yourself.
Marshall
