spring arch

Sorry to keep harping on springs – it is what I am working on at the moment. Per the long train of discussion a few threads down, PASB 84-3 lists specs of ’30-’38 PA springs including the “free arch”. Free arch is the distance from a line between the spring eye centers and the top surface of the main leaf at the bolt center when unloaded – i.e. car weight not on them nor with the axles hanging from them. I have always questioned the notion that springs sag significantly just from supporting a cars weight for 70+ years. “Creep” elongation of steel is generally a very high temperature issue. Measuring my original PA front springs indicates they have sagged only about 1/4″ from their original spec. I don’t think I would risk getting them more screwed up by having some spring shop trying to correct a 1/4″ by “re-arching”, particularly since the total arch of the spring comes from the combination of the individual arches of 11 different tapered leaves bolted together.