Reference: CMP seat back coil spring dimensions

[Grant Bowker]

Originally Posted by Grant Bowker

The "by the yard" springs we found that were closest to the springs we were finding in seat frames for OD and wire size (and thus stiffness) were listed at McMaster-Carr, their product 9664K52 https://www.mcmaster.com/#catalog/123/1277/=193uptc

More information on "by the yard" springs - springs of the same dimensions (same size + same material = same force) as the McMaster listing given are available from Century Spring. Century's E-20 spring is dimensionally the same as McMaster's 9664K52. http://www.centuryspring.com/extensi...ings-e-20.html
Although their site shows an eye on the spring I would be surprised if the long length springs actually have eyes. Unlike McMaster, Century will sell to Canadians (although I had the springs I bought shipped to the UPS store across the line). Century's instructions for forming eyes on the end of springs cut from long lengths are attached. Century's spring #576 is similar in length to some CMP seat springs I have.