i don't know if the high heat is good for leaf springs:

"here are two separate materials that are precisely dispensed through a high pressure, plural component internal mixing polyurethane spray machine. They are each heated to 120-140 degrees with the temperature maintained through a heated hose. Using high pressure, the materials are mixed internally at a 1:1 ratio at the tip of the spray gun. As the material is applied it takes less than 5 seconds for it to harden. As soon as LINE-X lands on the surface, it's dry!"

I was thinking cheaper more like this:

http://shop.advanceautoparts.com/webapp/..._T%7cGRP2050___