When most hot rodders think of steel it likely has something to do with a structure that requires strength and rigidity. When Mike Eaton of Eaton Detroit Spring thinks about steel his concern is strength and flexibility.
As Eaton explains it, springs must be made from steel with high yield strength. In other words, a material that will bounce back to its original shape after significant pressure is applied, and the best material for that is SAE 5160 high alloy spring steel. While you can’t tell by looking, there are cheap off-shore springs that use inferior 1095 steel