If you're cutting used springs, at the least you're going to want to measure and compare the springs first and make sure one's not sagged more than the other.
A step more sophisticated is to compress them with a weight on a lever and measure again to make sure they're not soft. You'll have to DIY a fixture to do it right.
Or you could do it the janky way. When I was in Vo-Tech thirty years ago, a fellow student heated all the coils on his square body and then just dropped the floor jack down. It was seriously slammed, and the next day he ripped the headers from the block driving over some railroad tracks.
A step more sophisticated is to compress them with a weight on a lever and measure again to make sure they're not soft. You'll have to DIY a fixture to do it right.
Or you could do it the janky way. When I was in Vo-Tech thirty years ago, a fellow student heated all the coils on his square body and then just dropped the floor jack down. It was seriously slammed, and the next day he ripped the headers from the block driving over some railroad tracks.