Dreamer ... that's what I thought too but I had that formula in my collection and it seemed to work (for another application); now I'm going to have to dig out the physics text and see what happens when you change the number of coils in a coil spring
Mike ... SUV? Yup, that's what it looked like! 1 1/2 coils = 3 7/8 so 1 coil should be right where I want it (4 1/2 -> 5"). Coil overs are in the future ... perhaps my wife can get them for me for Christmas!