Donald Farr
Former Editor, Mustang Monthly
March 26, 2010
Photos By: The Mustang Monthly Archives

MM: What should owners tell you when ordering springs?
Eaton: We need the year, make, model, body style, engine size, A/C or not, and any and all modifications made to the vehicle. Remember, springs support weight. And all those parts that are or aren't there equal weight. If you take a big-block engine and put on aluminum heads, aluminum intake, and headers, you're now talking about the weight of a small-block. So if you don't tell us about those changes and we send you big-block springs, you're not going to be a happy camper. Once we know all the information, we can design the spring. The other thing we need to know is how you want it to ride and how you want it to sit as compared to a stock vehicle.

MM: What if someone orders springs, providing all the correct information, and the car still sits too high or low?
Eaton: They should call us. We'll have one question right off the bat: "Is the car finished?" Sometimes they say, "No, I don't have the engine and transmission in it." Geez, they're missing about half of the weight. Sometimes they respond, "But me and my six buddies stood on it." That still doesn't matter because the weight isn't distributed the way it should be. So we tell them to finish the car, drive it like they stole it-accelerate it, brake, hit potholes-to let the springs work and settle to where they're supposed to be. If you do that and it's still not settling at the right ride height, we'll take care of it. We can tell you where to measure, and with those measurements we'll know what adjustments to make. Second phone calls are rare.

MM: You mentioned that springs can settle. Is that something that owners should expect with new springs?
Eaton: Once a spring is installed, will the vehicle settle? Yes. Coil springs will settle about a quarter of an inch and leaf springs might settle a half an inch. That's once they've been used. Everything we sell has been shot-peened to relieve stress and tension. We take the steel when it comes out of heat-treating and bombard it with hundreds of thousands of little steel balls at high velocity for about a minute to a minute and 10 seconds. We like to say the molecules are unhappy when they come out of heat-treating. They're under tension. Shot-peening turns the molecules into what we call happy molecules-they're relaxed and ready to go to work. That not only relieves some of the tension in the springs, it also increases spring life up to 10 times.

Just like anything else, you get what you pay for. A lot of the one-size-fits-all springs are made from 1095 steel. Our springs are made out of SAE 5160 steel-that's high-quality and high-cost steel, made just for springs. It costs more than springs made out of 1095 steel, which has no memory or life. But some companies make springs out of it; they just don't last.

MM: We hear about owners cutting the front coils to lower the front of a Mustang for better handling. Is that something owners should avoid?
Eaton: Cutting coils is fine. You have to look at the ends of the coil-how are the ends of the coils shaped? You can tell a square end if you stand the coil up and it stays standing up. That's a square-end coil. You can't cut that because it has to sit in the spring pocket, making contact all the way around. The other kind is a tangential coil; it just twists off into space. If you try to stand that coil up, it will fall over. That spring can be cut. Mustangs have a square end on the bottom and tangential on the top. Cut it with a hacksaw; don't use a torch. A torch heats the spring red-hot-hot enough to cut steel, as they say-and some place down the length of that coil, it's going to cool off. And where it goes from red-hot to cool, it can become brittle and break in that area.

MM: Obviously, Eaton Detroit Spring can supply a proper spring with the lowered ride height.
Eaton: Certainly. If they want to cut them, cut 'em. It works. Just don't cut too much off.