Stiffer front springs writeup from the old .net site


I wish I didn't have all of these balls in the air
15 Year Member
Dec 6, 2005
Marietta, Ga
Since this subject was recently brought up, here's an article from the old .net site about swapping/upgrading front springs. This is a copy and paste so as to not lose the info if the web.archive site lets it expire or goes down. That link is here. Posting so it can be added to the tech sticky.

Stiffer Front Springs by Mark Mitchel
When I first got my 1975 V8 Ghia I was surprised how much it leaned in the corners. This just really detracted from enjoying the car as anything more than a mundane commuter’s ride. As a former stock car racer this situation with the rocker panels threatening to scrape the asphalt in the corners, and the lumbering “ocean motion” ride that went with it, just became increasingly annoying. My preference is a firmer ride with a responsive, flatter, cornering ability. Besides, don’t tell anyone, but from time-to-time, when I’m alone on a winding country road, I like to pretend I’m at Daytona duking it out in a side-by-side race with Dale Earnhardt, Jr.

My initial attempt at a cure was to install the big front and rear sway bars offered on the Cobra II and some other models as an option. The biggest factory sway bars are a 1-inch for the front and a ¾-inch in the rear. With these installed things improved a lot. But, like everything else in life, if some is good, more sure would be a lot better.

So my research began.

What I learned was that the factory—in its attempt to create a pleasant and gentle noise-free ride for grandma—used very soft springs in the Mustang II. So I decided to improve on things some—Lee Iacoca didn’t get it all right, though I personally think Charlie Kemp did. First, I removed one of the stock front springs and put it in a coil spring rater: 350 lbs. per inch. If you don’t race stock cars you wouldn’t know, but this is a really, really soft spring. If I remember correctly the front springs in the early Mustang V8 cars from around 1965 to 1968 were about 450 lbs. per inch. After much sleuthing at a friend’s Fords Only wrecking yard (don’t you just love the name?) I found a super cheap alternative. I got a pair of coil springs from the front of a 1980 V8 Thunderbird. Even thought the car uses a strut type front-end the coil spring is the right diameter and the wire size is bigger—it’s just way too long. So like many things in a Mustang II owner’s life it would need some modification before it would fit. I used an air powered die grinder with a cutoff wheel and started shortening the spring a little at a time; checking the rate and ride height of my car as I went along. Now if you’re really good at it you can use a cutting torch, though it’s not recommended because the heat takes the temper out of the spring and the cut ends up pretty jagged. Anyway, after some experimentation I finally arrived at the point where I had shortened the spring to 12¼ inches in free height. This spring had a 475 lbs. per inch rate and lowered the front-end of my Ghia about ½ inch.

The results: there was no noticeable change in the ride except in the corners. Now the car had much less lean and responded more quickly, and decisively, to steering inputs.

Just so you know racing coil springs, either for road racing or stock cars, generally have a rate of somewhere between 750 to 1000 lbs. per inch. A stiff front spring on the street would be around 650 lbs. per inch and then the ride would start to become a little rough and choppy. When I put a pair of 650 lb. springs in my lovingly revamped ’65 Mustang my girlfriend said it rode like a “dump truck”—she’s gone now.

Like most do-it-yourself articles that encourage you to take the initiative, and be self-reliant, this one also comes with a caveat or warning. Life is short and being maimed—or, your untimely death—can really take the fun out of owning a Mustang II. If you are going to replace the front springs in your car use a coil spring compressor. Lots of tool rental places have them. Even though the springs in your Mustang II seem really soft and it looks as if you can pry them out with a crowbar DON’T EVEN TRY! The energy stored is those springs—even when the car is jacked up with no weight on the suspension—is unbelievable. If you could get one to pop loose, it would explode from the spring pocket, tear up the fender on its way out and still fly across the garage with enough force to really hurt someone. Besides, chances are your girlfriend actually likes the way you look with all your teeth.

Overall, changing the front springs is a day of dirty work, but I am very happy with my car’s ride and improved cornering ability now. And, I don’t expect, or want, everything to be clean and easy. If I did I would have paid someone to build me a Camaro. Isn’t that a pathetically sad thought?

Specialized Tools Needed:
  • Coil Spring Compressor
  • Ball Joint Removal Tool (“Pickle Fork”)
  • Air Die Grinder with Cutoff Wheel (“Cutoff Wheel”)
  • Chilton’s or Motor’s Auto Repair Manual (My 1977 Chilton’s has a subsection titled “Bobcat*Mustang II*Pinto” In there is a segment called “Spring Replacement”)

  • The motivation to make your Mustang II even better
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