Sedan Delivery Coilover Conversion
Last time you met our ’46 Ford, Elmer. I also made the embarrassing confession that Elmer still rides on a Corvair IFS. In fact, he’s rocking it like it’s 1976 all over again. (Play Free Bird!)
Part of the reason those frontends fell out of vogue with the introduction of the Mustang II IFS was the availability of decent rebuild and hard parts for the older, less popular Corvair cars. (We won’t even talk about the Corvair’s eccentrics or the camber issues inherent with the design. Oops guess I just did!)
With my commitment to stick to the meat and potatoes of how this truck was built years ago, I’ve made the choice to retain the Corvair IFS. After all, since rebuilding it, I’m already into that outmoded technology up to the ankles with both feet. Might as well stay there. Last time, I went over the rebuild of that frontend and steering setup. Those parts have served very well over the last few years of driving. They took us to California and back in ’14 and many, many miles since then.
That is until we were headed out to a rod run in Wayland, Missouri early last spring. That’s when we encountered a giant, unavoidable pothole passing through Omaha. I guess street crews hadn’t gotten to yet. Or they’d lost too much equipment in an effort to satiate it and had written it off. At any rate, it was a bone shaker. One that reminded me all about 50 year old spring steel, metal fatigue and stress risers.
My left front coil spring broke. Right along an old grinder nick in the wire where the coils had been cut years ago.
However, with the way the spring broke and knowing the suspension as well as I do, I was able to do a roadside alignment change and motor on for our weekend commitment at the show. (Dig the road rash on the lower control arm and compare the last article. Drive ‘em!)
We weren’t even home yet when I came to the realization that I was NOT going to pay the going rate for a new pair of Corvair springs. Not gonna happen. Especially when I’m going to lop 2 coils off of them to match the setup on the car anyway.
What I did recall was the similarity of design and geometry between a stock MII and my modified Corviar. Back to the parts counter. . .
Just as I suspected, I can make that work. Plus add a nice upgrade to adjustable height and selection of spring rate.
The main difference between the two spring designs is that one top is a tangential tail and the other a squared end. It’s pretty tough to go from a tangential to square but vice-versa is a snap. Well, a cut-off wheel anyway. (Note: Do not EVER cut a square-end spring that is to be retained in the square end spring pocket. If the pocket is designed to make full contact with the spring it must remain that way.)
If you must cut a spring don’t ever, ever use heat. A cutoff wheel makes quick work of the material without generating excess heat that will ruin the spring. You also must note that when you shorten a coil spring, the stiffness of the spring also increases resulting in a stiffer less forgiving ride. That said, I’ll show you how I repurposed these MII springs to work in my Corvair setup.
I made my cut at the very end of the flattened surface of the square end. This allowed the new spring to mimic the original perfectly. Remember don’t nick the next coil in line when you cut. That’s where all this extravaganza started. Don’t make a new stress riser in your spring.
My installation was a little different than the instructions indicate for a MII setup. In addition to needing to install the supplied 7/16” ID tube in the lower shock mount to accommodate my smaller lower bolt, I also had to install the spring in the pocket and work the shock into the sleeve as I fed it into the spring. Time consuming but all in all, not too bad.
Something else to note here. Splurge on the Torrington bearing that goes under the spring. I actually took this all back apart to install them. While you’re there also treat yourself to the heavy coil-over adjuster wrenches as well. Money very well spent.
Something to keep in mind. Springs settle. Sometimes they settle a lot. Overnight. It took me about a week of fiddling around and adjusting to arrive at where I wanted to be concerning ride height.
I used the 375lb springs at full low as my starting point and they ended up being just about right for my application. That is, after I adjusted them up about 2/3 of the way up the adjuster sleeves. My engine sits a bit farther back than some and I prefer a soft ride and low stance. Your preferences may require a different rate or some experimentation.
Until next time, thanks for reading!