OPERATION OLD SCHOOL TWO RIG: PART1
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Installing New Leaf Springs, Hangers and Shackles On a 1997 F-350

Let’s face it, with a mortgage, a minivan payment and all the other bills that come with middle-class life, a lot of us simply can’t afford today’s $70,000 trucks. At the same time we desperately need a reliable vehicle to tote our precious cargo to the jobsite, the track, the lake or the trail head. Faced with this predicament, thousands of truck owners turn to the aftermarket to transform their aging workhorses into formidable tow rigs—and we’re no different here at Diesel World. This month, we’re embarking on a journey with a 200,000-mile ’97 F-350. The mission? Make the old body style, crew cab, longbed Ford capable of towing 12,000 pounds with ease, and ensure that it can do it safely and reliably.

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While you’ll never get a 7.3L Power Stroke (or a pre-Super Duty truck) to enjoy moving the kind of weight a modern day 6.7L Power Stroke can, we believe the 7.3L is still a viable candidate to hook to a trailer, especially a modified 7.3L like ours. It’s been treated to a set of larger injectors, a bigger turbo, an intercooler, a built E4OD and custom tuning, and the tow-ready mods we plan to perform in the months ahead will only make it better.

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After the truck was positioned aboard a two-post lift at Flynn’s Shop, it was hoisted skyward and its wheels and tires were removed. Then Flynn’s lead technician, Jake Bosie, positioned a 2-ton jack under the rear axle and stuck an impact on the nuts holding the rear U-bolts in place. If the rear axle mounts shown here look odd to you it’s because they’re part of a set of One Up Offroad traction bars. The U-bolts aren’t the factory 5/8-inch diameter units, either, but rather ¾-inch U-bolts from an ’11+ Super Duty application.

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The rear anti-sway bar was loosened at the frame to get the rear axle to droop as much as possible. While Bosie could’ve opted to try to break the U-bolts loose that wrap around the axle, he knew it would be much easier to replace a bolt rather than a U-bolt (for which we didn’t have spares).

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With the rear shocks unbolted from their lower mounts on the axle, the axle was lowered and the factory 4-inch blocks were pulled. Then Bosie turned his impact loose on the front and rear spring bolts. The bolts in the rear shackles (which had been replaced in the past) were relatively easy to remove, but the front ones, corroded in place within their respective bushings, put up a bit of a fight.

During the course of the project we’ll throw the equivalent of $5,000 in parts at the old workhorse in order to bring it up to modern towing standards. In the long run—and even with the purchase price of the truck included—we’ll end up approximately $40,000 ahead of someone who opts for a comparable ’18 F-350 Crew Cab 4×4 XLT. Throughout the build, an air spring system, Class V hitch, heavy-duty transmission cooler, 5-inch exhaust and electric fuel supply system will be added. However, before we get too carried away with those add-ons, we’re kicking things off by replacing the truck’s factory suspension. After 21 years in the Midwest there was more than just a little surface rust on the leaf springs, hangers and shackles, and every bushing had seen better days. After a quick call to SD Truck Springs we had brand-new replacement parts waiting on our doorstep by the end of the week, and we spent that Saturday getting everything installed at Flynn’s Shop in Alexander, Illinois.

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Once the front and rear end of each leaf spring pack was free from its hanger, Bosie lowered them onto the rear axle and then tossed them in the scrap pile. The next item of business was deciding how to get the riveted hangers off the frame: air chisel, die grinder with a cut-off wheel, or torch.

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After less than five minutes using the die grinder/cut-off wheel combo, Bosie switched to the torch. Removing the rivets that hold the front of rear spring hangers to the frame proved to be the most time-consuming task of the entire job. In hindsight, we were lucky the rear spring bolts weren’t seized inside their respective bushings when we removed them. Our luck would run out up front, however, as each spring hanger bolt would have to be cut.

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Breaking the front of rear hangers free from the frame required a considerable amount of work with a dead-blow hammer. Then, with the hangers out of the way, the remnants of the rivets were knocked out of the frame via punch and hammer.

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Using a paddle wheel, Bosie cleaned up the mounting surfaces along the frame. After that, compressed air was used to remove any leftover debris and we hit each bare spot with two coats of Rust-Oleum rust reformer, a product that stops rust in its tracks, dries black and doesn’t require a topcoat.

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Sourced through SD Truck Springs, our OEM replacement front and rear leaf packs were manufactured by Dayton Parts, the parent company of Stanley Springs, which has been in business since 1922. Aside from the front of rear hangers (which were Automann USA components), the hangers and shackles were produced by Dayton as well. The front leaf spring hangers would be the only factory components we didn’t replace, but unlike the rear hangers they appeared to be 100% structurally sound.

“WHILE YOU’LL NEVER GET A 7.3L POWER STROKE TO ENJOY MOVING THE KIND OF WEIGHT A MODERN DAY 6.7L POWER STROKE CAN, WE BELIEVE THE 7.3L IS STILL A VIABLE CANDIDATE TO HOOK TO A TRAILER.”

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The new front of rear hangers (Automann USA PN M991) were mounted to the frame using ½-13 Grade 8 bolts and lock nuts. After running the nuts down with an impact, Bosie looked up the factory torque spec and tightened the bolts to the 90 ft-lb recommendation.

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As for the rear of rear hangers at the back of the frame, new 7/16-14 Grade 8 bolts (and lock nuts) would be employed and Bosie would treat them to 60 ft-lb via torque wrench. We’ll note that replacing these hangers was made easy due to the truck’s factory rear fuel tank being removed. After rusting out, it’d been pulled years prior. If the rear tank had still been in place accessing the bolts from inside the frame rail would’ve been much more difficult.

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The driver-side front of rear hanger proved a bit more difficult to replace, requiring Bosie to work around the E-brake cable. Additionally, the front fuel tank made pushing the new ½-inch Grade 8 mounting bolts through the frame more of a challenge, but luckily there was just enough working space to install the new fasteners without dropping the tank.

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Prior to installing the rear leaf springs, the new shackles were attached to the back of them via the Dayton 9/16 x 4.5-inch bolts, washers and nuts we sourced through SD Truck Springs. Each bolt was left hand-tight to provide for easy adjustment while the leaf springs were being positioned onto their new hangers.

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While Bosie was able to remove the factory leaf packs singlehandedly, setting the new rear leaf spring packs in place (which featured one additional spring per pack) called for an extra set of hands. Getting the leaf spring eyes lined up correctly on the hangers on the driver side required some downward force being applied to the truck’s exhaust system.

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To keep the new leaf spring bushings from experiencing any binding, Bosie held off on tightening the front and rear eye bolts (at the shackle in the rear and the hanger in the front) until after the truck was lowered to the ground. With the rear leaf springs installed, Bosie cleaned up the factory 4-inch blocks and reinstalled them under the springs.

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Sticking with the Super Duty square-style, ¾-inch diameter U-bolts in the rear, we had SD Truck Springs make us four replacements. With an extra leaf being present in the new rear leaf packs, and to ensure ample threads would be available with our traction bar mounts in the mix, we had the U-bolts made 14.25 inches in length. Later in the install Bosie would cut down the threads for us. In any type of suspension install it always pays to err on the side of longer U-bolts.

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With the U-bolt nuts installed hand-tight (they would receive final torquing once the truck was back on the ground, which was done to keep the traction bars from binding up), Bosie reattached the top mounting bolt of the anti-sway bar to the frame. Then the shocks were reattached to the rear axle and the work on the rear suspension was complete.

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Thanks to 21-plus years of rust and corrosion working against Bosie, removing the front U-bolts proved a pretty lengthy process. After trying his luck with an impact on the driver-side U-bolts, he switched to a long ratchet and used leverage to get the nuts turning. To our surprise, the front shackle bolts came out fairly easily.

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As for the passenger-side front U-bolts, it was a no-go both for the impact and the ratchet. But after a couple minutes of fireworks courtesy of Bosie’s die grinder and cut-off wheel, both factory U-bolts were in three pieces and he turned his attention to removing the front leafs from the hangers.

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While rust often makes steel brittle, it can also do a pretty good job of seizing two metals together. Although Bosie was able to remove the factory nut on the front leaf spring’s eye bolt, the bolt wouldn’t budge. After so many years of corrosion the bolt had essentially become part of the steel sleeve it resided in within the bushing.

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Once again turning to the die grinder and cut-off wheel, Bosie cut the leaf spring eye bolts (cutting into the bushing, between the hanger and leaf spring itself). This same scenario would play out on the passenger side of the truck.

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When it was time to pull the factory front leaf springs, Bosie used a pry bar to coerce the shackle out of its mounting point within the frame. Then, with the far end of the leaf pack free inside its hanger, the two-leaf spring pack was removed.

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Upon inspection of the stock front leaf spring pack removed from the driver side, it was clear the top shackle bushing was beyond shot. As a result, more than a quarter inch of ride height was being sacrificed.

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In preparation for the installation of the new leaf springs, a fresh set of Dayton front shackles was installed in the frame (PN 330-200). Because the top 9/16-inch shackle bolts were in exceptional shape considering their age, we reused them. On another positive note in light of the truck’s age, the radiator core support—a common hot-spot for rust on OBS Fords—is in tip-top shape.

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Bosie installed the front leaf springs by first setting the new leaf pack on the axle and then sliding the rear eye into position in the hanger. With a fresh 9/16-inch eye bolt in place and hammered home, he moved on to finagling the lower shackle bolt through the front leaf spring bushing.

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With the lower shock mount sitting on top of the front leaf springs and being secured via the U-bolts on the OBS Fords, Bosie’s next move was to reposition it onto the new leaf springs. Once it was lined up on the center pin, Bosie placed the U-bolts over both sides of the shock mount.

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Like the rear U-bolts, we had the front units made to order at SD Truck Springs. Direct replacements, the square-style U-bolts entail a ½-inch rod diameter, a 3-inch inside width and 8.25 inches of length.

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Unlike the rear U-bolts, which were left loose in order to properly re-seat the traction bars, the front U-bolt nuts were torqued with the truck still on the lift. However, the bolts in the previously installed front shackles were left hand-tight until the truck had been lowered so as not to place any of the bushings in a bind.

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With the truck back on the ground with the wheels and tires reinstalled, Bosie set about cinching down all the shackle bolts, along with rechecking the fasteners in all of the newly installed hangers. His final task would entail cutting down the rear U-bolts and then torqueing them to spec. Once he was done, we took the truck for a test drive and immediately noticed a plusher ride. It’s amazing what new leaf springs (and especially bushings) can do for a 1-ton truck’s ride quality.

SOURCES

Flynn’s Shop
217.478.3811

Rust-Oleum
Rustoleum.com

SD Truck Springs
888.774.6473
SDTruckSprings.com

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