With trailers to tow and cargo to haul, diesel pickup owners are always on the go. And as is par for the course in this blue-collar segment, there’s not always time to keep regular tabs on the truck’s suspension. After 21 years of use, you might be surprised at the kind of shape you can find a leaf-spring system in. Such was the case for this 210,000-mile ’97 Ford F-350 4x4. After more than two decades of living in the Midwest—where road salt, humidity, and regular exposure to precipitation had all wreaked havoc on the iron underbelly of the vehicle—its factory leaf springs, bushings, hangers, shackles, and hardware had all seen better days.
Because this 1-ton crew cab is a workhorse whose duties include towing 4x4s to the trailhead, the owner opted for OEM replacement suspension components. The direct replacement strategy would keep things simple in a suspension job that was anything but easy to pull off. Fighting rust-riddled hangers, dilapidated shackles, brittle bolts, and seized bushings would ensure this project consumed a 10-hour day. However, in the end it would prove to be more than worth the effort, as the truck now drives, tows, and rides like new—not to mention that it’s much safer while sharing the open road with everyone else.
This telling picture sums up the rationale behind our ’97 F-350’s complete suspension overhaul. Not only did the factory rear passenger-side shackle appear to be on borrowed time, but it had also rusted through, with a dime-size, see-through hole (see arrow) in its center section. If neglected long enough, the shackle would have eventually snapped and sent the leaf springs into the bottom of the bed. For a mere $1,300 we were able to replace virtually every suspension component on the truck—from the leaf springs to the hangers, the shackles to the U-bolts, and fresh Grade 8 hardware.
Starting with the rear suspension, the U-bolts were removed first. Then, the antisway bar was broken loose where the bushings meet the frame rather than where the U-bolts wrap around the axle. The reason? We had plenty of replacement bolts on hand, and we knew we had no replacement U-bolts for the antisway bar. With so many rusted fasteners encountered in a job like this, you must pick your battles wisely.
Surprisingly, both the front (shown) and rear leaf-spring hanger bolts were removed without much of a fight. On the more stubborn shackle bolts, we used a prybar to hold the bolt up while turning the bolt head with an impact, which helped keep the bolt straight when extracting it. Then with the leaf springs free from their respective hangers, we were lent a helping hand to pull each pack off the truck.
Manufactured by Dayton and purchased through SD Truck Springs, the replacement rear leaf-spring packs utilize a 4/1 spring arrangement (versus the 3/1 configuration we removed, which had long ago been robbed of the original overload springs). Each new spring pack also features 3-inch-wide leaf springs and a 2,700-pound weight capacity (the same as factory).
With the rear spring hangers riveted to the frame, a die-grinder equipped with a cutting wheel was used to begin the process of removing them. We’ve also seen an air chisel and even a torch used in this situation, but no matter which method you use, removing all the rivets is a lengthy process.
After 21 years of rust and corrosion buildup, the hangers were effectively seized in place on the frame. Even after all 20 rivet heads had been removed (10 per side), it still took a considerable amount of prying and hammering to break the hangers completely free.
Although the hangers, shackles, and leaf springs had been undercoated in the past, it did little to slow down the deterioration taking place on these components. With the front and rear leaf-spring hangers removed, we hammered the remaining fasteners out of the frame inward—and even had to extract a few with a drill bit.
Before bolting the new hangers in place, we took care to clean up the mating surfaces along the frame with a paddle wheel die grinder. Then we hit each prepped area with a coat of Rust-Oleum’s flat-black, quick-drying Rust Reformer. Unlike other rust treatment products, Rust-Oleum’s Rust Reformer doesn’t require a top coat, which saved us valuable time during the install.
With both new pairs of front and rear hangers attached to the frame courtesy of Grade 8 bolts (7/16-inch bolts on the rears, 1/2-inch bolts on the fronts) and locknuts, each new rear leaf pack was fitted with a fresh shackle prior to being installed. With the new leaf springs secured, the OEM 4-inch blocks were positioned beneath them. We’ll note that we also sourced fresh (front and rear) U-bolts from SD Truck Springs: 5/8-inch-rod-diameter square-style units out back and 1/2-inch-rod-diameter U-bolts up front.
Facing bolts that were seized inside their respective bushings on the front leaf springs, we had no other choice but to break out the Sawzall. To ensure that each leaf spring dropped completely out of its respective hanger, we made sure to cut inside the hanger mount rather than outside of it.
Thanks to 20-plus years of rust and dilapidation compromising the threads and essentially cementing the nuts in place, the only way to remove the U-bolts from the front leaf spring was to cut them off. As mentioned, we’d already planned to start with fresh 1/2-inch U-bolts, but we’ll note that in any type of suspension project where you’re dealing with an older vehicle, components found in this kind of shape aren’t worth salvaging.
Looking at the top of one of the factory front shackles, you can see just how shot the bushing was. Believe it or not, the steel sleeve was sitting half an inch lower than it should have been. With so much more weight hanging off the front of the truck (it is powered by a 1,000-pound 7.3L diesel), bushing failure was notably worse here than in the rear. Discovering the condition of the top front shackle bushings also helped explain the rough, jarring ride the truck had been plagued with for some time.
One of the biggest factors in ride quality in a leaf-spring suspension system boils down to the bushings. The Dayton leaf springs we installed came with RB-152 rubber bushings for an OEM-like ride. And just like factory, each pressed-in rubber bushing is encased in steel for optimum durability, and the rubber compound provides a softer ride quality than what you typically find with polyurethane units.
With the new front leaf-spring shackles attached to the frame, the leaf-spring packs were set on top of the axle and bolted to the hangers (via new 9/16-inch Grade 8 bolts). As direct factory replacements, no weight capacity was sacrificed with the new springs. Each Dayton spring pack offers the same 2,250-pound rating.
Once the new 1/2-inch front U-bolts were cinched down, we checked every other fastener we’d threaded into place during the job. Then the U-bolts were cut down to remove excess threads, and all hardware (including the U-bolts) was coated in a layer of flat-black paint to prevent rust from getting a head start on all the new components.