The evolution of F-100 front suspension modifications goes something like this: First there was the dropped axle, where original equipment was heated and hammered into a new shape. Then came the front clip graft, where the front of the truck’s chassis was cut away and replaced with a clip from a late-model car with independent front suspension (IFS). Then came the Mustang II and its IFS components, which could be easily cut out and dropped into the truck’s existing frame. Variations on the Mustang II concept followed, and finally the fully custom systems were born.
All of these techniques are still viable, each with its own advantages and disadvantages. Which one is right for your truck? Take a look at our thumbnail descriptions of the different options and see if you can find a favorite.
Stock/Modified Stock
Pro: It’s gotta stay there for a traditional buildup.
Con: It’ll cost almost as much to upgrade as an IFS swap.
If you’re building a traditional or retro rod, you may want to upgrade or modify the beam-axle/leaf-spring suspension that came with the truck. Keep in mind that what’s under there has been there for nearly 50 years, so it may need some extensive work to make it road-worthy.
A typical stock suspension rebuild should include new kingpins and spindle bushings, a rebuilt drag link, and rebuilt drum brakes. Depending on the abuse your truck has suffered over the years, it may need new spindles and new leaf-spring packs. If you plan on driving your truck a lot, consider upgrading to disc brakes and swapping the old manual steering for a power system. If you do that, you’ll need a new box, a new Pitman arm, and probably a new tie rod since, according to Bob Carlisle of Bob’s F-100 Parts, “the original ones had only 1/8-inch tubing. You add power steering and a set of fat radial tires and I can almost guarantee you’ll bend the original tie rod.”
While you’re at it, you may want to drop the axle. There aren’t any aftermarket dropped axles for these trucks, so if you’re going to drop one, you’re back to the blacksmithing tricks of heating and stretching the metal. It’s safe to drop the axle between 2 and 3 inches that way, “but I’ve seen 4-inch axles bend,” Carlisle said. Plan on spending about $100 per inch for the drop.
By the time you’ve done all this work (or had it done), the cost will be about the same as some of the less expensive IFS kits. So unless you really need the old-school look, you may want to opt for one of the modern systems that offers better handling, more control over ride height, is more easily aligned, and so on.
Front Clip Graft
Pro: It’s inexpensive and parts are readily available.
Con: How’s your welding?
The procedure is straightforward: You cut off the F-truck’s frame forward of the firewall and replace it with the framerails and front suspension from a donor car. The replacement pieces can come from a new-car dealer, but more often they are sourced from a salvage yard. (RB’s Obsolete Automotive splits the difference; it sells a “Serious Hardware” front frame clip to which you add GM A- or G-body front suspension pieces.) Either way, you’ll have a complete system, with control arms, springs, steering, and brakes. A Camaro clip has a track width that is almost identical to the F-100’s, and it also has disc brakes with 11-inch rotors (versus the smaller rotors on Mustang IIs) so you won’t have to upgrade the brakes.
There are several downsides to a clip graft, however. One is the complexity of the graft itself. The cost of the clip may be only $100 or so, but you’ll need to have a lot of metalwork and welding experience to properly measure, cut, align, attach, and blend the frame parts—not to mention needing a lot of time to do the work. Remember, too, that while a junkyard clip may be cheap to purchase, you may be buying some pretty tired components that will need rebuilding. So factor that cost into the clip’s cost and compare it with the new-in-the-box kit stuff.
Finally, check with your local Department of Motor Vehicles about any legal issues regarding building a truck with a cut frame. Laws vary from state to state; in California, for example, you are supposed to re-title a vehicle that has a cut frame with a salvage title.
Mustang II Kits
Pro: It’s inexpensive and easy to install, and there are lots of options.
Con: Is it stout enough for trucks?
Not every “Mustang II” kit uses actual Mustang II parts. The cheapest ones do; they consist of a weld-in crossmember and spring towers and require the builder to source all of the control arms, springs, shocks, spindles and other pieces. Then there are the complete “hub-to-hub” Mustang II kits that use all-new components based on the Mustang II geometry. Crossmember-only kits cost $300 to $450; complete Mustang II kits in basic form (meaning no fancy coilover shocks or tubular control arms) cost $1,600 to $1,800.
The Mustang II kits are the most common on the market, thanks to their adaptability and relatively low cost. Option choices are huge: stamped steel versus tubular control arms; coil springs versus coilovers versus air bags; standard 9 ¼-inch versus 11-inch disc brakes; manual versus power steering; plain versus polished or plated finishes; and so on.
A big advantage to a drop-in kit is that you are not cutting into the frame. Instead, you’re strengthening the truck’s original chassis by welding on a new crossmember and boxing the C-shaped framerails around the suspension assembly. Body mount and core support points remain unchanged. You still need welding skills and the ability to precisely locate the crossmember within the chassis, but the challenge is far easier than it is with the clip.
Good as they are, we’ve heard a couple of knocks against Mustang II kits. One is that the upgrade to the big 11-inch GM brake pieces is almost a must, so you need to factor that option into the kit’s purchase price. Some builders are also concerned about the size and strength of the Mustang II components. After all, a Mustang II (or a Pinto, another often-used source) weighs significantly less than an F-100, so its A-arms, spindles, and springs look delicate when compared to heavier-duty truck components. Check with your suspension house of choice to make sure that what you’re buying is appropriate for the weight of your truck.
Volare IFS
Pro: It’s as inexpensive as a Mustang II and easy to find in salvage yards.
Con: It requires frame notching.
This suspension upgrade is sort of a cross between a clip and an IFS kit, with a bias toward the kit aspect. The front suspension out of a Volare (or similar rear-wheel-drive Mopar of the era) can be cut away from the donor unibody as a self-contained unit and welded beneath the F-100’s frame.
The suspension seems ideally suited for the F-100: Its track width is nearly identical to the F-100’s; its low crossmember will accommodate just about any engine; it offers a 3-inch drop over the stock ride height (and the torsion-bar suspension can be cranked up or down to vary the height by another 2 to 3 inches); and the control arms, torsion bar, and shocks are beefy enough to handle the truck’s weight. Plus, the Volare’s 5-on-4½ wheel-lug pattern will match the pattern on a 9-inch rearend if you choose to use one. At Bob’s F-100 Parts, Carlisle can set up a Volare front suspension on an F-100 frame for about $1,600—around the same cost as a basic Mustang II hub-to-hub kit.
Unlike the Mustang II installation, however, you do have to cut a chunk out of the bottom of the F-100’s framerail to mount the Volare suspension. It’s not the same kind of radical ‰ surgery as the clip graft, as you’re not cutting through the rail, but the frame does get a good whack.
Custom IFS
Pro: These are show-quality systems with high-end options.
Con: Get ready to write a big check.
At the top end of the F-100 suspension spectrum you can get pretty much whatever you want for your F-100. Companies like Heidt’s, Kugel Komponents, and Total Cost Involved build gorgeous systems with polished, chromed, billet, and stainless components. A custom hub-to-hub Superide II kit from Heidt’s starts at $2,400, but Gary Heidt told us the kits usually wind up in the $3,000 range with all the right options. Kugel’s and TCI’s prices are almost exactly the same.
What you’re getting for the extra money is really form, not function. “It enhances the value of the vehicle, (the perceived value of the vehicle), a bit more than what you pay for the components,” Heidt told us. Functionally, you could set up a Mustang II kit with many of the same options to achieve similar ride height, spring rates, and braking ability. “They’d ride and handle about the same,” said Heidt. But a show truck should have finely crafted parts with a jewel-like gleam. Save the stamped steel for your daily driver.
Another custom option is the Wide Ride suspension from No Limit Engineering. Instead of using Mustang II parts, the Wide Ride is based on beefy Camaro components, with big ’70-’81 Camaro spindles on custom-fabricated A-arms to give the system a full 7 inches of travel (versus the Mustang II’s 4 to 5 inches). The bigger spindle also allows the use of 11.9-inch Camaro brake rotors. The Wide Ride will drop an F-truck’s ride height 4 inches. The No Limit Wide Ride IFS welds to the frame much like a Mustang II kit. Its price is about the same, too, starting at $1,500 for a base kit and running to $2,400 for a complete kit.
The Big Decision
So in the end, how do you choose what’s right for your truck? Choose just as you would for any other part of a street rod buildup. Consider your truck’s theme—retro, high-tech, daily driver—in equal measure with your budget. Factor in your own abilities: Can you scrounge in junkyard? Are your welding skills up to the task? Talk to friends who have firsthand experience with these kinds of suspensions. Then pick the system that best matches your circumstances. The good news is they’re all good, but one may be better—for you.