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Ford Super Duty Suspension - Playing The Odds

Posted in How To: Suspension Brakes on July 1, 2007
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We bet that risk factor was low on the minds of Ford's top executives when they decided to retire the Super Duty's tried-and-true front leaf packs in favor of coil springs for 2005. Coils are a proven concept, as everyone from designers and engineers to end users would agree. The switch prompted praise from all, including us. We predicted the revision would vastly improve ride quality on what some say is still the undisputed leader when it comes to hauling.

However, much of the benefit associated with coil springs was sacrificed on the Super Duty due to a combination of inadequate factory dampers with overly stiff coil springs. Unfortunately, the silky-smooth ride quality that much of the industry expected from the new configuration wasn't present in stock form. But we had to give Ford credit for making the change, successfully opening up a plethora of aftermarket opportunities that could improve both ride quality and performance. The move was good for all of us in Truck Land.

The proof of this became crystal-clear when Pro Comp introduced its new Double XX kit which features four-count 'em-custom-tuned 2.75-inch front coilover shocks, each with a remote reservoir and high-quality progressive-wound coil spring. Why four? The answer lies in dependability. The last thing you want to deal with in the middle of nowhere is a broken coilover shock, so Pro Comp, like many professional desert racers, spread the burden between two coilover shocks at each front corner. Doing so effectively improved the odds of dependability and strength.

Just like a roulette table in Vegas, we couldn't pass up a spin. So we tested the new 8-inch Double XX arrangement (also available in a 6-inch version). Follow along as we show you all the trick components, a few must-have complements to the kit, and our results from a full year's worth (50,000 miles) of testing by one of the most destructive volunteer testdrivers we know.

PhotosView Slideshow
PhotosView Slideshow

13. Once the new tires and wheels were mounted, we drove the truck around Los Angeles for a few days to get a feel for the new suspension system. While we loved the new smooth ride afforded by the kit, we found that the larger tires made slow, tight maneuvers in parking lots almost impossible. With worn-out arm muscles, we called Pro Comp to find out why this was. They told us that we probably had a Super Duty that came from the factory with a finicky steering box. "Some have no problem steering 37s, while others simply make it impossible," said Jeff Blakely of Pro Comp Suspension. To resolve this issue, we stopped by Off Road Unlimited (ORU) in Burbank, California, to have one of its killer ram-assist steering systems installed. ORU's ram-assist kits are, simply put, the best thing you can do to resolve the stiff Ford steering-box issue. In about six hours, we had steering that felt more like an Acura sedan than a 1/2-ton truck. Keep in mind that not all Super Duty pickups will need this modification, and that not everyone has puny little toothpick arms like the author of this story. But, should your truck steer much harder after a lift and bigger tires are installed, the solution is simply a phone call away thanks to ORU.

14. We tooled down the highway, happy as clams with the truck's new ride and steering feel. However, now we noticed that the speedometer was incorrect and that the truck seemed to lack power off the line. So we called our friends at Right Gear and Axle of Salinas, California. Right Gear and Axle specializes in gear swaps and drivetrain overhauls. They concluded that we should swap out the stock 3.73:1 axle gearing in favor of a lower 4.33:1 ratio. While we were at it, they suggested we also remove the OE limited-slip rear differential because, at 36,000 miles, it was probably not working anymore. A simple jackstand test confirmed this. We had the guys at Right Gear replace the non-functioning factory limited-slip with a Detroit Truetrac unit. Our buddies at Eaton/Detroit told us this was a very common swap, as the clutch-style limited-slips wear out quickly under the torque loads of the Power Stroke engine. The best part about a Truetrac, which uses helical gears, is that there are no clutches to wear out, and the units themselves are pretty much indestructible, unlike other limited-slips that use clutch plates and springs.

PhotosView Slideshow

With just over 25,000 miles on the Double XX kit, we decided to take it back to Pro Comp for a check-up. They were blown away that our testdriver was able to rack up so many miles in just over six months' time. We hadn't noticed any major issues with the kit, and the single-shear lower shock mounts seemed to be doing just fine. After a quick retorque session, they did discover that one of the front 2.75-inch shocks was weeping oil from a shaft seal. They told us that this was likely due to our shocks being assembled prior to actual production parts, but in any case the entire shock was replaced to allow Pro Comp's R&D department a chance to evaluate what went wrong. A simple seal failure was the culprit.

Next, we discovered that one of the rear-axle lower shock mounts was moving slightly from its intended position. This alarmed us at first, but then Pro Comp replaced this bracket with a brand-new one and instructed us to have each side of the bracket welded to the axletube to prevent further movement. We had this performed and haven't had a problem since. Keep in mind that our tester is very hard on his truck, jumping it any chance he gets, and in most cases is a lot harder than the average consumer would be. Pro Comp agreed with us that in most cases, the rear shock mount issue wouldn't happen at all.

A high-end suspension system like the Double XX kit allows for increased speed and mobility over all kinds of harsh terrain. We did a little testing with this kit down in Baja, Mexico, last year. Though the suspension system performed well in just about every environment, we did find one place where it gave our testdriver way too much confidence, allowing him to overdrive the factory headlights at night. It happened on a road we call "one of the worst roads in Baja," between the small fishing village of Puertecitos, about 100 miles south of San Felipe on the Sea of Cortez side, and Gonzaga Bay, another great fishing spot. This road is the type where suspension systems will make or break your trip. During the day, with a good suspension system, you can drive 60 mph easily, slowing only for the occasional washout, hard corner, or stray cow blocking one's path. At night, however, it's quite a different story, and speeds of 40 mph are flat-out dangerous with only factory headlights. Our tester installed these lights and headed south after the Baja 1000 last year, and found that the increased field of view afforded by the new HIDs, in conjunction with the Double XX kit, allowed him the ability to cruise through the darkness at speeds typical of a sunny day. These 9-inch HID lights are sold individually, and each comes with a clear, polycarbonate lens protector, built-in ballast, and a heavy-duty aluminum adjustable mounting bracket. The killer part about these lights is that each puts out more light than a standard 9-inch, 130-watt halogen type light, but only uses 2.9 amps of power, so your electrical system doesn't get zapped while 'wheeling at night.


Pro Comp Suspension
Chula Vista , CA 91914
Cleveland, OH 44114
Precision Gear
Suwanee, GA 30024
Right Gear And Axle
Salinas, CA 93908
Off Road Unlimited
4 Wheel Parts of Redondo Beach, CA

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