Ford Super Duty Suspension Install - Make Mine a Double XXPosted in How To on September 20, 2006
In the Stone Age of trucks (about 18 years ago) it was considered cool to stuff as many shocks as possible underneath each corner of your truck. Four shocks per wheel was a common sight in the off-road truck world. This ill-advised trend made our trucks ride like Old West covered wagons, and our backs began screaming in protest. We were both tragically hip and classically idiotic. In the Truck Stone Age, multiple shocks at each corner amounted to a good idea that was executed horribly.
Multiple shocks really do have merit. A shock's job is to convert kinetic energy (motion) into thermal energy (heat). Since shocks hold oil, adding shocks means adding more oil, which means adding the ability to dissipate heat. Overheated shocks fade, and the truck begins to buck and bounce uncontrollably. A look at the desert racing trucks of the late '80s and earlier reveals that it was commonplace to run three or four shocks per wheel. The difference was that the desert racing trucks rode smoothly, and the copycat street-driven trucks rode like tanks. Clearly, something had been lost in the translation from racecourse to pavement.
The missing link was sensible damping rates. The average off-roader didn't realize it at the time, but when shocks congregate, that assemblage needs to be adjusted (valved) to work as a group. When multiple shocks work as a group, the result is an off-road truck that rides smoothly without fading, even under prolonged abuse.
Pro Comp's newest kit for the '05-and-newer Super Duty 4x4 takes advantage of the ample room under the fenders of the big SD and has been dubbed the Double XX. Available in 6 or 8-inch lift heights, the Double XX places two 2-3/4-inch Xtreme 2.75 CR coilovers at each front wheel. The coilovers are built in-house at Pro Comp's Chula Vista, California, headquarters and feature rugged 7/8-inch shafts for durability. Each eyelet uses an equally durable spherical bearing which is easily replaceable via a snap ring. Thoroughly modern, the Xtreme 2.75 CR coilovers have been tweaked, tested, and valved correctly not only to work as a pair, but to work correctly while suspending a big-boy Super Duty. Coil spring rates have also been carefully selected to go with the double-shocked configuration. A smooth ride, both on and off road, and cool shock temperatures are the order of the day. It's good to be out of the Stone Age.