Ford F-250 - Ultimate Super Duty Part 2

Building a fullsize for rockcrawling is different than building any other type of vehicle for any purpose. Along with shear size that you don't have to deal with if you own a small SUV or compact truck, you have great expanses of sheetmetal to worry about. If you're hard-core, you don't worry too much, but we're working with a 3-month-old truck, so we worried.

The primary damage you can expect with a fullsize truck off-road will occur at and below the belt line. The rocker panels on Jeeps take a beating, so imagine what happens when you add a couple of feet to the wheelbase. We also have a nice gap where the bed meets the cab that rocks would just love to grab and rip into the corner of the bed. We can't have any of that, so we dropped the truck off at the Ultimate Adventure's official fabricator, Avalanche Engineering. We envisioned a pair of rock sliders tucked tight against the rocker panels that would protect the truck from upwardly mobile boulders.

But Clifton Slay and Tim Turner devised a rock protection system that extends all the way around the truck. They pictured the most vulnerable parts of the truck based on their off-road experience, and built protection that covered these spots. They also needed to devise strong methods of tying the tubing to the frame so the bars wouldn't deflect excessively when tested. With a plan penned, Turner and Justin Trumble started bending and cutting tube.

Building the sheetmetal protection kept us busy this month, but we also had a chance to put some more miles on the truck driving it home from Denver. We emptied a tank of propane and kept track of fuel economy in the various modes. You might laugh at fuel economy with a truck like this, but we know that this is pretty important to turbodiesel fans, so we're keeping tabs. All of the use has been with an empty bed and not towing, but we've gone from an average of 14.6 mpg combined highway and city driving with all the stock components to an average of 20.8 mpg with the ATS components (see last month's article for details on what we changed).

Next month we'll be bolting on all sorts of Super Duty goodies like a beefy front bumper, a Warn M15000 winch, and a rack of PIAA off-road lights.

The rocker protection needs to run the full length of the rockers to fully protect the truck. Before Tim Turner could start bending tube, though, he needed to figure out the fender trimming so the rock sliders can tuck in tight against the full length of the rockers. He cut access at the bottom of the front fender to see and feel what was behind the metal. He then laid tape in the arc he wanted.	There's a lot of stuff on top of the plastic inner-fender panel which kept us from raising the wheel opening. The ECM is mounted about half way up the rear portion of the fender arc, so this also limited us. We're using Michelin 395/85R20 XML tires, which are 46.7 inches tall. The plan is to trim and bumpstop the truck to fit these tires with the Tuff Country 6-inch suspension lift. Tall tires with short lifts are the rage because they work so well off road.	At the rear, we decided to open up the arch a bit, lose the front and rear plastic panels, and lop 11 inches off the bottom of the fenders behind the tires. Justin Trumble works the reciprocating saw to shed the sheetmetal. We also lost the rear bumper, hitch, and spare tire, all of which gain us over a foot of departure clearance.
Turner built the rock sliders from 134-inch, 0.188-inch-wall DOM mild steel tubing. Avalanche Engineering did all of the design and fabrication work on the bars to maximize protection but minimize driver hassle. The front and rear doors still open fully, and you can use the sliders as a step bar if you're a weenie.	Avalanche Engineering built a pseudo bumper that tucks tight under the rear and incorporated two shackle mounts into the design. The bumper and both sliders are actually all one piece and tie into the frame in about a dozen places at various angles. This is about the best rock protection a fullsize truck could hope for, and we'll be fully testing it during Ultimate Adventure.	We learned a lot about the ATS products during our drive to Denver and back. We got our best fuel economy (24.2 mpg) on the highway with the chip in towing mode and the LPG set at about 50 percent. The Ford overhead computer that tells you average mpg and miles to empty has no idea what's going on when using the ATS chip. The coolest part is passing on the highway when you switch to extreme mode. The truck will pass anything and leave it in a fog of black diesel exhaust.