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ultimate F 150 Part 5 - rear Brake Install - Photo 38351883

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The Pro 80 is fitted with a fixed-spindle, full-floating hub setup that will utilize RCV double-splined axleshafts and custom 35-spline drive flanges from Dynatrac. The rear brakes have built-in parking brake option and use special Jeep rotors that have been machined to an 8-on-61⁄2 wheel bolt pattern.

131 1111 01+ultimate f 150 part 5+welding the rear bumper

The stock rear axle in our F-150 is a 93⁄4-inch ring gear with locking differential. And as big as that is, we need a stronger axle up to the challenge of big tires and heavy weight from all the armor and tubing, and to be able to support the load of gear, parts, tools, and equipment we’ll have on board. We returned to Dynatrac to build a brawny Pro 80 full-floating rear.

Both the Pro 80 rear and Pro Rock 60 front use 5.38 and ARB Air Locker differentials. The 80 has an 111⁄4-inch ring gear while the front 60 has a 93⁄4-inch.

Our gears came directly from Dana Spicer. Dana Spicer makes some of the finest gears in the world used in many OEM applications. Budget gears are nice, but investing in top-of-the-line components are important when you’re out on the trail and don’t have time to wait for replacement parts.

The Pro 80 is fitted with a fixed-spindle, full-floating hub setup that will utilize RCV double-splined axleshafts and custom 35-spline drive flanges from Dynatrac. The rear brakes have built-in parking brake option and use special Jeep rotors that have been machined to an 8-on-61⁄2 wheel bolt pattern.

The selectable ARB Air Lockers are a trusted standard of many four-wheelers. We have found that care during installation results in nearly flawless performance from the ARBs, and we have never had an issue with a Dynatrac-installed Air Locker. Routing the internal copper line and proper tire pressure testing are important precautions.

To support the F-150 above the Pro 80, we went to Deaver Spring for a set of its long-travel Raptor/F-150 rear springs. Deaver makes springs for everything from race trucks to car trailers. With a full line of replacement and lift springs or custom built and repaired springs, Deaver had our suspension sorted.

These leaf springs are just slightly taller than stock, but with adequate fender trimming, different shackle hangers, and the larger axletubes, they will clear our 40-inch rubber. The Deaver springs also have a military wrap and torque wrap to reduce wind up of the leaves and still be strong under power.

Our axles and springs in tow, we headed back to Randy Ellis Design in Phoenix to finish up the truck. While we were away getting parts, the RED crew added some ventilation and visibility to the F-150 in the form of a custom sunroof opening. A snap-on vinyl top will be made for inclement weather.

The EcoBoost V-6 has two turbos feeding an intercooler that cools the air charge into the engine, resulting in additional power. We had to remove the intercooler to mount the winch and were not able to put it back in due to its size, plus we were worried about mud clogging the intercooler during the trip. Justin Scheller from Randy Ellis Design fabricated an aluminum intercooler.

The aluminum tubes run through a sealed aluminum box that is fed by the turbos and have cool fresh air running through them during on-road travel to cool the charge from the turbo. It isn’t as efficient a design as the factory piece, but it is less likely to clog with dirt. (Seeing as the trip is already over, we can say the truck was never short on power.)

In the rear the leaf springs hang from the factory front spring hanger and custom shackles built to pivot off the rear bumper. Made of 1⁄4-inch chromoly plate, they should be adequate against trail abuse.

Swinging the Pro 80 into place and setting up the leaf springs is not easy. We initially went with a 3-inch lift pack, but the truck sat way too tall. We also had a custom driveshaft built to deal with the rear slip yoke of the transfer case, and that required changing the pinion angle from stock.

To control our rear springs we went with a set of Fox three-tube bypass shocks with a 21⁄2-inch body. These shocks are overkill for a rockcrawler, but when you are building an IFS trail truck there is no guarantee it will only be a rockcrawler. Plus our prior experience with Fox Racing has been phenomenal, so we were excited to use its product. We also ran Fox air bumpstops at each corner. The front uses 2-inch travel units and the rear 4-inch. Notice how the bumpstop mount is built away from the frame to clear the leaf spring at full compression.

While the springs and shocks were finding a home under the bed of the truck, the guys from Coverall Technologies where prepping the bed for a spray-in bed liner. We opted for a spray-in liner to cover the seams where we bobbed the bed of the truck.

Coverall uses the Vortex bed liner system, which allows them to come to your home or shop and spray your pickup bed with very little overspray due to low-pressure application. They can also spray your garage floor, deck, or whatever needs a quick-drying, high-impact, durable coating to protect it from use and abuse.

Once the Vortex Bedliner was dry we installed the custom two-drawer Tuffy storage box. This lockable steel box will house all our tools and spare parts.

The long dual drawers have a strong sliding mechanism to support the weight of spare driveshafts and axleshafts, a large selection of tools, and sundry bits to keep our Ultimate trail truck running. In addition to time and money, we are out of space for any more buildup this month, but we’ll return next month to show you more of the IFS assembly and the hundred other things we had to finish such as front shocks, exhaust, driveshafts, paint, lights, and wiring.