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2006 Ford F-150 - Project Fast-150

Posted in Project Vehicles on February 10, 2014
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Our 2006 2WD F-150 project truck has been shaping up for a while. With our recent addition of a JD Fabrication long-travel front suspension, it was time to address the rear axle and suspension. We wanted a small lift, better-quality springs and shocks, along with re-gearing our axle and adding a limited-slip differential. The JD kit had widened our front track by 8 inches, so we wanted to also add some width to the rear track.

Spring choice was simple. We made a call to Deaver Spring and purchased a set of their long-travel lift springs with about 3 inches of lift height. The nine-leaf packs are designed to offer a supple ride, longer travel than stock springs, and better overall ride stability.

Looking at the rear axle, we had a few options to go wider and add some strength in the process. Our factory axle measured about 70-1/2 inches from flange to flange, and we wanted to increase that width. We could have ordered a custom Ford 9-inch axle to the width we wanted, but costs went up quickly for such an axle. Building a widened Dana 60 or similar may have been possible, but many axle shops don’t offer shaft blanks as long as we needed.

It was then we started considering using Raptor parts. A Ford Raptor rear axle measures about 76 1/2 inches wide, right in the ballpark of what we wanted. Salvage Raptor axles are available for about $2,000, but we’d need to swap out the 4.10 gears, come up with an electrical harness to run the factory locker, and address a way to restore our pinion-driven ABS signal to our computer.

The Ford 9.75-inch rear axle is a respectable piece of hardware. The ring gear is well sized and the pinion shaft and bearings are stout. It’s a semi-float design with C-clip retention, but uses respectable 34-spline 1.37-inch diameter shafts. Overall, the 9.75-inch is comparable in strength to a Dana 60 axle. Its biggest weakness is probably its relatively thin wall tubes, which are just under 1/4-inch wall thickness.

As an alternative, we built our own Raptor-width rear axle from a salvaged standard F-150 housing. We bought a core housing fairly cheaply and started making measurements. Our plan was to widen the housing and populate it with factory Ford Raptor axleshafts. Along the way, we swapped in 4.88 Yukon gears, a Yukon Dura Grip limited slip, Crown Performance stainless brake lines, and a Nitro Gear & Axle rear cover. Pinion flange, brake components, and ABS sensor all connected right up, making those swap features easy to deal with.

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22. Our new stance sitting on the 37-inch Baja T/A tires and 17x9-inch Weld Racing wheels. The Bajas roll smooth and round, very typical of any BFG carcass. They emit just a bit of highway hum at speeds but nothing annoying. Of course, they shine in the dirt.


Weld Racing
Kansas City, MO 64129
Nitro Gear & Axle
Sacramento, CA
Deaver Spring
Santa Ana, CA 92701
Crown Performance
Vista, CA 92081
JD Fabrication
Escondido, CA 92029
Randy's Ring & Pinion
Everett, WA 98204
BF Goodrich Tire Company
Greenville, SC 29602
(877) BFG-TIRE

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