Ford F-150 9.75 Axle Build - Unsung Hero

Our test mule was a '97 F-150 with the 5.4L V-8, 3.55:1 gears, and an open diff. With nearly stock-size tires, the owner opted to keep the stock gears, but he wanted a very streetable traction aid. Detroit's Truetrac gear-type limited-slip filled the bill in that department, and the 9.75 is a brand-new application. Eaton/Detroit Locker also makes a Detroit Locker available for the 9.75.

Being known as a bit of a lead foot, and a guy who tows trailers and does a bit of mild 'wheeling, our owner wanted some extra beef. To that end, we installed a pair of stout Yukon 1541H alloy axleshafts, with new wheel bearings and seals, from Randy's Ring & Pinion. Randy's also supplied a crush-sleeve eliminator kit.

The final building block to the 9.75 was TA Performance's diff cover/girdle. This heavy-duty 356 aircraft alloy, T-6 heat-treated aluminum cover does several things. The first is structural support for the housing in general, and carrier bearings in particular, via a pair of externally supported load bolts. Billet carrier caps are sometimes used in the same way, but it's been learned by race teams that a cap/girdle does the same thing and is easier to fit with no special machining needed.

It took a while for the aftermarket to step up to the 9.75, but in looking at its attributes, it's no wonder the Lightning boys with the older trucks and 8.8 axles are upgrading to the 9.75. The 9.75 could make a nice swap for any 1/2-ton-rated 4x4 rig, Ford or not. It has the advantage of having that "Three Bears" quality of being just right in the size and strength department to make a worthwhile improvement over the weaker 1/2-ton axles. Considering that used semi-floating Dana 60s are getting scarce, the 9.75 may become the new "junkyard D60" of the new millennium.

6. The Yukon crush-sleeve eliminator kit (the pinion seal is not included) replaces the pinion crush sleeve with shims. In high-stress applications, high torque loads or pinion yoke impacts on the trail can cause the crush sleeve to release the pinion preload with disastrous results. Not a common problem, to be sure, but the shims are a cheap way to add to beef and make setup a bit more precise. The earlier 9.75s had a short crush sleeve, but later ones have a long one, and the second thick spacer shown here is needed to fill the gap.	7. University of Northwestern Ohio Instructor Dave McPherson demonstrates the proper use of applied force on the carrier-bearing shims and bearings while installing the Truetrac. Installation is just the same as with any carrier. We installed new Timken carrier bearings.	8. The 9.75 is a C-clip axle. The Truetrac has a solid spacer installed between the two shafts behind this circlip-retained cover after the C-clips are installed.
9. The old crush sleeve (short style shown) provides a starting point for making up the Yukon shim pack. Measure the spacer and deduct 0.005 to 0.007 inch and test pinion preload...	...Add or remove shims to obtain the correct 15- to 19-in-lb preload with new bearings, or 6- to 8-in-lb with used ones.	10. TA Performance offers the option of aircraft-grade studs, nuts, and washers for the carrier caps. This adds considerable strength to the axle as well. The studs are installed and tightened to 10 lb-ft (120 in-lb) and the nuts to 85 to 90 lb-ft. The factory bolts are torqued to only 70 lb-ft.
11. The TA girdle is torqued to the housing. This is important as the cover actually adds to housing strength. Next, the load bolts are run in until the feet touch the carrier caps, then torqued to 5 lb-ft (60 in-lb). The jam nuts are then tightened to the same spec.	12. Installing the Yukon shafts is just as easy as the factory shafts. The big thing is to make sure you get the right shafts for your truck. To be safe, measure the area at the bearing surface. There are two possible dimensions, 1.620 and 1.705 inches, with the former generally seen on '97 and '98 trucks, and the latter on '99-and-up models. There was some crossover, especially in '99, so measuring is important.