There are only few go-to axles that we like to use when doing a budget axle swap. We typically look for these axles because they are strong, easy to find, inexpensive, and easy to modify. The Ford 9-inch is the king of swapped-in axles. No other axle enjoys as many aftermarket parts. Versions of the Ford 9-inch can be found under muscle cars, hot rods, roundy-round race cars, desert prerunner trucks, and of course Jeeps. You could even build a Ford 9-inch completely out of aftermarket parts. But our favorite wrecking yard version of the Ford 9-inch can be found under ’74-’86 F-150s and ’78-’86 Broncos. It features the legendary Ford 9-inch ring and pinion strength, 5-on-5.5 lug pattern (same as older Jeep), a 65-inch width at the wheel mounting surfaces, large-bearing semi-floating axles, and many can be found with hefty 31-spline axleshafts. Another bonus is that the axleshafts are of equal length, so you’ll only need to carry one spare should you choose to.
The V-8, manual tranny with 6.32:1 First-gear, and 37-inch tires proved too much for the Dana 44 rear axle in our somewhat-heavy ’73 J2000. Fortunately our favorite Ford 9-inch is a perfect swap in a Wide-Trac FSJ. We snagged a complete 9-inch from the local wrecking yard for just under $200. We actually ran it as-is in our Jeep with the same gear oil and brakes for several months before regearing it to match the front axle. But first it needed some modifications to get it under the back end of our J-truck.
We unbolted and removed the...
We unbolted and removed the stock Dana 44 rear axle from our truck. We pulled it apart to see exactly what had failed. We were at least a little surprised to find that there really wasn’t all that much left that was useable.
Along with twisted splines...
Along with twisted splines on one axleshaft we broke a few ring gear teeth whose bits took out our locker. With so many busted parts, it wasn’t cost effective or smart to rebuild the stock Dana 44 in our truck. Our application needed a little more mettle and steel. But we didn’t want to upgrade to an overly heavy eight-lug 1-ton rearend.
It doesn’t look like it from...
It doesn’t look like it from the photo, but the Ford 9-inch (top) is about the same width as our ’73 J-truck’s Dana 44 (bottom). It also has the same 5-on-5.5 lug pattern. When searching for a 9-inch, keep in mind that the F-150 Camper Specials will have a stronger nodular third member. Look for the “N” cast into the top of the centersection.
Our ’80-ish two-wheel-drive...
Our ’80-ish two-wheel-drive F-150 9-inch came with large-bearing 31-spline shafts. The ’74-’80 two-wheel-drive trucks will generally have 28-spline shafts; all Camper Specials and 4x4s will have 31-spline shafts. All of these housings can be upgraded to 31-, 33-, 35-, and even huge 40-spline shafts using bolt-on parts.
To snug the new axle in place,...
To snug the new axle in place, we used a Miller Spectrum 375 Xtreme plasma cutter and an angle grinder to lop off the 9-inch’s spring perches so that they could be relocated and reused. We scavenged the spring plates from the Ford truck that donated its axle and we ordered new Pro Comp F-150 U-bolts.
Since the Ford 9-inch doesn’t...
Since the Ford 9-inch doesn’t have a drain plug, pulling the third member with the axle full of oil can make a huge mess. Here’s a tip we picked up from a friend who preps race trucks—pull a shaft and tilt the axle into a drain pan. Not all of the oil will come out, but most of it will. Work on something else while it slowly drains.
With the housing centered,...
With the housing centered, bolted to the springs, and the suspension under load, we set the pinion angle almost parallel to the transfer case yoke (about 1-2 degrees down to compensate for axlewrap under load). Once the pinion angle was set, we tack welded the spring perches in place and removed the housing so they could be fully welded.
Once the third member nuts...
Once the third member nuts are removed, you’ll sometimes find the centersection glued to the housing with silicone sealant. You can pull it apart with a floor jack by carefully lifting up on the yoke until the seal breaks and the remaining oil drains.
We had to put our Superior...
We had to put our Superior Axle & Gear 4.11 ring gear (PN F90411) in the oven at about 250 degrees and put the 31-spline Eaton Detroit Locker (PN 187SL17B) in the freezer to get them to fit together. Never try to pull the ring gear to the carrier with the ring gear bolts. The ring gear should be sitting flat on the carrier before installing and torquing the bolts to 70 lb-ft. Use a rubber dead-blow or brass hammer to help knock the heated gear into place if need be.
The Ford 9-inch has one of...
The Ford 9-inch has one of the easiest ring and pinions to set up. We used a complete solid spacer install kit from Superior Axle & Gear (PN 35-2011D) and stuffed everything into the stock Ford 9-inch third member case and pinion support. Pinion bearing preload is set to 13 to 15 inch-pounds. We adjusted the carrier bearings and pinion shims until we had a good pattern in the gear marking compound. The final backlash is set to .007 to .010-inch using a dial indicator. Then the bearing caps are torqued to 60 lb-ft.
We used the included Superior...
We used the included Superior third member gasket and some silicone sealant on the mating surfaces before the nuts were cinched down. Here’s a tip, trim any overhanging gasket with a razor knife. In the past we have seen rocks snag and pull on the gasket causing a gear oil leak.
The 9-inch’s U-joint yoke...
The 9-inch’s U-joint yoke location is about 1.5-inches further from the transfer case than the Dana 44’s. Most Jeeps will need the rear driveshaft lengthened this much. Or you can do what we did and install an Advance Adapters 32-spline output (PN 50-3020) in your Dana 20 T-case. The new heavy-duty output is exactly 1.5 inches longer than the comparatively weak factory Dana 20 output.
We ordered our Advance Adapters...
We ordered our Advance Adapters 32-spline output with an optional 1350 yoke. For now, we mated the factory 1310 driveshaft to the 1350 yoke with a NAPA Precision conversion U-joint (PN 348, left). On the axle end we needed another conversion U-joint to go from the factory 1310 driveshaft to a 1330-Ford style yoke (NAPA Precision PN 372, right). Eventually we’ll upgrade the driveshaft.
We reused the F-150’s shock...
We reused the F-150’s shock mounts by cutting them off of the housing and rewelding them in the proper location. The brake lines are a combination of home-bent universal 3⁄16-inch steel lines and Earl’s Plumbing parts. The swap was finished off with an extended breather hose for the axle just in case (when) it gets submerged in mud and water.
We ordered our Advance Adapters...
We ordered our Advance Adapters 32-spline output with an optional 1350 yoke. For now, we mated the factory 1310 driveshaft to the 1350 yoke with a NAPA Precision conversion U-joint (PN 348, left). On the axle end we needed another conversion U-joint to go from the factory 1310 driveshaft to a 1330-Ford style yoke (NAPA Precision PN 372, right). Eventually we’ll upgrade the driveshaft.