Going Full-Width!
After breaking an axle shaft, due to a heavy right foot, in my own driveway (long story) it was time to upgrade my rear axle. Originally I was going to use an Explorer
8.8 that I had sitting around, but decided on a big bearing full width 9" out of an ’81 Ford F-150. My 28-spline 8.8 had served me well, but the breakage confirmed that the stock axle was not as strong as I needed it to be. The Ford 9" was a natural choice over the 8.8 for several reasons. It uses larger wheel bearings, has larger axle shafts, more gearing/locker options, bigger axle tubes, does not use C-clips and has larger brakes. The only real downside to this axle was the lower pinion placement, but there is usually always a trade-off. Oh, did I mention it was full-width, making it 7 inches wider then a stock ranger 8.8!
The Beginnings:
Obviously the first step was to find this axle. It didn’t take long before I found one at a swap meet minus the center section for $50. I picked up a donor center section from my buddy Grif for free or nearly free, I can’t remember. I knew I wanted this axle built well, so I went ahead and ordered new 4.56 gears and an ARB air locker.
The Build:
After my parts arrived, I went to work doing the hardest part first, setting up the gears and air locker. A 9" is pretty easy to setup, probably one of the easiest axles ever, but there are some additional steps that had to be taken because of the ARB. First I removed the old carrier and gears and tossed them aside. Then I started grinding on the third pinion bearing support to make room for the ARB. Before cleaning the housing, I also went ahead and drilled and tapped the hole where the air line was to be fed through the carrier housing. The
gear setup went fairly smooth except for a problem I had with one of the carrier bearing adjusting collars. It would just not screw in far enough to remove the side-to-side slack in the
carrier. I discovered that the collar was bottoming out in its hole before taking up the slack. I still don’t know where the tolerance problem lied, but I fixed it by carefully grinding off some of the thread off the end of the collar, allowing it to screw in further. 4 years and 50,000 miles later, still no problems. Once that problem was solved the rest of the set up went very smoothly. The final gear pattern was dead-on and everything looked good.
Prepping the rest of the axle was fairly easy, but labor intensive. I did not have the funds to sand blast and powder coat this axle like the front one because our local place
went out of business, so I pulled out the wire wheel and the Wal-Mart spray bomb and went to work. New brake parts were also ordered along with new spring perches and shock mounting tabs. Below is a picture of the axle loosely mounted in the truck:
Before welding on the new spring perches, it is important to make sure the axle is centered and the pinion is at the correct angle to avoid drive shaft vibrations. The
correct pinion angle will be the same angle as the transfer case rear output for a 1 piece driveshaft. If you are using leaf springs like I did, you will want to point the pinion down 1 or 2
degrees further to compensate for the pinion rising under torque load. This was also a good time to install the new shock mount tabs. I mounted the tabs level with the axle’s center line so they would not be hanging down and catching on rocks. It is important when changing the shock’s mounting position that you make sure it will still have enough travel in compression and rebound.
The brake install was standard for a Ford 9" with the exception of modifying the emergency brake lever to accept the E-brake cables from the ranger. It was not hard, but I had to extend the lever slightly to accommodate the short stroke of the ranger’s E-brake cable.
Final Touches:
Over all this is an easy swap. There are a few detail things that must be done to make everything work properly. First off, in my case, my rear axle was now wider then the front. To correct this without building a new front axle, I added 1.5" wheel spacers to each side bringing the total width of the front axle to 65" WMS-WMS. This had the added benefit of
tucking the locking hubs into the wheels further and keeping them away from the rocks. The downside was now I was running a greater offset and therefore increasing the stress on the wheel bearings. Once again, however, 4 years and 50,000 miles later, still no problems. Another “tweak" I had to make was adding an adjustable proportioning valve to the rear brake circuit. With the larger drums I knew the rear wheels would lock up much easier then before and therefore I had to reduce the line pressure to the rear to keep the system properly balanced.
Benefits/Performance:
The biggest benefit to this project was peace of mind. I no longer worry about breaking a rear axle out on the trail, and even if I did, the non-c-clip design will make it easier to change one out or limp it somewhere safe. The larger rear axle has also improved my load carrying ability through larger wheel bearings and larger brakes. The ARB was a huge upgrade over the Detroit locker. I no longer have the tire wear issues or funny street manners. It also makes snow driving easier. Articulation and stability have also improved as a result of the axle being 7" wider. The one downside is again the low pinion placement. There is not a whole lot you can do to resolve this cheaply. It forces me to be more mindful of my driveshaft placement, but most of the time it is not a problem. One solution is to install a high-pinion 9" center section. These are generally expensive and require special gears. The top two manufacturers right now are True High 9 and Currie. In my opinion the True High 9 setup is much better because it uses special reverse cut 9" gears made by Richmond Gear. The Currie HP9 on the other hand uses reverse cut 8.8 gears and is not truly a 9"
Final Product:
Good luck with your own project!
Disclaimer: This article is intended to describe my experience installing a new rear axle in my truck and is in no way a step-by-step guide for an axle swap. All modifications to your truck are at your own risk. It is advisable that if you do not fully understand all aspects of a given modification that you consult a professional for help.