Our project CJ-5 has come a long way in the last few years. We built the rear Model 20 axle as strong as we could, but it was still just a Model 20. It’s inherent weaknesses still providing the Jeep with its Achilles’ heel. As well, the poor axle tube design and axle seals that leaked after 6 months just had to go. We were pretty sure that the seals were leaking because the weak tubes were either flexing during our constant boulder assaults or slightly bent to begin with, either way it was time for a change.
After many heated office discussions regarding ground clearance, axle shaft strength, overall housing weight, ring & pinion gear strengths, parts availability, pinion angles and much more, it was finally decided that a Dana 44 would be the remedy for the rear of the Jeep. While a Dana 60 or Ford 9-inch seemed to be the ultimate answer, many factors went into the decision. For example, a Dana 60 or Ford 9-inch axles would be too expensive and overkill for our lightweight CJ5 with a mildly built, inline-6 mill. Moreover, the Dana 60 or Ford 9-inch have longer pinion and yokes, combine this with the lack of wheel base in the CJ-5 we would be forced to order a high pinion version of either, which is weaker than the non-reverse cut versions. As well, ordering a reverse-cut axle pre-built to our specs would set us back at least 2 grand with our tastes in lockers and disc brakes. On the other hand, building one from scratch meant expensive machining to have it narrowed to suite our needs, and still ordering a reverse cut center for the 9-inch. Besides we knew where there was a perfectly good early 70’s, centered Jeep Dana 44 rear housing (yeah baby!).
Here are some interesting facts about our choices. The Dana 44 ring & pinion is actually slightly smaller than the Model 20 using the same ratio, but the Dana 44 axles are slightly larger than the Model 20, 30-spline compared to 29-spline… our verdict? A draw. So the biggest difference lies in the strength of the housing itself, and the axle tubes. However, our CJ5 is a 1977, narrow track version, which makes the 70-75, centered-diff Dana 44 (which is available in some 70-75 CJ’s) a perfect match for our buildup.
Now it was time to start gathering the necessary internals for the build-up. A call to Randy Lyman, owner of Randy’s Ring and Pinion, had the ring and pinion gears on their way, along with their incredibly complete seal and bearing install kit. As well, NO rock crawler is complete without a locking differential, so a call to Tractech (Detroit Locker) armed us with a Detroit Softlocker for our Dana 44… the ultimate in strength. We knew that all of the carrier, axle tube and ring & pinion gear strength in the world isn’t worth dog droppings unless the axle shafts were up to snuff as well, so a call to Dutchman Motorsports and we had a set of their wicked-strong Chromoly Dana 44 axle shafts complete with bearings and seals installed.
Our final task was to find a qualified and competent professional to put all of this together for us. If you live in the Tucson, AZ area then there is only one answer for all of your differential needs, Tucson Differential. Check out the installation section to see the professional assembly of a super stout Dana 44 differential.
When it comes to setting up differentials, if you don’t know exactly what you’re doing don’t even attempt it. A Chilton’s or Haynes manual doesn’t do this process justice, so unless you’re a masochist, we don’t recommend trying it yourself. I’ve set up a few ring & pinions in my time and know that unless your fixing your rig just to sell it (not that we’ve ever done that) or if you’re working on a beater to just learn, it’s better to have a seasoned pro set this up for you. The bottom line is that if the ring and pinion isn’t set up correctly, the resulting damage, which isn’t usually obvious until it’s too late, is at least, if not more expensive to fix than the original set up. So let a professional and reputable shop set up your differential and avoid the worry. Again, we chose Tucson Differential to help us build our stout 44. While many people claim to know how to set up diffs, we wouldn’t think of trusting our 4×4 to anyone else. Trail fixes can be amusing, challenging and sometimes actually fun, a broken ring and pinion set isn’t something you want to work on or worry about when you’re miles from home in no-man’s land. Jay Sinclair, Tucson Differential’s owner, has more than 16 years of experience building axles, and has assembled everything from cut down drag racing and circle track diffs, to extreme off-road racing rear ends. Of course they can also analyze and mend the noisy pig in Granny’s Buick too. Armed with our empty housing, a truckload of the best parts we could get our grubby little mitts on, and our notebook and cameras in hand, we headed off to watch the experts build our new axles.
Editors Note: As stated earlier, setting up differentials is no simple task; unless you have years of experience, leave it to experts. As a precautionary measure, every differential that gets rebuilt at Tucson Differential is checked for absolute straightness. “It’s not worth squat building a diff if the tubes are bent” Says Jay Sinclair “and it will eat the bearings and seals in no time.” Not every shop checks this and we’re grateful Tucson Diff does, because our driver-side tube was slightly awry! Jay and the guys said, “No problem, we can fix that”. Sure enough, 20 tons of pressure (not from us) from the hydraulic press and the axle was like new again. That’s right 40,000 pounds of pressure!
After the housing was declared shipshape, it was thoroughly cleaned and prepped for the new components. Jay started by deburring the mating surface of both the ring gear and the Detroit locker, and mating them by using Loctite on the ring gear bolts and torquing to spec. Next the pinion shaft was taken to the press and the bearing installed. The yoke was then installed with the original pinion nut. The original pinion nut is used because the new one is meant to only be installed once (pinch style) and to set the pinion depth and preload. Next, Jay did some quick math in his head and grabbed a few shims he thought would be the best to use first. The shims were added to the carrier (Detroit Locker and ring gear) and was then taken to the press to have the bearings pressed onto it. Jay established backlash and carrier preload and then the pattern was checked for proper tooth engagement between the ring and pinion gears. Once the optimum pattern and backlash were obtained, Jay then installed the new pinion seal and nut. Again, the new pinion nut was saved until the end since the pinion shaft must be removed a few times during the set up and the lock nuts should never be reused. While this process sounds very simple, it’s not. What took the experts a little over an hour to do would have taken me a full day or more, and then left me a little leery. After watching Jay and the guys at Tucson Differential set up the rear end I know that it will provide me years of trouble free use. Now that it’s all done there is only one thing left to do, hang the housing under the springs, that’s right under, and go test it out! Stay tuned we will be installing the rear Dana 44 and doing a spring over conversion at the same time.