For Dana 44 With Tapered Axles

by Jim Wiseman

I used to have an IH Scout (1961) with rear D44 and tapered axles. I spent many years in that love/hate relationship. Somehow (some would call it abuse) I managed to bend or break two axles in just a few years. The first happened when we slid off a rock and the second was when I demonstrated how much torque one gets in low range (and did not engage the front hubs). Duh. My bad, but I never really liked tapered axles after that. When I picked-up my 1970 CJ5, semi-affectionately called Polluto, the tapered axles were on my worry list. The passenger side axle creaked every turn. It would stop if I squirted it with a little WD-40. When I went to tighten the nut, I found some gorilla mechanic had cross threaded the nut and stripped the threads. A new nut might only buy me time but I did not want to spin an axle. When opportunity arose, I decided to put in a full floater for the following reasons:

1. You get rid of the tapered axle.
2. Towing is made easier. You can use hubs normally found on the front wheels, on the back. Turn these to the ” free’ position and your drive shaft is disconnected, saving wear and tear on your transfer case too. Also, my potential tow vehicle isn’t the strongest (Polluto has more power) and needs all the help it can get.
3. If you break an axle, your wheel stays on. The wheels are on their own spindle, just like the front wheels. If your axle should break, the wheel doesn’t jam up under the vehicle or wander off into the weeds. Ideally, the broken axle, or parts of it, can be removed and replaced in the field but, who carries spares?
4. It looks way kewl!

One can poke around and be taken to the cleaners with an after-market solution (Warn) or have the fun of designing your own from pieces. Since Polluto is a project car and I have various degrees in engineering, I decided to go for the latter. Besides I got some encouraging pointers from members of the forum (thank you Nick Miller, et al) and the trail has been blazed by others (Vernco).

My first objective was to beat the after-market solution price by 50%. Wrong… How about 25%? Maybe.

Axles

The big dollar items are the axles. I found no one that stocked these as project parts. I was told Warn would not part out their kits for axles and/or hubs (they have a responsible marketing department) so I would have to go the cu$tom route. Expect to pay $300-$400 for these. I found two places that will make the axles; Moser Engineering and Dutchman Motorsports, there are others too. The custom axle design was simple, D44 19-spline inner, D30 27-spline outer, a seal region, and a snap ring groove. The hub supports the outer end of the axle and retains it via the snap ring and the spline. My D44 was stock with 19-spline spiders. I didn’t want to upgrade to the later 30-spline spiders because of cost and the feeling that 19-spline was sufficient for my application. I decided not to use a 10-spline outer (that would have matched my D27 front hubs) but match a D30 hub with 27-spline connections instead. Since the rear axle gets 100% duty (as compared to the front) I wanted the strongest connection I could get for the money. The following drawing is a result of stacking hub and spindle parts on my kitchen table and taking measurements. I don’t know if it will work for hubs other than Warn:

Measurement Illustations

Ideally, one would like to be able to take out the axle by just removing the hubs and pulling the axle out thru the spindle. The inner 19-spline is 1.25″ OD and the outer 29-spline is 1.20″ OD. The spindle would have to be about 1.26″ ID to remove the axle but, due to strength considerations, I did not want to go beyond 1.25″ ID on the spindles. The people that made the axles recommended I keep as much material on the axle as possible (and it was cheaper) but, as a chain is no stronger than its weakest link; the axle is most likely to fail at its weakest point (1.20″ part) no matter how strong the rest is. However, I opted to not be able to pull the axle w/o removing the spindle. In retrospect this conservative mindset may have been kind of silly.

Axle Shafts, Old and New

Wheels and Spindles

The axles eroded the budget, leaving little or nothing for the spindles, hubs, and bearings. The only solution was to recycle spindles from the front wheels. If they’re strong enough for the front, I might as well use them on the back. You can use stock wheel hubs from any D27 or D30 front end. The spindles have to be bored out to 1.25″ to allow clearance for the 27-spline axle (1.20″ OD). Some spindles already have a 1.25″ ID thru hole; others will need to be drilled out to size. The shoulder on the mounting face also has to be reduced to 2.87″ to fix within the rear axle housing. A buddy with a lathe sure would have helped. I had to look around to find a machine shop that was willing enough do this simple work (w/o soaking me too much). The wheel hubs were stock D30 or D27 drum brake hubs. Budget forced me to stay with drum brakes. I got the wheels and spindles from R&P in Oregon (#503 557-8911) for a reasonable price. I was able to get Timken bearings from a commercial outfit in Texas much cheaper than your typical 4-wheel catalog.

Free-wheel Hubs

Since I had decided to go with 29-spline outers, I had the choice of many stock hub designs. My front hubs were Warn 10-spline so, what the hey, I got Warn hubs for the back too. For vanity points, the hubs front and rear look the same. In some sense, Warn got their pound of flesh out of me on this project anyway.

Seals

The stock setup has a simple seal inside the axle housing near the outer bearing. Some schools of thought say that if you can, lubricate the wheel bearings with the differential oil. If the hubs have good seals, one can forgo the axle seal and let the differential oil circulate out to the wheel bearings. It is a better lubricant than bearing grease and might supply some additional cooling via mass transport. However, with this spindle/hub design, I doubted much oil would ever circulate out to the hub bearings to offer any appreciable amount of cooling but, any oil out there would require good seals at the hub. I didn’t want the possibility of an oily mess w/o the benefits so I elected to specify new seals in the location of the original seals. The housing can take a 58mm OD seal (tight) and the axle stock material could be dressed to 35mm at this location. I found a spring backed 35×58x10mm seal that fit the bill (CR #13894).

Axle and seal

Brakes

Brakes were not originally part of the project but, you know how that goes. After popping off the stock drums, I stared at an area that I don’t think anyone had been since the pyramids were built. I’d need new shoes, drums, cylinders, etc. Bummer. A quick call to the guy that supplied me with parts for my 11″ front brakes and I was back in business but with a seriously blown budget. I guess I’ll cut my income now. That is what the government does isn’t it? Yes, and they borrow from future generations.

Disassembly

Disassembly was simple. The creaky passenger axle came loose just by loosing the axle nut a few turns and taking a short drive. I was glad to get rid of that guy. The driver side was another story. I was going to have to call for an air strike or bunker buster nuclear weapons. I rented a wheel puller that looked like it had been used as a prop from War of the Worlds. Hey, what do I expect for $5? When applying the puller, I did not remove the axle nut. When the baby let go, there would be a lot of energy bound up in the puller and ‘d rather the nut suffer than my toe, or worse.

Hub puller

After I popped the wheel hub off, I removed the Paleolithic brake hardware including the brake backing plate, shims, etc. At this point I was looking at the axle bearings happily stuck in the axle housing. I don’t have a puller! Fret not. Pulling out the axle out of the housing is a snap if you can use the drum/hub assembly as a slide hammer. I just took the brake drum/hub that I just popped off, remove the key, put it back on the tapered axle, and put the axle nut back on with a few turns. I can use the mass of the brake drum as a slide hammer. Three curses and four or five hard pulls and I was dumped on my butt; but the axle was free. Whoa, those axles sure are a lot stouter than the Scout’s. Hey, what is this little thing on the end of the axle? Oh man, this is that little spacer Vernco talked about that is supposed to stay inside the differential to provide preload to the wheel bearings. It consisted of two little cylinders held together with a worn-out roll pin. After a little worry, I determined that I didn’t need it since the new axles float and are prevented from going any further into the differential than the stock axles by snap rings in the hubs.

Thrust Spacer

Assembly

Assembly was much easer than I expected. I was sure that somewhere I would have blown a dimension and I’d be left cursing at my oversight. First things first, I seat the seal and slide the new axle into place. When I first slid the new axle in through the seal, it bottomed out in the differential and stuck out a good 3/4″ further than it should have. Right off the bat, my worst fear started to raise it ugly head. I was not cherishing the thought of eating these axles for dinner. After reviewing my measurements, I was convinced that there wasn’t a dimensioning or machining problem; but the axle still would not seat properly. Even the original axle would not seat. It was obvious from witness marks on the original spline that it engaged into two internal spline areas inside the power lock differential. Somehow the innermost spline was not aligned with its neighbor. For the life of me, I could not see into the housing well enough to identify the problem but every indication said there was a misalignment. After putting the transmission into first gear and twisting on the axle with a pipe wrench, the problem was fixed and the axle slid into its proper position. Phew! Boy that thing sticks out there! On to the spindle!

Axle shaft in place

Since I was not expecting to have much oil in the void where the original bearings were, I had placed a little RTV gasket material on the back of the spindles and let it cure overnight. The spindle went into place and the axle didn’t look so long after all.

Spindle in place

I then slid the brake assembly backing plate on and tighten the nuts to spec (35 ft-lb). I sprung for the e-brake hardware in the drum brakes. I don’t need the hardware now but sometime in the future, I may forgo that cursed e-brake on the driveshaft. I stuck a rubber plug in the backing plate hole for the e-brake.

Backing plate and brake hardware

This is an opportunity to do some more “Tinker Belle” work and replace the six 3/8-16 hex head cap screws that hold the free-wheel hubs with double-ended studs. I was able to use some 3/8×2″ studs but they are marginal length-wise. The application really calls for 3/8×2.5″ studs to get the proper number of exposed threads past the 3/8-24 nylock nut.

Hub in place

Slide the hubs in place, tighten the six studs (35 ft-lb) and install the snap ring.

Hub part III

Brake drum in place

If it moves, paint it black; Darth Vader would be proud. Done!

If it moves, paint it black; Darth Vader would be proud. Done!

Now on to do the passenger side (in about 1/2 the time), bleed the brakes and go!

So, somebody in the back rows asks: ” How much did it cost” Well, not counting the brakes and shipping, just under $650. Much more than I wanted to spend, but it was fun.

Your mileage may vary, I can not guarantee you will be at all successful if you try this. Remember, should you, or any of your IM Forces, be caught or killed; the secretary will disavow all knowledge of your existence.

Good Luck!