Original Jeep Axles - Old SchoolPosted in How To: Transmission Drivetrain on January 1, 2006 0) (
In some ways, Jeep overbuilt their axles in the early years. Yes, there were some weak links here and there in the MBs, but the front- and rear-model 23 axles were over-engineered considering the 60hp engine used then. Improvements with the first civilian Jeep in '46 included a stronger Dana 25 up front and the short-used Dana 41 in the rear. With 1949 came the ubiquitous Dana 44, and things stayed that way until 1975 when there was a switch to the AMC axle and then back to Dana around 1987.
There was a big and much-needed change in the 44 used by Jeep in 1970. This was the introduction of the flanged one-piece axle that replaced the tapered-shaft and keyway two-piece axle/hub design of the Model A Ford era. Actually, this early design worked just fine (with the tires and wheels of that time period, that is). But with the advent of wider tires and wheels, the load increase caused tapers to loosen up and keyways to crack. Once this happened, the hub would just spin on the shaft and sometimes even the axle would break just at the end of the taper. Say goodbye to the hub, wheel, and brakes.
However, a lot of people, including myself, used these axles hard and with some fairly large tires for the time period. In fact, I used them on my first true race vehicle with some 34-inch tall tires. The big secret, as I remember it, was to make sure the nut was always kept tight at the recommended 175 lb-ft of torque. OK, I never owned a torque wrench with that kind of capability, so that resulted in putting my weight on a 1 1/2-foot breaker bar with a pipe on the end of the handle. I broke a few breaker bars this way, as well as earning a few skinned knees.
Ford pickups and some Mercury cars in the '50s used a flanged axle version of the Dana 44, but, naturally, it was wider. The wide-track thing wasn't as popular then as it is now, so in order to use them, narrowing was necessary. It was hard to find a shop that could re-spline an axle in the '60s. So, believe it or not, we would actually cut the shaft, take a piece out to get the desired length and weld the splined end back on! It was a real sophisticated process we used. A section of axleshaft would get cut out on a band saw, then we would chuck the axle ends up in a lathe and bore a 1/4-inch hole about 1 inch or so in the ends. A round piece of rod inserted in the holes brought the ends together more or less centered, and we would then weld the two shaft pieces together. By all means, they should not have held and some didn't.
We would then cut the axletubes down to the proper width using the axleshaft as an aligning bar when the tubes were re-welded. Most of the time, the tubes just got butt-welded together--sometimes a sleeve was used. Crude, but it seemed to work. But remember, we weren't working with 36-inch tall tires back then. THE DANA 60sIn the '70s I came across a Ford heavy-duty 1/2-ton rearend that was actually a Dana 60 with a 5-on-5.5 bolt pattern. These axles had the good Spicer Power Locks in them. OK, it didn't have the high-pinion that present-day long-travel suspension requires, but the larger ring-and-pinion was a great asset. By now I had found a machine shop with the capability of cutting axle splines. No more welded axleshafts for me. But again, I used the axleshaft as an alignment bar. It just so happens that most of the early Dana 60 full-floating rearends also use the same spline count and diameter shafts as the Jeeps and Scouts. Many years later, I built several Dana 60 rearends using Jeep or Scout flanged axleshafts and housing ends. By then I had a full-length, 1-inch-diameter alignment bar with corresponding end blocks to hold things more or less straight before welding the housings together. The early '70s saw a few other heavy-duty 1/2-tons, such as the one from International Harvester with the same rearends. Some Dodge performance vehicles and 440-powered Ram Chargers also used this rearend. Cutting one side down and having the axle re-splined gave you a pretty decent rearend.
I was determined to build a cheap Dana 44 frontend. I could have crudely narrowed a 44 from one of the then-scarce 4x4 trucks, but I most likely would have had to pay dearly for even a salvage-yard axle. For whatever reason, I had dragged home a very trashed Jeep Wagoneer. After looking at it for a while and doing some measuring, I found that its Dana 27 front axletube, with just a bit of lathe work, would slide inside the tube of the Wagoneer Dana 44 rear axle once the flanges were cut off. This was kind of cool because the tight fit kept everything straight, and the bell end of the tubes could be rotated to set proper caster and pinion angle before welding it all up. Being CJ width meant CJ axleshafts, but the benefit was the 44 ring-and-pinion and the availability of a wider array of locking differentials. Now remember, this is the old closed-knuckle style axle housing and, like any frontend, there are axle seals in the differential housing that are not used on rear axle differential housings. The 44 rear has no provisions for these seals, so I had to figure out how to make them. I found a large, worn-out surplus tap and, with some grinding work, modified it into a cutting tool to make the seal seat with. Coupled to a long rod and an electric drill, it was a slow process (but worked).
Later, I ran across an FC170 frontend, which was Wagoneer width, had 11-inch brakes, and it was a Dana 44. OK, it was closed-knuckle and the spring pads were on top, but it went into my '68 Wagoneer that way along with a narrowed Dana 60 in the rear.
A big problem with the closed-knuckle frontends was that they used bolts to hold the spindle to the knuckle, and it was all too common for the threads to pull out of the cast-iron knuckle. When this happened, the spindle would fall off the knuckle, taking the wheel, brakes, and maybe even the tie rod with it. The trick here was to take the knuckle off and machine a small pad on the inside above each hole then screw in a button-head Grade-8 bolt from the inside. Now you had a stud that wouldn't pull out.
By the '80s I was learning that wider was better. I was using Scout axles because they had Dana 44s both front and rear from about '73 on up. Then I discovered that the Ford 9-inch from some Mustangs and Rancheros was about the same width as the axles found in the early Broncos and the Scout 44s. All of which were wider than a CJ rearend. The only problem was the low-pinion made for some really steep driveshaft angles, but lifts weren't as high as they are now so it wasn't as much of a concern.
Ever heard of a guy named Basil Smith? Probably not, unless you have been Jeeping for over 30 years. How about Rock-ett Products, or maybe the name Smittybilt rings a bell? Yep, he was the founder. I believe he was building roll bars back as early as the late '50s. He was a smart dude (along with several other great ideas that we will get into when we cover other subjects). In the early '60s he figured out a way to make front spindles and hubs work on the rear. He made up some double-splined axleshafts and used Jeep drive flanges for a great, full-floating rearend. About the same time, another guy by the name of Harry Buschert, who owned a machine shop east of Los Angeles in the town of Hemet, California, was also putting together custom full-floating axles, along with specialized Jeep parts.
The weight of the vehicle was being carried on the spindle, so all the axleshaft had to do was the driving. Up front, the Dana 25 (and later Dana 27) front axles were eventually the weak link. However, they did seem to hold up to some pretty high-horsepower V-8s. Once in a while we would break an axle or two, but it was the ring-and-pinions that I seemed to have the problems with. Tires were just getting to where they actually provided some real traction.
For a locking differential, there weren't a lot of choices. In the '60s Jeep offered Power Locks (which were only limited slips), and on occasion even put them in the front too. These were fully enclosed cases with four spider gears unlike the open-case, two-spider Trac-Loks. They were stronger by far and even worked better than a Trac-Lok.
It was soon found that these could be modified with additional clutch packs for even better performance, but the locking action was a bit brutal on axleshafts. Military vehicles, such as the Mighty Mite had the Dana housing with Power Locks, so we would scrounge the military surplus places for low-cost units. However, these were all model 27 units, so we had to do some machine work on the carrier bearing journals to make them fit in a model 25.
Naturally, there was the old standby of using a "Lincoln Locker." This involved either welding up the teeth of the spider gears or welding them to the carrier. Some guys still do it today. While not a recommended practice back then or now, it did offer a solution to traction, and it was tough on axleshafts and tires. Sometimes it would cause the carrier case to break in half where the cross pin went through.
Detroit Lockers showed up for the Ford 9-inch in 1969 having been used for many years in large commercial trucks. A few years later, the Dana rearends got Detroits too. The first ones were quite harsh in operation and made a heck of a lot of noise when one axle would have to release when turning a corner. It wasn't hard to pull a prank and convince unknowing people that I surely had broken something in the rearend, and they had to get out and push my Jeep!
In 1973 Warn came out with its own locking differential and called it the Warn Positrac. This was of a roller clutch design, actually similar to the early Lock-O-Matic hubs. It was short lived, and I never actually saw one in operation.
The Gleason-Torsen differentials were also available. They used a binding gear principle and they actually worked darn good--they were very similar to the True Track of today. I once did a test where I put one rear tire on a set of rollers and the other on cement with the Jeep pushing up against a steel post. It would actually smoke the tire on the cement and just slowly turn the one on the rollers! Unlike the Detroit Locker, it didn't have sudden unloading characteristics that led to lane changes on icy roads. High manufacturing costs and production problems pulled it off the market for Jeeps anyway, but it's now making a comeback in certain high-performance vehicles, Indy cars, as well as being used in some Hummers.
I was getting fairly good at setting up rearends. But as anyone who has worked on a Dana axle knows, it's a pain to press the bearings on and off during a gear setup. Especially when you're using a piece of pipe and big hammer or a mechanical screw jack and the vehicle's weight as a press. It seemed that about half of the time I would destroy a bearing when pulling it back off to change the shims. It must have been in the late '60s or early '70s that we got smart and honed out the center of a set of bearings to use for setup. It took time to hone them out, but it was well worth it. Being able to slip the bearings on and off by hand became a real handy set-up tool. Once you got the proper preload, backlash, and gear pattern, the set-up bearings were replaced with new bearings. It was years before I ever got a housing spreader, so I relied on a couple of big pry bars to remove the differentials and installed them with a big hard-rubber hammer.
Locking hubs? The first ones were made in 1948 by Warn and were nothing more than bolt-on flanges that supported the end of the outer axle but had no coupling splines. I had a set of these and what a pain. I would have to unbolt the Warn hubs and bolt on the drive flanges every time I anticipated using four-wheel drive. It didn't take me too many times of doing this before the fun went out of it, and I bought a set of real Warn lock-out hubs. There were other makes of hubs too, such as the Dualmatic and Cutlass. Sears even got on the wagon with their Powr-matic locking hubs.
The early Warn designs used multiple pins that were pushed into a housing. Several other manufacturers used two cams that, when rotated--either by a separate tool or built-in levers--locked an inner-splined center to the housing, engaging the axle. There was never any question as to which hub was the better one, both in ease of operation and strength.
I am still scrounging parts to build my own axle housings, but I use aftermarket parts to finish the job. In fact, my present flatfender Jeep has a 60 rearend made out of a free frontend from a wrecked Ford F-350 truck. The frontend of the Jeep is out of an International truck. Yes, now one can buy complete custom-built axles from brake to brake from numerous sources, and they are much better than anything I could build. But then there is the cost factor!