Narrowing a HP Dana 44 for an Early Bronco
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DANA 44 FRONT AXLE TECH
Of all the Ford High Pinion Dana 44 axles that are out there, the 1978 and 1979 models with the cast in radius arm mounts are usually the least desirable for swapping into other vehicles. But that wont stop us from narrowing one down for an Early Ford Bronco! If you are using the Ford style radius arm suspension there is no need to shy away from these axles.
If you look at the axle shaft lengths for the High Pinion axles and the low pinion Early Bronco axles you will notice that the drivers side axle shafts are almost exactly the same 18.91 vs. 18.31 and the passenger side axle shafts have all the difference in them 33.91 vs. 27.94. When you put the two axles side by side you will see that the radius arm mounts are 43 apart on the High Pinion vs. 37 on the low pinion. Doing some math you will see that by narrowing the passenger side axle on the High Pinion axle by 5.97 you will have an axle that will bolt right into an early Bronco and be able to run standard Bronco axle shafts (just buy aftermarket shafts with the larger 760x u-joints, or have your high pinion axle shaft shortened by 5.97).
Since we are only narrowing the long side of the housing we do not need to mess with the cast in radius arm mounts or deal with the fact that the axle tube does not run the full length of the axle (it disappears in the cast portion of the axle, so you can't just cut the cast portion off the tube, there isnt any tube in it!). BUT you can cut 5.97 of tube from the middle, make a press fit sleeve and weld the axle back together at the correct width. The key is carefully measuring for your cuts and keeping everything tight and square when you weld it back together.
When I lay out a narrowing job I start by cleaning the tube in the area I am going to work - sand paper, scotch bright, elbow grease.
I then lay out a straight line that will be at least twice as long as the piece I am going to cut out.
I then make two sets of marks - the exact length of the piece I am going to cut out and another set of marks outside of the cut area that will be my reference marks. I mark my points with a center punch then highlight them with a paint marker. In this example I have laid out 6 for the cut piece and 10 for my reference marks. When everything is cut and my cut marks are gone the reference marks will remain and they should be exactly 4 apart when I weld everything back together.
For cutting I use either a chop saw or a porta-band. For the porta-band I use hose clamps set at my cut marks as guides. For the chop saw I get everything blocked, squared and jigged up and cut slowly to keep things square.
Once I have the two cuts made, I bevel the edges for welding. The tube is pretty thick so you need a pretty good bevel to be able to get down into the tube sleeve.
Looking inside of the cut off tube into the 'cast' portion of the axle. Notice that the tube disappears....
Another angle of the missing tube inside the 'cast' section.
For the tube sleeve I use DOM (ASTM A513-1020) tubing that most closely matches the inside diameter of the axle tube. For this HP Dana 44 the axle measured out to 2.975 outside diameter with an inside diameter of 2.450. I bought a piece of 2.50x.375 DOM tube and had it turned down to be a press/hammer/put in the freezer while you heat the axle tube fit of approximately 2.452.
With the tube sleeve installed between the two axle pieces, I line up the marks, check my caster on both sides, check my reference mark distance and then check it all again! After checking everything again and again, tack everything together with some heavy tacks. Then check everything again. Once I am fully satisfied I burn in the welds in short passes rotating around the tube to keep any warping or distortion down to a minimum.
And you are done - you now have a High Pinion Dana 44 for your Early Bronco - youve made what Ford/Dana should have been making from the beginning. :D
I buy all of my small pieces of tubing (less than 4 feet) from onlinemetals.com. They seem to have the lowest prices for less than a full stick of tube. And shipping isn't that bad, I usually save at least 25% compared to my local metal supply places.