Dana Replacement w/ American Axle?

[RamRunnerRob]

I have a '94 2500 auto w/210k + mi and am hearing that familiar growl from the Dana 70 rear end again. I replaced the original @ 115K.



My questions: Has anyone tried to do a Dana / American Axle swap?



If so, or not, what problems am I likely to encounter?

I am not too concerned about the speedo ratios matching, because I would be going from a 3. 54 to a 3. 73, so I know that I will have to recalculate speedo gearing anyway.



Any suggestions on where I might find the engineering specs (spring perch dimensions, input shaft size, etc) on the new AA??



TIA for your help on this...



RamRunnerRob

 

[Reb.B]

it would be cheaper to just change the pinion bearring and the carrier bearrings. Parts are $160 at Blumenthal and u might be able to buy them chaper else where. Get somebody with a spreader bar and some differencial smarts, amd u'll be on the road again.

 

[Extreme1]

Originally posted by Reb. B

Get somebody with a spreader bar ...

A pry bar will work too.



I'd fix your existing also, cheaper and faster.

 

[RamRunnerRob]

I guess that I should tear my diff down to see what is wrong this time, but

last time, the bearing spun in the housing and it was ~ . 150" OOR. I have a WHOLE BUNCH of metal filings on the mag dip stik, so I expect the same problem as before.

I would really like the disc brakes and the 373. That is why I am considering the A/A conversion. . This is my work truck and I have not considered replacing it for a few more years yet. .



I would like to hear from anyone that has any info re: the new A/A diff.



Again, TIA for any help. .



RamRunnerRob

 

[Extreme1]

Well if you're going to be that way about it!

Your best bet is to head over to the dealer's lot with a tape measure. If you're willing to the extra few miles (fab work always starts out innocently enough), you can put any kind of rear end you want in there.



To bolt in an AA you need to check the spring pad distance (center to center), spring width, pad width and pad angle versus pinion angle. To be a true bolt in without long term problems, these would need to be the same.



Of course, if they aren't you can make them the same by welding the right spring pads in the right place. If you're not familiar with this form of entertainment, it's best left to those who are.



The connection at the driveshaft flange will probably need to be modified as well. If the same u-joints are used in both trucks, it's easy. Use the yolk and drive shaft flange for the AA and have your shaft shortened or lengthened (much more expensive). This is a job for experts. The length is important as a long shaft can wreck stuff and short ones (in addition to wrecking themselves) can pop apart at the splines.



Hope this helps...

 

[Joseph Donnelly]

The common problems with the Dana 70 (and all other diffs for that matter) come from overloading or bad/missing lube; less commonly from poor setup. The axle housing can be bent from heavy loading and that will cause problems after a while.



The Dana 80 has about 40% bigger carrier side bearings. I'd do some measuring to see what fits other than the 80 unless you find an 80 at a reasonable cost in good condition. I rather doubt the '03 diff will drop in since Dodge changed the frame at the same time, but if it does, you still have the problem of finding one.



If you want a one-off conversion, you can get your brackets welded to pretty much anything, and the 14 bolt Chevy is one of the good alternatives--commonly available and should be relatively cheap. You will have to get the housing checked for straightness after the welding. Dana 80s are harder to find and the Ford version has a different wheel bolt pattern, I think.



If your 70 was in good shape and straight, and set up correctly, and not overloaded, it should last hundreds of thousands of miles, not just one hun.

 

[john krmpotic]

I am currently in the process of changing my 70 rear axle up to an 80 that I purchased from a wrecking yard. My truck is parked for the winter so I'm not in a hurry. I got tired of fighting with carrier bearings and ears. If I can be of any assistance, just drop me a line. John