Off Roading heat straightening axle tube

[mschoenheider]

Has anyone here had luck heat straightening an axle tube before? Specifically I want to straighten the tube on my rear Dana 44 on my Cherokee. I suspect by looking at the axle that the passenger's side tube is bent. To verify this, I pulled the axle shafts and carrier, and tried to pass a piece of inch and a half schedule 80 pipe (OD = 1. 900") through from one axle shaft flange through the axle tube, carrier, other tube, to the other flange, and it will not pass all the way through. If the axle was straight, the pipe would fit with about 1/8" of clearance.

I know heat straightening is used as a means to repair bridge girders when trucks hit them. Anyone tried it on an axle tube?



The tube is bent up near the passenger's side tire, roughly 122 inches in from the tire. I plan on performing a series of heating and cooling cycles. I will heat a longer section on the bottom of the axle tube, and taper down to a point at the axle centerline, or just above the center line. I am confident I can tell when it is straight using my pipe passed through the axle method. Any comments?





I also plan on trussing the axle housing when I'm done so I don't bend it again.



Long term plans are to swap in a shaved 14 bolt, but that is still a ways off.

Mark

 

[Scot]

There are large truck shops that are capable of doing this. I would let them do it and truss it myself later.

 

[fj40charles]

I'd go buy an axle from a bone yard. . I'm sure it would be easy to find and not too expensive.

 

[bighammer]

An axle shop can replace the tube. Assuming the rest of the axle and components are in good shape, it may be a good way to go.

 

[fj40charles]

Labor from the axle shop will be more than the cost of a replacement D44 axle. Also, I would advise against trying to straightening the axle tube. . Good chance there might be damage to the pumpkin. Also, you really need a jig to make sure the tube is straight or you'll be going through axle shafts and bearings.



I read you sig. . and since you're looking for a 14 bolt, I'd buy two of them since you can find them for like 50 to 100. 00 each and shave one... If you mess up, then you have the other one.



IMHO, not worth polishing a turd...

 

[Philip]

Most large truck shops will tell you if it has over 1/4" of bend in it to replace. Over that amount bends the center section out of line also. This makes anything you do to a tube mute.



I went threw this with a 307 geared model 70 that I had. It was bent 1 3/16" straight back at the angle of the driveshaft.

 

[mschoenheider]

Let me rephrase my quesion, does anyone have any tips on techniques or methods for heat srtraightening the 44?



My current axles are from the bune yard. Iactually have another 44 housing, but I don't want to fab up new brackets on it for my 4 link and coils. I am going to try to straighten the current one, and if it doesn't work the jeep will sit till I have time to setup a 14 bolt. If I can straighten it, great, if not, no big loss, just some time and gas.

Anyone have any experience with heat straightening?

 

[fj40charles]

Excuse the he11 out of me for trying to help. Good luck and have a great time.

 

[SRadke]

Heat straightening is a very simple process. Find the part of the material that has stretched, heat it to a dull red and cool it quickly. The problem here is that you've likely stretched a very large portion of the tube and it will be very dificult to "shrink" it evenly again. Also, I don't know what alloy axle tubes are made of but you may get hard, ie brittle, spots in it if it is not tempered after the rapid cooling.



-Scott

 

[mschoenheider]

Thanks SRadke.



I did some work on it last night and the initial results are very promissing. I am about 80% of the way to straight. I can now pass the pipe all the way through the axle with very little resistance. I heated the "long" side of the tube to dull red, then let it cool slowly and it seemed to work well, other than taking a good hour inbetween heat cycles to let it cool. I have no illusions that I will get the axle perfectly straight, but I think it will be close enough for a rock crawler.

I will try the rapid cooling process next time I get to work on it. Would you recomment spraying it with water to cool it quickly? Do I need to preload the axle so it doesn't deform the wrong direction during the heating part of the cycle?

 

[SRadke]

In the example you used (working on bridges) yes, they would spray it with water to cool it quickly and you will get significantly more shrinkage. If you've gotten this far by simply heating and allowing it to cool slowly I would not go so far as the water. Keep in mind the more the material bends from your heating the more stress it is under. Internal stresses are what cause future breakages. Also I don't feel you will gain anything by preloading during the heating process. The steel wants to expand as it shifts structure (happens around 1333° F) and physics guarantees it will come back.



-Scott

 

[randyn]

A friend and I once straightened a 12 bolt rear axle just by welding beads across the section we wanted to shrink. He used a really hot rod/setting combo, & made about 4 passes. We measured after each pass using squares & plum bobs. Worked great.



RandyN