My dad's 31 has a 9" Ford rear that has developed a 12" crack on the axel tube. It is straight as a ruler and is located on the back side right in the center of the tube. It does leak fluid only while driving due to the location. Ever seen this? Can I just weld it without pulling it out and taking it apart?
You have nothing to lose by trying. Grind a v notch the length of the crack and clean the area of any paint or oil then weld it up. Those tubes can warp so weld about an inch then let it cool.
I'd jack it up and relieve the axle housing of vehicle weight first. Place stands under frame. Locate the absolute ends of the crack, drill a 3/16" hole at each end. Vee the crack with a die grinder, about 1/8"-3/16", the length of the crack. Clean it up with carb cleaner (or Brakekleen) Blow it clean & dry with compressed air. Skip weld it up in increments, 2" at a time, beginning with the rosettes at the holes.
This is pure speculation but I bet you could MIG weld it if you first drain the rear, drill a small hole at both ends of the crack, then make a very small V along the crack and then place a tack weld at one end of the crack (let it cool). Then tack weld the other end of the crack and let it cool. Then go back and tack weld the other end of the crack and let it cool. Then tack weld the other end of the crack and let it cool. Do this until the crack is filled. This is just an idea that came to mind. No doubt, the best way would be to remove the rear and jig it up to prevent warping.
I would as stated above but pull the axle and clean the inside of the axle tube also and not sure I would use brake clean some of those will cause some bad gas when welded.
There has been quite a bit of discussion on Brake clean causing some serious risk to folks health if they clean parts with it then weld the parts up after using it. I'm still thinking that is the original weld on the tube that the guys who built the car originally ground down really smooth and ended up grinding a lot of the original weld away.
I agree with Mr48chev, I had a 9" crack just like your Dad's. Unfortunately mine was due to the chrome shop grinding the weld smooth. Mine split on the dragstrip during the launch, not only did it split it flexed, binding the spiders and blew up the pumpkin! I didn't repair mine, I didn't trust it to hold up anymore so I built a new housing and tossed my custom narrowed and chromed housing ($$$, ouch) in the scrap pile. Funny, someone nabbed it I guess, I tossed it 20 years ago and it showed up on Craig's list a couple weeks ago.
My first question would be, WHY did it crack ? Sounds like the crack follows the seam in the tube, but that doesn't answer why. What kind of rear suspension in the 31 ?
From what I heard it needs to be non chlorinated or Phosgene gas is produced. Probably a faulty tubing seam from the factory, all 9" rears I've seen use actual tubing for the ends and no weld seams that could have been ground off.
As far as welding, after prepping, I might run 1/2" beads, letting it cool to the touch between welds. Run each starting away from the last and going back to it to help guarantee penetration. Check the opposite side with a ruler after and if it warps, controlled heat can be applied to bring it back. A mig weld will do the job but will require extra grinding.
Brake Cleaner's active ingredient is tetrachloroethylene. When it's mixed with heat and argon gas it can make phosgene gas. Doesn't take much phosgene exposure to fuck you up for life or worse. Just keep it simple, don't clean anything you're gonna weld with brake cleaner. Read this: http://www.brewracingframes.com/id75.htm Kevin
Bare housings aren't THAT expensive. I think I would just replace it rather than try a weld repair. 12" long welds like that on a tubular housing are tricky to do without warpage. I can buy empty 9" rears from the local Pull-a-part for about $50.
If you decide to weld that housing, figure out a way to pull the housing ends (bending the housing) away from the crack. You'll need to stress the housing a bit so that when you weld on the other side the warpage just pulls it straight again. Otherwise, like fatkoop said, bare housings are cheap. If you need to narrow the housing, there's lots of guys in your area with alignment bars and pucks to do it right.
Every rear end I've ever seen had a crack in it, oh wait, you're talking about a differential. By the time you get done welding 12" it will be bent like a banana, I'd do as others have suggested and get another. Less hassle!
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