Rear axle tube leak

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Oakster97

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Hello all first post here. I've done some research and I'm kinda tight for $ at the moment. Curious what you guys would do for repair on this axle. I got around to new ubolts cause the others are quite old and noticed gear oil just barely leaking out of a microscopic pinhole. However the affected area is much larger. Does this wear constitute a replacement or can you guys see a repair in the future for me? I've cleaned the area up and you can see the culprit. Thanks in advance.
 

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Oakster97

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Btw 10 bolt rear end 'k1500 if relevant. This is on the driver side looking to the rear and the ubolt shackle masks this whole deal. I'm proficient in all welding processes and if I can repair this I plan to use my tig welder. Is this worth the hassle? Surely a well penetrated weld could solve this issue for the remainder of the life of the axle as the leaf springs are what is taking the brunt of impact.
 

evilunclegrimace

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I would be better to replace the entire assembly instead of trying to repair a rusted through tube. It is a good time to upgrade to a bigger diff if you want to.
 

Schurkey

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I have said that a 10-bolt axle on a full-size truck is totaled when it needs the gear grease changed.

Mostly, I stand by that. It's not much of an exaggeration.

The K1500s are supremely easy to switch over to a 9.5" semi-float rear axle; tremendously stronger and comes with much better rear brakes as a bonus. You'd need new U-bolts, a conversion U-joint, and a decent, usable 6-lug 9.5" 14-bolt axle/brake assembly from a "light duty" K2500 that has the correct gear ratio.




But given that you're a welder, you have the tools and skill...sure. I'd think you'd have to drain the grease, and clean any residue before hot-melting a patch over the hole. You'll still need new u-bolts, and this is a fine time to verify your U-joints, gears, brakes, and seals are good.

When it was me, I scrapped the weak-asp 10-bolt, and got rid of the crappy leading-trailing shoe brakes at the same time. GM had no business putting a 10-bolt axle under these trucks.
 

Oakster97

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Figured I'd update. Obviously just to get me through hope to find something nice at the junkyard this weekend. I took this pic halfway through while I allowed things to cool down. Opened the fill cap to allow vapors to escape and expand and tried resurfacing as best I could. I've read through the other forums and it seems pretty simple exchange just having a hard time finding anything thats not rusted all to hellthanks guys
 

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RichLo

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That'll plug the leak but I'm glad you have a plan to replace it.

Nice TIG work BTW, how did you get it to not have porosity up the A$$?
 

GoToGuy

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One thing, your statement about impact is wrong. The axle is the load bearing, load carrying, and every bump and crack, pothole are jarring impacts.
The corrosion has eaten away material, enough that it penetrated the tube. 25 % surface reduction is considered a significant reduction in structural strength.
I would recommend that since you took the time to fully reveal the cause and condition, that you fill the area completely, building up the missing material.
Good luck. Nice weld!
 

1998_K1500_Sub

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One thing, your statement about impact is wrong. The axle is the load bearing, load carrying, and every bump and crack, pothole are jarring impacts.

@GoToGuy got me thinking...

There are forces at work here that, I believe, are not recognized.

In my mind's eye I drew the sheer and bending moment diagrams for the rear axle.

The bending at the point where the spring mounts to the axle tube is as great as it is anywhere along the length of the axle. You might want to "bang" that area hard with the ball end of hammer. See if it yields in any other spots. Better to find out now, if there's a problem, than later.

Finally, I'm going to check the same spot on my axle. That lower shackle area is quite rusty on mine. I've been eyeballing it for years and I think it's time for me to take a closer look.
 

GoToGuy

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A known problem that engineers should have thought about, is the shackle saddle acts as a bowl. So any road debris, rocks, sand mud, water, fresh or salt or other misc' crap. Sits in there stewing into metal cancer.
I drilled a half inch hole in bottom, when I wash the vehicles, I do all under, running gear also. Good luck.
 

Oakster97

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Good idea GoToGuy, you're right I'm misinterpreting common sense. As for the porosity I just wire wheeled it nice and good and acetone with a buffing pad seemed to get in there well enough, it looks cleaner in person. Only issue was creating a good wind block. I used 70-s6 for filler 100%argon with #10cup and all is well. I see a lot of forums about older gm axles but does anyone have an idea if 2014+ 12bolt axle would fit? Can't seem to find much info besides obs.
 
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