LCA welding from both sides

Hi,

A couple of months ago I was advised to weld LCA axle mounts from the inside (from between them, where LCA go). Those mounts are 1/8" thick and are welded on the outside (I do not like the fact that they are not welded all the way, but this is another point).

In an attempt to understand what welding is about I went to MIG and today TIG safety classes at Techshop. MIG instructor told me that you do NOT want to weld material from both sides, it makes material much more likely to break. TIG instructor told me that material should be melted all the way through (which is definitely not the case around the axle).

So, is it a good idea to weld the mounts on the other side or not ?

Please specify, what comes from a speculation and what comes from your welding experience.

Thank you,
Andrey

Contrary to popular belief there is some carbon added during MIG, which makes the welds harder than the surrounding material. Also the uneven cooling, the heat being leeched away from the weld to the surrounding metal causes uneven tempering of the weld area.
Slow cooling makes it soft, fast cooling makes it hard. Welds often crack where the weld meets the base material. Or in other instances where it's the hardest, sometimes near the middle of the weld from the extra carbon introduced during welding and depending on how fast it cools.
Nothing wrong with redundancy, multiple passes are OK, besides adding weld material, they broaden the heated area and the weld base area often making for a more uniform temper.
Take a pointed hammer, a rod welding slagging hammer works well and starting away from the weld, dimple the metal towards the weld, you can see what you have for a temper.
Adding large nuts and bolts, if possible and large washers as redundancy is also OK.
I repeat, letting the weld cool slowly softens the material, quenching it hardens the material.
When in doubt I make multiple passes, add mounting material if needed, back up with bolt type hardware. Periodically inspect the welds after stressing them during use.
If there is any cracking, heating with a torch till red and letting the area cool slowly often relaxes over hard metal.
When welding uneven thicknesses and wanting to get a good burn on the thicker material, I often wet the whole area with water from a pump sprayer. This helps prevent burn through and also helps keep the heat localized, which helps prevent the surrounding material from getting soft (or being annealed).
A lot of this you only learn from experience and it's hard to explain or teach.
Lastly, it doesn't have to look pretty, it has to hold. Trying to match machine welds with a shop MIG is often a waste of time. When in doubt weld the chit out of it. Most of my experience is with farm machinery, I have very few call backs to redo my repairs.

8Mud said:

Contrary to popular belief there is some carbon added during MIG, which makes the welds harder than the surrounding material. .

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this became obvious to me when i first tried to hack off shock mounts... you realize cutting through the weld sucks.... while the mount itself cuts like butter

thanks for welding class

Thank you

The best be for reinforcing the LCA axle mounts is to weld a 1/4" pad accross the bottom of each. That's what I did, on two different axles, and its held up great. The pads create a box, and also act as skids on rocks.

Welding thin vs welding thicker material.......

I agree with the initial response you got from your instructor, WHEN welding thin stock (1/8"). This is because the penetration SHOULD be complete on the first pass.

When welding a material that is thicker (1/4"-3/8") you can and should weld from both sides to assure proper penetration.

xjbubba said:

The best be for reinforcing the LCA axle mounts is to weld a 1/4" pad accross the bottom of each.

Click to expand...

something like this one ?

http://www.knowwhere2jeep.com/catal...cts_id=6860&osCsid=sv3n84d5sbglvgoe9v9uqutdn4

I run a single pass on the inside of the LCA brackets and then add this plate to the bottom. Never had a problem with them tearing off the axle.

If I weld mounts/skids to dana30, do I have to
1. Take it out of the jeep ?
2. Drain all the oil ?

Thank you,
Andrey

Slonopotam said:

If I weld mounts/skids to dana30, do I have to
1. Take it out of the jeep ?
2. Drain all the oil ?

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i have welded the skid to the LCA mounts without doing either of those, without a problem

when welding to the tubes(or to the pumpkin), some of the oil inside gets cooked to carbon and other byproducts. The metal inside probably oxidizes and flakes off some. Not a great deal of abrasive material generated, but at the minimum I'd drain the oil and do a couple of changes over the next month or two.
Any abrasive material you get out of the diff is likely to be beneficial in the long run.

I doubt welding skid pads to the bottom of the LCA brackets will have any adverse affect on diff oil.
The after-market pads XJkeeper showed, are nice, and require one short bead to the housing.
The pads I used on my D30 did not connect to the tube, and thus, did not require welding to the tube.
The pads were only welded to the lips of the LCA brackets.
I can tell you they were "forced" over many rocks without ill affects.