4x4 Action Group

While crawling around under the SJ doing prep for Carnage canyon I spotted a oil weep on one of the welds holding the spring perch on the rear diff.
It looks as if the weld in question has a hairline crack. Can't see it but it is definitely weeping oil so must be cracked.

I have a spare diff housing that I can swap out but time is some what short between now and the trip so I was wondering if any one can suggest a Viable temp fix to see me through the canyon trip.

So some questions....

1/ With the springs and perches being U-bolted to the axle tube how much force is actually applied to the spring perch welds?
If the load is only light maybe some epoxy to seal the leak would be the quickest way to go but with the least structural strength.

2/ Would running a new weld while the axle is still assembled be a viable option?
I am worried that the oil will contaminate the new weld and just end up cracking / not penetrating along with the excessive heat.

Any input will be most appreciated as I will need to make a decision fairly urgently as how to proceed.

Thanks

W

It will be wise to take out the diff.

If you find the crack drill about 4mm holes at each end.
Take a pencil grinder and do a proper V of the crack.
I will use a Low Hydrogen rod like 7018. Good filler rod with high stress abilities.
If the crack is longer than a 100mm use short runs. One run at 100mm plus might cause the casing to bend slightly.

Hope this helps

I don't know if you are aware or recall at the last Carnage Canyon event Sakkie cracked his rear diff housing on a rock.
He repaired it on site with an epoxy glue. The important point he made was when applying the epoxy he used a hammer to force the glue into the crack while it was still workable. He finished the event and got home.

Obviously this was an emergency repair and I don't think it would be advisable to do this in your situation

Woolf wrote: ↑

Mon Feb 07, 2022 7:31 pm

I don't know if you are aware or recall at the last Carnage Canyon event Sakkie cracked his rear diff housing on a rock.
He repaired it on site with an epoxy glue. The important point he made was when applying the epoxy he used a hammer to force the glue into the crack while it was still workable. He finished the event and got home.

Obviously this was an emergency repair and I don't think it would be advisable to do this in your situation

Problem with epoxy fixes it can ruin future welds if you are not able to remove it 100% afterwards.

I asked Sakkie for his input, he very kindly sent this reply....

I fixed a crack in the diff cover and it is still running with no problems. There is a big difference though. The cover I "fixed" takes no strain.
The fact that there is a crack where described means there is stress. If there is enough stress to crack it, epoxy is not the way to go. As soon as it hardens, it will just crack again.
A temporary fix in this case would be something flexible, like silicon sealant (red devil )
The best of course is to weld it shut, and fit gussets to spread the stress.

Thanks for the input guys, much appreciated.

Think I was being a bit hopeful with the epoxy

If it was a non-structural section of the diff I would go with the epoxy but in hind sight if there is enough force on the spring perch to crack the original weld, Epoxy won't stand a chance. Especially in a place like Carnage canyon.
Looks like the only reliable solutions are weld or replace.

If I have to remove and strip the diff to weld it I might as well just swap the diff cases over with the spare one.

Thanks again for the input.

Cheers

W

Just some follow up feedback.....

Took the SJ around to a diff place near me yesterday.
They took one look and said the only way to repair properly was to cut the perch off completely and repair the crack in the axel tube first.
Then weld the perch back

So the plan is to swap out the diff housing, will be quickest

Mad Manny wrote: ↑

Mon Feb 07, 2022 5:25 pm

I have no idea, but I've asked others who may have an idea to come look...

… hope you dont mean me Manny,
as I am currently indisposed …

BushWacker wrote: ↑

Fri Feb 11, 2022 11:41 am

… hope you font mean me Manny,
as I am currently indisposed …

No, I fontn'd meant you, Chas