Loud Bang, Shudder in 4x4

[Stricken]

I tried searching didn't find anything that sounded quite like my issue.

I picked up a 2013 SCREW this summer, and when in 4x4, there is an occasional very loud bang. The whole truck shudders. It seriously feels like an axle or gear snaps. It happened once while I was towing a trailer in deep sand, and again when I was crawling up a steep hill. Both times happened within a minute of switching into 4H with the rear locker on and did not recur.

It doesn't seem like it's coming from the front end like other threads I found. The first time it happened, I thought it was the rear locker skipping a tooth while I was turning hard. The second time I was going pretty much straight. It feels like it's coming from the center or rear end but maybe it is the front.

Anyone have a transfer case or rear end issue like this? Maybe it is the front end, but it sure doesn't feel like it. It's coming up on dunes season, so I'd like to get this sorted before flogging it in the dunes.

 

[1pyeman]

I have the same thing and it’s driving me nuts. Only in 4x4 and underload.
A very loud bang that comes mostly from front left, but I think occasionally from from right as well.
It’s been doing it for 3 months or so, every time I change something I test drive and it actually seems to be getting worse. Wish it would explode then I would know what to fix.
So far I have:
Changed hub,
Changed actuator,
Looked at externals of axle, but not removed it.
Checked and changed oil on diff. Oil was in good condition, minimal shavings.
Found a loose mounting bolt on diff case. Torqued it to spec but no change.
Had chain changed in transfer case,
Had vacuum lines replaced.

I’m running out of ideas.

My thoughts are:
Change axle, not sure why but haven’t done that yet.
Take diff right out and rebuild. Could be badly shimmed, but I would expect to see more signs of damage in diff oil change.
Change cogs in transfer case, the new chain went on old cogs so maybe there was unnoticed damage.

Experts please chip in with ideas!

 

[1pyeman]

Sorry forgot to mention, it’s 2013 Scew with 85000 km.

 

[Dane]

Go to the thicker RCV IWE rings. It's an IWE issue. I've broken many of them, but none since the RCV rings.

I've also broken a CV - but that stays broken and doesn't keep happening. The IWE slipping keeps happening and just gets worse and worse. It causes the banging you are describing - sometimes followed by rapid clicking.

In addition to the vacuum line, make sure you change the vacuum valve. It's cheap and simple.