Popping noise/vibration after driving 1/2 mile in snow in 4WD

[1987Comanche]

I finished converting Georgia to 4WD (yes I need to update my build thread), using the 3.07 front axle, external slip yoke NP231J, linkage, and front d/s out of a '96 XJ with 123K miles.  The front axle was rebuilt with new:  side gears & spider gears, upper & lower ball joints, axle shaft U joints, wheel bearings, and control arm bushings.  I also replaced all 3 u joints in the front driveshaft.  I did a functional test on the transfer case at the jy and it shifted easily and performed appropriately when shifted/input shaft spun by hand.  It had very little fluid but I assume the jy drained the t-case.

 

  This past week was the first time I've used the 4WD extensively and the first 1/2 mile of driving on a snow covered went fine.  Suddenly I experienced a loud popping/grinding noise and vibration.  I pulled over, went back to 2HI, and drove for a mile or so.  Everything was ok so I went back to 4HI.  Within a 1/2 mile it started again.  I left her in 2HI and slid the rest of the way home.  There was no black pavement in sight on the entire drive...it was all snow so binding shouldn't have been an issue.

 

The noise sounded almost exactly like this:

 

  I think the issue is in the transfer case, specifically I think the chain stretched out.  How can I troubleshoot/prove this theory?  I think the fact that I can drive in 2HI @ 75 MPH with no NVH issues exhonorates both the front driveshaft and the axle, leaving the linkage and the T-case.  I'm familiar with the noise a T-case makes when not fully in 4WD as Maura's linkage bushings were shot and it would always take a few tries to get her into 4WD. 

[Jeep Driver]

How? Take apart.

[jimoshel]

Hold one shaft so it can't move. Then see how far, or how much play is in the other one,

[1987Comanche]

 

Hold one shaft so it can't move. Then see how far, or how much play is in the other one,

 

  Excellent idea.  What do you think excessive would be?  Greater than say 10 degrees? 

 

Found this while researching.  Interesting read regarding chain wrap:

http://www.pirate4x4.com/forum/jeep-hardcore-tech/36971-what-could-causing-loud-clunking-noise.html

[Eagle]

Are you absolutely certain the gear ratio is the same in both axles?

[1987Comanche]

Yes, absolutely certain they are both 3.07s.  It was hard to find a front D30 from an AX-15 equipped XJ but I cross checked axle tag numbers, T-case shift linkage P/Ns, and physically saw the donor XJ to be sure. The external axle tags were on both the donor D30 and Georgia's D35 and I verified the information stamped on the ring gear for both axles when I dropped the cover to service each one.

[richasco]

As already mentioned, just jack it up, put it in 4wd and hold one shaft while turning the other both directions. There shouldn't be much slack at all. If there is, you need a new chain. The good news is that the chain is easy to replace and you don't have to remove the t-case to do it. In my experience, a good chain can stretch very quickly if the case is allowed to run low or dry. You might want to replace the seals while you have it apart.

[poopypants]

I agree with the chain...find a decent incline and in 4wd bump it and it will bang loudly as the chain jumps
The rattling is the stretched chain dragging on the bottom of the case

Just pull the fill plug and put some sand in there and it will be fine...the sand helps engage the sprocket by decreasing lubrication ;)

[1987Comanche]

I did some troubleshooting/experimentation this afternoon.   I found a nice, icy hill, disconnected the linkage,  manually shifted her into 4Hi at the T-case, then gunned it in first on the hill.  I got both front & rear wheels spinning on the ice but there was no popping.  I'd think that would make the chain jump for sure.  Linkage issue?

[Jacob Ochs]

I'm having this exact same problem! It vibrates like crazy the feels like something pops loose and then slowly starts to vibrate again!

[1987Comanche]

Turns out it was a bent linkage.  The little jy I sourced the T-case from bent the linkage up badly.  I got everything in a 5 gal pail and it took me a while to assemble the jigsaw puzzle but, with no frame of reference, I installed it as-is.  I found another external slave 4WD AX-15 at the jy and grabbed the center link from it. Check out the difference:
 

 

Problem solved :D

[Jacob Ochs]

Turns out it was a bent linkage. The little jy I sourced the T-case from bent the linkage up badly. I got everything in a 5 gal pail and it took me a while to assemble the jigsaw puzzle but, with no frame of reference, I installed it as-is. I found another external slave 4WD AX-15 at the jy and grabbed the center link from it. Check out the difference:

 

 

Problem solved :D

 

Thanks most likely my problem too then! Where is the linkage located at?