Even metal shift forks can break!

[H3slate]

Last time I was on a trail in 4-low there was an intermittent clunking sound. It usually occurred while going uphill but wasn't consistent. The noise went away in 4-Hi Lock and 4-Hi.

Finally got the transfer case out and dissassembled. Found metal in the fluid and on the magnet inside. Found this towards the bottom of the case.

This is the lower shift fork that shifts between 4 hi and 4 low. It has gouged out the side of the fork.

I still need to see if there is any play in another component to cause this, then everything will be thoroughly cleaned and put back together.

 

[f5moab]

With the 06, are you running the correct fluid level? Takes more fluid than the amount obtained by filling to the bottom of the fill hole. And broken forks is an indication of a low fill and lots of 4 low usage.

 

[H3slate]

With the 06, are you running the correct fluid level? Takes more fluid than the amount obtained by filling to the bottom of the fill hole. And broken forks is an indication of a low fill and lots of 4 low usage.

Thanks, I think this is the culprit. Earlier this year I was having a heck of a time getting a rear t-case output shaft seal to not leak. Discovered it while out on the trail. I ended up replacing two just to find one that would seal properly. Those leaks create quite the mess.

When I am not having leaks I have been following the instructions I found on another Hummer forum that was very specific about the the fill levels and recommended fluids. I think he used to work for GM, think his forum name was f5stop?? Always got really useful information from him, very knowledgeable. :cheers:

Here are my original printouts of the info you shared with us for proper fluid types and fill amounts.

 

[4speedfunk]

Yeah looks oil-starved to me. It didn't really "break" but, rather wore itself out.