Ditto on the transfer case, my drive shafts are off and I turned the transfer case flanges by hand and there is a fair amount of play and it produces a soft thunk by hand, I can imagine it will be louder when the engine is running.

 

yes its drive line slack.. but make sure like everyone else said to rebuild your front drive shaft with greasable u joints and a new centering ball kit. also you could check the rear drive shaft the rubber coupling point can become cracked.

 

Well, I too am in the same boat with the transfer case 'Thunk'. I notice it shifting from forward to reverse and if I am off and on the brake. My concern is that this is doing damage to the internals of the tranfer case. Is there a way to solve this (short of replacing the TC)? BTW, before someone asks, I hve rebuilt the front shaft and checked the flex-disc.

 

when was the last tiem you gave your TC some loving with some new fluids?

 

TC fluid last replaced ~45K mi. ago (currently @ 115K mi). It was replaced with the LR OEM synthetic stuff. I have been toying with the idea of replacing again.

 

You should replace your gear lube every 30k, thats both diffs and t-case.
Use 85w-140 in all three, that will help quiet it down alot.
Other than that...nothing you can do so dont worry about it.
Even with the noise it will last you well into the 200k range as long as you keep it full and change the fluid every 30k.

 

Another thing to take a look at is the fluid level in your differentials. When I first got my DI, it made a very noticable thunk just like you de4scribe.

As I learned more about the vehicle, it was evident that I needed to catch up on the major service items. When I drained the front diff, what little fluid was in there was pretty black and not much was still in there.

I used the Mobil One 75w90 gear lube on both front and rear diff's, made a noticable diff in the diff's with fresh lube and topped off. Later got around to draining and refilling the transfer case with the 85w140 and it's all working much smoother now. Also drained and refilled the tranny.

If you do not know when the fluids were changed, I would go ahead and do them all.

 

Well, I got around to 'sharing the love'. The TC and rear diff were fine. Oil came out golden without any filings, but the front dif was an f-ing disaster; black oil and tons of filings ; I am guessing the front diff is on its last legs. All my play (and the thunk) seems to be originating in the front diff. The rear diff has no play, but the front has 1/16 of a rotation. On the bright side, a front diff is cheaper than a TC....