Tcase output bearing?

[sam24th]

So went on a wheeling trip yesterday with Andy out to URE. Had a blast, but after leaving the outpost and driving home I noticed a loud rattle/whine noise coming from the Tcase. Also noticed the front output seal was leaking a little bit. Checked the fluid level and it was a tiny bit low but otherwise ok. It took about a quarter of a quart of fluid to fill it to full again. I threw the Tcase into neutral (twins sticks) and put the truck in gear. No noise. It only makes noises while driving and I can feel a faint vibration. U-joints checked out and Ive ruled it out as the culprit. Im thinking the output bearing on my Tcase is Toast. Any thoughts or opinions?

T-case in question is an 86 gear case top shift with advance adapters 4.8 case gears.

 

[KidVermicious]

Does it do it in 2wd, or just 4wd? I had exactly the same trouble with my 4.7, and I decided to rebuild it. I yanked it out, put my 2.28 case back in so I could drive it, and it's still doing it, so in my case it wasn't the case. Are you SURE it's not a ujoint? What about a wheel bearing? Diff pinion bearing?

 

[sam24th]

It does it in both 2wd (hubs unlocked and case in 2wd) and 4wd. I think it's the tcase because it started shortly after the case installed (used) but it got worse after the last trip. I also think it probably sounds louder after my 5.29 install because the output shaft on the case is now spinning much quicker.

I'll look over the ujoint and whatnot again this weekend as I just did a quick once over Sunday afternoon.

 

[fourwd1]

Disconnect the DS from the t-case and wiggle it around to see if it had excessive play.
Also try rotating by hand to see if you can feel/hear any unusual sounds like clicking, etc.

 

[sam24th]

Thought I'd update this thread since I finally found time today to go mess with my Tcase. I got under it today pulled the rear shaft, and put the case in neutral. Wiggled the rear output shaft a bit and notice it had a tiny bit of play, not much but I think definitely enough to be signs of a bad bearing. I have a spare case in the garage and had a gander at it aswell and found zero play in the rear shaft. Im not talking about rotating, its more of an up and down side to side type of play. Early indicators point to a bad bearing. I plan on putting the rear apart tomorrow and seeing if the bearing is bad or not. If not looks like time for a case rebuild which will have to be done over break after finals.

 

[sam24th]

Well with exams over and the help of a buddy of mines last night we finally pulled the case and took it apart. Found a couple of things I thought I would note and throw up on here to help anyone in the future. Unfortunately with it being late and us being in kinda a rush we neglected to snap any pictures.

Anyhow here is what we found when we broke the case open. The rear output bearing had a slight bit of play in it, not horrible but we replaced it with a new one anyways. I think I found the source of my grinding noise though and it appeared the new case gears from advance adapters were grinding against the case itself just ever so slightly to make a metal on metal rubbing noise. It left a nice mark in the case from where it was rubbing and wearing into the case a bit. We decided to take a dremel and remove a bit of the material to clearance the housing. After reassembly with new RTV seems the case is back in functioning order. Probably one of the fastest tcase removal and rebuilds I have ever done. We started at 6 PM and finished reassembly and install in truck at 11PM then went to go get some beer and wings after. :cheers:

I suspect that the reason the noise got louder after the last trip was because I had just regeared the truck and the case gears were now spinning at a much faster rate.

SIDE NOTE: The drainplug makes a great magnet to remove the little ball on the tailshaft to remove the inner bearing.