So I just picked up this runner a few days ago. When I picked it up there was vibration. The guy thought the tire (front pass) needed to be balanced. I did that, but nothing. Went underneath, shook the steering components and noticed the idler arm is very loose. 30 mins later and found out it wasn't the idler arm (due to replacing it) and all steering components were tight. Out of researching this and many other forums, I headed to the drive shaft sure that it was the U-joints. Shaking the crap out of that, I did notice the U-joints were loose and there was some play. I purchased three new moogs. Additionally, there was a lot of play where the rear driveshaft bolts to the T-case (on T-case side past the U-joint). I am thinking now that my outer transfer case bearing is bad and it will need to be replaced. I have a hunting trip coming up next weekend and need to get this done by then. I have looked up videos and have seen everything from people removing the seal and doing work there to dropping the transfer case and tearing into it. What would you all suggest would be the easiest approach?

94 runner 3.0 4wd

All help and comments are appreciated. Thank you.

 

This has happened to me. At first I thought it was the rear bearing, but the nut was simply loose. I also dropped the tiny bb into the case changing that bearing, the one that hold the speedo giver from turing on the shaft. It can be done with the tcase in the truck.
After I replaced the bearing, it was still there. Replaced ujoints. Still there, but less.
The vibration that was left was most noticeable going from throttle to engine braking and back again. Right through the "middle" = vrrrrrrrrt

This culprit was the rear diff pinion bearings.

The entire thing starts, I think, when the leafs flatten out. This gives you a pinion angle that always vibrates, even more so if you fix the sag with extended shakles.

 

I definitely notice it more when I go from throttle to engine braking and back. I guess I better start looking at how to replace the pinion bearing. I will replace the U-joints tonight and hopefully have it finished and check after that to see how bad the vibration is and if I can live with it for a month or so. Did you just replace your pinion bearing or did you rebuild the whole diff? Thank you for the info. It is much appreciated.

 

With experience: It will drive for 10 years like that, then boom. The pinion will get red hot, and somthing will snap off. Teeth usually




Quick 3rd swap is what I did.
I really want to learn to setup diffs. I have watched all the vids and now have one to play with, since I put a used one into my truck.


Bad pinion bearing, should move like your tcase output

 

This is awesome information! I will be checking out these videos later as I am going to need this wisdom to tackle this project. Getting ready to start my lunch break now. going to run home and try to turn the wrench a few times and maybe drop the drive shaft before I have to be back.

 

Dropped the driveshaft last night. Both Ujoints were shot and the nut going to the rear t-case shaft was very very loose. Checked the pinion bearing and it still seems nice and snug *fingers crossed*. Once I figure out how to add this forum to my phone, I will upload pics of the Ujoints. Thank you so much for your help.

 

You can simply retorque both nuts, tcase and 3rd. Check on how to do it correctly on the 3rd. The tcase, just make it tight! Maybe use a dash of loctite. Restake the nut, better - get new ones. The oem have a washer under them, some aftermarket have the washer attached. With those, you leave out the oem washer.
Cross your fingers, but it will probably hold (and not vibrate that bad) for the time you need to get new 3rds And Marlins Tcase rebuild kit.

Tcase rebuilding is nothing hard, just need a press, some creativity for tooling and some pullers. And an angle grinder for the really "close to gear" bearings

 

I will definitely do that. I found a Tcase for a hundred bucks on CL that I am picking up and will rebuild that one. Question though. I have decent mechanic experience and have done a lot when it comes to the engine bay and everything inside. But I have never heard of 3rds...What is it? haha

 

3rd member, aka differential. I think the term 3rd applies if it a a removable diff. (vs. 10 bolt for instance, with rear axle cover but no "dropout" third member (3rd)?