Decided to Be More Off-road Serious with the FJ40

[Ditcherman]

Well nothing conclusive from the transfer case inspection panel. Inner mounting bolts nice and tight. Noise and binding feel goes away with rear driveline removed. I took a drive down the road with 4WD engaged to be propelled by the front drive-in. (no rear driveline)

No noise.

So now the question is: is it the rear diff or is there something involved with the output shaft of the transfer? I would think if it was the transfer, it would still have symptoms when being driven with the front driveline engaged. There isn't any difference in the main gears used in the transfer other than the front gets added to the mix. Right?

That leads me to think its rear diff.

If you can replicate it on jack stands maybe you can use a mechanics stethoscope to locate the source of the noise. If you can reproduce it without the rear driveshaft in that should be pretty conclusive I would think.

 

[NikP]

If you can reproduce it without the rear driveshaft in that should be pretty conclusive I would think.

I thought only it would be easy to find since I could reproduce the sound on jackstands. I was wrong but I learned a lot along the way. I suspected it was my rear diff since there was no sound with driveshaft removed. I regretted not replacing the pinion bearings when I installed lockers. Live and learn. The bearing was clearly bad so I took care of them. While there, I decided to install a new ring and pinion gear. I couldn't get a good gear pattern when I installed the locker but now realize you can't with used gears. I now have a great pattern.

After all that work, I had a new diff but the sound persisted.

Long story short, the sound was the Orion trying to pop out of gear and the sound was created by the HI/LOW shift sleeve riding on the dog teeth just before popping into neutral.

After reading 48 pages of the Orion thread, popping out of gear is a common issue especially if you use you old output shaft. Mine clearly shows wear.

I embarked on replacing the transfer output shaft with a new one and also installed a new HI/LOW shift sleeve. First test drive seemed positive and no more noise!

I'm crossing my fingers.