pirate crew to the rescue? Driveline noise

[peiserg]

Too bad i changed more than one thing. Oh well. I simultaneously fixed some leaks on the TC (rear output shaft, speedo, and idler shaft o ring), and swapped out some worn 2 inch lift susp. for new OME 2 inch lift (I am still using my old ext. shackles for a total 4-4.5inch lift). 1975 fj40

Now i notice a driveline sound, most noticeable when doing 50-60ish, if i put the truck in neutral and coast.

Couple issues with my repairs. WHen i did the idler shaft, i accidentally slid the shaft out a little too far based on what Pirate wisdom recommends. The recommendation is for the absolute bare minimum required to expose the O ring on the idler shaft for replacement. I'm guessing it popped back 1/4-1/2 inch beyond the idler O ring before I slid the O ring on and pushed the idler shaft back in. i worried that the thrust washer fell off. I used a camera to peer as best i could into the TC and did not note a washer.

After about 200 miles with this noise, i opened the TC again, and didn't note any scoring on the gears or metal on the magnetic drain plug. the idler shaft gear seems pretty firmly immobile on the shaft with no play.

Other issue, if it is one, is the driveshaft. I disconnected it at the TC to pull off the rear output shaft seal. I didn't mark which part of the flange on the driveshaft bolted to which specific part of the flange on the output shaft. I didn't think it matters.

So...

The shaft is back off.. i took it into a shaft shop, and he is rebalancing right now. said it was off 8/1000" at 1500 rpm. I don't know if that's significant or not. Cant hurt to have it done tho.

My concern is did i mess up something on the TC, and it is now making noise vs. the driveshaft.

I did measure my angles. The rear differential is angled up at 15 degrees from the horizontal. the TC output is angled about 2 degrees DOWN from the horizontal. Does this seem acceptable for a 4-4.5" lift with a CV driveshaft?

I have my pre-existing 4 degree shim (fat side toward the front of the truck) under the rear springs. These worked for the last 10 yrs with my old 2 inch springs.

SO the cliffs-- worked on TC leaks and am worried thrust washer fell off idler shaft, even though theres no evidence after a couple hundred miles of internal damage. Put in replacement 2" lift OME springs at same time. Now have new noise on deceleration.

[Flatty]

Sounds like a bearing in the output shaft of the tcase. When it is loaded up, it has constant pressure on it, but the minute you coast, the pressure is gona, allowing it to flop around.

DIma

[peiserg]

Originally Posted by Flatty

Sounds like a bearing in the output shaft of the tcase. When it is loaded up, it has constant pressure on it, but the minute you coast, the pressure is gona, allowing it to flop around.

DIma

good thought. thanks for the idea.