90_cherokee

So recently I swapped my front and rear diffs from a 3.55 to a 4.11. The rearend I swapped in is open and was just fine/quiet up until I installed my Aussie Locker which I removed from the 3.55 rear.

Now when I drive I get a whining noise from my rearend, which I never had prior to the locker install. The rearend functions fine on and off road otherwise.The rearend will whine under acceleration but when I let off the accelerator the noise stops.

In the 3.55 rearend I was using 80/90 weight gear oil. Does the 4.11 rear require a different oil due to the thicker ring gear?

What might be causing this whining noise and is it something to be seriously concerned about. What might the locker install have to do with the reatend whining?

mechanic6339

I'm curious if the ring gear and or pinion depth got screwed up some how with the locker install. Did u paint the gears and check them during final install? Not trying to insult your intelagince but did u replace the crush sleeve?

90_cherokee

Install instructions the locker doesn't mention anything about the crush sleeve or anything else. Doesn't mention anything about gear pattern change either. It basically says if you can do a set of brakes, you can install this locker.

Taro2413

From what i'm reading you swapped in a different set of axles front and rear to get to 4.10's instead of regearing? Am I wrong on this? With the only change being the locker I would have to point to that causing it.did you re-install the thrust washers with the Aussie? if this is a seasoned axle did you inspect the thrust washers for excessive wear?....if worn try just replacing the thrust washers and re-installing.
If you did re-use the thrust washers putting them on the opposite side they came off of might cause some noise

90_cherokee

Yes, that is what I did. I pulled the 4.11 front and rear axles out from under an 86 Cherokee and installed them under my 1990 Cherokee

The instructions state to usex a feeler guage to check tolerances between the locker and center pin. I did this and all was in spec. The whine didn't actually start until about a week after I installed the locker.

I decided to climb under the Cherokee after returning from a wheeling trip that was about 250 miles round trip. I felt the bottom of the rear diff and it was warm...not hot...but noticeably warm...is that normal?

Taro2413

That's normal as long as you can hold you're hand on it for a few secs its fine.

did you inspect the axles before you installed them? Did you use fresh fluid and or pre lube bearings so they wouldn't run dry while the oil was trying to reach everything? Might just be old and need rebuilding, might have ruined a bearing if didn't pre lube everything.

90_cherokee

Well I don't know how much it matters but tomorrow I'm going out of town (150 miles round trip) so I decided to check my fluids. When I pulled the plug for the rear diff (Dana 35) the gear oil just flowed out the hole like it had no viscosity(very thin and runny) shouldnt 80/90 be a little thicker? Think maybe I should go to a thicker fluid like 75/140?