[psfpilot]

Well, I installed an Aussie Locker in the rear end on the FJ80. About 200 miles after the install, we were returning from a weekend canoe camping trip with our 80s. A few miles from home it started to make a pronounced moaning noise (not a whine) whose volume correlated directly to velocity, but was unrelated to acceleration or deceleration.

We pulled over and I checked the pumpkin temperature. It was hot enough I could have burned myself with more than a quick touch of my hand. I pulled the fill plug to check the oil level and a small trickle came out, so it probably wasn't oil starvation of a bearing that caused the noise. The better half drove it in circles in a parking lot while I jogged next to it to further diagnose the noise. It sounded like it was coming from the rear end, so we limped home for further evaluation at 25mph. The moaning noise became louder on the way home.

This weekend I removed the third member from the axle. The magnetic drain plug (pictured below) had a fair amount of ferrous debris on it. When I wiped it off with a paper towel, it was all of a powdery consistency without any noticeable larger flecks of metal.

Once the third was removed, I tried rotating the companion (input) flange by hand. It will move, but it is jerky in both directions of rotation and takes a bit of effort to get it started. It's definitely not buttery smooth.

FWIW, when I installed the Aussie Locker, the spacing with the factory-original left and right side gear shims gave me .006" and .010", respectively. The minimum is .006" per side, so I wonder if being this close to the minimum gap somehow added a bit of stress that the 264,000 mile factory-original drivetrain couldn't tolerate.

I'm thinking about ordering new side bearings and pinion bearings, on the assumption that one of those is the source of the loud moaning noise, and then taking it to a differential shop to have them replaced, as I'm not equipped to set backlash in my garage, but I'm wondering if something else is what went wrong.

Questions:

#1.- Is this rough/jerky movement of the removed third member considered "normal"?

#2.- What part or parts have failed?

#3.- What replacement parts should I include in the repair? (It's a semi-floater, so the differential gear oil bathes the wheel bearings as well.)

#4.- Was this failure related to my installation of the Aussie Locker, and if so, how can I make the rear work reliably with the locker?

Drain Plug with Residue:

[DanKunz]

a trickle of gear oil?

Did you get a good seal when you put it in?

Sounds a LOT like it was starved for a long while...

[psfpilot]

That trickle was out of the fill plug, not the drain plug.

My initial assumption the night it started moaning was that perhaps I hadn't properly sealed the back of the pumpkin after the locker installation, thereby running the rear dry, but it didn't leak a drop until I drained it all out while disassembling it this weekend.

[DanKunz]

hmmm, when you inspected the diff, did the ring and pinion appear to be okay aside from play?

I am assuming by input flange you are talking pinion? Does the pinion nut look tight and well staked?

I don't think the replacement of the carrier with your aussie locker would cause the ring or pinion to start grinding the way you have described...

Almost sounds like the pinion may have started getting loose on you over time?

[psfpilot]

Frankly, I don't really know much about R&P setups, so I'm not sure what to look for. I gave it a visual inspection without disassembling it, and nothing appeared to be obviously amiss.

It does look like the pinion nut may have moved from its original position, as there is a deformation along the rim of the nut that appears to be have been punched into a keyway in the threads as a means of preventing incremental loosening, and it has moved about 7/8 of a turn loose from that "staked" position.

[Cruiserdrew]

Originally Posted by psfpilot

It does look like the pinion nut may have moved from its original position, as there is a deformation along the rim of the nut that appears to be have been punched into a keyway in the threads as a means of preventing incremental loosening, and it has moved about 7/8 of a turn loose from that "staked" position.

Ouch-that is likely your problem. Is there any play in the pinion flange? If you loose the preload on that bearing, it will wear rapidly, and a bad pinion bearing kind of "moans" usually worse on decelleration. If the stake nut has loosened, tighten it up to where it was (and no further), re-stake it and see what the noise does.

[psfpilot]

Hmm...I tried to jiggle the pinion flange with my hand, but it doesn't seem to have any play in it. I'm going to be otherwise occupied for a few days and won't be able to throw the third member back in to run that test just yet. The noise it made sounded like a klaxon siren stuck on one loud pitch, but it didn't change based on deceleration or acceleration. It just got louder in a linear relationship with my velocity.

BTW, thank you for your recipe for pan-fried tenderloin with a brandy and cream gravy that you posted in chat a few weeks ago. We enjoyed it greatly.

[Tools R Us]

Zuk has some good pix on what to look for.

http://www.gearinstalls.com/

[psfpilot]

I want to close this out and thank folks. I took the 3rd member to Mud Connection, one of our local 4x4 shops. After disassembly they diagnosed it as bad pinion bearings.

[Tools R Us]

Brother Brian had the same failure, nut still staked, no pinion play, looked good until we pulled the carrier, then the pinion made noise when spun. Got the bearings from Kurt @ Cruiser Outfitters, slapped them in and that shut it up!

[BROKEROB1]

I have also been having some pretty serious moan coming from the rear end (wow that sounds bad). Kevin, I saw the pinion bearings diagnosis in another post (I think), as I was doing some searching. My difference is that the moan/whine is ONLY under acceleration. Could this still be a possible culprit? I was leaning more towards the center diff. I may start an additional post as I continue to read/search. Any initial thoughts are appreciated.

[-Spike-]

People around me tend to complain when I get a loud moan from my rear end.

-Spike (Sorry, couldn't resist. I did wait until the tech was exhausted )