FZJ80 making high pitch whine/vibes on freeway in axle or drivetrain help!?

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But yea
A "shot" front third would make a lot more racket than what he's describing. I replace a "shot" front third in my brother in law's 93 because he's an idiot and let the fluid go low. It makes a constant whine and howl. That's not what I'm hearing the PO describe.

Personally, I'd rather spend an hour in clean dry clothes doing the exercise I describe than get all grubby and pull the third, pay $100 shipping each way while the truck's disabled for 2 weeks and have the shop say "looks fine". But that's me. I have always found checking the easy stuff first pays dividends.
I agree easy stuff first always. I guess I’m just a little more casual about pulling a diff out, to work on or have a look.
 
But yea

I agree easy stuff first always. I guess I’m just a little more casual about pulling a diff out, to work on or have a look.
You sound like a diff ninja bro! I haven’t gotten into a birfield axle in for ever, I’d prob just mess it all up now ☺️
 
Ok quick update:
I just measured the BFG’s circumstance and it’s not that bad maybe: tire 1 is 101”s, tire 2 is 100.25”s, tire 3 is 100.5”s, and tire 4 is also 101”s.

the tallest and shortest tires are paired up though, maybe I should swap it so the 101’s are paired?

also, I NEVER drive on these BFG’s, and the howling started right after putting them on so maybe that’s the simple issue at freeway speeds.

Although the earlier post about clanking & popping I heard at slow speeds was with my 35’s on. Maybe that’s more representative of the gears grinding? Metal in diff issue etc. hmmmm... I feel like I’m at long last tracking this s*** down though, feels good.
Thanks again you guys.
 
Just a head's up. Don't do the measuring and stuff first as you just implied. Do what I suggest and get a fresh baseiline of the noise, its characteristics, the throttle and speed and such. Then come home and swap the tires F/R and go see what has changed. I want you to do that for a reason. If I'm right, the current combination of tires has one axle or the other with tire of a significant enough size difference that this is happening. (Although now Im trying to recall that you changed tires and that changed something already?) So I want you to put whichever axle is getting the coasting gear tip pressure on the other axle as the purest way to see if reversing the forces cause a noticeable change. Do the measuiring and other stuff in the wrong order and you're back to randomness unless you purposely put the smallest 2 on one axle and the largest 2 on the other and re-establish a baseline sound, then flip them

I already feel this is your issue based on the change in sound from the different tires as ruined diff bearings don't sound much different with this issue going on in one direction or the other.
 
Well, OK. I just posted and found you're already on this. No worries. So I guess now I'll change my advice and suggest you measure the 35s, and pair the smallest on one axle and the largest on the other. Drive/ listen. Then swap them F/R. Drive/listen and report what you find.
 
Hi Fortuitous-
The debri on the magnetic plug and the whine going away with the DS off sure sounds like the outer pinion bearing is starting to disintegrate. I know what you mean about 529 would have been the ticket.....Heck, now's the time to make that happen as I see a bearing rebuild in your future anyways. 90% chance the 488 ring/pinion is A-Okay still. I will answer the conversation you started ....
Ken
 
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Hi everyone, quick update here. My local shop that did my gears was concerned about the metal shavings and asked to help by re-servicing the front axle and seeing what’s up. I was fully expecting too see some carnage of some kind but the gears looked pretty good. They deduced a bit of metal broke loose called “seal protection rings” on the outer side of the axle shaft and got chewed up on the gears. That was likely the metal in oil changes. (Picture of it attached)

The gears looked good, with no damage apparent but the guys fully rebuilt it with new bearings and parts just to be super safe.

I love working with Kurt & Bryce at Wasatch Cruisers & Olly, they are stand up dudes.

All that done I feel mucho better about the axle/gear situation. But damnt, the highway noise and vibes still persist!!!
 
Pics of it all

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