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

[Fortuitous]

My 97’ Cruiser is making a new not fun noise at freeway speeds. Accelerating up to 70 MPH is no issue, but once there if you lift off the gas pedal the drivetrain howls and loudly wines. New 4.88’s were installed by a local shop two years ago and this is a third vehicle that gets very little use... followed the break in procedure to a T and swapped out the diff oil at suggested intervals, but there have been some larger metal shavings on the oil changes.

I have also pulled each driveline independently and the howling noise was exactly the same with the rear pulled, running on front d-line only. But with the front driveline pulled out on rear power only the loud howling/wining noise went away completely.

I also had a shop spin the front axle for balance ,check out the u-joints, and it’s overall condition. They are saying it’s in great shape and balanced well.

what am I missing? What should I be looking into?

Kinda freaking out a bit here that the front gears/axle could be coming apart on me. any carnal troubleshooting knowledge and experience from folks on here would be very much appreciated. Thanks in advance!

 

[Fortuitous]

Nada? I’d love input from anyone who’s chased down similar issues. I respect folks opinions on here.

quick update:
It’s making a loud wining sound more at 70MPH now. And mostly when I pull off the gas and there is “slack” in the drive lines. I had the front d-line off and the humming/vibration noise went away entirely in 2WD. Had the front driveline rebalanced and it’s all good.

more-installed it and the loud humming vibes at 70MPH are back. Help! Lol.. Thanks guys.

 

[BILT4ME]

Year?
Lift?
Lockers?
Brakes?
Bushings replaced? Type?
U-Joints?
Greasing service?

 

[Fortuitous]

Year? 1997
Lift? J-Spring Old Man Emu. With Castor Plates that corrected things up.
Lockers? Yep
Brakes? Slotted rotors and Yellow stuff pads
Bushings replaced? Type?
U-Joints? Fully swapped out with new joints less than two years ago.
Greasing service? Yes, freshly zerked up

 

[BILT4ME]

Are you 2WD converted?

If not, check the phase of the front DS. It should be 90' out of phase.

Also, the slip yokes of BOTH DS should be towards the front of the truck.

Did the MIL accidentally turn on the rear diff lock and drive around the mall?

Is the rear locker still locked and not releasing?

 

[Fortuitous]

Are you 2WD converted? Not yet, that’s on the list.

If not, check the phase of the front DS. It should be 90' out of phase: I’ll research this a bit, I’m not sure how to verify this at the moment.

Also, the slip yokes of BOTH DS should be towards the front of the truck: my driveline guy had me turn my front slip yoke you towards the transfer case just a few days ago. I can take it off and put it back towards the axle. Think this has a big impact?

Did the MIL accidentally turn on the rear diff lock and drive around the mall? Nope, all lockers including center diff are verified off. Thanks for the assistance! Keep it coming

Is the rear locker still locked and not releasing?

 

[BILT4ME]

Do you have a double cardan front DS?

Which DS are you referring to above about putting back towards the axle? Front or rear?

 

[Fortuitous]

À we e

Do you have a double cardan front DS? No double cardon, it’s a stock shaft.

Which DS are you referring to above about putting back towards the axle? Front or rear? Front d-line has the slip yoke on the t-case side currently.

 

[Fortuitous]

Here’s a picture of it right now. Looks to be 90 degrees “out of phase” so that’s good.

 

[BILT4ME]

Yes, it does appear to be correctly out of phase, but it DEFINITELY needs to be swapped end of end, as the clearance to the sway bar is also an issue.

Any evidence of the sway bar rubbing on the DS?

Slip yoke needs to be to the front.

 

[Fortuitous]

Ok swapped the driveline around the right way now, and.... same metallic high pitched clunking wining sound on the freeway at 70 MPH. Right in the sweet spot off the throttle between acceleration/deceleration when the drive lines are or should be “slack” or free of accel or decel forces.

help Bros! Maybe my front gears are just sloppy and screwed??

 

[IdahoDoug]

Wait, why did you just express that your FRONT gears are sloppy and screwed? I thought we were talking about the rear axle area? I suggest having a look at the rear diff oil - drain it through a filter to look for fines. Have the fill plug out, so maximum drain speed will suck anything out possible, versus the slow burping drain technique.

On the lockers - does your MIL have someone in her circle of friends or a son who might have gone out and messed around with the Cruiser and used the lockers? Overall it sounds like you have a pretty stout setup, so if it were my vehicle I would suspect that while it was out of my sight, someone wanted to see how tough Cruisers really are and unintentionally damaged it by driving with the lockers on. Years ago, some asshat driver for a flyfishing shuttle service drove my Cruiser on pavement with a locker on and tore up a tire. They paid for it, and yes I was extremely pissed someone who gets paid to drive was messing with my personal stuff.

 

[LandLocked93]

May be time to put it up on stands, shift into drive and crawl around listening.
I'd recommend against doing the part-time thing, jmo.
Assuming the regear isn't coming apart on you...I'd say you still have a phase/orientation thing going on.
You describe the very symptoms I had immediately following some tranny work I had done on mine. The shop put the DS's in backwards. It took a while to figure it out, but once phased and oriented correctly - even with tight, original vintage u/j's, - the symptoms vanished completely.

 

[Fortuitous]

Wait, why did you just express that your FRONT gears are sloppy and screwed? I thought we were talking about the rear axle area? I suggest having a look at the rear diff oil - drain it through a filter to look for fines. Have the fill plug out, so maximum drain speed will suck anything out possible, versus the slow burping drain technique.

On the lockers - does your MIL have someone in her circle of friends or a son who might have gone out and messed around with the Cruiser and used the lockers? Overall it sounds like you have a pretty stout setup, so if it were my vehicle I would suspect that while it was out of my sight, someone wanted to see how tough Cruisers really are and unintentionally damaged it by driving with the lockers on. Years ago, some asshat driver for a flyfishing shuttle service drove my Cruiser on pavement with a locker on and tore up a tire. They paid for it, and yes I was extremely pissed someone who gets paid to drive was messing with my personal stuff.

Hi Idaho Doug! Thanks so much for taking the time to chime in I really appreciate that. In my 11/20 post I more narrowed it down after I removed the front driveline and the noises completely vanished at both low speed and on the freeway.
Good thoughts on the lockers and possible abuse. I explained it to her and even taped over back the locker switch and center diff lock button just to idiot proof things for her. I’m pretty convinced it’s just a coincidence at this point.... this rig rarely ever gets driven.

but I’m pretty concerned about the metal shavings coming out of the front diff. On the first oil change I’d expect it, but the last two times (me just being overly cautious and changing diff oil more than needed) it’s concerning that it still has quite a bit of shavings...

Could things just be loose in and around the front axle also? Like the pinion nut or something?

 

[Fortuitous]

May be time to put it up on stands, shift into drive and crawl around listening.
I'd recommend against doing the part-time thing, jmo.
Assuming the regear isn't coming apart on you...I'd say you still have a phase/orientation thing going on.
You describe the very symptoms I had immediately following some tranny work I had done on mine. The shop put the DS's in backwards. It took a while to figure it out, but once phased and oriented correctly - even with tight, original vintage u/j's, - the symptoms vanished completely.

Hi Landlocked! Yeah I’m hoping it’s something simple and not a big gear issue...

That’s awesome all you had to do was switch your driveline around to fix your noises. I was sure hoping mine would clean up the noise after flipping it around today.

What a PITA!!! Lol

 

[Stevesnj]

Could be the slip yoke is packed with hardened grease and can't compress the yoke sleeve properly. I cleaned out the old hardened grease, used the correct spec grease and problem solved.

 

[IdahoDoug]

You need to help us out here and I"m going to be brutally frank here. You are all over the place with symptoms, sounds and locations and I'm to the point I feel like just throwing up my hands at the difficulty of internet vehicle analysis being compounded by you steering the conversation all over the place on sounds/locations.

So you keep talking about the front diff (shavings, etc), but I was pretty clear in my mind it "sounded like a heavy hammer tapping on the rear axle". But there's some indication that's gone (true?) and now its a 70mph humming/whining? That alone completely changes what I'd suggest you look at. I'm going to ask you to do something in a second, but I want to point out a mistake you've made in assumption. You removed the front driveline and the sound went away, so you assumed it was the front diff. Be advised the link of the front and rear axles via the drivelines being in place causes tension in the drivelines that is relieved when one is not present. So it may well be the issue remains in the rear axle/driveline, but removing the front driveline merely eliminated this normal tension. So don't jump to any conclusions.

What I'm going to ask you to do is please post a single post with the symptoms and their location as best you can. Each of your posts above was a different set of noise descriptors and concerns over locations. so tell us again in a single post what's going on. It's likely we will quickly narrow this down then with followup questions. Tx.

 

[Fortuitous]

You need to help us out here and I"m going to be brutally frank here. You are all over the place with symptoms, sounds and locations and I'm to the point I feel like just throwing up my hands at the difficulty of internet vehicle analysis being compounded by you steering the conversation all over the place on sounds/locations.

So you keep talking about the front diff (shavings, etc), but I was pretty clear in my mind it "sounded like a heavy hammer tapping on the rear axle". But there's some indication that's gone (true?) and now its a 70mph humming/whining? That alone completely changes what I'd suggest you look at. I'm going to ask you to do something in a second, but I want to point out a mistake you've made in assumption. You removed the front driveline and the sound went away, so you assumed it was the front diff. Be advised the link of the front and rear axles via the drivelines being in place causes tension in the drivelines that is relieved when one is not present. So it may well be the issue remains in the rear axle/driveline, but removing the front driveline merely eliminated this normal tension. So don't jump to any conclusions.

What I'm going to ask you to do is please post a single post with the symptoms and their location as best you can. Each of your posts above was a different set of noise descriptors and concerns over locations. so tell us again in a single post what's going on. It's likely we will quickly narrow this down then with followup questions. Tx.

Yeah I can see how it would seem a bit jumbled as to sounds/location/symptoms. Thanks for your thoughts.

I have an idea... a “jump” to conclusions mat!! Anybody?!?! . (Office space) Lol. Yeah, I could be troubleshooting too quick without understanding how things work between using driveshafts independently vs The effects when both are installed admittedly.

I’ll edit my first post to be more succinct for folks who only read that, and try to offer suggestions. Also, I’ll attempt to better describe things now.

Here goes: The truth is it used to be the first post problems with low speed rear end clunking. Then it stopped, and is now more highway speed “whine and vibration”. This could have changed possibly when I changed out the 35” muds for my 33” winter BFG’s the issues/sounds have shifted. I guess it’s possible that the tire change out alone is making the drivetrain behave and sound different... maybe the bigger heavier tires soaked up vibration and drivetrain noise?

Current state: As of right now, there is no longer any low speed clunking as described in my first post.... It is currently (maybe because of the tire swap?) the freeway drivetrain whine/howl/vibes at 70+ MPH in between constant speed and deceleration that I’m trying to solve for. I’ll try and post a video of the noise so you guys who are really good at sound troubleshooting can get a better idea. I’ll also post the metal shavings from the front diff at the last two diff oil changes to see if you all think it’s way bad, or somewhat normal. I’d love the feedback gents.

Again, thanks so much for the help. This community is so awesome, and a great resource as we all wheel our rigs and try to keep them in good shape. I hope to be able to contribute more to folks, as I’ve gotten so much value out of lurking around

 

[Fortuitous]

Metal shavings from front diff oil change a few months ago. None in the rear at all.

 

[richardlillard1]

That looks like a little more than metal shavings, looks a little like pieces of something. I would check it again, take some other pics.

The whine in gear float (that’s between drive and coast) is something a lot of 80s I’ve dealt with have. It’s a bearing howl of some kind. Perhaps pinion. But I’ve heard it in some trucks for years without incident. Seems to be something worth keeping an eye on, but not the end if the world.