Vibration Dampeners?

[Wrath]

What the heck are these things? They're on the transfer case and rear axle on my '97 XLT, which rolls quietly, but not on my '99 Limited (4wd) which howls at speed. They're also not on my '98 Sport, but it's a 2wd. The guy I bought the Limited from replaced bearings and the transfer case trying to eliminate the howl. Is the absence of these iron donuts the true culprit?

 

[410Fortune]

probably not
I delete them on all of my rigs, no wild vibrations yet

The sport trac even has one more on the front diff
The 95-01 explorers have a 3rd rear shock
v8's have control bars on top of the leaf springs too
I remove all of it!! The way see it as a band aid, if your U joints, CV's bearings tires alignment, etc etc are all in good working order then bye bye
Saves like 30#! hahahaha

Now if you are chasing a weird vibe even after trying a different set of tires and checking all of the above....then have at it start bolting them back on for testing

 

[Wrath]

probably not
I delete them on all of my rigs, no wild vibrations yet

The sport trac even has one more on the front diff
The 95-01 explorers have a 3rd rear shock
v8's have control bars on top of the leaf springs too
I remove all of it!! The way see it as a band aid, if your U joints, CV's bearings tires alignment, etc etc are all in good working order then bye bye
Saves like 30#! hahahaha

Now if you are chasing a weird vibe even after trying a different set of tires and checking all of the above....then have at it start bolting them back on for testing

So they are not required then? I may still have a bad bearing somewhere if that is the case.

 

[Wrath]

probably not
I delete them on all of my rigs, no wild vibrations yet

The sport trac even has one more on the front diff
The 95-01 explorers have a 3rd rear shock
v8's have control bars on top of the leaf springs too
I remove all of it!! The way see it as a band aid, if your U joints, CV's bearings tires alignment, etc etc are all in good working order then bye bye
Saves like 30#! hahahaha

Now if you are chasing a weird vibe even after trying a different set of tires and checking all of the above....then have at it start bolting them back on for testing

Thanks for the quick reply! Yes, different tires and wheels, sound persists. The donuts were already absent when I purchased the vehicle, but I might bolt them on one at a time then test drive, see which end is actually making the noise.

 

[MuscleJunkie]

Please let us know what you find. It's interesting

 

[410Fortune]

So your 99 Limited has no vibration dampers and it has a howl at speed
4.0 sohc engine or v8?

(I do not think they made a limited with the pushrod 4.0 in 99)

Is it a wheel bearing noise? where is it coming from and what does it sound like?
remove front d shaft see if noise persists

 

[CDW6212R]

Yes that sounds like bearings of some kind. How is the rear, is the gear oil good, with no metal debris in it? If it's from the back end, I'd expect the axle bearings to be bad, and the axles often get worn soon after the axle bearings go. You don't want to ever see any grease(gear oil) outside the rear brakes or axles, that points to the axle seal, which is usually the bearing there.

 

[Wrath]

So your 99 Limited has no vibration dampers and it has a howl at speed
4.0 sohc engine or v8?

(I do not think they made a limited with the pushrod 4.0 in 99)

Is it a wheel bearing noise? where is it coming from and what does it sound like?
remove front d shaft see if noise persists

I did and the noise is still there. Sounds kinda central to the drivetrain usually. Engine is a 4.0 sohc

 

[Wrath]

Yes that sounds like bearings of some kind. How is the rear, is the gear oil good, with no metal debris in it? If it's from the back end, I'd expect the axle bearings to be bad, and the axles often get worn soon after the axle bearings go. You don't want to ever see any grease(gear oil) outside the rear brakes or axles, that points to the axle seal, which is usually the bearing there.

It sounds central, but the T-case has already been replaced.

 

[410Fortune]

Replaced or just replaced some bearings?

The control trac t case is suspect imo unless it was completely rebuilt and even then….but for now let’s assume it’s good

How does transmission fluid look?

What about wheel bearings like cdw said?

 

[C420sailor]

I had bad rear axle bearings that I could’ve sworn were up front. Noises travel.

 

[fdbiii]

Bearings usually make a roar and may change with side loading in the case of wheel bearings. A howl is usually a poor tooth pattern in the rear end especially if it changes between pull and coast. Mine had not been shimmed with any ring gear carrier preload and the carrier was slopping around side to side. Re-shimmed and set a good tooth pattern, done.

 

[Wrath]

I'll have to start debugging this noise once we're back up and running. In the midst of swapping out the engine so I can rebuild the one coming out, and noticed the crank pulley/balancer has deteriorating rubber. This might have contributed to the noise as well I'm thinking. Will update as newsworthy findings come up.