OSCILLATING HUMMING NOISE/VIBRATION AT HIGHWAY SPEEDS, GOES AWAY IN 4H

[John94]

Not yet, she goes under the knife Tuesday to isolate the cause, unfortunately I checked the availability of the axle/disconnect assembly and it is on backorder with no ETA, which means I'll have to slog through COPIS to get them to redirect a part from the assembly line to me, perks of working in the parts department at the dealership, I don't have to hope that somebody does there job to get the parts because that somebody is me

I am going to keep this in my back pocket for next time I need a part.
Keep us Bronco6g brethren in mind!

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[cnycyberorangeobx]

I am going to keep this in my back pocket for next time I need a part.
Keep us Bronco6g brethren in mind!

Will do

 

[andersman02]

Looking forward to seeing what happens.

I have a similar issue, about 45 mph a on 1.5 sec off 1.5 sec vibration, not wheels, and it goes away instantly if you switch into 4wd. It lightly audible and happens about 25% of driving trips.
I also have a 100% vibration, .5/10 severity, that happens at all speeds. This also stops in 4wd.

Here's the kicker, i checked my front diff fluid, it was black. Had a little sludge/metal on the magnet. Changed the diff oil and had about a 50% reduction in the on/off vibration severity. It still happens the same % though. just less severe.

Maybe the FAD is not functioning completely?

I have 23k miles

 

[John94]

Looking forward to seeing what happens.

I have a similar issue, about 45 mph a on 1.5 sec off 1.5 sec vibration, not wheels, and it goes away instantly if you switch into 4wd. It lightly audible and happens about 25% of driving trips.
I also have a 100% vibration, .5/10 severity, that happens at all speeds. This also stops in 4wd.

Here's the kicker, i checked my front diff fluid, it was black. Had a little sludge/metal on the magnet. Changed the diff oil and had about a 50% reduction in the on/off vibration severity. It still happens the same % though. just less severe.

Maybe the FAD is not functioning completely?

I have 23k miles

BUDDY I AM SO GLAD to have seen this. You and I have the exact same issue.
Have you attempted to take it to a dealer for this issue? I have multiple times and they simply claim they can not feel the vibration.

My coworkers (automotive engineers) seem to think its a drive shaft phase balance issue... but the problem is getting ford to test /rebalance the shaft when they claim not to feel the issue in the first palce

 

[RunningJerk]

I’m getting the vibration almost 100% of the time now. But, I noticed that when I accelerate the vibration goes away a little, and returns when I let off the gas.

 

[John94]

I’m getting the vibration almost 100% of the time now. But, I noticed that when I accelerate the vibration goes away a little, and returns when I let off the gas.

Same. The fact that it gets lessened when accelerating is typically not indicative of a driveshaft issue which makes this all the more perplexing

 

[Tex]

Are you guys going from 2H to 4A to stop the vibration, or from 2H to 4H, or 4A to 4H?
It's not a good idea to run 4H on the pavement except when it's slick and you need it (or you're diagnosing something for a second), but 4A is fine for any length of time at whatever speed.

I'm curious about this issue, and how it might translate to a sort of similar problem with my wife's expedition. It's more of a repeated thumping than a sound or vibration. When you accelerate, it feels like it's rapidly engaging and disengaging the front drive as it only happens in 4A as opposed to 2H or 4H where it's either engaged all the time or not at all. Based on other forums, it's either the t-case clutches or the disconnect on the front axle not fully engaging, I can't remember it's been a while since I looked it up.

 

[andersman02]

Are you guys going from 2H to 4A to stop the vibration, or from 2H to 4H, or 4A to 4H?
It's not a good idea to run 4H on the pavement except when it's slick and you need it (or you're diagnosing something for a second), but 4A is fine for any length of time at whatever speed.

I'm curious about this issue, and how it might translate to a sort of similar problem with my wife's expedition. It's more of a repeated thumping than a sound or vibration. When you accelerate, it feels like it's rapidly engaging and disengaging the front drive as it only happens in 4A as opposed to 2H or 4H where it's either engaged all the time or not at all. Based on other forums, it's either the t-case clutches or the disconnect on the front axle not fully engaging, I can't remember it's been a while since I looked it up.

2h to 4h

 

[Tex]

2h to 4h

Off hand, do you know what happens on your Bronco when you switch from 2H to 4A? Does it persist, is it reduced, or does it disappear?

 

[Calm horse]

I have 22 2.7 sas...at 4000 miles I started to notice the smallest of vibration at high speed..roughly 75 or 80 mph...can't hear it yet but I can feel it in the shifter and slightly in the pedal...my wife and kids think I'm little nuts but I know how smooth this vehicle drove for the 1st few thousand...was thinking maybe the tires at first but my gut says maybe something else...I'm now at 5800 miles and it hasn't gotten worse ....I ve never tried to throw it in 4hi at those speeds and don't think I want to try either

 

[RunningJerk]

Are you guys going from 2H to 4A to stop the vibration, or from 2H to 4H, or 4A to 4H?
It's not a good idea to run 4H on the pavement except when it's slick and you need it (or you're diagnosing something for a second), but 4A is fine for any length of time at whatever speed.

I'm curious about this issue, and how it might translate to a sort of similar problem with my wife's expedition. It's more of a repeated thumping than a sound or vibration. When you accelerate, it feels like it's rapidly engaging and disengaging the front drive as it only happens in 4A as opposed to 2H or 4H where it's either engaged all the time or not at all. Based on other forums, it's either the t-case clutches or the disconnect on the front axle not fully engaging, I can't remember it's been a while since I looked it up.

I have the Black Diamond with 7mt. No 4A here! Going from 2h to 4h stops the vibration and sound immediately. Switching back to 2h causes an increase in noise, vibration, and increases the speed at which the on/off pattern occurs, then quickly returns to the new normal of noise and vibration.

My brother in law (a mechanical wizard and engineer) and I plan to pull the wheel and check everything out at some point. He has a theory we want to test, wondering if putting a little bit of different pressure (wrong word) on the cv axle will eliminate the sound. He thinks maybe torque going thru the axle when in 4h is the important clue, and perhaps some sort of bungee cord on the axle and driving in 2h (briefly) we can see if that addresses the noise and vibration. He’s got an idea how to do it, and I’m not quite sure what he’s thinking, but as long as it doesn’t hurt anything we will try it out.

I am curious to ask- how many people who’ve experienced this issue also have the ford performance tune installed? That’s been on my mind lately. Could this somehow be a software issue causing the front diff to not fully disengage, or is this 100% a mechanical issue? Has ford pushed out ANY software updates that could affect the front diff via over the air updates?

 

[JohnnyBronco]

If you have had your tires balanced I can almost assure you its not them.
Some folks at my work (engineering firm) are suggesting CV joint issues

Back in 70-72 or so we had a full size Dodge with bad vibration. Kept real ancient g tires even recounting on different wheels. Turned out to be belt separation in the sidewalls (early years of radials on 5000# tubs)

 

[JohnnyBronco]

I have the Black Diamond with 7mt. No 4A here! Going from 2h to 4h stops the vibration and sound immediately. Switching back to 2h causes an increase in noise, vibration, and increases the speed at which the on/off pattern occurs, then quickly returns to the new normal of noise and vibration.

My brother in law (a mechanical wizard and engineer) and I plan to pull the wheel and check everything out at some point. He has a theory we want to test, wondering if putting a little bit of different pressure (wrong word) on the cv axle will eliminate the sound. He thinks maybe torque going thru the axle when in 4h is the important clue, and perhaps some sort of bungee cord on the axle and driving in 2h (briefly) we can see if that addresses the noise and vibration. He’s got an idea how to do it, and I’m not quite sure what he’s thinking, but as long as it doesn’t hurt anything we will try it out.

I am curious to ask- how many people who’ve experienced this issue also have the ford performance tune installed? That’s been on my mind lately. Could this somehow be a software issue causing the front diff to not fully disengage, or is this 100% a mechanical issue? Has ford pushed out ANY software updates that could affect the front diff via over the air updates?

A misalignment of u joints can cause noise and vibration that application of torque can temporarily eliminate. Would not be first vehicle where shafts could be installed out of phase or where the extra welded tab to prevent misalignment is missing from factory. It's why we always mark shaft positions before removing from vehicles - even lowly farm equipment.

 

[John94]

I have the Black Diamond with 7mt. No 4A here! Going from 2h to 4h stops the vibration and sound immediately. Switching back to 2h causes an increase in noise, vibration, and increases the speed at which the on/off pattern occurs, then quickly returns to the new normal of noise and vibration.

My brother in law (a mechanical wizard and engineer) and I plan to pull the wheel and check everything out at some point. He has a theory we want to test, wondering if putting a little bit of different pressure (wrong word) on the cv axle will eliminate the sound. He thinks maybe torque going thru the axle when in 4h is the important clue, and perhaps some sort of bungee cord on the axle and driving in 2h (briefly) we can see if that addresses the noise and vibration. He’s got an idea how to do it, and I’m not quite sure what he’s thinking, but as long as it doesn’t hurt anything we will try it out.

I am curious to ask- how many people who’ve experienced this issue also have the ford performance tune installed? That’s been on my mind lately. Could this somehow be a software issue causing the front diff to not fully disengage, or is this 100% a mechanical issue? Has ford pushed out ANY software updates that could affect the front diff via over the air updates?

No performance tune installed. BD Sasquatch auto with 4a.
We have very similar issues.

Please advise us of your findings.

 

[John94]

A misalignment of u joints can cause noise and vibration that application of torque can temporarily eliminate. Would not be first vehicle where shafts could be installed out of phase or where the extra welded tab to prevent misalignment is missing from factory. It's why we always mark shaft positions before removing from vehicles - even lowly farm equipment.

What I find is that the issue does not go away on acceleration.

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