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Discussion Starter #1
Frickin A. I just spent the last couple days putting a new differential in my '04 only to discover that the exact same whine/hum is still there. The diff is brand spankin' new.

My car developed an odd whine/hum somewhere along a 200mi drive. The noise wasn't there when I left my house, but as I approached Schaumburg, IL I slowed down and heard a "decelerating" hum. I thought FOR SURE it had to be the whine that so many V owners have referred to, and seeing my diff had been leaking for a while, I knew it was low and assumed the gears where fried (I forgot to check the level before I left).

Well. After installing the new diff, the noise is still there. It's virtually silent up til 30mph or so then the noise starts to show itself. It sounds like an "accelerating" hum/whine as I speed up and a "decelerating" hum/whine as I slow down. Also, it sounds as though its coming from the rear of the car. I don't "think" its a wheel bearing because as I swerve left/right right/left the noise doesn't really change much.

Have any of you had symptoms such as these?

My best guess is that its the driveshaft center bearing. My dad (old school gear head) thinks it could be a CV joint going bad. We both considered a bad wheel bearing until we couldn't get the noise to change (it also is a hum rather than the warble you usually get with a bad bearing).

Thoughts?
 

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I have the same, decelartion whine has gotten more prevalent lately. The diff whine is most noticeable with light acceleration is that true with yours? A lot of people have reported that new diff produced whine from day one, did you use the proper fluid and additive? Brand new 25xxxxxxxx series diff? If turns out to be something else then please keep us updated on your findings.
 

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Discussion Starter #3 (Edited)
^^^ I used Amsoil Sever Gear 75w 90 w/ the additive already in it. I find it hard to believe that with .8 miles on the clock the whine would be EXACTLY the same way it was PRE diff replacement. I'm guessing its something else. The noise doesn't really sound any different other than increasing in pitch as I accelerate. No noise whats-so-ever below 30mph.

Anybody?
 

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I have this too man thats why I am going with the 9" that Gforce is designing on my other thread. All V diffs whine from what I have heard, some are just worse than others. They are CRAP! Sorry dude. Solution-turn up radio or get louder exhaust!

I use the same Amsoil that you do fyi but I added the slip lock additive.
 

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I have 9k miles on my second differential and it does not whine (or at least it didn't before I typed this). There are other causes of speed variant whine, such as drive shaft problems, and tire noise.
 

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The carrier bearing noise is usually quite distinct.
Most of the time it doesn't come in until about 40-50 mph and then it is just there, loud, and changes with vehicle speed.
It sounds rearward but it is really coming from below the center console just behind where the armrest is.
It is usually higher pitched and can be incredibly loud and disturbing if you don't know what it is.

The diff noise is usually a whine when loading the diff lightly that comes in around 45 and stays pretty much after that, but usually you can kill it by letting off the gas and bring it back by reloading the driveline.

GM hub bearing noise is a low growl that comes in around 30 mph and increases in pitch and it usually changes when loading the vehicle left and right but not always.
 

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Discussion Starter #7
^^^ i just took it for another ride. this time my 4yr said, "dad! i hear an airplane!"

anyway, i noticed that it comes on almost exactly around 30mph and it's there constantly. the sound does not vary except in pitch and from owning an old '87 325es back in the day with a similar drive shaft set up, I was leaning towards a bad carrier bearing. the sound is familiar. based on your description, I think I'll see what I can do to source a used drive-shaft. even if just to put in and take for a drive to confirm before dropping the cash on a new one. from what i understand the bearing is not serviceable.

if it is a bad bearing, am i going to wreck anything else if i continue to drive it? i'll have to baby it for a while because now i have to break in the new diff.
 

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I couldn't say nothing else will be damaged, but I can't say what may or may not happen anyway.
I haven't seen anything major surrounding this failure on the ones I have had but they didn't seem to go too long after the noise started until I got them.
If it is a bearing failure obviously it can increase friction and generate heat and do Lord knows what, however I am not sure of the actual source in the carrier bearing.
I wouldn't go on a trip but I don't see why an average commute or run to the grocery store would put you in any sort of danger.
It certainly shouldn't affect anything else.

No it isn't serviceable, mainly because there are no parts to be had even if you can get the shaft apart and press the bearing off.
 

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I've had a bad diff and and a bad carrier bearing. The carrier bearing squeal was MUCH louder. It sounded like when you are running a hose or a sink with a lot of pressure and you turn the shutoff to almost barely closed and the water is pushing through making a squeal. The diff whine didn't and was easy to make stop, with a push of the clutch. The carrier bearing would only start at highway speeds. Where as the diff whine was at lower speeds.

Ewill has said much of this as he is the master, but I thought I might be able to give some clarity on to what it sounds like. Like he said the bearing isn't serviceable, so prepare for a grand or two to get a new one installed.
 

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^^^ i just took it for another ride. this time my 4yr said, "dad! i hear an airplane!"

anyway, i noticed that it comes on almost exactly around 30mph and it's there constantly. the sound does not vary except in pitch and from owning an old '87 325es back in the day with a similar drive shaft set up, I was leaning towards a bad carrier bearing. the sound is familiar. based on your description, I think I'll see what I can do to source a used drive-shaft. even if just to put in and take for a drive to confirm before dropping the cash on a new one. from what i understand the bearing is not serviceable.

if it is a bad bearing, am i going to wreck anything else if i continue to drive it? i'll have to baby it for a while because now i have to break in the new diff.
GForce1320 will be designing a 1 piece aluminum driveshaft very soon I have heard if you can wait a couple of months.
 

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Frickin A. I just spent the last couple days putting a new differential in my '04 only to discover that the exact same whine/hum is still there. The diff is brand spankin' new.

My car developed an odd whine/hum somewhere along a 200mi drive. The noise wasn't there when I left my house, but as I approached Schaumburg, IL I slowed down and heard a "decelerating" hum. I thought FOR SURE it had to be the whine that so many V owners have referred to, and seeing my diff had been leaking for a while, I knew it was low and assumed the gears where fried (I forgot to check the level before I left).

Well. After installing the new diff, the noise is still there. It's virtually silent up til 30mph or so then the noise starts to show itself. It sounds like an "accelerating" hum/whine as I speed up and a "decelerating" hum/whine as I slow down. Also, it sounds as though its coming from the rear of the car. I don't "think" its a wheel bearing because as I swerve left/right right/left the noise doesn't really change much.

Have any of you had symptoms such as these?

My best guess is that its the driveshaft center bearing. My dad (old school gear head) thinks it could be a CV joint going bad. We both considered a bad wheel bearing until we couldn't get the noise to change (it also is a hum rather than the warble you usually get with a bad bearing).

Thoughts?
1- Its the rear.

2- That 200 mi drive didn't help things if it was at a constant rpm. Part of the new break in period is not taking long trips or extended driving periods.

that being said,
I am on my second gen4 rear in a month after simple around-town easy driving. First one whined nicely right out of the box..on decel 50-40, and on accel from about 48-60.

the second one seems to have lost the decel whine, but I still have a (slight) accel whine in the same speed range.

dealer ruled out all the variables before replacing the first one including putting new tires on the car for a test drive.

I think these gen4s are junk. The gen3 I got in 08 was solid feeling and whisper quiet for a long time.. I actually didnt notice it whining until a couple months ago after a 1000mi road trip...

This gen4/am motor mount combo is turd soup compared to that 08 repair. I am cussing myself now for letting the dealer keep the pair they took out of my car.
 

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Discussion Starter #15
1- Its the rear.

2- That 200 mi drive didn't help things if it was at a constant rpm. Part of the new break in period is not taking long trips or extended driving periods.

that being said,
I am on my second gen4 rear in a month after simple around-town easy driving. First one whined nicely right out of the box..on decel 50-40, and on accel from about 48-60.

the second one seems to have lost the decel whine, but I still have a (slight) accel whine in the same speed range.

dealer ruled out all the variables before replacing the first one including putting new tires on the car for a test drive.

I think these gen4s are junk. The gen3 I got in 08 was solid feeling and whisper quiet for a long time.. I actually didnt notice it whining until a couple months ago after a 1000mi road trip...

This gen4/am motor mount combo is turd soup compared to that 08 repair. I am cussing myself now for letting the dealer keep the pair they took out of my car.
The 200mi drive was with the old diff. I installed a new one (brand new) and the whine began again immediately exactly where it did with the old diff.

I paid closer attention this time to the whine (the first time around I automatically assumed diff and didn't give it a second thought) and noticed a couple things:

1. IF it was the diff, I would think the whine would "change", perhaps even "pause", as I get on and off the gas. There is no change in sound other than pitch.

2. It's freakin' loud. Music doesn't drown it out. Not subtle in the least.
 

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The 200mi drive was with the old diff. I installed a new one (brand new) and the whine began again immediately exactly where it did with the old diff.

I paid closer attention this time to the whine (the first time around I automatically assumed diff and didn't give it a second thought) and noticed a couple things:

1. IF it was the diff, I would think the whine would "change", perhaps even "pause", as I get on and off the gas. There is no change in sound other than pitch.

2. It's freakin' loud. Music doesn't drown it out. Not subtle in the least.
hmm. Maybe I am wrong about my new diff, perhaps it's the center bearing...ewill's description matches perfect. I spent alot of time listening to diff whine, which seems to come more from the trunk/behind the rear seat..this is most noticeable when accelerating- I can't say that I hear it on decel at all. I remember my diff whine to be terrible on decel.. Im going to drive with the back seats down to see if the noise is worse or not.

I dont know what symptom to describe to the dealer to address this, but it's worth mentioning anyway. I hate the fact that the new diff seems to whine and I haven't revved much over 4k rpm in a few weeks. I also hate the fact that a possibly perfect diff got tossed out over a misdiagnosis.

I'll report back if I ever get it replaced.
 

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Sounds like lots of misdiagnosis..

1st, laying the seats down isn't going to do anything....maybe make a sound travel more so thru the car...

2nd, the shaft can put sounds to the back or front of the car, it is connected to both ends and has the ability to transmit sounds and vibrations to either end....

Calm down, take a good few minutes to really go thru some process of checks and really know wth is making noise....

Many times you can't just drive a car and go......oh sh-- you need a rear....or you need a hanger bearing....
You must be new here.
 

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No im not new to hearing, seeing misdiagnosis.

A whine in a new diff can be resolved, if the whine is from the new diff and not a hub, or other bearing being transmitted thru the car..and being mistaken for a diff... (which i can tell you of about 132 instances of customers having made the same mistake, and those are the ones i remember from the royal rip off being performed on them)

If a new diff is set up PROPERLY for normal use it should be quiet....
During the initial break in which is to be performed without load on the diff (in the air) for 30 mins, the builder/owner will hear the noise and make changes if he didn't notice prior to when assembling, before you should see the car...if not and you see the car, you should have them ride along...
If a rear starts whining after a few hundred miles, something may have loosened up...or been on the loose side of the set up parameters

What causes whining...

To tight BL, to tight to root, sloppy bearing, loose adjustment on preload or carrier side load.
All depending some whining is ok if it was purposely set up for a specific use, like hard drag racing use it would be acceptable for a slight whine
 

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I'm starting to lean towards non diff issue. I just did my axle and cradle bushings yesterday and my whine is more noticeable, especially when clutch isn't engaged. It'll start whining on accel at slow speeds, let out the clutch and it continues to whine at a different pitch. I'm thinking bearing somewhere.
 
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