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Discussion Starter #1
Is it always really loud or can it be quiet? I think I've heard a soft whistling noise at 45-55ish mph but I sometimes hear tire noise as well which I might mistake for the differential. I took my GTO on a drive with a service manager at the dealership and most of the time he said it was likely tire noise but towards the end of the drive he said he noticed something that might be the characteristic rear end whine. My car is an 05 A4 with ~1200 miles.
 

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Some guys described a loud whine, some have reported a barely noticeable whine. My whine isn't that bad but it is noticeable. It was noticeable enough for the service manager to verify a new rear was in order. He also told me that another guy was in with one and complained of whine but it was not enough to warrant a replacement.

I don't know if this is true or not, but I was told that GM is tightening their belt on wholesale replacement of rear ends. They are requiring further examinations or other alternatives before replacing.

All I know is my replacement is on a ship headed for the states, and is due in mid Feb.

IMO...if it is true what I am told, I'd suggest getting it taken care of before GM decides not to replace them anymore.
 

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When it gets to the point where its noticeable, you'll know. I am on my second one and its starting to whine after 300 miles. Back to the Dealer I go.....:cool
It's usually between 48-55mph and only under acceleration.
 

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HotRodGuy said:
what exactly causes the whine, is there damage inside the rear end or is it really just a normal thing?
Here is my best guess..... the root cause is improper gear tooth contact due to an assembly process control problem setting the proper pinion to ring gear engagement and backlash. These settings are critical to obtain quiet gear mesh :cheers
 

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EEZ GOAT said:
do it cut the performance or is it just noise?
It's just noise but if it continues to get louder the differential could eventually fail. My second diff. makes a faint whine and I will monitor noise level and go back to the dealer if the noise increases :cheers
 

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I just noticed mine last night.. cruising at 50 mph in 6th I could hear it clear as day without the music on.. but only at like 15% throttle (just a guess not an exact measurement people) basically enough to keep the car at a constant speed.. but when I stepped on it a little bit it went away completely or when I let off the gas same thing.. I don't know.. I can deal with that if it doesn't get worse.. besides its a rareity that I'm ever off the gas or not accelerating or that I'm not playing music.. lol..
 

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It doesn't directly affect performance but it results in uneven wear on the gear set and premature failure.
 

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My Goat is at the Dealer for the my Third Dana Diff (axle assembly) . The whine that I've had sounds like a failing fuel pump. The first occured on accel from 45-55 but not on decel , the second was same but also at the 80-85 cruise. I was able to hear the whine until I turned the CD volume above 30. No one has told me want the cause is , they ride in it and order a new one. The First took 3 months to arrive , the second took 2 months . As far a performance I'd say that yes it does have a negative effect. I don't track so no numbers but from the Dyno tune I had done , I feel the RW numbers were down. With an A4 , I quess 15% is normal loss from Crank hP to RW hp , mine was more with the whining diff. To each his own , but this issue should have generated a recall.

If this Third Diff goes , I can say hello to Lemon Laws . The Dealership is spending more time this install - I pushed to have the rearend cradle tool used to check alignment and they are using it to check rear cradle alignment prior to replacing another Sealed LSD. Time will tell...

My Goat is a blast to drive and my daily driver - the rearend whine has been the only problem - but a drag of a problem...

Edit:
Mileage wise : first started whining at +- 4000 , second at 11,000 , I/m at 20,000 miles at dealership. Took about 3500 miles +- between replacement and whine reappearance.
 

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So what aftermarket rear end will give this car the beef it needs?

JET
 

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Do people with the 3.91 gearsets installed have the same problem? If this is simply a matter of a pinion/gearset adjustment being done incorrectly at the manufacters. Then having it done correctly over here should fix it. If thier doing it wrong over there It doesn't matter how many rearends you get your still going to have the same problem. Just wondering...
 

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derf said:
It doesn't directly affect performance but it results in uneven wear on the gear set and premature failure.
That's the crux of the issue right there (other than the annoyance of the noise). What is "premature" failure for a diff? 200,000 miles? 100,000 miles? 50,000 miles? Anyone actually have one fail (as in stop working), or is everyone just replacing them while they can under warranty due to the whine?

If there is increased wear on the gear set, but failure is still hundreds of thousands of miles away, are there any other precautions that should be taken... such as increased diff fluid changes to remove the wear particles?

I certainly don't know the answers to these questions.

As an FYI for those desiring to keep their GTOs for a long time but are worried about this issue, I had my diff rebuilt this winter after three race seasons of use for about $1000. I think a new diff with turnin is about $2000. :cheers
 

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I'm a little baffled on this topic.

My GTO has the whine at certain speeds usually under acceleration. The reason why I am so unsure on this topic is that in my Camaro ('87) it ALWAYS had/has a sound at certain speeds coming from the rear. That car has 108,000 miles and the rear was never replaced and the sound never elevated nor produced menchanical problems. This is the SAME sound I hear in the GTO. I assumed this was 'normal' for a RWD car. Am I wrong? The sound is not really that loud, but definitely noticeable.
 

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Guess I'm used to transfer case and differential whine in 4WD and AWD.

Any differential whine in my GTO is so minimal I never notice it.
 
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