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Should I fix the rear gear whine?

I have rear end wine that starts around 65 MPH and stops at 80 MPG.
It has been there since around 1k mile. The dealer said they will fix it under warranty.

1) If not fixed, what is the long term adverse effects other than the noise?

2) IIRC many people have reported the same noise and the dealers " fixed" the issue , but in many cases it came right back; sounds right?

3) What is exactly the reason behind this whining noise?

Thanks
 
I'd like to know the answers as well!
After my rear end was replaced by the dealer due to an accident, it has been whining alot.
The noise got a little louder after 3 track seasons, but it has stayed the same for the past year. It gets annoying on the hwy when you're trying to keep a conversation with a passenger.

EDIT:
I asked a similar question to Rev Auto when I was getting the clutch replaced. They said they would realign and gap the gears, but it would whine again after a few thermal cycles and loads at the track.
 
It's harmonic from the differential. I got the same noise at about the same speed. It's even worse now that I got rod-end everywhere and a rear set delete.

My solution is to crank up the volume on the radio or go a little faster.

New gear will help but the noise will be back. If you put new gear have them polished. It should help.
Something like that : http://www.innovatorswest.com/REM-gear-polishing.html

Also a thicker oil should help too.
 
Swiss Boss said:
It's harmonic from the differential. I got the same noise at about the same speed. It's even worse now that I got rod-end everywhere and a rear set delete.

My solution is to crank up the volume on the radio or go a little faster.

New gear will help but the noise will be back. If you put new gear have them polished. It should help.
Something like that : http://www.innovatorswest.com/REM-gear-polishing.html

Also a thicker oil should help too.

3.73 is a noisy gear for what ever reason.. go smaller or larger next time! for light weight go with a 3.15 gear like I did.. had two very loud whining 3.73's before swapping to this light weight 3.15 and there is almost zero noise now.
 
I tried to have my gears replaced under warranty and finally gave up. I paid a speed shop to replace them with new FMS 3:73 gears. 90% of the whine is gone. I think Ford had a batch of bad gears. I also think the upper control arm sends noise and vibration straight to the chassis from the center section. Previous Mustangs has two control arms mounted at the end of the axel tubes. That might have masked the noise on older cars.
 
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seca954 said:
I tried to have my gears replaced under warranty and finally gave up. I paid a speed shop to replace them with new FMS 3:73 gears. 90% of the whine is gone. I think Ford had a batch of bad gears. I also think the upper control arm sends noise and vibration straight to the chassis from the center section. Previous Mustangs has two control arms mounted at the end of the axel tubes. That might have masked the noise on older cars.

We have a WINNAH!!! For some reason the new chassis seems to transmit gear whine better than the old Fox body cars, Although the 8.8 is a pretty touch diff they do seem prone to gear whine more than the rest. IMO gears should never whine and mine don't but I think your right about the Ford gear situation as well.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
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13Boss#3328 said:
Will the gear whine lead to malfunction eventually?

Hi 13Boss3328:

The answer is Yes, it is possible. However, some gear noise, (slight), may also be acceptable without it leading to a failure.

It depends on the noise. Generally there are two types of failure, a sudden snap bang and it's broken type failure or it happens over time from wear. If you hear a noise and it gets worse over time and miles it could very well be an indication of an impending wear type failure.

Any noise should be checked out by your Ford Dealership service department. Sometimes it's wise to take the SA, or Tech on a road test so you can demonstrate the noise. Especially if the noise is an intermittent condition. Have you had your service department look at your Boss?

Good luck with getting your noise sorted,
Dave
302 HP
 
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Here's some history..ever since I ran 5.13s in my 56 chevy station wagon back in the day I've been a nutjob on gear whine..talk about harmonics running through the car and to the driver!!!
The dragster guys run a tighter backlash in their cars to prevent the gears from "slapping" and therefore breaking when they let the clutch fly at 10,500. In order to accommodate this they are willing to put up with more noise, now recently they have gone to a "soft" gear material that won't break as easily but of course, needs more frequent replacement. You should be aware of these types of gears if you ever purchase "race gears" you won't want them for what we do. The factory style gears are usually fine if set up properly, although the 8.8 is more susceptible to noise (it seems) they can be set up to run quiet. You have 2 issues here, if they have been run very long, IMO they will never be right because they have taken a wear pattern, so basically, you're done, you may move the noise around but it has been my experience that it will always be there someplace. If it's not so bad that it's putting metal shavings into the cooler, bearings and what not (it will tend to a little more than usual but it shouldn't be large chips like the stars at night when you're looking at the oil) you should probably just deal with it. Secondly, although the wear will be accelerated it probably won't meet it's demise for some time and if so not catastrophically,it will usually give you plenty of warning via the "noise monitor" and observation of the oil.
FWIW noise on acceleration is more commonly backlash too loose, on deceleration..too tight or possibly a pinion bearing. Right and left turns can indicate bearing wear on the "loaded" axle.
hope that helps.
 
13Boss#3328 said:
Considering the uncertainty of the whine outcome, I will likely take it to the dealer.

I thought the same thing and they were kind enough to replace it with a brand new 3.73 kit including bearings.. they even test drove it and re-adjusted the backlash.

They put a huge chip in my Brembo wheels in the lip. The gears started making even more noise a few days later. I took it to my cousin's shop and he put new 3.15's in they are silent and that's been 5000 miles now. Not sure if its the 3.73 gears that were bad or the dealer didn't have a good day.
 
twistedneck said:
I thought the same thing and they were kind enough to replace it with a brand new 3.73 kit including bearings.. they even test drove it and re-adjusted the backlash.

They put a huge chip in my Brembo wheels in the lip. The gears started making even more noise a few days later. I took it to my cousin's shop and he put new 3.15's in they are silent and that's been 5000 miles now. Not sure if its the 3.73 gears that were bad or the dealer didn't have a good day.

I seriously doubt the dealer replaced them. He just told you he replaced them.
 
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IMO, again, adjusting old gears with a wear pattern will just move the noise around it will not get rid of it. It has been my experience, that once a set of gears whine (and take a pattern) they will always whine.
 

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