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Discussion Starter #1
Of 05 owners who's rear diff started howling, and the car only has 7000 miles on it! Kind of weird though as every bad rear end ive ever heard howled at all speeds under cruise or light to moderate accelleration, mine ownly howled at 50mph in 4th, 5th or 6th. Anyhow, the dealer just finished the steering rack install and should be doing the diff today or wednesday depending on the parts arrival. I love this car, but the dealer trips are wearing me out! I plan on changing the fluid in the new diff to hopefully stop it from developing a howl as well. Can anyone advise as to how long to break in the new Diff and what fluid and modifier to use?

StolenFox
 

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Discussion Starter #4
Perhaps I was mistaken then. When I searched for whining rear diffs, I thought the majority were 05's

Clearly, more research is due......


StolenFox
 

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I believe they changed the diffs partway through the '04 model year. Holeshot has no problems with his "first 250" build car, where as my May/June '04 whines big-time on decel...(40-55 mph)... the first batch of '05's still had this problem, dunno if all did... StolenFox, what's your build date underhood?
 

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I have no whine at all on my '04. What does the whine sound like?
 

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Discussion Starter #7
RobertHammen said:
I believe they changed the diffs partway through the '04 model year. Holeshot has no problems with his "first 250" build car, where as my May/June '04 whines big-time on decel...(40-55 mph)... the first batch of '05's still had this problem, dunno if all did... StolenFox, what's your build date underhood?

Goat is still at the dealership getting the diff replaced so I cannot look under the hood. I think it was built mid-year 05 but I cannot remember with certainty.


StolenFox
 

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I had mine replaced in January. Its been quiet ever since then.
 

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My diff whines and I have an 06 with 8500 miles its really noticeable in fifth and sixth like 50-80 mph. I have a full track II so Im sure I hear it better due to the poly bushes. All in all its not the whine that bothers me its the grinding im getting. I think I want a new rear but we will see what Rossi has to say its going in tomorrow.
 

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I am so glad I changed out that nasty gear oil that GM uses. I think that's part of the problem.
 

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If I have a noise at 30-40 mph that goes away at 50-60 MPH does that suggest it's not the rear end? Also, mine is more of a hum or a whooo than a whine. (Does not sound like a jet engine.) Could also be a wheel bearing.
 

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Discussion Starter #12
RobertHammen said:
I believe they changed the diffs partway through the '04 model year. Holeshot has no problems with his "first 250" build car, where as my May/June '04 whines big-time on decel...(40-55 mph)... the first batch of '05's still had this problem, dunno if all did... StolenFox, what's your build date underhood?

Born on date: June 2005

Got the goat back today and so far all is well. There is a barely audile whine upon decelerating around 40mph but Im betting it will be silent after a 1000 miles or so of break in. Then I am changing the diff fluid to prevent future problems!!! Opinions on what brand gear oil and modifier?


StolenFox
 

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I put Royal Purple in, don't remember which weight. Quieted it down significantly. If I still had the stock fluid in, I would have pushed a Pontiac dealership to swap the diff, it was driving me so nuts (most of my work commute is 45 mph speed limit - right in the middle of the area where it whines)...
 

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hardball75006 said:
I am so glad I changed out that nasty gear oil that GM uses. I think that's part of the problem.
Amen to that. I changed out the diff fluid also. It's quieted the diff. Robert, I believe I used the RP 75-140 weight gear oil. I'm too lazy to go to the garage & look.
 

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damn could GM use decent fluid anywhere in the cars they build? :bomb:
 

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MMHHHMM Thhats tha biitch
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my 05 started howling or whining at about 1900 miles, never knew what it was, but now i do and its going to the dealership.....damn, it just got out for the synchros....i only have 4000 miles on her
 

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speeddemon said:
damn could GM use decent fluid anywhere in the cars they build? :bomb:
No. It would cost a dollar more to build each car. One dollar less profit. :bomb:

Although, the problem had been traced back to GM using too much friction modifier in the diff.
 

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It's a GTO problem...not a specific year. Mine whines, it started at ~3000mi and it still whines after putting in RP. Nature of the beast, I say. It still lays down two strips. When it stops that, I'll have the diff replaced by the dealer...might anyway around 35k miles.
 

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TonyTJ said:
I have no whine at all on my '04. What does the whine sound like?
Same here - 11K on it & quite a few runs down the track. Mine was built on 9/13 or 9/14/2003.

Maybe the the first cars for 04 are okay.
 

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From what I've read and observed, the diff whine comes standard on the '04s and the 05's. This might not count for much, but every car that I've ever owned has done it. Both my S-10 blazers had it, and my '02 Grand Prix does too. It even happened with my '96 subaru legacy. I look at it this way, At Least it doesn't have that notorius ford power steering whine. Honestly, I thought my rear end was going bad in my 05, and it has less than 5000 miles on it. Then I rode in my buddy's 05 Suburban, his does it too. As far as changing diff oil, I tried that too. And it didn't change.
 
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