# Growling?



## Supersam (Apr 21, 2013)

Before any one says it yes i used the search bar. I just want to be sure this is the problem. 

I have a 04 M6
I have a growling noise in my drivetrain. It is loud and is speed dependent meaning the growl gets faster as the car does. coasting with the car in neutral the sound is still present just quiet, under any load it gets significantly louder. I'm thinking its the rear diff but I want to be sure before i get into it. I was going to use royal purple for the diff but after doing some reading I'll be using torco with a type f fm. I would just like to hear others thoughts on the problem, if it could be the tranny or any other problem. The engine and tranny have a limited warranty from the dealer so if its the tranny I'll get it fixed by them. I'm on a budget so its hard to just try everything till i get it right.
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## svede1212 (Nov 1, 2005)

A lot of our diffs are noisy. If it sounds like it's coming from the back Torco and Ford FM may help it a bit. It wouldn't be a bad thing to do anyways so it would be a good start. A little further forward the center carrier bearing on the drive shaft sometimes gives trouble. Hope that it isn't that as you can't get one anymore and either need to go used or replace the DS with a one piece


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## GTO JUDGE (May 14, 2005)

Supersam said:


> Before any one says it yes i used the search bar. I just want to be sure this is the problem.
> 
> I have a 04 M6
> I have a growling noise in my drivetrain. It is loud and is speed dependent meaning the growl gets faster as the car does. coasting with the car in neutral the sound is still present just quiet, under any load it gets significantly louder. I'm thinking its the rear diff but I want to be sure before i get into it. I was going to use royal purple for the diff but after doing some reading I'll be using torco with a type f fm. I would just like to hear others thoughts on the problem, if it could be the tranny or any other problem. The engine and tranny have a limited warranty from the dealer so if its the tranny I'll get it fixed by them. I'm on a budget so its hard to just try everything till i get it right.
> Sent from AutoGuide.com App


http://www.gtoforum.com/f3/growling-clunking-noise-coming-rear-14102/


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## Supersam (Apr 21, 2013)

I've seen and read that thread a lot. I just want to be sure this is the correct symptoms of that problem and not a problem in my transmission, cause both could producw a similar noise

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## GTO JUDGE (May 14, 2005)

Supersam said:


> I've seen and read that thread a lot. I just want to be sure this is the correct symptoms of that problem and not a problem in my transmission, cause both could producw a similar noise
> 
> Sent from AutoGuide.com App


Your car used? Chances are the oil was never changed. More than likely needs fresh oil and friction modifier. My newly installed rear end had growl too. The viscosity of the oil breaks down. Dana didn't always use the best oils... I know..... I worked for them. More then likely if you change it out using Synthetic oil and the proper F.M. the growling will subside. Give it a day or so and back up a few times to allow the oil to do its job. Some oils have the FM in it already as svede indicated with Torco. The key is PROPER friction modifier.


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## Supersam (Apr 21, 2013)

Yes its used. That's what I'm thinking and also why i ordered torco oil and fm. My buddy who is a pretty good mechanic said it might be the slave something or other . i can't remember. 

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## svede1212 (Nov 1, 2005)

No, neither the slave nor the slave throw out bearing will cause that.


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## Supersam (Apr 21, 2013)

Well what in the tranny would cause that noise if anything.

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## Supersam (Apr 21, 2013)

ok i replaced my diff fluid with the torco and added the fm. how long will it take before the noise quits?


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## svede1212 (Nov 1, 2005)

If it isn't gone now that is not going to fix it. You could have bearing problems on the output or input shafts. A noise like that needs in-person diagnosis unfortunately


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## Supersam (Apr 21, 2013)

Yeah she is already slotted to go into the shop. Looking at a rebuild of the rear end. Just depends on what the problem is.

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## Supersam (Apr 21, 2013)

Just some closer on this thread ended up being the ring and pinion gears. They are shot so i swapped out the rear end for another stock one last Sunday no more noise at all from the rear end. 

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