: Rear End Noise

Black Sunshine
06-01-07, 05:34 PM
First a pre-emptive statement.

I've been hanging around here since before I bought my V last year and I like to chat with the best of them but......

I have spent hours sifting thru rear end threads (containing 95% BS) looking for helpful information only to be disappointed. Nothing on the FAQ page that I could find either.

I ain't buying a new rear end from a vendor when the car is still under warranty.

Now to the symptoms.

At slow speed, while turning, I'm getting a growling sound (almost like wheel rub) coming from under the rear of the V.

It was getting progressively louder.

No signs of leakage.

Took it into the dealer about two weeks ago and they did a rear diff. fluid change.

The sound went away for about ten minutes.

The growl is back with a vengeance to the point that it scared my wife and kids when driving to a wedding last Sat. Again, at low spedd during turning or moving from an incline to flat road surface.

I have an appointment this coming Monday morning to drop it back off at the dealer for inspection.

Anyone have similar problems?
If so, what was causing it?
What was done to fix it?

I'm also looking for links/pointers to any TSB's, docs., etc. that I can take with me to the dealer in reference to any and all rear end issues.

If you have links or can email docs that you have please do so.

(NOTE: PLEASE post replies to this thread of a technical nature ONLY so that, in the future, it might help others like myself that are having a hard time finding information for all the "fluff". Thanks!)

06-01-07, 08:25 PM
No problems with my diff, but I have a copy of an informational bulletin regarding Shudder or Bind on lowspeed turns. Something about a growl or groan. Can't locate it right now, but the procedure was to replace the fluid . . . which it sounds like they have already tried. Did they add the additive when they changed the fluid?

06-01-07, 08:39 PM
welcome to the world of the disintegrating diff.....your time has come....get GM to replace it.


Redline CTS-V
06-01-07, 08:39 PM
It definately sounds like you have something going on with the limited slip... Sounds like a new diff might be in order... I would make sure they performed the fluid change according to the attached TSB...

06-02-07, 09:55 AM
LS clutch noise.

06-02-07, 09:56 AM
is it coming from the driver's side rear?

Black Sunshine
06-02-07, 11:13 AM
The dealership did replace the fluid and the additive. I think I remeber them saying they were told to double up on the additive. I know I run two bottle in the Eaton on my Impala, so that makes sense.

Thanks for the TSB link. I notice it recommends replacing the clutch packs in the rear if the noise returns. This isn't the same thing as a rear end replacement, is it?

It is very hard to identify which side of the rear it is coming from. I'll see if I can get the wifey to sit in the back while I reproduce the conditions to try to identify.

Thanks you for your "on topic" responses.

06-02-07, 12:09 PM
This sounds like the clutchpacks in the diff. I have been told, repeatedly, that the dealers do not rebuild diffs, only replace them. Something about not having the correct tools on hand.

With that being said, mind does this and has for about 5,000 miles. I change the fluid myself and am using RP which makes it somewhat quieter. I have also added dynamat under the rear seat and in the trunk - so inside the noise is certainly not a bother anymore.

When turning in a parking lot or a slow speed uturn with the windows down I still notice it. I also have NOT noticed any particulates in the fluid when changing it above what I'd consider to be normal (on par with the second fluid swap). FWIW I'm swapping the diff fluid shortly (has about 10,000 miles on it now) and will post on this forum if I find any different. 23,000 miles on this diff with fluid swapped at 800, 2000, and 12,000 miles.

Good luck.


06-02-07, 01:13 PM
I would say clutches, but it should subside with new additive.

I concur, your unit isnt long for this world.

06-02-07, 01:20 PM
gotta watch for the ol' impending half shaft break too, esp. if noise is coming from the passenger rear side.

good luck. these cars make so many f*cking noises from back there it makes one's head spin.

06-02-07, 02:14 PM
Was in my car today, and I'm starting to get dif whine ... again. Starts at about 42 MPH and becomes quite loud at 52-55 MPH with very slight throttle opening. The dif that's in there was put in 11 mos ago, has 6k on it, and has seen one minor burnout and two hard 1-2 shifts ... THAT'S IT!!!

When I realize what a complete wuss of a driver I am 99.99% of the time, I also realize how utterly dismal these Getrag difs are. I mean, utterly ...:horse:

06-02-07, 03:26 PM
I know none of you will believe this - but I've been quite hard on my current diff - much harder than the first two - and it is holding together fine.



Black Sunshine
07-02-07, 03:53 PM
It's taken a couple weeks to get off the road and take the car back to the dealer but I finally got it back to them this morning.

I had asked before but they said they weren't sure what parts the technician had ordered. So I kinda demanded to know this morning when dropping off the car and guess what they're doing....

Installing new clutch packs.

Yes, instead of replacing the rear end they got authorization to do a rebuild. This kinda surprises me since I've only heard of the rear unit swap being done.

I guess we'll see how long this last.....(yea right)