CHASLS2

My 06 a6 with 8000 miles also does it. Guess i will have my tuner give it a good refill.

routesixtysix

If you change the fluid and additive yourself this little pump makes the job easy. Got it at Advance Auto. They also sell it at Wal-Mart.

tama2112

I took my car in last week to have the service mentioned earlier. Noticed this morning that it did it again.. Backing up, with the wheel turned.. It was a knocking sound - felt like that wheels were going to fall off!

Whats the next step?

su8pack1

I've started to experience the same thing, I guess it's time for it's first service call to get it documented before the warranty runs out.

PAmotorman

try going to a open parking lot and making slow figure"8" to get the lube in to the posi plates. also check the axle nuts to make sure they are tight

jim213

Really appreciate the input. I had taken my 06 in to the dealershio for a oil change and mentioned this problem. Their explanation was it was normal. Not having anything to compare with I just accepted their statement.

I think I'll make another trip back to the dealership with a copy of this Service Bulletin.

That should prove to be interesting.

xlr8rvette

I've had two causes of these symptons. First was rear clutch packs (which seems to be consensus). Adding additive only lasted short time. Dealer replaced clutch packs and no more problem.
Second event turned out to be loose sway bars (front and rear).Dealer replaced connections. Problem cured.

While symptons were similar the clutch pack noise occured when going slow in parking lot and turning. The loose connection pop/thump noise occured going slow in parking lots that were a bit bumpy.

These noises are not normal. Good luck !

S2K

Every time this issue comes up, the rear diff is blamed by the majority. However, that can be a red herring as it was in my case. I spent a lot of time getting Amsoil and changing fluid, etc., only to discover that this in fact was not at all the problem. The sound seemed like it was coming from the rear, however, someone outside of the car was actually able to confirm hearing it from the front! From inside the car it absolutely sounds like the rear. For me the issue turned out to be the sway bar end links on the front. Once replaced, the the clunking sound went away.

Not to say that you don't have a problem with the diff, but people should be aware that other issues can and do cause this problem.

calemasters

You need to be careful about DTBs. Some are old and do not contain the latest information.


Document ID# 2048181


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Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)



Models: 2004-2008 Cadillac XLR (Including V-Series and Export)

2005-2008 Chevrolet Corvette (Including Z06 and Export)




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This bulletin is being revised to change the fluid recommendation and to remove the requirement of adding friction modifier. Please discard Corporate Bulletin Number 07-04-20-002 (Section 04 -- Driveline/Axle).


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Condition
Some customers may comment on a clunk and/or chatter type noise from the rear of the vehicle while making turns.

Cause
This condition may be caused by slip/stick of the posi-traction clutch plates due to insufficient limited-slip axle additive. As plates slip and stick, a jumping or jerking feel occurs accompanied by a clunk noise.

Correction
Important: DO NOT remove the differential cover from the rear or the two sides. It is not necessary to flush the old fluid from the differential.

Drain and refill the rear differential fluid using the procedure listed below.

Draining Procedure




Raise and support the vehicle.
Clean any dirt from around the differential drain plug.
If not equipped with a differential cooler, remove the drain plug (1) and washer (2) from the differential.



If equipped with a differential cooler:
4.1. Using a bent tip screwdriver, remove the quick connect fitting retaining ring (3) from the quick connect fitting (4) and discard the retaining ring.

4.2. Remove the differential cooler inlet pipe from the differential nut.

Drain the fluid.
Filling Procedure




If not equipped with a differential cooler, install the drain plug (1) and washer (2) to the differential.
Tighten
Tighten the differential drain plug to 35 N·m (26 lb ft).





If equipped with a differential cooler:
2.1. Install a new retaining ring.

2.2. Connect the differential cooler pump inlet pipe (2) to the differential. A distinct snap should be heard or felt when assembling the cooler pipe to the fitting.

2.3. To ensure the cooler line is properly installed, give the cooler pipe a gentle pull.

Clean any dirt from around the differential fill plug.
Remove the fill plug and washer from the differential.
Important: DO NOT add any limited-slip additive (friction modifier). With this new fluid (Dexron LS Gear Oil 75W-90) it is no longer required to add friction modifier. If friction modifier is added, it will cause the fluid to lose some of it's friction reducing properties as well as reducing seal life.

Fill the differential with the new DEXRON® LS gear oil, P/N 88862624 (Canadian P/N 88862625). Refer to the table listed below for lubrication specifications.
Check the fluid level to ensure it is even with the bottom of the fill plug hole to no lower than 6 mm (0.25 in) below the opening.
Install the fill plug and washer to the differential.
Tighten
Tighten the differential fill plug to 35 N·m (26 lb ft).

Important: Steps 8-13 are for vehicles equipped with the differential cooling system. For vehicles not equipped with the cooling system, proceed to step 14.

Raise the vehicle so the wheels are about a foot off the floor. Make sure the wheels can spin freely without obstruction from the hoist or any nearby items.
Start the vehicle and put the transmission in second gear. Slowly accelerate to 10 mph and hold this speed for one minute.
Turn the vehicle off .
Raise the vehicle.
Check the fluid level in the differential. Add fluid until the recommended level is reached.
Lower the vehicle.
Once the differential fluid has been changed, the vehicle must be driven in 8-10 tight figure eight maneuvers to heat the fluid and allow the fluid to be worked into the clutch plates.
Lubrication Specifications Application
Quantity

Metric
English

2004-2005 XLR (Including Export) and 2005 Corvette (Non Export)
1.72 liters
1.85 quarts

2006-2008 XLR (Including V-Series and Export) and 2006-2008 Corvette (Non Z06)(Non Export)
2.0 liters
2.11 quarts

2005 Corvette Export
1.88 liters
1.99 quarts

2006-2008 Corvette Export (Non Z06)
2.16 liters
2.28 quarts

2006-2008 Corvette Z06
2.75 liters
2.91 quarts


Parts Information
Part Number
Description

88862624 (US-1 Quart)

88862625 (Canada-1 Liter)
DEXRON® LS Gear Oil


Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

F9709*
Drain & Refill Rear Axle Fluid
0.6 hr

* This is a unique labor operation number for bulletin use only. It will not be published in the Labor Time Guide.




GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


© Copyright General Motors Corporation. All Rights Reserved.


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Document ID# 2048181

djgrelli

I've only had my 05 for a few months and the previous owner had the fluid changed in July 07. It started acting up about two months ago when the weather started getting a little colder. I took it in two weeks ago and they changed out the fluid and additive. I have only put about 130 miles on it and it still does it on right hand turns only. After it warms up after a few minutes the noise disappears. I called the service manager and he said to put another couple hundred miles on it before bringing it back to give the additive a chance to work into the packs.

I can't stand this noise. I had the same problem in my 78 about 13 years ago but it happened after a long run when the fluid was hot (just the opposite). I sold Amsoil back then and did a flush and fill with additive and when I sold it last Oct the same fluid was in it. I will give the Service guy a brake and give it a little more time but I think I'm looking at new Clutch packs. My warranty runs out in May so it'll be done before that.