djgrelli

Anybody out there have a copy of the TSB on the drain and fill of the rear differential. I'm on my second drain and fill and still have the chattering when cold. I want to have all my ducks in order when I take it back in. I want them to change out the clutch packs especially the passenger side. The last time I was in the Service Manager said to put a couple hundred miles on it and give the additive time to do it's job. Then he said they will have to contact the General to get authorization to do the change out if needed.

Thanks in advance.

overrev64

Having a slight chatter when the rear is cold is perfectly normal. I have had many clutch type differentials over the years and they have all exhibited some chatter with no ill effects.

Vet

Check the second post of the below linked thread:
http://forums.corvetteforum.com/show....php?t=1497063

calemasters

Document ID# 2048181
2005 - 2008 Chevrolet Corvette


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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
2005 Chevrolet Corvette

Vet

Thanks calemasters! I'll add this to my differential FAQ thread asap!



(Now updated... thanks again!)

http://forums.corvetteforum.com/show....php?t=1497063

...

FloydSummerOf68

If you go in complaining about this problem will they just fix it because they know it exists? Or will you still have to get them into the car and drive around in a circle so they can hear it?

C6V3tt3

Yea they will have to be in the car and replicate the same noise. Most likely they will say its normal or will not hear it, and the TSB means nothing to most dealers, unless there is a recall, which there is not. I have been throught this many times, the dealer can not even look up the TSB # I felt like I was taking crazy pills when I heard this from dealers, after seeing all this talk on the forum.

djgrelli

Thanks everyone. I don't have any problem with the service writer. Every time I go in he is very co operative. It's the serviece manager that won't give in. It's back to the dealership this week with a copy of the new TSB.x

calemasters

All GM dealers have access to ALL GM Dealer Technical Bulletins, in SI (Service Information) through the GM DealerWorld portal.

C6V3tt3

Well I went through it when I had a case with GM and when I show it to dealers. They couldnt get anything from that number. Maybe they lied.

FloydSummerOf68

:sighs: that's what I feared...I know they'll say it's normal.

Guess I'll have to take my chances and try...because it's getting bad.

djgrelli

I went to the dealership yesterday with the new TSB in hand and the service writer already knew about it. They changed out the old fluid with the new Dextron LS fluid. This is the third change out. I told the Service Manager this was his last chance to eliminate the problem. He agreed and said to give the fluid a chance to work into the clutch packs. Next step is new clutch packs. You would think that a problem such as this would warrant a recall. It's a PIA to take time and go to the dealership for this problem. Anyway I will have it taken care of before my warranty expires in May. Been thinking about an extended warranty as I drive this car much more than the 78 that I had. Anybody out there who has purchased an extended warranty.

Michrider

The part of the process most fat lazy technicians skip is the figure 8s right after changing the fluid. Sounds like they did this to you, if they told you to give it time to work it. Lazy SOBs.

Time to work in doesn't work. The car needs to be driven in figure 8s just like the bulletin says. Take it to a parking lot and give it 20-30 minutes of slow figure 8s. That is the only way to work in the LSD stuff into the clutch packs.

It will last a little while, but clutch chatter is the nature of the beast with clutch type differentials. I've had countless clutch type LSDs and they all do it. The won't be a recall, I doubt the noise will cause any safety issue.

The problem in recent years is the LSD additives just aren't as good as they used to be. Back in the 60s and 70s it was magical stuff, I think it was some type of whale oil or something else politically incorrect. The LSD additives today maybe last a year if you lucky. The popping is just the clutches slip/sticking, nothing is actually wrong, they are just protesting a bit saying come on change this crap we are sticking too much.

piva242

The rear-end of my 07 makes some strange grinding noises when I'm turning slow loops in the parking garage. I haven't taken it to the dealer for the differential fluid exchange, but it's on my to do list...

So my question is: will delaying the fluid exchange some how damage the rear differential?

TCW

GM says that the noise doesn't hurt a thing.

Tom

Vet

New clutch packs are not the answer. They will eventually chatter just like the ones that came with your car. Several owners that have had new clutch packs put in have already reported chatter again. Your best bet is to NOT have new clutch packs put in (you know, don't fix what ain't broke) and just make sure you have the new good fluid in there, do the figure 8s immediately after the fluid swap, etc. The fluid is important... with the old fluid, once GM stated to use TWICE the amount of additive, that seemed to do the trick for many people... the new Dextron stuff is likely a formula similar to the old oil plus at least 8 ounces of the additive or more... which is a lot more "slippery" than what came with the cars when new. I have to question the effect this new fluid will have on the operation of the posi itself, the posi may not "lock" as well with ultra slippery fluid in there, but... as long as it works "well enough" for street use, then it's good. I think one member reported being able to leave two thick black stripes after changing the fluid and putting in 8 ounces of additive... so, if true, then the "slipperier" fluid is the solution... not new clutch packs.

wbear

If I was a fat lazy technician the figure 8's would be the last part I would skip. I would take great pleasure in doing them for a picky, complaining owner. To make sure it was mixed well I would do them at 3/4 throttle followed by a couple test drives thru the gears at full throttle to make real sure the noise you complained about was gone. Later, you could bring it back and have the new noises my testing created fixed.

vcrz

Here is a deal:

LINK

seamus2154

The service Mnger is not lying to you about letting it work in. The advice above is dead on. It will not work in w/ just mileage. You have to be doing alot of hard turns. Hence the figure 8 advice. The new fluid has to work into the clutch paks and the only way that will happen is figure 8's. You can drive 4000 mls on the hwy and still have the problem that could have been solved in 200 mls and alot of figure 8's.

Zip Corvettes

There is so much mis information out here on this it is unreal and GM is not helping. First your Corvette has a POSI diff in it, if it is working correctly it is going to chatter when you are backing up and it is cold no matter what clutch goes in the car. There have been so many people complaining about this GM actually went back to the old design that was not as good as the new one. Now you can change the fluid and add more slip additive to it and it will help, but if you don't want any chatter then you need to either figure out a way to adapt a open diff to the car or buy a Quaife unit for it. GM did a very good job on diff and now we have gone backwards with it because allot of the customer do not understand how a POSI works. It will chatter when there is no oil in the clutchs, just as your valve train will also, the difference it the engine has an oil pump to push the oil through the engine, the diff lubricates itself by oil being slung when it is in motion, so when the car sits all the oil drains off the clutchs and bearing etc, until you drive the car. This means it will chatter when they clutch are dry and there is absolutely nothing wrong with that. You are not hurting them and as soon as the oil starts getting warm and moving through the housing and clutches it will go away. What we are going to see now are clutches wearing out earlier because they are not as good as what they were. As far as a dealer changes the clutches in your car, If it is a C5 he cannot, in a C6 I would run with my car away if they were going to do this. The diff for one needs to be removed from the car in order to do this properly, second the whole diff has to come apart, do you really want someone doing this who does not build these. I would make them install a whole new diff before I allowed this, and if there were a real problem which there is not if you are talking about clutches. I know there is a TSB out there, it is because of customer complaints not that there is actually a problem. Save yourself the time of dropping the car off and leaving it somewhere unless you just want them to change oil for you. This has always been a complaint in the Corvette back as far as I can remember. Long before the C5's and C4's, and with them it was never a real problem, to me it means it is working correctly. I am not trying to be negative here, but I am seeing just way to much mis-information. If anyone has more technical questions please feel free to PM or respond here.
Thanks
Justin