I had the differential clutch pack change out done today. The TSB fluid change was done 2 months ago but the grinding/popping came back.

As of a week ago the car makes a single "knock" sound each time it moves forward in first gear. (Sounds like slop in the drive train.) I thought the clutch pack change would solve this but it is still there. I'm thinking there is now other damage in the differential that would not have occured had the bad parts been replaced early rather than just the TSB recommended fluid change.

I also noticed the work order stated the clutch carrier was "reconditioned". That tells me it has been damaged in some way. Sounds like GM's trying to get off cheap causes more damage.

 

does anyone have the TSB number for this?. I am taking my car in on Tuesday...and want to make sure these guys know where to start. I dont have any faith on service advisor.

 

Should not be a problem unless they messed something up..."reconditioned" is simply the warranty terminology required by GM documented on the repair order in order to get the tech paid for disassembling and reassembling the unit

 

Are the owners of these cars with differential problems track cars or cars that are driven hard? What is causing the rear end to need replacement? When reading the TSB is says for the first time to drain and change fluid. Second time repair rear pinion gears if first time didn't work. Didn't the C-5 also have problems with their leaky rear ends?

 

I am having the same problem. I had the dif. fluid changed 6 months ago and it did get quiet for a while and now it is very grindy at low speed turns with gear engaged. Plus some pop noises on initial rollin if wheel turned. All the sounds seem to come from the back. My car was never tracked or power shifted. I do shift hard though at least once or twice a month. I am getting ready to do the clutch pack change next.

2005 MN6 Z51 16k miles.

Joe

 

Document ID# 1705987
2005 Chevrolet Corvette


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Subject: Rear Axle Chatter Shudder on Turns - keywords differential fluid noise oil #PIP3559 - (09/22/2005)

Models: 1999-2006 Chevrolet Corvette

2004-2006 Cadillac XLR



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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Rear axle chatter or shudder on turns on Chevrolet Corvette and Cadillac XLR.
Recommendation/Instructions:
If this is the first complaint for this condition flush and fill the rear axle with P/N 89021669 (in Canada 89021670) gear lube and 4 ounces of the friction modifier additive P/N 01052358 (in Canada 992694).
If this is a repeat complaint or the condition persists after the flush and fill, replace the right and left rear axle clutch packs following published service procedures.
After clutch pack replacement use 1.6 l (1.69 qt) synthetic axle lubricant GM P/N 12378261 (Canadian P/N 10953455). and 4 ounces of the friction modifier additive P/N 01052358 (in Canada 992694).
Note: 2006 Z06 equipped vehicles require 2.55 l (2.70 qt) synthetic axle lubricant GM P/N 12378261 (Canadian P/N 10953455) and approximately 190 ml (6.4 oz) limited-slip differential lubricant additive GM P/N 1052358 (Canadian P/N 992694).
Note: Export vehicles use 2.01 l (2.12 qt) synthetic axle lubricant GM P/N 12378261 (Canadian P/N 10953455) and approximately 150 ml (5.1 oz) limited-slip differential lubricant additive GM P/N 1052358 (Canadian P/N 992694).
Once the axle fluid has been changed the car must be driven in 8 - 10 SLOW figure eights to work the fluid between the clutch plates.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

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.
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© Copyright General Motors Corporation. All Rights Reserved

 

I had my rear diff changed out, but I'm still getting a tiny amount of noise. I don't launch hard, moderate spirited driving.

 

Hopefully this won't be a wide spread problem. I won't change the rear end differential fluid for this very reason now as I found out the fluid is life long unless you do encounter a problem like this or a leak per owner's manual.
It goes with "If it ain't broken don't fix it"
With my luck I would have ended up changing to another synthetic brand oil (yes just to get out metal shavings) and if something happened at that point in time I wouldn't know if it was switching to another brand of oil or just having it opened caused the problem which is why I'll leave it be for now and see what happens. No one has worked on the rear diff. it is factory filled and torqued.

 

I dont track my car at all. I have only 5000 miles on it.

 

Any modifications?

 

My car is not tracked. Some spirited driving but never abused. The differentials craping out is a known problem.

 

This might be a dumb question, but why does the export version contain a different quantity of oil?

 

If you have had your diff clutch packs changed...

You are going to want to read my thread with the subject line:

"so...ummm...yeah...you're not going to believe what my c6 did..."

I posted it this morning.

My clutches were changed out about 6-7 weeks ago and yesterday the rear end locked up completed backing up traffic in a huge way. If you have had the clutches changed, be very aware of any humming sounds coming from the back end as it probably means they didn't lube the drive shafts properly. Don't let it happen to you....

 

If this happens maybe this is a good time to put in Amsoil Extreme Gear fluid 75w/90 But for now if it ain't broke don't fix it.

 

I'd like to give it a try but I think GM will tell you it voids the warranty and all damage will be the owners responsibility.

 

WTF ?? Do the Export vehicles have a larger differential case?

 

The GM 75w/90 synthetic gear oil; is a long life lubricant which is why it doesn't need changing

 

As long as the fluids you use meet GM specs.

 

The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 meets GM specifications for the C6 differentials and won't void your warranty. GM can't void your warranty for using an aftermarket fluid that meets their specifications.