2015c7

Casual User
Oct 6, 2014
29
12
muskoka
VetteCoins
505
Car
coupe
On some of the "other " C7 forum boards you may have noticed a great number of posts regarding a warble or chirping noise coming from the back of the car especially at 1500 RPM using light acceleration like going up a slight incline,( most noticeable in 6th or 7th gear).About two years ago GM bought a customers warbler and after extensive testing found it to be coming from the differential. The "word of mouth" explanation for this is the result of an improper assembly of the ring and pinion gear assembly.Owners of "warblers" who had the differential replaced reported the noise was gone.
When I took delivery of my 2018, base, A8 in Late June 2017 I did not put very many miles on until we left for Florida in the fall. During that drive I heard the warble noise and was able to capture several recordings of it on the PDR. I continued to hear that noise all winter long in Florida and delayed the repair attempt until returning to Ontario late April, 2018. When I took the car to the dealership I was informed they had not heard of this issue. Over the course of the winter I did a lot of research on this issue, spoke to owners who had the differential replaced and spoke with a service manager at a Florida dealership that had knowledge of this issue and had fixed a couple of "warblers" . I also learned that at least two "forum" members had taken their cars in for repairs and the first thing the dealer did was check the diff fluid. No metal was found but the fluid drained out was only two quarts which is one quart under filled.Proper three quart fill fixed their warble problem.
Back in Ontario armed with this information I took the car in. I do know how much service managers hate "google garage". Our service manager is excellent and agreed to do a differential service as a first step. The drained fluid was clear except for a very small amount of metal "shedding" to be expected with a new unit during break in. Only TWO quarts came out of the differential ! The diff was filled with three quarts and the warble noise is gone in the 1500 km I have since driven the car.
I pass this along for three reasons;
1) Because of the very few number of cars in Canada most dealers probably are not a aware of this issue and probably do not know that GM TAC and the Corvette brand quality manager are fully aware of this issue and are a resource that MUST be utilized. They assist in helping the parts department getting a "qualified " replacement differential that will not have the same assembly faults............very important.
2) Many forum owners have reported they have discovered differential factory under fills going back as far as 2015 MY and seems to continue to be a problem. As a side note I did ask that the diff fluid level be checked on my 2015 as part of the PDI process but forgot to ask for the 2018 PDI.
3)This warble only seems to effect base A8 cars as the Z51, GS, and Z06 have an elsd which is different than the differential in the base A8. I am not aware of any elsd equipped cars being reported as warblers on other boards.
............just an FYI
 
On some of the "other " C7 forum boards you may have noticed a great number of posts regarding a warble or chirping noise coming from the back of the car especially at 1500 RPM using light acceleration like going up a slight incline,( most noticeable in 6th or 7th gear).About two years ago GM bought a customers warbler and after extensive testing found it to be coming from the differential. The "word of mouth" explanation for this is the result of an improper assembly of the ring and pinion gear assembly.Owners of "warblers" who had the differential replaced reported the noise was gone.
When I took delivery of my 2018, base, A8 in Late June 2017 I did not put very many miles on until we left for Florida in the fall. During that drive I heard the warble noise and was able to capture several recordings of it on the PDR. I continued to hear that noise all winter long in Florida and delayed the repair attempt until returning to Ontario late April, 2018. When I took the car to the dealership I was informed they had not heard of this issue. Over the course of the winter I did a lot of research on this issue, spoke to owners who had the differential replaced and spoke with a service manager at a Florida dealership that had knowledge of this issue and had fixed a couple of "warblers" . I also learned that at least two "forum" members had taken their cars in for repairs and the first thing the dealer did was check the diff fluid. No metal was found but the fluid drained out was only two quarts which is one quart under filled.Proper three quart fill fixed their warble problem.
Back in Ontario armed with this information I took the car in. I do know how much service managers hate "google garage". Our service manager is excellent and agreed to do a differential service as a first step. The drained fluid was clear except for a very small amount of metal "shedding" to be expected with a new unit during break in. Only TWO quarts came out of the differential ! The diff was filled with three quarts and the warble noise is gone in the 1500 km I have since driven the car.
I pass this along for three reasons;
1) Because of the very few number of cars in Canada most dealers probably are not a aware of this issue and probably do not know that GM TAC and the Corvette brand quality manager are fully aware of this issue and are a resource that MUST be utilized. They assist in helping the parts department getting a "qualified " replacement differential that will not have the same assembly faults............very important.
2) Many forum owners have reported they have discovered differential factory under fills going back as far as 2015 MY and seems to continue to be a problem. As a side note I did ask that the diff fluid level be checked on my 2015 as part of the PDI process but forgot to ask for the 2018 PDI.
3)This warble only seems to effect base A8 cars as the Z51, GS, and Z06 have an elsd which is different than the differential in the base A8. I am not aware of any elsd equipped cars being reported as warblers on other boards.
............just an FYI
I have a 2017 Z51 vette with 13K Km on it and I have heard a noise (rattle) inside the car going around 1250 to 1500 RPM especially going uphill under light acceleration. You refer to a noise as a warble and I don't know if this is the same noise? I took the car to the dealer and they diagnosed the noise as the Shudder and changed the trans fluid to the new Mobil 1 Blue label but it did not help at all. I am not sure if your problem is the same as mine and the warble is my rattle. The dealer says they have no idea what the problem is. I have this noise on many videos on my PDR and wonder if you can give me me more info.
 
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