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Guys i have 2016 a8 stingray with 2,200 miles and day 2 of ownership i srarted getting a strange warble sound at around 1500 rpm when lightly accelerating. Power through the 1500 point and you do not hear it. Lot of us a8 stingray owners have this problem. I have a post on the corvette forum with over a 100 responses. My dealer said it was the exhaust so they replaced it without a fix. Now the say GM ENG says to replace the rear end. I am no eng. But i knew it wasn't the exhaust and i don't think it is the rear end either. I don't think i am going to let them replace the rear end without some assurance it will fix my problem. Do you guys have an opinion on this issue.
 

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I have heard of this problem before. I think if you search this site you will find one or more threads on the subject.

Does the sound occur at 1500 RPMs regardless of what gear you are in, as long as the load on the drivetrain is light?
 

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I have heard of this problem before. I think if you search this site you will find one or more threads on the subject.

Does the sound occur at 1500 RPMs regardless of what gear you are in, as long as the load on the drivetrain is light?
I have seen those posts before too. Posted 2 links below.
 

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For what it's worth, I figured out it's the tires. I noticed the warble. I had it on another car. It went away after a bit. I think it's the unidirectional tire tread reacting to the road surface.

I have 6k miles and I no longer hear it.

fltsfshr
 

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I have heard many terms used to describe rhymic tire noises, including harmonic dissonance. Whatever it is called, certain types of pavements, coupled with our especially wide tires, can easily produce such irritating sounds. Usually but not always, this source is easy to diagnose, by hearing differences when the road surface changes.
 

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And my least favorite surface noise is that caused by concrete pavement interspersed about every 100' with a perpendicular tar strip. Tire whine, then thump...; whine, then thump..., etc., even with MSRP in its softest setting.
 

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Discussion Starter #9
Yes under light acceleration no matter the gear ( a8) sorry if it is a duplicate, i tried the search but no luck, i am still trying to get used to navigating this forum.
 

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Yes under light acceleration no matter the gear ( a8) sorry if it is a duplicate, i tried the search but no luck, i am still trying to get used to navigating this forum.
Okay, check out the threads linked above in post #5 and post #4.

As pointed out in those links, since your problem is related to a constant RPM and not a constant speed, then the source should not be in the rear differential, or the axle, or the wheels. If I were you, I would not let them replace my rear differential at this point in time. Check those threads for more details, and pay more attention to the later posts in those threads when more information was available.

My take on the summaries from those threads (which I quickly scanned again today) is that no known solution exists at this time.
 

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Sorry for recreating the wheel, didn't see the other post during my search. Admin feel free to delete, thanks
 

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Okay, check out the threads linked above in post #5 and post #4.

As pointed out in those links, since your problem is related to a constant RPM and not a constant speed, then the source should not be in the rear differential, or the axle, or the wheels. If I were you, I would not let them replace my rear differential at this point in time. Check those threads for more details, and pay more attention to the later posts in those threads when more information was available.

My take on the summaries from those threads (which I quickly scanned again today) is that no known solution exists at this time.
rdslon01:

Actually, there are quite a number of us that have this problem (if it is one) mostly documented in another forum. We all have the same symptoms i.e. the odd noise at exactly 1000 RPM and then again at 1500 RPM. Most, if not all, are from C7, A8 transmission equipped cars. There is no other symptom except for the noise. It doesn't happen under hard acceleration-just when you accelerate gently. My service manager is convinced its the exhaust although others have had the entire exhaust system replaced with no results. However, he has no permission from GM to do anything and, to be honest, I'm not all too willing to jump on the idea of shotgunning parts at the car. The real frustration is the realization that this is a a GM issue, not the local dealer. And all GM does is fire it back to the dealer who can do nothing, at least in my case. I'd give anything to be able to get beyond the robots at GM's customer service and talk to someone who counts and is able to at least give me an idea of what they are doing about it, if anything. Besides all my bitching, I'd like to know what your take on the odd sound is.
 

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I am sorry, Flatlander. I don't know what the solution is.

I have not noticed the problem in my car.

The thread posted in link #5 above is the best resource I have seen on the subject.

I understand what you mean when writing that GM points you to your dealer instead of taking a more active role in the ownership of the problem. I find it annoying when I see that happen to others, and I can only imagine how frustrated it would make me if it happened to me personally.
 

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Flatlander, I started the thread on post #4 and I think the problem is the transmission and the way it was programmed, specifically the shift points set for fuel economy. When in D the car always seems to be in the highest possible gear for that speed and when you push the gas the transmission does not downshift immediately, and the engine has no enough torque to speed up the car and traverse that 1200-1500 rpm range, once it downshifts you suddenly see the rpms going up and the noises go away. It needs a lot of pedal input to downshift b/c the throttle response is set very slow even in Sport or Track.

If it was the exhaust valve, then how come it does not do it when you traverse 1500 rpm in 1,2,3,4 gears? The problem happens w/ high gears right?

My car does not do this anymore b/c After I installed a vitesse throttle controller the throttle response is very aggressive and a small pedal input produces the downshift. The TCM has learned that driving mode. It took a lot of traversing that range for that shift to get smoother, but it finally responds fast, smooth and no noises.
 

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I started posting questions about this noise in Feb 2016 as I was driving home from Kerbeck in Atlantic City, NJ with our new car and it started at about 40 miles. Been doing it ever since.
I have post on this forum and Corvette Forum. BJones has the primary thread going which we are all using to contribute updates to on that forum.

Road surface does NOT affect whether or not I get the noise at 1500 rpm. I do not believe it has anything to do with tires.

Here's the video clip I've posted on both forums:


"Warble" noise heard on 2016 Corvette C7 A8 Trans. NPP Exhaust. Most noticeable at the 35 to 40 second mark, 1:09 to 1:18 min and 1:42 to 1:50 minute mark, and 2:35 to 2:42 minute. Can also be heard less noticeably through out when going up hill. Most always at 1500 rpm, regardless of V4 or V8 mode, or any other mode settings. Light pressure on the gas pedal.
 

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Manta C7

Actually, NO...... it will do it in 4th, 5th, 6th, 7th and 8th....... but I haven't noticed it below 4th gear. It may do it @ 1500 rpm in the lower gears, but I haven't noticed it. FOR SURE in 4th or higher.
 

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GM Executive Mgmt has contacted 3 of us to start lining up them sending Engineers from their Proving Grounds in to our local dealerships to determine Root Cause Analysis and a solution to fix this noise.

Those of you with this WARBLE type noise, stay tuned, as in the coming weeks we should have a better understanding of what is the actual cause, and hopefully a solution.

If you are experiencing this noise from the rear of the car at a steady 1200 to 1600 RPM with light acceleration, in any gear, or driving mode....Please reply back to this thread.....

See my YouTube video/audio clip shown on posting # 15 of this thread..... you can hear the sound.

We will update this as soon as we get data in the coming weeks.

thanks,
Richard
 

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I am glad that GM is taking this very seriously, and working on finding the root cause and some corrective action.
 

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I started posting questions about this noise in Feb 2016 as I was driving home from Kerbeck in Atlantic City, NJ with our new car and it started at about 40 miles. Been doing it ever since.
I have post on this forum and Corvette Forum. BJones has the primary thread going which we are all using to contribute updates to on that forum.

Road surface does NOT affect whether or not I get the noise at 1500 rpm. I do not believe it has anything to do with tires.
"Warble" noise heard on 2016 Corvette C7 A8 Trans. NPP Exhaust. Most noticeable at the 35 to 40 second mark, 1:09 to 1:18 min and 1:42 to 1:50 minute mark, and 2:35 to 2:42 minute. Can also be heard less noticeably through out when going up hill. Most always at 1500 rpm, regardless of V4 or V8 mode, or any other mode settings. Light pressure on the gas pedal.

I have a `15 Z06 w/A8 and mostly drive with M(manual paddle shifters). However, when I have used D (auto) I have noticed a light "rattle" (or flutter) at times when the engine switches to A4 at low 1500-1800 rpms. If I paddle to M it stops immediately.

http://www.stingrayforums.com/forum/stingray-corvette-problems-issues/22945-fluttering-noise-light-throttle-between-35-50-mph.html

Have you tried testing with the paddles only at same rpms?

I think my issue may be the "belt tensioner" issue that has a TSB out. I have not gone further as it is not leaking any oil, but it seems to have symptoms associated with that TSB.
 
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