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Whine from back end (plus poll)

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  • Whine from back end (plus poll)

    Hi, all - Having an issue with a speed-dependent whine from rear end which I get once the vehicle has been driven a bit, from 5-10 miles. Basically what happens is that starting at about 37 mph under very light acceleration or steady speed, I get a whine which from 37-40 mph also has a sort of grinding sound, which to me sounds similar to what you'd hear when you get a duplicate key made--i.e., not good.

    From there it goes to a whine which increases with speed, again under very light acceleration or steady state speed (it is pretty sensitive to throttle position), all the way up to about 55 or so mph, at which point it used to more or less disappear, but lately it just gets much much more faint above 55 but can still be heard.

    The pitch of the whine does not change if I select a different gear, so definitely not in the gear set. It varies only with vehicle speed. It goes away if I either lift off throttle or apply it with more pressure or disengage the tranny by pulling both paddles simultaneously. It returns if I go back to steady state or very light acceleration. It's loud enough between 37-55 mph to be heard even when radio is on at moderate volume. Here are two PDR videos of it that I took last week with commentary:
    https://vimeo.com/496485103
    https://vimeo.com/496485254

    Running into issues getting dealer to take it seriously. Their Service Manager insists it's "normal" and doesn't seem to want to take it any further. He based this analysis on driving a C8 owned by a co-worker a full 10 days after he drove mine, not exactly the best way to go about this to put it mildly. He filed a TAC with Chevrolet Tech only after I pushed him on it, but he basically gave them a ridiculously soft-pedaling one sentence description (customer states slight whine, when in fact I'd told him it was loud and annoying, and no mention of grind below 40 mph). They too came back with "normal behavior", but this was based upon an inaccurate description, without them actually hearing it. So to me, it being "normal" sounds unlikely as so far I've yet to see anyone posting here about this sort of thing other than me, and plus as much trouble as they took to make this thing very quiet in tour mode, I doubt this would have made it past the NVH team...

    But anyway, I figure if this is normal, lots of people here should be experiencing it too, so figured I'd go ahead a post a poll. Would really appreciate it if you could respond so I can see if this is, in fact, "normal" for this car. If you try to duplicate it, remember that at least for me, it needs to be driven from 5-10 miles before the noise becomes prominent. Thanks in advance!
    32
    Yes, my C8 has this same whine in rear end once it's warmed up
    31.25%
    10
    No, my C8 does not have this same whine in rear end once it's warmed up
    68.75%
    22
    Last edited by improviz; 01-05-2021, 11:03 AM.

  • #2
    Any chance you can record it and post it here?

    Comment


    • #3
      Originally posted by ABorC View Post
      Any chance you can record it and post it here?
      Hi, I did post two links in my post to PDR vids I took last week. Are they not working? Thanks

      Comment


      • #4
        Originally posted by improviz View Post

        Hi, I did post two links in my post to PDR vids I took last week. Are they not working? Thanks
        whoops, i didn't see them... my bad.

        Comment


        • #5
          I didn't see if you indicated, so I'll ask, do you have a Z51 optioned Stingray, or the base model? Your description sounds like it could be something amiss in the differential/rear end. Have you asked to have the differential fluid level checked? Sounds like it's something that's related to putting a load, even slight, on the drive train. Suggest you have the service manager ride with you and take it for a drive to demonstrate the full range of noise coming from the rear of the car.

          Comment


          • #6
            Originally posted by jovette View Post
            I didn't see if you indicated, so I'll ask, do you have a Z51 optioned Stingray, or the base model? Your description sounds like it could be something amiss in the differential/rear end. Have you asked to have the differential fluid level checked? Sounds like it's something that's related to putting a load, even slight, on the drive train. Suggest you have the service manager ride with you and take it for a drive to demonstrate the full range of noise coming from the rear of the car.
            Hi, I do have a Z51. I'm not sure if they checked diff fluid when I took it in, they did not give me any indication of it nor so state on the ticket. Yes, service manager did ride with me when I brought it in and take it out for a drive after that with a tech.

            Comment


            • #7
              Sounds harmonic. Reminds me of some early torque tube issues on the C7. Seems if its related to speed and not RPM could it be more on the axle?.

              Comment


              • #8
                so what did they say/determine? Did they tell you it's normal?

                My C5Z had diff whine when you were cruising, but at tip in and under load, it went away. It was far less after a Diff re-build. The eLSD is a non-serviceable item, so if there's something amiss back there, it's likely going to need replaced.
                Not saying it is...but if it is the Diff, that's someting you want addressed. You don't want the thing locking up on you on the highway or something.
                Brian Huber
                Previous Corvettes
                2002 Z06 - SCCA autocross car - 58SSR ( Sold 4/20 )
                2003 Vert - Wife's stress relief/therapy car ( Sold 7/20 )

                2021 Coupe Black #6936 - Natural two-tone. 2LT, Mag-ride, NPP, Edge Red Calipers. NCM delivery ( Status 3000 as of 1/11/21 , 3300 as of 2/16/21, 3400 as of 3/9/21, 3800 as of 3/15/21, NCM Delivery 3/29)

                Comment


                • #9
                  Occasionally I hear some odd sounds from this car, for example when I park it it after driving, the rear end "burps" several times. It's a hollow metallic pinging sound, sounds like metal contracting or something, it doesn't bother me.

                  Comment


                  • #10
                    Originally posted by AverageVetteNut View Post
                    so what did they say/determine? Did they tell you it's normal?

                    My C5Z had diff whine when you were cruising, but at tip in and under load, it went away. It was far less after a Diff re-build. The eLSD is a non-serviceable item, so if there's something amiss back there, it's likely going to need replaced.
                    Not saying it is...but if it is the Diff, that's someting you want addressed. You don't want the thing locking up on you on the highway or something.
                    Yes, they're telling me it's normal based upon a comparison of my car with another, which they drove literally 10 days apart. Not exactly the most sound way of performing such an analysis.

                    Agree 100%, this is a potentially serious and dangerous issue, and that's what bugs me: they're acting like it's a squeaky brake rotor.
                    Last edited by improviz; 01-05-2021, 01:00 PM.

                    Comment


                    • #11
                      Recommendation since you and your dealer seem to be at an impasse. Please read your Owners Manual specially page 302 which is entitled “Customer Satisfaction Procedure.” Then in writing, still being polite, follow each and every step sequently, documenting every one. Do not deviate from a single direct appeal step.

                      Best of fortune.
                      GBA Black; HTO Twilight/Tension interior; Z51 & Mag Ride; E60 lift; 5VM visible carbon fiber package; 5ZZ high wing; FA5 interior vis CF; ZZ3 engine appearance; 3LT; Q8T Spectra Gray Tridents; J6N Edge Red Calipers; SNG Edge Red Hashmarks; VQK Splash Guards; RCC Edge Red engine cover; VJR illuminated sill plates. Lifetime, annual contributors, and 23 year members of National Corvette Museum. Home is the beautiful Pacific Northwest.

                      Comment


                      • #12
                        Thanks so much, John. I'll reach out to them one final time and if they're unwilling to address this issue, will go from there.

                        Comment


                        • #13
                          Is it possible for you to try another dealer for another opinion?

                          Comment


                          • #14
                            Originally posted by improviz View Post
                            Thanks so much, John. I'll reach out to them one final time and if they're unwilling to address this issue, will go from there.
                            And politely let them know you will. "You now have left me no recourse....."
                            Murray - Uxbridge, Ontario, Canada
                            2020 Torch red Stingray coupe, Adrenaline red 2LT Q8Q E60 NPP
                            Deposit: July 30/19, 1100: Sept 15/19, 3000: Feb 14/20, TPW WAS May 18, August 24 and lastly July 27,
                            3300: July 15, 3400: July 22, 3800: July 30, 4200: Aug 06, 5000: Aug 7, 6000: Aug 12!

                            Comment


                            • #15
                              improviz said "The pitch of the whine does not change if I select a different gear, so definitely not in the gear set. It varies only with vehicle speed. It goes away if I either lift off throttle or apply it with more pressure or disengage the tranny by pulling both paddles simultaneously. It returns if I go back to steady state or very light acceleration."

                              I listened to your videos and I have only heard this sound from a ring and pinon in the rear end, another car not a Corvette, that had to much play in it. If you hold the throttle steady=no sound, but either lightly on or off the throttle makes the same sound from the backlash between the two gears.
                              2020 1LT |Torch Red/Black | MSRP $59,995 | DOB=8/31 | Home on 9/24.
                              Splash Guards, Cargo Nets, All weather Jake Floor Mats and Cargo Area Liner, and Front Grille Screens behind grilles.

                              Comment

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