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Whine from back end (plus poll)

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  • #46
    Hi Sabre, it’s a coupe, Z51, mag ride.

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    • #47
      I did the Spring Mountain school 3/8-3/9 and asked every instructor I could tackle if they have experienced a whine in the transmission of any of their C8s. Not one of them said they had heard it, even though some of them drive C8s to work and back. As for the C8 I drove, I couldn’t hear much because I was always wearing a helmet.

      I will pursue my issue with the local dealer and then up the ladder, if necessary.

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      • #48
        Good luck!

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        • #49
          Originally posted by improviz View Post
          Yes, as mentioned on the other site, it has developed a very slight whine above 50 mph in the last 100 miles or so. I just crossed 500 miles, but I'm still gonna granny-drive it for a few hundred more to give it all the time in the world to break in gently. Right now it's very slight, but it has gotten more noticeable as I accrue miles (deja vu), so let's see how it does over the next few hundred miles. Keeping fingers crossed.
          Just wanted to add a final follow up: the slight whine I noticed after the transmission replacement seems to have been a temporary phenomenon. I gave it a full break-in period after the installation, and so far it's been picture perfect. So while I'm not particularly thrilled with the tranny having to be replaced on a new car, I'll chalk this one up to a Tremec issue that GM, after some prodding, took care of. They did have to fix one thing: the exhaust. They hadn't put it back in place correctly when they put the new tranny in, and it was giving me some rattling noises and a very weird sound at startup.

          So I am happy to report that it is running like a top and driving like a dream. Hoping for a trouble-free ownership experience from here on out.
          Last edited by improviz; 06-30-2021, 11:09 AM.

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          • #50
            Originally posted by improviz View Post
            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!
            My 2022 has gear whine at higher speed, ~60-65 mph, loudest at about 63. Like yours, it is road speed dependent, presumably from the final drive.

            2022 LT2, Elkhart Lake Blue, Natural
            Ordered September 2020, Delivered, October 2021

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