40flier

First week production 2016 base, now 8K miles. Day one I heard soft thud sounds upon accelerating and to a lesser extent shifting which have become slightly louder. I think there is excessive backlash? Two dealer service managers have deemed it normal. Finally ran into a GM Milford Proving Grounds guy who knew exactly what I was describing, (reassuring to my mental health) routinely drives them there, and says some cars inexplicably make that noise and some don't. In his experience the condition has not manifested into anything worse, his guess is it is related to the dual disk clutch.

Anyone else encountered this situation?

Patches

I just had my '14 Z51 M7 with 31.5k miles looked at by the dealer for this while I was getting the air bag recall and rotor TSB done. They could not reproduce the sound/feel I described because it's intermittent on my car and not easy to recognize if you don't know exactly what to look for. I told them I would monitor it and bring it back in if it manifested into a worsening condition. It's a somewhat muted/subtle characteristic so you need the drive the car enough to recognize when it happens. Car drives perfectly otherwise.

40flier

Here goes nothin as they say... mine is not intermittent, imagine a half dozen golf ***** rolling back and forth in a 6" PVC pipe for a duration of 1+ second, emphasis on a mild booming hollow sound. Sometimes a lazy shift into 2nd will produce it. I cannot imagine how the clutch discs could produce it?

Patches

Holy crap! No, that's definitely not what I'm experiencing. No way I would consider that "normal". Mine has been driven fairly hard and raced at HPDE events several times in it's life and it feels normal except for that subtle, occasional tap in the driveline. I'm being picky here but yours definitely would have me at the dealer asking for a fix.

American Heritage

OP were you with the dealers when they heard it or did they tell you they heard it and it was normal?
Your description is not the norm.

40flier

At my local small town dealer I demanded the service mgr ride with me, he said it was normal from his experience with performance cars. Went in for keyless ignition fault and software updates to a mega chain Cadillac Taj Mahal dealer with a performance center, I was called in this time to ride with the service mgr who is a racer, saying it was normal. Damn, I was rubbing shoulders with Ken Lingenfelter Saturday at a show...