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Grinding Noise on Regeneration

Discussion in 'Model S: Driving Dynamics' started by ohmman, Feb 1, 2016.

  1. ohmman

    ohmman Maximum Plaid Member

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    I hesitate to wake this thread, but I just dropped my MS back in for semi-emergency service. A terrible grinding noise under regen, but completely silent during acceleration. SC thinks it might be a rock stuck in the rotor, and I'd definitely be relieved if that were the case. But it certainly sounded more like a drive unit issue - especially given the ability to modulate based on energy input. Some other issues so they're keeping it for a while. I suppose I'll find out soon - but I haven't heard this particular report before.
     
  2. supratachophobia

    supratachophobia Active Member

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    I've had that sound, can confirm rock between rotor and the vent shield.
     
  3. ohmman

    ohmman Maximum Plaid Member

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    That's very reassuring. Did it sound kind of like this? Note, I'm modulating it on purpose with regen.
     
  4. ecarfan

    ecarfan Well-Known Member

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    100% drive unit failure rate??

    That sounds like a wounded T. rex. [emoji6]
    Sounds mechanical, like something grinding against a rapidly rotating piece.
    Would you consider having a mod split this into a new thread? That noise is very different from the "whirring" cicada sound.
     
  5. ohmman

    ohmman Maximum Plaid Member

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    Perfectly fine with it. I probably should have waited to post until after I get a diagnosis anyway. It just freaked me out.
     
  6. supratachophobia

    supratachophobia Active Member

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    Mine was actually more high pitched, but it was a tiny rock. I can see it making that sound of there was a larger/flatter surface area to rub on.

    BTW, wounded trex, spot on.
     
  7. AmpedRealtor

    AmpedRealtor Active Member

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    And how, pray tell, would a rock get inside of the DU?
     
  8. ohmman

    ohmman Maximum Plaid Member

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    Not inside the DU. Inside the brakes.
     
  9. trils0n

    trils0n 2013 P85

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    Brake rotor, not the drive unit rotor. (Took me a sec to figure this one out)
     
  10. AmpedRealtor

    AmpedRealtor Active Member

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    Oh thank goodness! One less thing to worry about...
     
  11. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Hey pithecanthropus erectus:
    Did you try to back out the (possible) rock? Back-forth-back-forth, etc. Give it a good 15 feet each direction.
     
  12. ohmman

    ohmman Maximum Plaid Member

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    I did. I have yet to hear from my SC (as I mentioned, they were slammed), but will be interested if this is what was happening. I still don't get why regen would cause it to start - it would immediately kick in on the slightest of green, so I don't think it was the deceleration that somehow "threw" the rock back into place. I had another issue crop up a few days prior to the noise, which was that my suspension or alignment seemed to be off. The car would torque pretty hard to the left if I hit the throttle. SC thinks it's unrelated.

    I'll report back once I hear something.
     
  13. ohmman

    ohmman Maximum Plaid Member

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    It appears this is suspension related, and possibly some kind of driver error. :redface: They're continuing to look into it, but it could have been damage from snow chains. I don't exactly know how they can damage the suspension components, but that's what it looks like. We took the car over Donner Pass with z-chains this winter. We didn't exceed 25mph.. but I suppose it's possible something happened during that drive.

    The good news - drive unit looks fine. The bad news - a rock sounds a lot cheaper.
     

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