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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.
     
    • Disagree x 1
  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 Well-Known 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 Well-Known 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.
     
  14. mikeulrich

    mikeulrich New Member

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    Wondering what the ouctcome was. I just had the same thing happen tonight. Loud grinding noise on regen breaking.
    Thanks
     
  15. ohmman

    ohmman Maximum Plaid Member

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    Ah, sorry I didn't wrap this up. It was a suspension component and it was caused by my use of chains on the vehicle. IIRC, it cost me something like $1200. And I've never put chains back on the car or taken it into winter conditions. We use the X for that.
     
    • Like x 1
  16. scottm

    scottm Active Member

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    The clearances between tire and suspension parts is so slim... I can see chains f*ing up a few different things pretty fast.

    The ball joint on the front upper A-arm is right over the tire with not much room to spare... When you're driving on chains they fly up and rise off the tire and would whack that thing..

    Bolts on the lower front hub/knuckle holding on the suspension arms are scant distance away from the inside of the rim... you can't a finger width in there...

    Someone on here posted pix of using chains that almost sawed off suspension arms they interfered with...

    eek! this car is not meant for chains.
     
  17. mikeulrich

    mikeulrich New Member

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    Thanks!
     

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