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[Resolved] My P85 has developed the milling noise and Tesla won't fix it.

Discussion in 'Model S' started by kenkamm, Sep 16, 2015.

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  1. Freudianly

    Freudianly Banned

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    I do not drive a car. I cannot stand the noise. I will buy one when I am absolutely sure it is silent in the long run, and with at least the autonomy of a Model S.
     
  2. AB4EJ

    AB4EJ Member

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    Does anyone have experience with what happens eventually if the milling noise occurs and then is never fixed? Does the gearbox eventually overheat and fail, or what?
     
  3. mknox

    mknox Well-Known Member

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    I believe it is an electrical sound, not a mechanical sound. Probably related to high amperage ac current causing a winding or something to vibrate. Tesla tells me it's a "cosmetic" issue, so I think they must agree. They hopefully wouldn't push off my repair if I was in imminent danger of having an outright mechanical failure.

    My first drive unit developed a completely different sound. It was a very loud, but low frequency hum that reminded me of standing next to a big power transformer. It only happened when power was applied, and not under re-gen or if I was coasting with the power meter near zero. They replaced that one right away. It never had the "clunk" between power and re-gen that my current unit developed.

    I think there have been mechanical failures, but they are very rare compared to this.
     
  4. Lyon

    Lyon 2016 S P100DL, 2016 X P90D

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    FWIW, these issues seem to be limited to vehicles with performance drive units. If you get a regular dual motor unit you should be fine.

    Also, I'm on DU 3 at the moment in my late 2012 P85. Only 23,000 miles on the car. So far so good with this one but the receipt they sent me indicated a remanufactured unit so we'll see. They're getting much faster at doing the swap though.
     
  5. apacheguy

    apacheguy S Sig #255

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    The milling noise affects base DUs as well.
     
  6. mknox

    mknox Well-Known Member

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    Yep. Mine is a base. Interesting though, Tesla told me that the problem is more aligned with Performance models. They said with a base drive unit, they may have a replacement for me sooner as a result.
     
  7. kenkamm

    kenkamm Member

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    No sir. This is clearly a mechanical sound. This is reinforced by the fact that Tesla sometimes refers to it as "bearing noise." It has a distinctly different sound from any of the electrical noises I've heard.
     
  8. Zextraterrestrial

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    yours may be.
    pretty sure the cicada (milling?) is electro-mechanical though, like a resonance that develops in the inverter.
     
  9. mknox

    mknox Well-Known Member

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    I wonder if we're talking about the same thing? Since the whole drive train is always connected and spinning, why, for example, do I only get the sound when under power and not when coasting or under re-gen if it is mechanical?
     
  10. yobigd20

    yobigd20 Well-Known Member

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    The "milling sound" is caused by a bearing that gets worn and goes bad. It does sound electrical though , like phone interference. Some describe it as cicadas. It's not a grinding sound. I don't know what "mechanical" would sound like. I'd describe the "clunk" issue more like a mechanical one.
     
  11. Zextraterrestrial

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    so how is a bearing dependent 100% on Kw power draw? there are 2 types of 'milling'
    I think the bearing issue is the Elon fixed w/ a shim one and the other is?? replace DU and hope it doesn't happen again too soon
     
  12. kenkamm

    kenkamm Member

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    Simple. A worn bearing develops slop. A sloppy bearing causes a variance between two gears, for instance. The distance between those two gears must be tightly controlled to remain quiet. The sloppy bearing allows the clearance between the gears to move away from optimum, and a noise results.
     
  13. mknox

    mknox Well-Known Member

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    Yeah, but why on a drivetrain with no clutch or torque converter that is solidly connected does it only occur when under power? On smooth, flat roads, I can turn it on and off like a switch with the accelerator pedal as I coast along. I do not get it all all under any level of re-generation. Wouldn't a mechanical noise be present whenever the whole mechanism is spinning?
     
  14. kenkamm

    kenkamm Member

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    As an example: When motor power is applied, the sloppy bearing allows the two gears' mesh to change unfavorably. Gears tend to want to distance themselves under power. If the bearing is allowing relative movement because it's worn, the gear mesh may part slightly, only under power. Gears like these need to be very carefully aligned to wear properly and remain silent. When motor power isn't being applied, the worn bearing allows the gears to mesh back together to proper alignment, and the noise goes away.

    Another example. These gears are spiral cut (like all modern transmission gears, because it's quieter.) Thrust bearings are required because the gears want to move axially under power. If it's a faulty thrust bearing, it will make noise when put under the stress of the pressure applied to it when the gears are under power from the motor.
     
  15. mknox

    mknox Well-Known Member

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    Fair enough... that does make sense. At least in my case Tesla has said they will replace my DU once they have parts and can schedule me in.
     
  16. Cyclone

    Cyclone Cyclonic Member ((.oO))

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    My non-Performance drive unit had the "milling" sound in low-power drive or regen. It was easier to reproduce for testing in drive though since I could "hold" power in the range needed than I could hold regen in that range.
     
  17. kenkamm

    kenkamm Member

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    Well I'll be darned. I just got a call from the Rockville MD service center (should I mention who called me?) and they explained that they want me to be happy with my car, and have scheduled me for a DU replacement at 9 AM on October 9th.

    I have to say, the Rockville guys have always taken care of me in the end. A couple of times it has taken a little bit of negotiation, but now that they have agreed to replace my DU I can say that they have addressed every concern I have had to date.

    Feeling much better now about my car and Tesla.
     
  18. yobigd20

    yobigd20 Well-Known Member

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    in the 3 or 4 DUs now that i've had that had the milling noise, one of which was EXTREMELY excessive, the milling noise NEVER occurred during regen. it was only when power was > 0kW
     
  19. KidDoc

    KidDoc Supporting Member

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    Here is a recording of my DU noise I recorded with windows down in a parking garage so you can really hear it fairly well. I just got a new DU last week and it works great.

    Tesla Model S new noise - YouTube
     
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  20. Gizmotoy

    Gizmotoy Active Member

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    Tesla seems either unusually proactive about this issue or worried about the public perception of it. If you post about a DU problem here, you pretty much always get a call from your SC (presuming they can link your username to real name). A week or so ago I mentioned that my clunking noise had started to return after being replaced and got a call... which reminds me, I still have to return their call. Whatever the reason, it's nice that they seem to care our issues are being resolved.
     

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