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Shuddering When Coming Out of Turn

Discussion in 'Model S: Driving Dynamics' started by Chasedrgc1223, Aug 26, 2015.

  1. Chasedrgc1223

    Chasedrgc1223 Nearly Insane

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    I have an 85D and for a while now I've been getting an inconsistent shudder or shake when I accelerate hard out of a turn and straighten the wheel. This does not seem to be related to recent software updates, unlike the 3-4 mph shudder issue, and I've brought it up to service. Just curious if anyone else has experienced this.
     
  2. NigelM

    NigelM Recovering Member

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    There's a whole bunch of not so fun reasons and best to have service look at it. I did have a similar thing about a year ago when one of the (21") wheels had become slightly egg shaped after hitting a pothole a little too hard.
     
  3. pax

    pax Member

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    I might be having this issue and service has not been able to figure out what is wrong; they have had it twice. They replaced the right rear shock / strut but that made no difference.

    Mine will shudder under hard acceleration from 0-5mph and shudder for a second or so. The amplitude of the vibration varies, when it is maximal it rattles something in the car. It does it in straight line acceleration but I have noticed it is more pronounced if accelerating out of a turn, say a highway onramp.

    Car is at the SC now and I don't think they have a solution. They balanced and rotated tires which is nice but in my opinion not likely to be the root cause of the problem.

    - - - Updated - - -

    Sorry forgot to say, P85D may delivery (so the lame suspension).
     
  4. Chasedrgc1223

    Chasedrgc1223 Nearly Insane

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    The P85D just got the .46 update today, which fixed the low speed shudder at around 5 mph for the other D's. My issue seems to be coming out of a turn and up until around 40-45 mph, and keeping constant acceleration. It seems to be more pronounced when the suspension is on high mode, which makes me believe this is a hardware issue. However, the low speed shudder did feel like the shudder I am experiencing at higher speeds. Perhaps the motors get slightly out of sync when turning and applying heavy acceleration, as I believe the motors being out of sync was the issue for the low speed shudder. Let us know what happens when you get your car back!
     
  5. David99

    David99 Active Member

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    could it be the traction control kicking on when the tires lose grip? You say it happens when accelerating hard coming out of a turn. That's usually the case when the tires start to lose grip. The traction control reduced power quickly which regains grip but that causes a very noticeable jerking of the car.
     
  6. pax

    pax Member

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    Thanks for your comments David99 and Chasedrgc1223.

    I am not sure we have the same issue so let me describe my situation a bit more carefully. Here are the conditions:

    1. Starting from very low speed 0-5 mph. It won't do it if starting from higher speed, presumably because the torque is highest at lower speed.
    2. Hard acceleration. It will do it in both sport and insane modes but more easily when in the insane.
    3. It happens launching straight or while turning slightly. I can make it do it on demand; it is not sporadic.
    4. Pretty much instantly the car will shudder. I think the source is in the rear of the car but its hard enough vibration that something in the cabin will rattle. SC thinks they fixed the rattle BTW.
    5. It shudders for about .5-1 second at what I guess is 600 Hz (wild guess on the frequency, about 10 cycles per second). I will try to measure this, the iPhone sensors might be able to pick this up.

    @Chasedrgc1223: Is your shudder similar to this?

    @David99: I think you might be right about traction control. I had discarded that theory because I thought the frequency was too high but since its an electric motor I suppose it is possible. My P85D came with the 245 contis in the rear, if it is traction control I wonder if more rubber would fix it.

    Will definitely let you know what happens when I get the car back.
     
  7. Chasedrgc1223

    Chasedrgc1223 Nearly Insane

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    I've watched to see if the traction control light came on and nothing.
    @pax it sounds pretty similar to your issue. If it's not the motors our of sync, maybe it is somehow related to a small degree of torque steer when the motors are distributing power, though I doubt it because torque steer feels different than this. Could you try replicating the issue with range mode on first and if that doesn't solve it try with and without creep mode. On my 85D, the low speed vibration did not occur at all with range mode on, but was 100% replicatable without it. Turning creep on made the problem replicatable about 75% of the time, though it was much less prominent.
     
  8. pax

    pax Member

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    @Chasedrgc1223: Good suggestions, will try those variations and post results as soon as I get my car back from SC.
     
  9. pax

    pax Member

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    I still don't have my car back from the SC. It has been 11 days. However, I got a call today and they said they fixed it by replacing the front motor mount. I am picking it up tomorrow.
     

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