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I thought we had antilock brakes

Discussion in 'Model 3: Driving Dynamics' started by Nikola M3, Jul 2, 2018.

  1. Nikola M3

    Nikola M3 Member

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    I was driving 45 - 50 today in the left lane passing a very large truck, when he suddenly moved into my lane, either he did not see me or was pre-occupied. In any case i hit the brakes hard to fall behind him and the wheels locked and I skidded. It felt like the back is what locked up but I can't be sure. Has anyone else had the wheels lock up?

    skid 1.jpg
     
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  2. Daniel in SD

    Daniel in SD Active Member

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    That seems bad. Have you tried to use them again? If the problem is repeatable it should be easy to diagnose. Make sure no one is behind you!
     
  3. S4WRXTTCS

    S4WRXTTCS Active Member

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    Maybe this whole updating the ABS through a SW update wasn't such a good idea afterall. :p
     
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  4. richrootes

    richrootes Member

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    Did you feel the brake pedal oscillate under your foot?
     
  5. Daniel in SD

    Daniel in SD Active Member

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    This is a lot better than the other possible failure mode!
     
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  6. S4WRXTTCS

    S4WRXTTCS Active Member

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    This does bring up a good experiment for us to do.

    We know ABS is designed to prevent full lock up, but does that mean that it's not possible to lay some tread down while braking?

    ABS has been around for a long time, but I constantly see brake trails like this. So what causes it?

    Is it because it pulses so quickly that you're still going to get some tread laying down, and you visually can't see where it releases?
     
  7. Daniel in SD

    Daniel in SD Active Member

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    I think there are still a lot of cars and trucks out there without ABS. I drive one :eek:.
     
  8. Skysurfer

    Skysurfer Member

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    Yes, the Model 3 certainly has ABS. Haven't needed to do a full panic stop but have had the ABS kick in when one wheel hit a patch of gravel.

    What is with the burn out picture in the right lane?
     
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  9. Nikola M3

    Nikola M3 Member

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    After it slid I wanted evidence to show the SC, I went back and took this photo of where the tires locked. Not a burn out.
     
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  10. Nikola M3

    Nikola M3 Member

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    I had this happen last week but I had hit the brakes when in I went into (sand on pavement) on the side of the road, That time it also slid but I had discounted it because of the surface.

    Today was a real panic stop on hard surface. I did not feel a pulse but it did stay straight.

    I will report back when I get some feedback from the service center.
     
  11. PhilDavid

    PhilDavid Member

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    I think that was probably Traction Control or Dynamic Stability Control where momentary brake application is performed on individual wheels. To really notice the benefits of ABS you need to do a panic stop and the key benefit being the wheels should not lock up.
     
  12. Daniel in SD

    Daniel in SD Active Member

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    You don't have to panic though, just press hard on the brakes and the ABS will activate :p
    If the wheels lock up, there's a loud screeching noise and there's a lot of smoke your ABS is broken and you've probably flat spotted your tires. If the ABS is working you will feel a pulsation in the pedal and hear the solenoids modulating the brake pressure to all the wheels.
     
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  13. PhilDavid

    PhilDavid Member

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    So if you don't feel the solenoids, then you panic? :p
     
  14. Daniel in SD

    Daniel in SD Active Member

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    Haha. Then you let off the brakes so you don't flat spot your tires. If your OTA firmware update failed and your solenoids are stuck open, disabling your brakes, then you panic :p
     
  15. silentsnow31802

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    Wait... if you were in the left lane why are the marks in the right lane?

    Also those do seem like acceleration marks to me. They are dark at the start and get lighter as they go on.
     
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  16. alcoolaid

    alcoolaid Member

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    Fake news? Fake pic? lol
     
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  17. Gen3

    Gen3 Member

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    ABS is designed to allow you to STEER, because the front wheel will steer a lot better when not locked. If you want to stop the fastest at the limits of traction, you will lay down rubber.
     
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  18. Nikola M3

    Nikola M3 Member

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    Good catch, I didn't even notice that. It is a typo. I tried to edit in the original post but it won't let me.

    I was in the RIGHT lane, the marks ARE from my car and they ARE from braking.
     
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  19. JohnSnowNW

    JohnSnowNW Active Member

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    Are Tire Marks Still Useful with ABS Systems? - CED BLOG

    Granted the beginning of the skid marks are darker than the above description seems to imply, but the idea that ABS equipped vehicles do not leave skid marks is incorrect.
     
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  20. Daniel in SD

    Daniel in SD Active Member

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    The static friction (sticking) of a tire is a little bit higher than the dynamic friction (sliding) so the ABS system try to keep all the tires right on the verge of locking up. A properly functioning ABS system should not lock up any of the wheels. Maybe some of the older system did? But all modern ABS systems are 4-channel so that they can control braking to all the wheels.
    ABS leaves very faint marks and you should also see the pulsation in the mark. When you use ABS you can hear that it is skidding a little bit it sounds nothing like fully locked brakes. The marks in the picture do acceleration to me or maybe braking in the opposite direction coming to a full stop. I'm not an accident reconstruction expert though...
     
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