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When my brake pedal travels to the floor...

Discussion in 'Model S: Driving Dynamics' started by Todd Burch, Nov 1, 2012.

  1. Todd Burch

    Todd Burch Electron Pilot

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    In my current car (automatic transmission), if I step on the brake and the pedal goes to the floor (yikes!), I can grab the handbrake and pull it, also shifting into 1/2 for additional engine braking.

    What do I do in the S? No handbrake, no emergency footbrake. Where's the backup brake in the Model S? Not sure if regen is enough to qualify...
     
  2. doug

    doug Administrator / Head Moderator

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    Flintstones stop?
     
  3. EarlyAdopter

    EarlyAdopter Active Member

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    Touchscreen->Parking Brake ?
     
  4. Doug_G

    Doug_G Lead Moderator

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    Shouldn't happen in the first place. Cars have two independent hydraulic systems going to opposite corner wheels. If this happens you've probably been ignoring a nice big red warning light on your console for far too long.
     
  5. Todd Burch

    Todd Burch Electron Pilot

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    Thanks. I'm feeling a bit stupid now. How long have cars had independent hydraulic braking systems?
     
  6. hcsharp

    hcsharp Active Member

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    The Model S actually has a completely separate hydraulic e-brake that is separate from the dual opposing-corner system. It even has it's own caliper and pads. It is activated by a control on the touchscreen. I have a similar concern about how you modulate the amount of e-brake you want to apply. For example, is the touchscreen control a large button or a slider control?
     
  7. Doug_G

    Doug_G Lead Moderator

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    Longer than I've been driving cars. Here's a typical "dual diagonal" system (diagram from here):

    i23997.gif
     
  8. NigelM

    NigelM Recovering Member

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    Yes.

    It's a huge button.
     
  9. doug

    doug Administrator / Head Moderator

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    Are you sure it's hydraulic? I'd guess its operation is binary, rather than something you can modulate.
     
  10. ahimberg

    ahimberg Member

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    I once had the brakes go completely unresponsive in my prius (pedal all the way down doing nothing -- felt like all the pressure went out of the pedal). turning off the car and back on brought it back, and luckily when it went out I was going uphill at an off-ramp that naturally slowed me enough to have time to think. (of course engine break mode and emergency brake near at hand there too...)
     
  11. Doug_G

    Doug_G Lead Moderator

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    It's electric, not hydraulic.
     
  12. cinergi

    cinergi Active Member

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    I don't believe the Model S e-brake can be used above 5 MPH. And there's no modulation that I'm aware of. I haven't tested either of these yet :smile:
     
  13. NigelM

    NigelM Recovering Member

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    I was told it can be used as an emergency brake. Press and hold until you come to a stop.
     
  14. strider

    strider Active Member

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    You just put the Model S in park and it will apply the e-brake and bring you to a stop.
     
  15. hcsharp

    hcsharp Active Member

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    I was told by a Tesla tech (which may or may not make it accurate) that it is hydraulic. The hydraulic system is activated by an electric actuator of some sort. He also said they have to flush the e-brake lines along with the regular brake lines at prescribed intervals. Accurate? Don't know. But this I know to be true: You can definitely use it at any speed as it is designed to be used as an emergency brake, not just a parking brake. This was confirmed by Tesla in public comments to the NHTSB.
     
  16. Sig698

    Sig698 Model S Sig Perf #698

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    This is what my delivery specialist told me as well. Hold the park button down and the vehicle will come to a very abrupt stop, but will not lock up the wheels.
     
  17. Doug_G

    Doug_G Lead Moderator

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    IMG_1399.JPG

    There it is. That sure looks like an electrical cable, not a hydraulic line. Also the engineer present (this was the Fremont factory event) said it was electric.
     
  18. EarlyAdopter

    EarlyAdopter Active Member

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    Ah, that looks like the same sort of servo actuated parking brake as on newer Audi's.

    At a high performance driving school I had an instructor pull up on the electric e-brake on my S4 while I was turning on the skid pad, hoping to lock up the rear wheels and induce a spin on me. The car just slowed itself down quickly to a stop, perfectly controlled while still turning. :)
     
  19. hcsharp

    hcsharp Active Member

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    Thanks Doug for confirming that! Sorry for the wrong information that I was given. The good news is that we don't have to flush an extra set of brake lines.
     
  20. cinergi

    cinergi Active Member

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    You can hear it actuating when putting the car in park. It sounds like it's screwing down onto the rotor.
    Some day I'll try the e-brake when it's safe to do so ...
     

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