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Finally experienced brake anomaly; possible reason?

Discussion in 'Gen 3 Prius Main Forum' started by Texas911, Jun 2, 2010.

  1. Texas911

    Texas911 Member

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    So I finally got the brake release thing while braking and hitting a bump. Funny thing is that it only happened this past couple of weeks. I wonder if the hotter summer temperature is causing it? I haven't adjusted my tire pressure yet, but if its like my other cars (with psi readings in the instrument panel) then the pressure has increased. I wonder if there is a corollary with higher tire pressure and the activation of the "release". I know that its popular to have tire pressures increased for mpg here on PC. Just thinking out loud.
     
  2. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Reason: Unsmooth pavement, VSC kicked off the regen braking

    i.e. normal.

    Generally higher pressures can cause the stability control to act up more frequently, so reducing your pressures might help reduce the occurance.
     
  3. dogfriend

    dogfriend Human - Animal Hybrid

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    Potholes cause it.
     
  4. qbee42

    qbee42 My other car is a boat

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    Yes. With higher tire pressure you are more likely to lose traction over a bump. Higher pressure makes a tire bouncier, and less likely to absorb energy and conform to the surface.

    Tom
     
  5. ajc

    ajc Member

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    i.e. normal :confused: How is that normal? :rolleyes:
     
  6. qbee42

    qbee42 My other car is a boat

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    He meant ABS, not VSC. ABS activation from loss of traction is normal. That is what ABS is designed to do.

    Tom
     
  7. ajc

    ajc Member

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    ABS or no ASB when you put your foot on the brakes you are to stop not go forward.
     
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  8. dr_d12

    dr_d12 Member

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    ^^
    For some drivers, ABS leads to a false sense of confidence. ABS is safer than no ABS under most road conditions, but you still have to be in control of the car, and not expect it to safely drive itself no matter how fast you're driving and turning under less than ideal conditions.
     
  9. usbseawolf2000

    usbseawolf2000 HSD PhD

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    or stick with the recommend tire pressure. pun intended.
     
  10. Texas911

    Texas911 Member

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    If normal, then why did I only start experiencing it lately? Its no big deal for me anyway, it wasn't the acceleration everyone was crying chicken little about, but I can see how it would freak out some people. Just seeing if lowering the tire pressure to recommended levels would help alleviate this.
     
  11. Codyroo

    Codyroo Senior Member

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    I experienced my first "brake" incident over the weekend. It was in an area where they are doing road construction, and as I was slowing down through an intersection, the car went from the untouched asphalt to the construction area. The rate of deceleration changed for a split second. By the time I processed what happened, the incident was over. Although it doesn't get icy in Pleasanton, I can appreciate the description of "black ice", the car just felt like it slid for about 5 feet (the deceleration change). I was still slowing down, just not as fast.

    I can see where people would think that they had lost braking or were accelerating for that instant. Best advice is to brake earlier and don't tailgate.
     
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  12. justlurkin

    justlurkin Señor Member

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    Remember that when your tires are brand new, they are at their grippiest. Once they are broken-in, that initial super-grippiness goes away, which means the Antilock Braking System will kick in more often to protect the regen braking system when it senses a loss of grip when going over a pothole.

    The momentary ABS-induced interruption of regen braking is a predictable behavior you can learn to compensate for. Initiate braking a bit earlier, and if you encounter the bump-induced momentary regen-braking cutout, press the pedal HARDER to bypass regen braking and engage the friction disc brakes.

    If you understand the phenomenon and know how to deal with it, this braking behavior is NOT an issue.
     
  13. silentak1

    silentak1 Since 2005

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    I experience this strange thing (that I'm going to assume is normal): Sometimes when I'm lighting pressing the brake and press it harder, it feels like the car doesn't really apply braking force, as if the power braking was not assisting. So I have to let go of the brake and re-press it again and then feel the some real braking power.

    It's kind of like when your engine is not on and you press on the brake while the car is moving...the brakes are being applied but you have to press the heck of it to have some real braking power. Again, i'm going to assume that this is all normal unless anyone else cares to explain? And no, i have not flipped to the braking section of the manual.