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I'm new to ABS

Discussion in 'Gen 2 Prius Main Forum' started by mywhitenoise, Mar 21, 2007.

  1. mywhitenoise

    mywhitenoise New Member

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    I was wondering if this was normal because of the Brake Assist, VSC, or ABS. The car brakes fine if i'm coasting at several hundred feet from the stop, and slightly press on the brake until it gradually hits 0. Now when I coast and i'm getting close to a stop sign, and the speed is down to about 7-3 mph, I brake a little harder (because i'm used to this) all of the sudden it's a very sharp stop that rocks back, and kind of makes a sharp noise. Is this normal with ABS? Seems like it brakes a little too hard and sharp for that speed.
     
  2. efusco

    efusco Moderator Emeritus
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    I don't think it has anything to do w/ABS. It sounds like you're experiencing the transition from regenerative braking to friction braking. There's usually a slight 'give' at 7mph as regen drops out. If you're applying brakes a bit more firmly you may feel the friction brakes catch a little.

    If it's dramatic you can have it checked, but I suspect it's just a normal thing you're noticing b/c of your gentle braking.
     
  3. SomervillePrius

    SomervillePrius New Member

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    What efucso said. It's a quirk of the regenerative breaking system. Regenerative breaking is a great feature where energy that would otherwise be lost to friction in normal break pads and are instead stored into your batteries.

    The problem is that as you get down to low speed the car can't rely on regenerative braking alone so it switches to normal friction brakes (like the ones in a normal car). This transition can be felt, more so in a new car. It might be stronger if you increase the brake pressure just as the system is switching. It shouldn't be a sharp transition (but can be felt) in normal cases. If it is I would have it checked. In my car with 12000 miles it is barley noticeable, but I could feel it more before.
     
  4. qbee42

    qbee42 My other car is a boat

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    The transition is noticeable, but it should be fairly smooth. I feather the brakes a bit when I get to the transition point at about 7 mph, which is something I would do anyway with a normal car.

    Tom
     
  5. Texas911

    Texas911 Member

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    I've had my Prius for 3 weeks now and you get used to it and actually anticipate it to stop smoothly. Come to think of it, I find myself trying to coast as much as possible, to try and charge the battery. I think I'm getting Prius fever.
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Also remember to lift up slightly just before you come to a stop to "catch" the suspension rebound and avoid your head flinging backwards into your seat when the car stops.
     
  7. redrockprius

    redrockprius redrockprius

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    <div class='quotetop'>QUOTE(Tideland Prius @ Mar 21 2007, 12:19 PM) [snapback]409663[/snapback]</div>
    Huh? Didn't Newton say something about objects in motion tending to stay in motion in the same direction? If you (and your car) are moving forward and the car stops, wouldn't your head continue in a forward direction instead of "flinging backwards"?
     
  8. redrockprius

    redrockprius redrockprius

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  9. redrockprius

    redrockprius redrockprius

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  10. GeekEV

    GeekEV Member

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    <div class='quotetop'>QUOTE(RedRockPrius @ Mar 21 2007, 01:49 PM) [snapback]409770[/snapback]</div>
    Huh? Didn't Newton say something about not posting the same thing 6 times? :lol:

    j/k - I realize that was probably some sort of malfunction... I just had to do it anyway.
     
  11. redrockprius

    redrockprius redrockprius

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    <div class='quotetop'>QUOTE(Mr. Zorg @ Mar 21 2007, 03:27 PM) [snapback]409782[/snapback]</div>
    My sincere apologies to everyone on the forum. I attempted to post the message but kept getting an error message that there were too many users. I assumed that the post had failed. I had no intention of posting the same message more than once. When I returned to the site a few hours later, I discovered that what I thought had been failed attempts to post had apparently been stored and posted later.

    By the way, I was not able to figure out how to completely delete the extra messages. All I could do was to delete the content of the messages. Is there a way to completely remove a message?
     
  12. Tideland Prius

    Tideland Prius Moderator of the North
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    <div class='quotetop'>QUOTE(RedRockPrius @ Mar 21 2007, 06:15 PM) [snapback]409900[/snapback]</div>
    No, the mods will delete it.


    Yes.. but spring has a spring constant and thus will rebound if compressed. Not to mention your seatbelt also has a 'rebound'