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Brakes Stutter right before the car stops.

Discussion in 'Gen 2 Prius Main Forum' started by lowspeed, Mar 6, 2006.

  1. lowspeed

    lowspeed Member

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    Our new 06 prius sometimes doesn't stop smooth when it reaches the 2->0 Miles an hour. I thought that maybe the brakes need to brake in ... but we now passed 1000 miles.


    What could cause this ? should i take it to the dealer ? or time will fix it ?


    ** Attention **

    I really think this happens in a very limited amount of cars. maybe less than 1%, and i think only 06's

    I want to start a VIN# collection. Maybe we can find a pattern.

    Please send at least your VIN # and name to [email protected], you may also include a phone number, but that's optional.

    If we get enough people participating i will be able to at least contact Toyota's president office to get this escalated.
    Thanks!
    P.S only cars that have the "before stop stutter"... AND PLEASE read the entire thread to make sure your problem matches these symptoms.
     
  2. jared2

    jared2 New Member

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    Maybe the breaks need to brake in. Ask the dealer to give you a brake. Or a break as the case may be.
     
  3. modernsituations

    modernsituations New Member

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    Yeah i get that same thing...i'm at 700 miles. It does it just how you describe. Anyone else have a similar issue that was resloved or know if this is normal? :eek:
     
  4. aaf709

    aaf709 Ravenpaw of ThunderClan

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    What is it exactly? Is it a shudder? Is there a sound like a squeal? When it happens, is it always when the engine is warm or cold (or at both times)?
     
  5. modernsituations

    modernsituations New Member

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    It's kind of like something is gripped and then released with a low grunt everytime you step on the breaks coming to a stop. I thought it was a cold engine thing, but i've noticed it happens both times. It's pretty strange...and i don't like it...
     
  6. unruhly

    unruhly New Member

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    Mine does this as well. Not too sure why, but I know it's normal 'cause I test drove three different cars. Heres my take.

    As you slow down, the majority (if not all) of the braking is being done by the motor. As you reach about 8 MPH the amount of drag from generating power falls off, so the computer has to estimate how much pressure to apply to the brakes to finish stopping the car.
    Almost simultaneously, as the brakes are being applied by the computer, you are letting up on the brake pedal for a smoother stop. This end up letting too much pressure off of the brakes as the computer will try to stop smoothly by itself.

    I have tried steady pressure on the brake pedal, and it does stop much smoother, but gives a jerk at the very end. I've noticed too that the "let off" feels like it happens on the left wheel, then the right wheel causing a sort of rocking motion.

    It sure would be nice to have a theory of operation manual. Does anyone know if one exists?
     
  7. lowspeed

    lowspeed Member

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    Exactly... i didn't have that on my 2004 prius.
     
  8. lowspeed

    lowspeed Member

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    It's not normal... it happens way after the mechanical breaks are already in use.

    Right before the car stops.
     
  9. aaf709

    aaf709 Ravenpaw of ThunderClan

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    Well, there's the 5 Stages of Hybrid Operation. I was trying to see if it was the shudder that happens sometimes when stopping.
     
  10. Airgetlam

    Airgetlam Junior Member

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    I'd hazard a guess that there may be an issue with the anti-lock brake sensor.

    Not happening on my 2005, for sure. Although I do get annoyed when accelerating from a stop over gravel and the car decides I'm on ice and reduces engine power.....
     
  11. lowspeed

    lowspeed Member

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    I does feel like its letting loose and then gripping again. I thought maybe the rotors need a little rubbing to breakin ... but it seems like thats not the case.

    One thing though... it doesnt happen all the time. I would say 50%-75%
     
  12. unruhly

    unruhly New Member

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    I meant that I believe it to be a "normal side affect" of computerized braking.
    In other words... Poor programming or limitations that can't be overcome?

    Don't get me wrong, I'm quite annoyed with this too and have thought about calling the dealer about it. It's just that I know what they are gonna say "It's the way the system works." but I would really like to know why.
    I guess it's my computer technical background with a hobby of fixing cars that gets me obsessing over things like this.

    BTW; Mine is very consistant with this happening.
     
  13. lowspeed

    lowspeed Member

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    But like i said ... i had a 2004 and that did not happen.

    Also its purely mechanical at that point... (well there is break assist) but its no longer using regenerative breaking. (that stops around 6mph as far as i recall, and i can tell when its only mechanical)
     
  14. Rancid13

    Rancid13 Cool Chick with a Black Prius

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    Here's another recent thread that may have something to do with what you're experiencing with your brakes.
     
  15. unruhly

    unruhly New Member

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    If it is "Purely Mechanical" at that point, then it must be the anti-lock brake system causing it. ABS was my second thought but only because of the sound it makes when it happens.
     
  16. MBranstein

    MBranstein New Member

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    Mine does the same thing - I have always figured that it was the brakes grabbing right at the end of a stop.
     
  17. lowspeed

    lowspeed Member

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    Crap it looks like a wide spread problem ....

    MODS can you merge these threads?
     
  18. V8Cobrakid

    V8Cobrakid Green Handyman

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    mine does it too.. my guess is since all generators and anything else causing drag basically let go around 8mph.. it all goes to the breaks. If you do an emergency stop, around 5mph, the wheels lock up... unless you're on ice or other slippery condition.

    but the "let go" i think is when the generators literally stop turning with the wheels and start creating the "idle"... so you start to get force with the car instead of against it.
     
  19. lowspeed

    lowspeed Member

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    Then you're not having the same problem.

    I'm only talking about right before it stops. when you slide into a stop before a red light or a stop. right when the car almost stops at 1mph it will stutter and let go a little then stop.

    If you have a problem in the transition between the regenerative and the mechanical breaks open i a new thread.
     
  20. chich2000

    chich2000 Junior Member

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    I have noticed it in mine too. I figured it was the elec. motor supplying power to the wheel (creeping) and the brakes at the same time trying to slow the car down at such slow speed.... But now I starting to thing it is something else.. and I am kind of confused? :unsure:

    I tend to remove the pressure on the brake pedal as I come to a stop. That is why I think this happens, but I could be wrong?? Does any of this makes sence to anyone? :D