2010 brake system

Discussion in 'Gen 3 Prius Technical Discussion' started by bwilson4web, Jan 30, 2010.

?

Details on braking anomoly

Poll closed Feb 13, 2010.
  1. Happens in the beginning of braking

    19.4%
  2. Happens after braking for a bit

    79.1%
  3. Had a load in back of Prius

    1.5%
  4. No significant load in Prius

    70.1%
Multiple votes are allowed.
  1. qbee42

    qbee42 My other car is a boat

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    If the brakes were not applied, the car would not accelerate, but would continue at the same speed. Losing braking action in no way causes a car to accelerate.

    Tom
     
  2. cpatch

    cpatch New Member

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    Given that a large number of people who are experiencing this problem describe the car as accelerating it's at least worth noting that because you are going from a state of negative acceleration to one of zero acceleration the perception is that you're accelerating (you are, in fact, experiencing a positive change in acceleration).
     
  3. Twidmer1970

    Twidmer1970 New Member

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    Yeah- my complain is stick brakes in reverse. It likes to lurch at times. Not bad, but annoying.
     
  4. qbee42

    qbee42 My other car is a boat

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    The acceleration at that point is zero. The change you describe is the first derivative of acceleration, which is often referred to as "jerk". You could accurately say "the car jerked forward", but you could not accurately say the car accelerated. There is no change in velocity. Acceleration is the first derivative of velocity, which is zero in this case - no acceleration.

    Tom
     
  5. Nic

    Nic Junior Member

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    maps.google.com/?ie=UTF8&ll=42.690957,-71.214151&spn=0.001149,0.002462&t=h&z=19

    The above URL hopefully shows the location. It is a left turn I do everyday, just before it there is a bit of a bump on which the brake issue happens - i.e. as I slow down to brake, go over the bump the car kinda 'jumps'. The first time was scary but I do this everyday and it happens every day and I've got used to it.

    One additional piece of information that may be relevant is that the car when I first got it had to have a front end alignment.

    Let me know if you need any more information.

    PS: URL is posted in an odd way to work around the posting issue.
     
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  6. bwilson4web

    bwilson4web i3 and Prime

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    Thank you Nic,

    Here is the URL:
    Google Maps

    I take it is the left turn lane on Shattuck Rd? Your headed north and trying to make the left hand turn?

    There is no Google Street View. IF you get a chance, a digital photo would work great. Shoot me an e-mail and I'll reply so you can attach the photo. I'll contrast stretch (improves fine detail), resize to 640 width and add it to the collection.

    This is the type of helpful posting that lets us get a better definition of the anomaly.

    Thanks,
    Bob Wilson


     
  7. Nic

    Nic Junior Member

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    Yes it is a left turn from Shattuck Road. (Similar to the arrow painted on the road.) I'll post a picture within a day or two.
     
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  8. buzzard767

    buzzard767 New Member

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    I hate to be such a dork, but deceleration is merely reduced. It is not zero as the effects of pavement/wheel friction and wind direction/velocity are still in play. :)

    I've experienced the brake problem twice in 6000 miles. Until Toyota gets the fix in, if you're a tail gater, you're asking for trouble.

    Buzz
     
  9. MD_Silver

    MD_Silver New Member

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    Brake problem is a little disconcerting, but very minor for me, 10,000+ miles and we have only had this a few times when the vehicle is transitioning from regen braking to friction braking.

    Most of the time I brake very gently, try to almost never use the friction braking until I'm going less than 5 mph.

    Car is safe for me, as was my 2004 Prius that did not seem to have this same effect, probably because the regen braking was not used as much.

    Lots of Prius-haters out there in SUV land, most of them just don't understand how the car works.
     
  10. Joe166

    Joe166 New Member

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    That is a true statement, regardless of whether Toyota gets any fix in or not.

    I am constantly annoyed at people who tailgate me and appear to have the attention span of a gnat because they are too busy doing something besides driving.
     
  11. qbee42

    qbee42 My other car is a boat

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    Absolutely correct. Compared to the effects of braking, those other factors are lost in the noise.

    Tom
     
  12. pulley

    pulley New Member

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    I am trying to get a handle on the brake problems discussed.
    I have 5500 miles on my 2010 V. Last month I drove from Virginia to Arizona with approx. 500lbs load plus one passenger. Drove
    through rain and some snow, for the most part interstate driving,
    some mountian, mostly flat and 65 to 80mph with no issues that
    I can identify.
    This being the first hybird I have driven and first front wheel
    drive. The Prius for me has so many noises at different time
    and it certainly doesnt handle like any other vehicle I have driven.
    So far, I am 100% satified. Even the interior comfort (I am 6'6")
    and have plenty of space and comfort.
    pulley

    2010 Prius V
     
  13. freo-1

    freo-1 New Member

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    Very good point! Up here in New England, it is a all too common occurrence.

    By the way, why is this issue focused on the Gen III? I thought I read somewhere that Toyota changed the brake system on the Gen III (to make it more conventional) from the Gen II.

    Can anyone here shed some light on this?
     
  14. adrianblack

    adrianblack Member

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    Excellent work gathering up info Bob.

    I've personally never experienced this and have even tried to reproduce it by intentionally hitting potholes and manhole covers while braking...

    Could another possible factor be tire inflation pressure? Perhaps an over or under inflated tire could cause it to bounce more and trigger the skid control ECU to think there is an issue? (I keep my tires at the recommended PSI -- in the low 30's)

    OR perhaps we should look at the tire brand. Maybe one brand resonates over bumps sending bad data into the speed sensors. (I'm grasping here ...) I have Avid S33's FWIW.
     
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  15. jeffreykb

    jeffreykb Junior Member

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  16. adrianblack

    adrianblack Member

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    Top selling car in Japan?? WOW!

    Anyway, I hope this "fix" does not reduce regen braking. If that's the case I won't be taking my car in for (most likely) software fix...
     
  17. Earman

    Earman CDN Prius III Technology Blue

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    I do have the breaking problem over bumps on my 2010 Prius.

    In Vancouver (BC) it happens every time I brake when reaching the intersection of E King Edward Avenue and Kingsway, coming from the West. Of course it happens at several other places but that's where I can consistently demonstrate it. 1 or 2 persons in the vehicle nothing in the back. Speed is relatively slow as I am coming to an intersection.

    My daughter has also experienced the same problem several times while driving to work everyday in her own 2010 Prius (purchased 1 month before mine) and it also happened at the same location as well. The road there has a bit of a ripple pavement.

    Nothing dramatic, just a weird feeling which makes both of us uneasy.
     
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  18. bwilson4web

    bwilson4web i3 and Prime

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    Is this the right area?
    E King Edward Avenue, Kingsway, Vancouver, BC - Google Maps

    Bob Wilson
     
  19. ePrius

    ePrius Member

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    I have about 3000 miles on mine and have not encountered this problem.

    Loving every minute!
     
  20. Earman

    Earman CDN Prius III Technology Blue

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    1 person likes this.
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