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Car brakes heavily around 5 mph

Discussion in 'Gen 2 Prius Main Forum' started by Jerry Ku, Aug 29, 2013.

  1. Jerry Ku

    Jerry Ku Junior Member

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    2005 Prius
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    One
    Hello,

    I have a 2007 Prius with about 68k miles on it. It was running fine since I got it 6 months ago. I've put about 5,000 miles on it since I got it.

    But now it seems to suddenly brake heavily whenever I slow down to a stop. So I will be going 40 mph... then brake... once it gets around 5 mph or so, the car's brakes will suddenly feel much heavier/stronger, so the car will come to a less smooth, more abrupt stop than usual.

    If I let my foot off the brake a bit before it gets to that point, I can usually avoid that heavy braking moment.

    Any idea what's going on?
     
    #1 Jerry Ku, Aug 29, 2013
  2. Britprius

    Britprius Senior Member

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    This can be caused by a number of problems.
    Number one is rusty discs (rotors). The reason for the sudden change in braking is that at speeds above 7mph the braking is done by regeneration of electricity, this is what slows the car down. Below this speed the normal brakes take over and rusty discs cause the brakes to grab.
    Another cause is air in the hydraulic system. This will need bleeding out.
    The final cause again is rust and poor adjustment of the rear drum brakes, "this is for North American Continent cars only" because the rest of the world get disc rear brakes.

    John (Britprius)
     
    #2 Britprius, Aug 29, 2013
    alekska likes this.
  3. nh7o

    nh7o Off grid since 1980

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    To continue John's post, the way to proceed is to get the car up to speed and carefully brake to a stop after switching the shifter to neutral. That forces the car to use the friction brakes only, and will clean the rust off the disks. You may want to do this in an empty parking lot or something similar.
     
    #3 nh7o, Aug 29, 2013
    drysider likes this.
  4. Kurzweil

    Kurzweil Member

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    Moisture will do it too. Lots of rain in Atlanta this summer.
     
    #4 Kurzweil, Aug 30, 2013
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