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Brakes Grab When Wet

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by Oldwolf, Jan 11, 2016.

  1. Oldwolf

    Oldwolf Prius Enthusiast

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    I had a situation that when the brakes where wet (from rain), and not heated up from use, they would grab on the first few applications. I assumed it was the rear shoes grabbing, since they would nearly lock up, but that did not turn out to be the case.
    The front rotors had an odd wear pattern and the dealer said it looked like something had been sprayed on them. The wear pattern was causing them to brake too heavily under certain conditions.
    I have never sprayed anything on my rotors and overall the car has been driven very easily.
    Anyway, they turned the rotors as a solution. Seems to have corrected the problem in the short term.
    Although I think I am beginning to feel the same grabbing occurring again, time will tell.
    I had to pay for the turning (not covered by my 100k mile warranty), but I am wondering if the rotors will be found to be defective.

    I am not the first to report this problem.
     

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  2. maddog61

    maddog61 Junior Member

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    2012 prius c... I replaced my frt. rotors and brk pads at 60,000km. The rotors were badly rusted and worn, with inside brk pads worn down . Brakes must have been sticking from all the salt used during winter months. Rotors and brk pads are not usually covered.

    I watched a utube video on frt brakes and changed them myself, was fairly straight forward. I found gold colored drilled rotors and ceramic pads in Amazon for $190 Canadian. Good luck
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    If one pad's wearing more than the other it could be sticking caliper pins, in need of relube.
     
  4. ChapmanF

    ChapmanF Senior Member

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    Ohh... Oh, dear, dear, dear. From the sound of it, this is total, indisputable proof that ... you're driving a Prius.

    You're posting about one of the best known sort of endearing quirks the Prius has always had, entirely because it makes such light use of the brakes, they don't dry readily as you pull away after being parked in the wet. Every Prius generation back to Gen 1 has been known to do this, and the solution is really, really simple. If you've been parked in damp, and you are pulling away, and you notice the brakes are noisy and/or grabby, shift into neutral, brake gently two or three times, shift back into D, and notice that the brakes are quiet and smooth again. That's genuinely all there is to it. It gets to be completely second nature.

    Any amount that you spend on "fixing" it is both useless and unnecessary, because it doesn't indicate anything needing to be fixed, and any mechanic who accepts your money to "fix" something for it, instead of just showing you how to shift into neutral and brake a couple times, had better be completely ignorant about this basic Prius fact, because otherwise it'd be kind of unscrupulous.

    You can find postings about it on PriusChat going as far back as you care to search. It has to be one of the best-known things about the car. Yet somehow the word still doesn't get out well enough to new owners, and too many people do end up spending unnecessary money thinking the brakes need to be fixed, or making NHTSA safety reports about it, etc. I'm not sure how to spread the word better.

    The strange wear pattern on the front rotors is also a thing that can happen, though it isn't the cause of the damp grab/noise issue, it's just another thing. Usually seems to happen on the inboard rotor surface (where it is hardest to see to check, of course). A good check is most easily done by unbolting the calipers and lifting the rotors off. If it is bad enough you can have them turned on a lathe, but if caught earlier, a vigorous circular motion with some 150 grit wetordry paper is all you need to clean them up. You'll be confirming free motion of the slide pins at the same time. Adds a few minutes to a tire rotation once a year or so ... seems to be often enough.

    -Chap
     
  5. maddog61

    maddog61 Junior Member

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    caliper pins had lots of lube
     
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  6. cutter44

    cutter44 Member

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    I learned about this "feature" shortly after buying my Prius C and subsequently joining this very forum. Now, first drive in the morning, I usually approach my first stop in neutral and apply the brakes. By the next stop, there's no grabbing. I forgot to mention this to my wife when I let her borrow the car one day and she came back saying "Wow, your brakes grab a lot more than mine do!"
     
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  7. XRinger

    XRinger Member

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    Thanks Chap,
    I read about this fluke a while back, but just plain forgot.. Now I can stop asking my wife if she remembers what I told her (last year?) about the brake-grab problem..
     
  8. Yup, been doing this in moderation (well, rarely, on an "as I feel that I really need to" basis) since I saw this a few years back. It sounds grindy until dry.
    The thickness of my pads just went from the green category to the yellow category on the dealership's scale at the end of last year.

    Actually when they're wet, a light tap on the brakes at slow speed and it's like the car suddenly slows. When dry, it's more normal.
     
  9. Oldwolf

    Oldwolf Prius Enthusiast

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    Neither my Gen2 or my V do this.
    Just my C.
     
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