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Scoring on brake discs/rotors.

Discussion in 'Gen 4 Prius Main Forum' started by The Professor, Oct 3, 2019.

  1. ice9

    ice9 Active Member

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    If it's just your rear wheels, that could be your parking brakes.
     
  2. sam spade 2

    sam spade 2 Senior Member

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    BAD advice, based only on that picture.
    NO....no warranty possible on brake wear in general.
    The real bottom line is:
    I think based on all that he SAID, that his rotors are perfectly normal.
    Most ALL will be shiny and many will show uneven groves due to uneven pads.
    Uneven groves is QUITE different than SCORING.
     
  3. bisco

    bisco cookie crumbler

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    really? it seems you're the only one (n)
     
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  4. Striker325

    Striker325 Junior Member

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    Vehicle currently has 28,000 miles. I believe something got stuck like debris on both rear rotors causing the uneven wear. It's not bad but visible and uneven enough to feel it as you run your finger on the rotor surface.
    I can take a picture and post it. My solution at the moment is just wait until the pads are worn out to get new ones and get the rotors then resurfaced.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    No one's done a rear brake job though? That can screw them up; don't ask me how I know... :oops:
     
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  6. kithmo

    kithmo Couch Potato

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    A fault with the ABS unit could be something that could cause all 4 brakes to be affected.
     
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  7. The Professor

    The Professor Senior Member

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    I'm not noticing anything weird, such as friction noises, scraping noises, squeaks, etc. Fuel economy is normal. Discs are cold after a typical drive.

    They're less shiny this morning. I guess they just looked polished in the picture as they're recently been used quite hard.

    The only thing I've ever noticed (and it's been doing this side I purchased it) is that the brakes do let out a brief quarter second vibration/groan just as you're coming to a stop and I'm reducing the brake pressure to reduce the jolt, but I doubt that's the cause as it's it's probably only doing it for 1/8th turn on the wheels every time I come to a complete stop, and the brakes are being pressed very gently (barely pressed at all).

    Does anyone else's make that noise?
     
    #47 The Professor, Oct 8, 2019
    Last edited: Oct 8, 2019
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  8. bisco

    bisco cookie crumbler

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    that might be the friction brakes kicking in around 6-7mph?

    without having other prius experience, its hard to know what's normal and what isn't
     
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  9. The Professor

    The Professor Senior Member

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    No it's at the very end of the friction brakes kicking in... Going maybe 0.5 mph. It's the brake pads vibrating against the discs, making a musical note.
     
  10. bisco

    bisco cookie crumbler

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    that doesn't sound normal, but may be due to the state of the rotors. or perhaps something defective in the calipers?
     
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  11. Striker325

    Striker325 Junior Member

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    Can you perhaps get it on video of the noise to get an idea. I'd recommend using compressed air and brake cleaner to remove any debris from all four brakes and apply a light coat of brake lubricant on the parts that move.
     
  12. The Professor

    The Professor Senior Member

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    Here's a video of it. I'm deliberately releasing and activating the brakes in a way that produces the sound. As I'm pointing downhill your also hear the noise on release of the brakes. Or appears to be just the brake pads resonating against the discs. It only happens if I press the pedal just hard enough to make contact.

     
  13. The Professor

    The Professor Senior Member

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    imgur DOT com/a/8Jrz6SC
    ...Looks like the website breaks the URL.
     
  14. sam spade 2

    sam spade 2 Senior Member

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    Of those who have commented maybe.
    But that does not necessarily make it wrong.

    More information is needed.
    Wild guesses usually aren't really helpful.
    Yes, really.
     
  15. sam spade 2

    sam spade 2 Senior Member

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    That does NOT by itself indicate a problem.
    Many/most/all disc rotors will display some rippling of the surface as they wear.
    That is because of an uneven composition of the pads.
    In general, the better the pads, the less rippling.
     
  16. sam spade 2

    sam spade 2 Senior Member

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    You are just FULL of bad advice on this subject. :(

    If you have a light enough touch with your foot, you can make the disc brakes on almost ANY vehicle squeal or chatter slightly when just barely moving.
     
  17. kithmo

    kithmo Couch Potato

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    That doesn't sound normal to me, it may be that the pads are glazed too.
     
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  18. sorka

    sorka Active Member

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    Mine had no ripples or grooves at 300K miles on my gen II prius. I just replaced the original pads, front rotors and rear drums.
     
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  19. Mendel Leisk

    Mendel Leisk Senior Member

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    I'm seeing/hearing it ok now, and that sounds fishy. Maybe mechanic from the dealership can test drive?
     
  20. hill

    hill High Fiber Member

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    of COURSE you didn't have such dynamics. Anyone with relatively moderate breaking skills can keep Prius rotors/pads for an easy 6-figure amount of miles. But there's no point in giving experiential advice really - after post #42 - as there will always be somebody here that will countermand 38yrs experience in the electro/mechanical aerospace field, w/out so much as a fraction of a basis why they would make such irrational notions.
    Rotors with visible grooving as in the pic above - means that they are likely as deep as .015" which in some states, by law you have to either resurface or junk 'em. There are lateral irregularity regulations as well in many areas. The batch of metal (alloy) may be flawed, or incorrectly heat-treated. That may be why on the other thread, Toyota was quick to do a replacement on another's Prius regardless of warranty.
    .
     
    #60 hill, Oct 8, 2019
    Last edited: Oct 8, 2019
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