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Scoring on brake discs/rotors.

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

  1. alanclarkeau

    alanclarkeau Senior Member

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    Video is working OK.

    Have you talked to TOYOTA or the dealer?

    It sounds like just one wheel - or something totally different. If it was all 4, it would be odd that they're all doing it at exactly the same moment. Could it be a Brake Master Cylinder or one of the many valves in the system?
     
  2. bisco

    bisco cookie crumbler

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    just one squeaking, but all four in the same condition?
     
  3. CooCooCaChoo

    CooCooCaChoo Senior Member

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    Do you remember having to brake hard in the Prius prior to noticing the scoring on the rotors? This may have something to do with it because of the design and utilization of the mechanical brakes in the Prius.
     
  4. alanclarkeau

    alanclarkeau Senior Member

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    Just thinking laterally - someone already mentioned parking brake. But brakes are used (or implicated) in many operations on PRIUS. Just as a distraction, the brake pedal needs to be pressed before <POWER>, or gear selection.

    But brakes are used by Traction Control and Stability Control. If you've got DRCC - linked to brakes, as does AEB and the Clearance SONAR. Hill Start Assist uses brakes too.

    Not that any of those (apart from SONAR) should be in operation in the video - but the computer could be confused. The diagram of the Master Cylinder shows 32 valves, sensors and moving parts!!!

    You haven't had any malfunctions showing up in the Data Recorder?
     
  5. The Professor

    The Professor Senior Member

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    It's the front 2 brakes making the noise. Pretty sure it's making the noise in the same way a bow of a violin does.

    No error codes at all.

    I have had to brake hard a few times in the car, sure. For example, just last week I was doing 70mph and an incident appeared (traffic stopped for debris on the road) and had to very hard brake down to around 5 mph. That sort of thing has happened a few times since owning the car. Could that, combined with the way brake pads are constructed, account for it?
     
  6. alanclarkeau

    alanclarkeau Senior Member

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    I doubt if the occasional hard braking would do that - I've had a few similar ones with no ill-effects.
     
  7. Harters

    Harters Active Member

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    Mine make exactly the same noise and have from day one and my disc and pads look totally fine. I have just clocked up 11,500 miles.

    I can't comment on your scoring/appearance of your discs, but I have had that kind of noise on all my recent new cars and have just accept it as normal due to the type of pads used now a days. Come to a stop with a very light pedal at the end and it makes the noise, but brake firmer and there is no noise. The "the the same way the bow of a violin does" is a very good description.

    Attached are a couple of photos I have just taken now of my front offside side.

    [​IMG]

    [​IMG]

    I hope this helps.
     
    #67 Harters, Oct 9, 2019
    Last edited: Oct 9, 2019
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  8. The Professor

    The Professor Senior Member

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    Thanks. That does help.

    I'll keep a close eye on the discs, maybe get them independently checked by someone I trust just to be sure.

    At the end of the day they work very well at stopping my car, but with a wife and 2 kids I don't want a small brake issue becoming a big one right when I need them.
     
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  9. Harters

    Harters Active Member

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    This may help too, it should take you to the right part 7:07, I remember it made me chuckle when I first watched it.

     
  10. bisco

    bisco cookie crumbler

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    how does the vpns apply?

    does he really think that is the brakes?
     
  11. alanclarkeau

    alanclarkeau Senior Member

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    That's an awful noise - or has he amplified it.

    Not sure how authoritative he is - mention of "The Exhaust Valves are made of Sodium". I hope not Ugggh.

    upload_2019-10-9_22-59-17.png

    Na is highly flammable. And as for salt??? He needs to keep away from chemistry, leave it to the experts.

    [The valves are likely "sodium filled" - which run cooler due to better thermal management - and is technology which has been around in cars since before I was born, and in aircraft in WW2.
     
  12. Harters

    Harters Active Member

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    Mat is usually pretty knowledgeable but it does seem that he has got some of his facts skewed, but I zero knowledge in the subject :oops:

    I can make ‘Percy’ do very similar to what he is showing if I try, but not as dramatic so it may have been amplified as you say.
     
    #72 Harters, Oct 9, 2019
    Last edited: Oct 9, 2019
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  13. sam spade 2

    sam spade 2 Senior Member

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    Given that one picture as the only real "evidence", it means no such thing.
    That is still just a guess and it needs further inspection.
     
  14. sam spade 2

    sam spade 2 Senior Member

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    Yes. And "it" still might not be a real problem.
     
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  15. The Professor

    The Professor Senior Member

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    Thanks for the input all.

    I agree. It's only a problem if something is wearing out my discs super quick, or impacting safety, or some other annoyance.

    All I can really do for now is get them checked and keep an eye on them.
     
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  16. sam spade 2

    sam spade 2 Senior Member

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    And as you proceed with this please remember:
    Brake shops are in business.......TO SELL BRAKES.......whether they really need attention or not.
     
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  17. The Professor

    The Professor Senior Member

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    Absolutely. Yeah the person I have in mind is a friend.
     
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  18. Tande

    Tande Active Member

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    Good! .......no need to ask the fox if the chickens are OK!........
     
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  19. Elt31987

    Elt31987 Active Member

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    Almost sounds like the hill start assist is holding you in place even on flat ground. Possibly a problem with the sensor that monitors the pitch/angle of the vehicle? Is there a little bit of resistance when you apply the pedal?
     
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  20. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Can you activate hill assist on the level? I'm thinking you can. Easy to test.