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Scoring on brake discs/rotors.

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

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  1. The Professor

    The Professor Senior Member

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    My Prius had its second annual service today. Everything was fine, other than they noted deep scoring on all 4 of my brake discs. See picture. I was pretty shocked at how bad and deep the scratches are. On all other cars I've ever owned, the discs are smooth. The discs also have a pretty deep lip on them (where they've not worn away). At this rate, I'll need replacements in a couple of years.

    For what it's worth, I'm a pretty gentle driver. I try to use regen for braking as much as possible, and brake very gentle unless it's an emergency.

    Any ideas what could be causing this and how to prevent it?

    I asked the guy at the dealership and he replied "It's because it's a hybrid. The Prius first uses engine braking to slow down, and then the gearbox. This heats up the brakes a lot and that's why you're seeing the scratches." o_O:confused: Fascinating...
     

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    #1 The Professor, Oct 3, 2019
  2. bisco

    bisco cookie crumbler

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    hard to tell, do they all look like that? if it was one, i could see a foreign object getting caught or something.

    how many miles on her? i am also a gentle brake, and they look good at 66,000. i wonder if they have changed materials?
     
    #2 bisco, Oct 3, 2019
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  3. davecook89t

    davecook89t Senior Member

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    Mine look nothing like that, probably because (likely) I have fewer miles. I also see some rust on yours. Do they use a lot of salt on the roads where you are in the UK?
     
    #3 davecook89t, Oct 3, 2019
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  4. hill

    hill High Fiber Member

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    if you bought the car used, it could be assumed the prior owner did a lot of hard braking & ran the pads all the way down until metal-on-metal was contacting. That's really the only way that rotors ever get that scored, other than poor heat treating of the rotors. Did the dealer take this picture? If so, and because his rationale was so false, I would suspect dishonesty at the service center. Other but of course - that never happens

    .
     
    #4 hill, Oct 3, 2019
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  5. The Professor

    The Professor Senior Member

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    Thanks or the replies...

    They all look that bad. 18,500 miles. 2 years old.

    During the winter months, yes. But there hasn't been any salt on the roads here since maybe last March.

    It's an ex-demonstration car bought directly from the dealership. It had, I think, 1,600 miles on the clock. Pretty sure it's the original pads as they still have 10mm on the rear and 8mm on the front (12mm when new I think?).

    I took the picture.
     
    #5 The Professor, Oct 3, 2019
  6. bisco

    bisco cookie crumbler

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    hmm... ex demo, that might explain it. any idea if they were inspected prior to purchase?

    did they give you pad measurements?
     
    #6 bisco, Oct 3, 2019
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  7. davecook89t

    davecook89t Senior Member

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    Ok, not many miles on your car either. The rotors on our Gen 2 look better than that, and it has 278k miles. I know the pads were changed on our car right before I bought at 211k, but there is nothing on the invoice about the rotors. I don't know what advice to give you. Maybe others will weigh in.
     
    #7 davecook89t, Oct 3, 2019
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    How are the pads? :confused:
     
    #8 Mendel Leisk, Oct 3, 2019
  9. The Professor

    The Professor Senior Member

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    They look ok. Still plenty left.

    I wonder if it's environmental. I do travel along a gritty/sandy/dusty road at the top of a big hill quite often. Maybe stuff is getting jammed between the pads and the discs...
     
    #9 The Professor, Oct 3, 2019
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  10. The Professor

    The Professor Senior Member

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    They didn't give me pad measurements when I bought it, but it's 10mm at rear and 8mm at front at the moment. That was from the service but I've measured them with calipers just now and it's correct. They appear to be wearing evenly.

    The thing is, I don't recall seeing this scoring before. I'm sure around a year ago when I was having the tyres replaced the discs were fine. It also wasn't noted in the previous service.
     
    #10 The Professor, Oct 3, 2019
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  11. ChapmanF

    ChapmanF Senior Member

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    To my eye that looks both scored and very shiny/glazed, as if the brake was dragging. They typically last a long time, but some oddball problem can sometimes crop up between inspections, and do some damage unexpectedly quickly.
     
    #11 ChapmanF, Oct 3, 2019
  12. bisco

    bisco cookie crumbler

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    this sounds plausible. have you, ever since purchasing?
     
    #12 bisco, Oct 3, 2019
  13. The Professor

    The Professor Senior Member

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    Have I ever what? :D
     
    #13 The Professor, Oct 3, 2019
  14. bisco

    bisco cookie crumbler

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    been going over that hill?
     
    #14 bisco, Oct 3, 2019
  15. The Professor

    The Professor Senior Member

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    Yeah, weekly
     
    #15 The Professor, Oct 3, 2019
  16. bisco

    bisco cookie crumbler

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    maybe that's not it then
     
    #16 bisco, Oct 3, 2019
  17. alanclarkeau

    alanclarkeau Senior Member

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    Sounds like the dealership chap needs to study LOGIC - that made no sense.
     
    #17 alanclarkeau, Oct 3, 2019
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  18. alanclarkeau

    alanclarkeau Senior Member

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    There was another member a few months ago - she had much the same problem, can't recall the outcome?
     
    #18 alanclarkeau, Oct 4, 2019
  19. kithmo

    kithmo Couch Potato

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    The glazed look on those look like the brakes have been overheating, maybe binding. What's the fuel economy like, any change in the last 12 months ?
     
    #19 kithmo, Oct 6, 2019
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  20. The Professor

    The Professor Senior Member

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    They are shiny indeed. Getting about 60 over last month. That's very normal. Felt discs just now immediately after a 1 mile journey and they're cold.
     
    #20 The Professor, Oct 6, 2019
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