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Noise during hard braking?

Discussion in 'Gen 3 Prius Technical Discussion' started by jayvee, Oct 9, 2009.

  1. jayvee

    jayvee Member

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    I have noticed a somewhat strange sound upon moderate to hard braking, such as coming to a stop coming down a steep hill, or on more sudden stops. The only way I can describe it is the sound of thick rubber on metal - kind of a very short, low pitched "groan" or "grunt".

    It happens just before the vehicle comes to a complete stop. For this reason, I suspect that it might be the regenerative braking disengaging right before the vehicle fully stops.

    Is anyone else experiencing this type of noise? I have no history with previous gen Priuses, so I'm not sure if this is normal for the regen brakes.

    Thanks!
     
    #1 jayvee, Oct 9, 2009
  2. djasonw

    djasonw Active Member

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    I think what you may be hearing is precisely what you described. It is more pronounced in the pre 2010 models. When you are slowing down normally and then get to say 10mph or so there seems to be a sensation of secondary braking power. The noise you may hear is the transition from regenerative to the actual standard brakes kicking in. Please correct me if I'm wrong.
     
    #2 djasonw, Oct 9, 2009
  3. jayvee

    jayvee Member

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    Thanks for the reply - It doesn't occur when I'm moving that fast (although I think I know the sensation you describe) - it's only in the last foot or two before the vehicle is completely stopped. I'm going less than 1 mph at that point.
     
    #3 jayvee, Oct 9, 2009
  4. Bobsprius

    Bobsprius BobPrius

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    Jayvee,

    I believe the sound your hearing is what you have described. There are a lot of "New" sounds you will eventually aclimate to in time, once you have heard them. But the sound that you describe sounds to be the Regen Braking taking place before Friction Brakes are in full swing. It's doesn't sound abnormal to me. You can learn a lot as well by watching your monitor and seeing your in regen with the recharge in the monitor...
     
    #4 Bobsprius, Oct 9, 2009
  5. jayvee

    jayvee Member

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    Thanks Bob,

    See my last post - it isn't when the regen brakes engage (at speeds >5 mph or so, as you describe) - it seems to be when they are releasing, a fraction of a second before the vehicle has come to a complete stop. (Think of the sound of a metal bumper car glancing off a rubber bumper on the track. Sorry, trying to find a way to describe this sound...) That's the sound, short and low-pitched, and right before the vehicle stops. It really sounds a bit concerning - but it may be totally normal sound when the regen brakes disengage during hard braking....
     
    #5 jayvee, Oct 9, 2009
  6. Bobsprius

    Bobsprius BobPrius

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    Sounds like your trying to describe a "groan" of the brakes, or RUBBING sound...Hmmmmm I have not noticed it my 2010, but then again, I have not experienced the backup brake issues. Do you think it is something with the Discs and needing adjustment??? I believe I understand now what your hearing I will have to listen to mine as well. Do you notice this with windows open and between cars/buildings to hear the resounding noise, or do you actually hear it in your car???? Do you feel you are applying the brakes hard or more moderate in the last seconds? I wondered since I will try it with my car on the way to work this afternoon and see if I can reproduce. I will also try in the lot tonight and let you know...
     
    #6 Bobsprius, Oct 9, 2009
  7. jayvee

    jayvee Member

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    It's not a "rubbing" or "groaning" sound - it's a short burst (0.1 second or so) - and almost a rubbery "clunk" sound (man, this is hard to describe... maybe I will try to post an audio file of the sound.....hmmm...) And yes, it really only is present at the very end of moderate to hard braking. Windows closed, I hear it IN the car. Sounds like it's coming from the engine compartment or the brakes.

    I honestly don't think it has anything to do with the discs. It's not a metallic scraping or rubbing sound. It actually sounds a bit like loose/damaged engine mounts used to sound in older cars. But I don't think that's what this is - I'm sure the engine mounts are nothing like they used to be. Like i said, this might just be what the regen brakes do at the end of hard braking.

    Anybody else hear anything like this?
     
    #7 jayvee, Oct 9, 2009
  8. qbee42

    qbee42 My other car is a boat

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    This is what Bobsprius is saying. You may want to reread his posts.

    Tom
     
    #8 qbee42, Oct 9, 2009
  9. jayvee

    jayvee Member

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    Well, I thought I did read his posts carefully. They said this:

    My sound takes place long after the friction brakes are fully applied. The vehicle is at almost a dead stop. And:

    It is neither groaning or rubbing. It's a short burst of sound. Can you tell me what you are suggesting I'm missing in Bob's response (which I very much appreciate, by the way!)

    Thanks!
     
    #9 jayvee, Oct 9, 2009
  10. maxjlone

    maxjlone New Member

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    I have 9,200 miles on my 300C Heritage and while at the Dealer (my Dealers name has changed, still selling DCX) getting my free oil change I told the Service guy I had a grind/clunk noise when brakeing, got the 23 point inspection, they found nothing, no charge.
     
    #10 maxjlone, Oct 17, 2009
  11. bobbilr

    bobbilr New Member

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    I get a dull thumping sound from the rear of the car as it comes to a complete stop.Only happens during a fast stop. It sounds like something has shifted. Checked the spare and what I could see of the battery. All looked good. Don't know but it is something that is not right.
     
    #11 bobbilr, Oct 18, 2009
  12. DerBuchster

    DerBuchster New Member

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    Did anyone ever figure out the cause or solution to this problem? I think I have the same thing.
     
    #12 DerBuchster, Dec 11, 2010
  13. hakobh

    hakobh New Member

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    Hi Jayvee,

    I think you were describing exactly what I am experiencing now.
    Please see attached zip with 3 sound files (file #02 cought it best) I recorded in my car. Is it same as yours.
    Could anyone with the same issue respond how did they resolve the problem.

    Thank you!
     

    Attached Files:

    #13 hakobh, Mar 20, 2012
  14. jayvee

    jayvee Member

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    Yes, it might be the same - although it's hard to tell from the audio files. My car really doesn't do it anymore, unless I'm really braking hard. My original post was almost three years ago...

    Yours sounds somewhat worse than mine, though, and I wasn't able to get mine to repeat very easily (sounds like you can). Yours is also severe enough that I would take it in to be checked. In my case, I think it is/was simply the regen brakes releasing just before full stop. I have not had any other brake problems with the car.

    Good luck!

    Jayvee
     
    #14 jayvee, Mar 21, 2012
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  15. hakobh

    hakobh New Member

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    Jayvee,
    You say your car doesn't do it anymore, unless you're really braking hard.
    Does this mean that you learned to live with it, and there was no fixing/repairs done ? Or the problem gradually went away ?

    Yes, I am going to take the car in to be checked (4th time).

    Thank you.
     
    #15 hakobh, Mar 21, 2012
  16. tach18k

    tach18k Member

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    On my 2012 II, I noticed in the last moment of breaking, the brakes seem to all of a sudden 'grip' the rotor and comes to a quick stop. Not all the time but at a slow movement. Its the last foot or so before stopping.
     
    #16 tach18k, Mar 21, 2012
  17. bjayakody

    bjayakody New Member

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    I'm new to this car (2010 GenIII) and I too hear this sound exactly a moment before the full stop. I got it checked at a service station (Not a Toyota dealer) and they suggested me to change the brakes. Anyway, I'll be taking my car to Toyota very soon to get it diagnosed and If course the sound it verymuch similar to the Audio files shared.

    Cheers!
     
    #17 bjayakody, Mar 23, 2012
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