A single clunking noise from the rear after each time the car comes to a stop

Discussion in 'Prime Main Forum (2017-Current)' started by leaftoprius, Dec 12, 2018.

  1. leaftoprius

    leaftoprius Junior Member

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    I started to notice that my 2017 Prius Prime Plus makes a single clunking (knocking) noise from the rear of the car each time the car comes to a stop. In the past I only noticed it once a while and attributed it to me braking too hard. But recently, I noticed that it occurs every time when I brake and the car comes to a stop (except in the most gentle rolling/gliding to a stop). As the car brakes, inevitably the front end dips and the rear raise a bit due to the momentum. Just as the car comes to a full stop, a single clunking noise can be heard when the rear settles down. It could be repeated even in parking lot: just taking the foot off the brake and let the car move by itself and then apply the brake firmly, the front will dip enough to raise the rear. When the rear settles down, the noise can be heard.

    I only drive the car occasionally (10% of the time) while my wife is the primary driver. Now I am aware of it, I notice it all the time. But my wife said the noise was there from day 1 when we had the car brand new (1 year, 8k miles ago). Does this happen with everyone's Prime?

    I have seen this post Prius "clunk" when coming to a complete stop with moderate braking | PriusChat. My car's symptom seems very similar to it. Just wonder if this is something I should bring the car to service to check out.
     
  2. schja01

    schja01 One of just a few in Chicagoland

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    My Venza makes a single clunk after startup when it reaches 8 mph the first time. It’s the ABS initializing. I’ve not heard a similar sound from the Prime. I would have the dealer check it out.
    J
     
  3. leaftoprius

    leaftoprius Junior Member

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    I wasn’t asking about noise heard when the car gathering speed. I was asking the noise just AS the car comes to a complete stop and the rear end settles down.
     
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  4. sam spade 2

    sam spade 2 Senior Member

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    YOU need to lighten up a bit.
    His comment was not out of line in the least.

    Before you visit the dealer, take a GOOD look at everything that you have access to in the trunk area.
    That means opening any "trap doors" and looking under the carpets.
    There might be something rolling around loose somewhere.
    Might even be under the back seat.......but might not be a good idea to take the seat apart yourself.

    Also, might be a seat belt buckle flapping around loose.
     
  5. bisco

    bisco cookie crumbler

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    isn't there a bad strut nut or something?

    have you done any searching?
     
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  6. leaftoprius

    leaftoprius Junior Member

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    Thanks for the suggestion to check the trunk/back seat for loose items. I searched all over and did not find anything rolling/flapping around.

    There is a T-SB-0144-16 on 2016 Prius "Some 2016 model year Prius vehicles may exhibit a clicking noise from the support nuts on the rear shocks. " The assembling process was supposed to have been improved to prevent the problem on car manufactured later. I am not sure if that TSB (which was for 2016 Prius, not Prius Prime) applies to 2017 Prius Prime.

    I recorded a 10 second video (posted on Google Photo https://photos.app.goo.gl/zhcbSyQiATsagJGB6) with sound to show the speed the car was going and the braking. One could hear the noise at the end.

    I made an appointment to bring the car into the dealership to have it checked out.
     
    #6 leaftoprius, Dec 13, 2018
    Last edited: Dec 13, 2018
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  7. bisco

    bisco cookie crumbler

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    ah, that's what i was thinking of, thanks!
     
  8. bisco

    bisco cookie crumbler

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    wow, that is a very obvious sound
     
  9. SteveMucc

    SteveMucc Active Member

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    that sounds like something banging more than a suspension noise (which usually sound more creak-ish).

    after the thump if you hit the accelerator hard to you hear a corresponding thump the other way ever?

    the back seat bottoms pop up really easy just give a little yank. make sure you're lug nut wrench and jack are secure.
     
  10. leaftoprius

    leaftoprius Junior Member

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    I did not get the same noise when accelerating hard.

    I checked and the lug nut wrench and jack are secured.

    Hopefully the recording is helpful for explaining to the service department tomorrow.
     
    #10 leaftoprius, Dec 13, 2018
    Last edited: Dec 13, 2018
  11. leaftoprius

    leaftoprius Junior Member

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    Oh, the back seat bottom seems stable. I could not get any movement by pressing/seating on various part of the back seat.
     
  12. KrPtNk

    KrPtNk Active Member

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    I would definitely take it to the dealer. The noise is obvious and easily reproduceable. They should be able to find and fix it easily.
     
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  13. leaftoprius

    leaftoprius Junior Member

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    I took the car to the dealership today. They had one of their mechanics to test drive with me. He had no trouble to reproduce the problem.
    It was fixed under warranty and seems to be fine so far.
    Here is what was included in the invoice for the service.

    CUST STATES CLUNK NOISE FROM REAR WHEN COMING TO A STOP
    ADVISE
    Cause:
    Correction: CONMFIRM CUSTOMER COMPLAINT CLUNKING NOISE FROM THE REAR CHECK
    REMOVE REAR TIRES TO CHKECK REAR SHOCKS FOUND SHOCKS SECURE PROPERLY TEST
    DROVE VEHICLE NOISE STILL PRESENT . CHECK ALL SUSPENTION NUTS AND BOLTS FOUND SOME
    REAR SUSPENSION NUTS AND BOLTS A LITTLE LOOSE TORQUE AND SECURE PROPERLY TEST
    DROVE VEHICLE FOR NOISE STILL THERE REMOVE TIRES DEGALZED ROTORS SAND PADS AND
    LUBRICATE GUIDE PINS AND FIT KIT FOR PADS APPLY SPECIAL BRAKE GREASE TO SHIM KIT AND
    FIT KIT SECURE TIRES ROAD TEST VEHICLE NOISE IS NOT THERE ANYMORE
     
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  14. bisco

    bisco cookie crumbler

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    wow! i'm surprised we're not hearing more of this. sounds like prime brakes are factory defective.
     
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  15. SteveMucc

    SteveMucc Active Member

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    Only thing I can think of is that the guide pin was in there but completely untightened/unattached. After some use it could have slide out sufficiently such that the caliper was no longer secure to the bracket. That would cause the caliper to rotate away from the rotor under breaking and the clunk could occur when it fell back into place after breaking was complete. Could also be why they had to sand the pads down (which, honestly I'd be a bit pissed about since they just took off some life from that pad on you) since there would be a lot of uneven wear on that pad.

    Glad you got it fixed, that could have lead to a complete loss of breaking on that side (not to mention if the caliper pin got some place it shouldn't and locked the wheel up on you).
     
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  16. leaftoprius

    leaftoprius Junior Member

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    Thanks for the analysis. I am not familiar with how the various brake components interact with each other. Any good site that has diagram or animations that shows how it works?
     
  17. leaftoprius

    leaftoprius Junior Member

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    Found this video
    . It helps to get a better idea.
     
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  18. KrPtNk

    KrPtNk Active Member

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    This has been an excellent thread. Thanks for the initial post and the report from the mechanic. You appear to have found a very competent mechanic, remember his name.

    I would have never guessed that would have been the cause of your problem.
     
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  19. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Hopefully gone for good. Odd that there doesn't seem to be anything definitive. I'm almost thinking in the course of all the wrenching something got shifted slightly. Or, they finally took the loose water bottle outa the hatch, lol.

    Just for giggles, I would raise the rear, verify both rear wheels are spinning semi-freely: if the brakes are sim to third gen correct reassemble is critical to proper brake operation, avoiding drag.
     
    #19 Mendel Leisk, Dec 15, 2018
    Last edited: Dec 15, 2018
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  20. bisco

    bisco cookie crumbler

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    is the shim kit standard?
     
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