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HELP! brake caliper problem

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by fyc2001, Jan 13, 2016.

  1. fyc2001

    fyc2001 Junior Member

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    Long story short I removed the front tire, caliper, and rotor to change a broken lug nut stud. When I tried to insert the new stud I started the car and shifted it to N to turn the wheel so the stud can be inserted. When I am ready to re assembleeverything back. My caliper piston is extrude all the way out, I couldn't use a C clamp to push it in like I did last year when I changed the brake pad, I tried to remove the bleeder on the caliper, doesn't help at all. SO I came inside and googled the problem. I think I messed up the brake actuator.

    What do I do now?

    TIA.
     
    #1 fyc2001, Jan 13, 2016
  2. ChapmanF

    ChapmanF Senior Member

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    Fear not, it isn't likely that you messed up the actuator.

    If the piston pushed all the way out, it is likely you lost some fluid around the caliper. Did that happen? (Or it may all be trapped behind the rubber dust boot.)

    The piston in the caliper bore is a very close fit ... the kind that, if it comes out, will feel like it isn't ever going in again at all. You have to keep jiggling and trying until the miracle happens when you get it aligned exactly straight and then it slips in. Force does not help. If it isn't aligned and you try force, you won't get anywhere, but might chew up the piston. But the piston is only something like $18.

    If you say you did open the bleed screw and still couldn't move the piston, that has to be your answer. If the bleed screw is in fact open, there is nothing even a messed-up brake actuator could do to stop you pushing the piston.

    If you did lose fluid when the piston came out, you may have air in the actuator. That takes a more involved bleed procedure and it might be more than you want to DIY, but you will probably be just fine as soon as it is bled.

    -Chap
     
    #2 ChapmanF, Jan 13, 2016
  3. fyc2001

    fyc2001 Junior Member

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    thanks for giving me some hope.
    no fluid came out before I remove the bleeder screw.

    I hope you are right about alignment of the piston. because it was so far extended/ out, I couldn't get get my C clamp on the caliper with the year old brake pad, so the c clamp is only pushing on one side of the piston. I did notice it was not centered. I will play with it when I am free.

    thanks again.
     
    #3 fyc2001, Jan 13, 2016
  4. ChapmanF

    ChapmanF Senior Member

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    If the piston came all the way past the inside seal, some fluid almost certainly escaped the cylinder ... if none was visible, then it's probably all been trapped behind the rubber dust seal. That's good news about the integrity of your dust seal :), but you will have to let that fluid out before everything will go back as it ought. You may as well use the opportunity to check out the condition of the piston and bore before shoving the piston back in. There is brake bleeding in your future anyway. :)

    Or even reassemble with new rubber; the rubber kit from Toyota's only about $30, with all the rubber for two calipers, and the proper internal grease in a little packet. Then you'll have turned your mishap into a newly-refurbished caliper for the long haul.

    If the bore and piston are clean, with new rubber and grease, you should find nothing more than good thumb pressure is needed to push the piston back home. The C clamp can watch from the other side of the room.

    -Chap
     
    #4 ChapmanF, Jan 13, 2016
    fyc2001 likes this.
  5. fyc2001

    fyc2001 Junior Member

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    Went to autozone, got the brake loaner tools, centered the piston got the piston in, reassembled everything.

    Took it for a test drive. the brake feels much harder + dashboard
    brake (red light), VSC, tire, and another yellow signs were all lit up.

    do I need to reset them by disconnect the 12V battery?
     
    #5 fyc2001, Jan 14, 2016
  6. ChapmanF

    ChapmanF Senior Member

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    Read the codes, they'll probably tell you pretty clearly what it's griping about.

    -Chap
     
    #6 ChapmanF, Jan 15, 2016
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