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removing stuck caliper pistons

Discussion in 'XJ Technical Chat' started by bensalf, Oct 5, 2012.

  1. bensalf

    bensalf Well-Known Member

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    this is for anyone who has experiensed trying to remove stuck pistons from "dual" piston calipers.as on my xj600.
    i know the methods of removing stuck pistons on single piston calipers have been covered on here, using either air or grease gun methods, but they dont work on twin pistons, due to the fact that when one piston pops out, you have an open pot, so air or grease wont hold in to force the other piston out.
    so the trick is to "block the open pot, then force in either air or greace, to push the other one out.
    heres how i did it by using a bit of flat plate, a piece of old inner tube and an old tyre valve, with a couple of g clamps
    [​IMG]

    shave the end of the shrader valve down till it screws into the banjo bolt hole
    [​IMG]
    clamp a piece of 50mm or so ,wide, bit of scrap metal across the face of the piston pot, using the bit of innertube as a gasket.
    and clamp this tight ,with another piece of metal, i used a large spanner (oops wernch)
    [​IMG]
    then attatch the air line to the shrader valve(remove the shrader valve first)
    my piston pushed out at about 70psi with a pop ,
    cover the caliper with a rag first.
    [​IMG]
    can also work using grease gun by blanking the banjo bolt hole with correct size bolt and pumping grease into the bleed nipple.
    hope this may help someone who was in the same position as me, at very little or no cost
    cheers
    stu
     
  2. bensalf

    bensalf Well-Known Member

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    oops. missed this picture out, shrader valve screwed into banjo bolt hole,
    that held 70psi!!
    [​IMG]
     
  3. wizard

    wizard Active Member

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    Been done before, but nice pictures, good job.
     
  4. hbwb

    hbwb Member

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    Or instead of using a rubber wrapped spanner you can just use a piece of wood like a 1x4 or such. I like wood cause it cannot hurt steel, even though the rubber works fine. It comes down to whatever you have handy.
     
  5. MiGhost

    MiGhost Well-Known Member

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    Which begs the question.
    Once you have the first piston out. How do you remove the other piston?


    Also. A properly sized Hose Clamp would be a much simpler way to hold the piston in place.

    Ghost
     
  6. schmuckaholic

    schmuckaholic Well-Known Member

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    Um.

     
  7. FJ111200

    FJ111200 Active Member

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    Your best bet is to use a worn out brake pad clamped up on one piston, then push the other piston out, then replace the piston "o" rings and the piston, push it back in, then clamp up that piston and start on the piston that still needs working on.
    Push the piston in, remove the old brake pad then fit new pads and connect up to the fork leg.
     
  8. hbwb

    hbwb Member

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    Do you have access to compressed air with a blowgun? If so split the brake calipers in half and put the o-ring seals on the side you wish to remove the piston. Hold this side face down on a block of wood and use the blow gun to blow through the bleed hole or brake line hole. You may need to wrap tape around the blow gun to get a good tight seal.
    Should pop right out and the wood will stop it from coming all the way out and shooting across the room.
     
  9. bensalf

    bensalf Well-Known Member

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    ------------------------------------------------------------------------------------
    Which begs the question.
    Once you have the first piston out. How do you remove the other piston?


    Also. A properly sized Hose Clamp would be a much simpler way to hold the piston in place.

    Ghost

    ------------------------------------------------------------------------------------
    ------------------------------------------------------------------------------------

    Your best bet is to use a worn out brake pad clamped up on one piston, then push the other piston out, then replace the piston "o" rings and the piston, push it back in, then clamp up that piston and start on the piston that still needs working on.
    Push the piston in, remove the old brake pad then fit new pads and connect up to the fork leg.

    ------------------------------------------------------------------------------------
    ------------------------------------------------------------------------------------

    i dont think some of you grasped the reason or the method of the post.
    the reason was to remove "both" pistons from the caliper, to allow spraying or blasting.

    the bit of plate ,with the piece of rubber, is to seal the hole, left, after the first piston has been pushed out, the seccond piston is then blown out with the airline.
    no need to split the caliper,or disturb the o rings

    yes,, an old brake pad would suffice instead of the plate, to seal off the hole with the rubber.
    cheers.
    stu
     
  10. MiGhost

    MiGhost Well-Known Member

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    Your write up was a bit confusing. It did not make note that you were starting with one piston already removed, and then procede from there.

    So that we all understand. This write up is for removing the second piston in the dual piston caliper system. As found on the XJ700/700X.

    Ghost
     

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