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Brake caliper disassembly - how to get the pistons out?

Discussion in 'Technical and Troubleshooting Torque' started by Loz, Dec 15, 2007.

  1. Hey party peoples.

    The Minja's brakes are operating in an odd way. They're 6-pot calipers and the pistons are actuating unevenly, on both calipers the top right and bottom left pistons are the easiest to move, so the pads are wearing diagonally.

    I've spent a fair bit of time locking all but one down and pumping them out as far as I can without popping them out and cleaning with brake cleaner and a toothbrush, but it hasn't made much difference.

    So I'm thinking I might need to go all the way and remove all the pistons, take the calipers apart and give them a good clean, maybe replace the seals etc.

    Two questions then:

    1) Would it be expensive to just chuck them at a mechanic and get them serviced with new o-rings?

    2) Has anybody done it themselves on a 6-piston caliper? Once you pop one piston out, there's no hydraulic pressure to pop the others out. So how do you remove those cheeky bastards?

    Cheers all!
  2. Loz,

    When I rebuilt the 4 pistons on my car, I used compressed air and a couple pieces of wood. Jammed a piece of wood between 2 pistons, get compressed air and pumped one out. Get 'nother thin piece, close over exposed bore, pop opposite out. Keep going 'till all 4 are out (or all 6 in your case).

    Just don't be a smartarse and see how much force those pistons come out like I did. Got a nice bruise on my finger for a week :)
  3. A bit of lube on the piston and a g clamp attached to a flat piece of metal seemed to open up the pistons on my old honda.
    this was a twin piston though so it may take more fiddling with the 6 pot version.
    I'm pretty sure there is a specific lubricator for the pistons.
  4. Just opened up my handy book: 101 sportbike project, and project 17 is caliper rebuild. It has similar words to flexo's link. Get the caliper on the bench. Face the pistons downward with a piece of wood in between and gently blow in some compressed air. The idea of the wood is to stop the pistons fully extending, coz if one pops out, the others lose driving force.

    Then the book says "if you're lucky, you should be able to pull the pistons out with your fingers, or use a pair of "soft jaws" on a pair of locking pliers."

    Funny I was just looking at this for my bike.
  5. Loz, your front wheel is in the air a lot. Your calipers are suffering from altitude sickness
  6. Hmm, it doesn't seem to be affecting the REAR wheel... :grin:
  7. Shouldnt be too hard. Just put a piece of wood in between with pads in, and pump them so all pistons are mostly out. Then pump one out, and the rest should come out quite easily using a rubber glove or something to grip them. If they are still not coming out. U can use some pliers with some rubber and just twist very slowly.