I have a set of Avid Juicy 3 calipers that I have sucessfully replaced the pistons and seals on. Getting the pistons out of one of the calipers was not so easy though, and I ended up drilling the middle of the piston, putting in a self tapping screw and pulling out the piston with a mole wrench, like the cork from a bottle. This was OK because I was renewing the pressure foot as well as the seals. The downside was the little dimple left in the caliper body where the drill overshot or the screw pressed.

I have a couple of other caliper bodies in need of some work with a similar problem and wonder whether there is a better method or a trick to ease the piston/pressure foot out (potentially so it can be reused!).

I have tried compressed air with no success and hydraulically seperating the caliper halves with rubber over the port then pumping the bleed port with dot fluid and the syringe, also no go. I feel like I'm missing something but it may be that the caliper is completely siezed and the corkscrew is all that's left.

  • When you use compressed air what goes wrong? Oct 20 '21 at 17:13
  • @NathanKnutson I can hold the pressure from a track pump for a while at 100psi or more, but nothing happens. I could make up a hose to use the compressor but as this runs at 100psi, I'm not convinced it will make a difference. Do the seals glue themselves in after a while? The brake is a MY2008 and hasn't been used for maybe 5 years so I'm not ruling anything out. Thanks!
    – JoeK
    Oct 20 '21 at 19:28
  • I've seen them get stuck by expanding from exposure to the wrong fluid, usually as a result of doing a full bleed or specifically lubricating the pistons with it. Oct 20 '21 at 22:47

Not sure if it's helpful but here is a generic plan for popping pistons with a compressor.

Use this kind of blower attachment, with a conical rubber or plastic nozzle.

enter image description here

Split the caliper in its two halves and drain the fluid best as possible.

Most caliper halves will have one side with the hose inlet, and then when you open it there will be a port for fluid to pass through into the other half. The other half will have the bleed valve, which you keep closed, and a port for fluid that joins with the one on the other half.

juicy 3

Starting with the half with the bleed port, put it down on a bench and take a rag and hold it over the piston so it doesn't go flying when you pop it out. Then jam the conical air blower into the fluid port and let it rip. Typically they come out with a loud pop; it's an actual explosion you're creating so be ready. The other side is the same except you have to have one fingertip covering either the hose port or the fluid port on the caliper split while the blower jams into the other entry point.

If this doesn't work then the piston seal is probably some especially terrible kind of destroyed, like expanded from fluid contamination. I don't have a great generic plan for what to do then, as it's a rarity for me that I'd be trying to bring a system like that back to life.

  • 2
    Thanks Nathan. I am missing the rubber cone attachment for my air hose and I can see how that would give the best effect. Of course, it may not work but now there's a best method to work with. I wouldn't usually waste so much time on these but the caliper is colour matched with the frame logos and it's not a bad brake when working properly.
    – JoeK
    Oct 21 '21 at 12:14

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