Tech help needed – brake pistons won't fully retract

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  • Tech help needed – brake pistons won't fully retract
  • dhrider

    Can you refit the old pad and then use something to prize them apart again and push them back to where they should be or are they pushing forward again from this point?

    Premier Icon RobinL

    I’ve tried using old pads but I can’t push both back, only one at a time, once one’s back the other comes out slightly.

    Ta ?

    Premier Icon tmb467

    Couple of ring spanners

    Old pads out, use ring spanner to push piston all the way in on one side

    Do same on other side – one at a time til both pistons are fully retracted. If one moves out when the other one moves in just try and wedge it using another ring spanner

    Premier Icon RobinL

    I’ll go try the ring spanners ………. I’ll be back ….

    Thanks for the advice ……


    Undo the fluid reservoir cap on the lever and then push the pistons back (slowly). Ensure reservoir is horizontal and cover the front caliper with a heavy duty rag etc to stop any fluid spilling from the reservoir.

    make sure there is no muck or build up on the pistons. Maybe careful clean the pretruding part and add a little brake fluid if you have any and push back in. Sometimes if the push/pressure isn’t perfectly square then the pistons do not go back in too.

    post above ^^ is probably most relevant though


    I had this trouble on some Avid Elixirs.
    Tried all sorts to get the new pads to fit to no avail. It turns out to be a common fault, where the original pads are a mm or so thinner than new ones, and the fluid in the reservoir was put in to suit the thinner pads, so, the pistons could not be pushed all the way back in, not matter what I did to them.
    Draining the excess fluid off cured it – I undid the hose to caliper bolt slightly, then pushed the pistons into the body, which forced some of the fluid out of the hose fitting.
    No problems then. I hadnt realised the brake lever had such little movement until I did that, I’ve had Hopes before, and just thought the lack of movement was the way Avids were, but suddenly there was some feel again to my brakes.


    undo the bleed nipple on the caliper half a turn then push pistons back.
    nip up bleed ..

    sounds like its been a little over filled bud

    first i would try this – undo the lever reach adjuster so the brakes are on maximum extension – ie for massive hands..then try the pistons.. then readjusting if this works.

    Premier Icon RobinL

    Could use the ring spanner to push one piston back at a time, no chance of fitting two spanners in there.

    I’ve now managed to loose the tiny clip which stops the pin holding the pads in coming out ( although it is threaded ).

    The brake fluid has never been touched since I’ve had the bike and pads fit last time so I’m cautious about releasing fluid ( especially as I don’t class myself as a competent bike mechanic ! ).


    +1 Paver456 and allthepies

    halfauds sell split pins – used sometimes to secure pads on some models. May work on yours as a quick temp fix. could probably get them in DIY / hardware stores too

    Premier Icon RobinL

    Please could anyone offer advice on how to get the brake pistons to go fully back in to fit new pads.

    I’ve fit numerous sets of pads without problems but this time the pistons won’t retract and remain there. I can’t get both sides to fully retract at the same time. I can push each side back using an old pad but they don’t stop there once released.

    Once the new pads are inserted there is no chance of the rotor fitting in.

    I’ve tried with used pads from the front but I can’t even get the rotor in with those.

    As I’m one of the few on here with just the one bike it looks like there’ll be no riding tomorrow … or next week now 🙁

    Premier Icon RobinL

    Still no success, rounded the hex of the threaded pin now ……

    I don’t seem to have anything which undoes the bleed screw and I have tried opening the lever adjustment as much as I can without success.

    Patience lost I’m afraid, the bike will be going to the bike shop to be fixed by someone competent.

    Thanks for the prompt help anyway !


    It’s wine o’clock now then as I’m not riding tomorrow !

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