Viewing 14 posts - 1 through 14 (of 14 total)
  • Hope v4 pistons stuck out
  • marksnook
    Free Member

    So my v4 rear brake was binding on my last ride so I planned to follow the Hope video of piston lube and bleed etc. How ever I can’t push one of the pistons back in. Used some old pads and put serious force on it but it won’t budge. All the others went straight back in with no effort. Pistons are cleaned and lubed now. The other 3 pistons all come out at different rates when pulling the lever. Any ideas?

    leegee
    Full Member

    The tool to remove the caps behind the pistons is only a few quid as is a seal kit.

    Onzadog
    Free Member

    Sounds like it’s come out on a bit of a wonk. I use a nicely sized bit if flat bar across the piston face and very gently walk it back in until it’s level. Obviously, you need to push on the high side first.

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    ta11pau1
    Full Member

    Sounds like it’s come out on a bit of a wonk. I use a nicely sized bit if flat bar across the piston face and very gently walk it back in until it’s level. Obviously, you need to push on the high side first.

    This – lubed my v4 pistons the other day too and found that some needed a bit of working to get moving but once they move, they go back in very fast! Try levering against the other piston, I find a small ring spanner is perfect, start with an 8mm or similar, slim enough to fit between the 2 pistons when both pushed out, then go to a 12mm. Be careful not to push out the other pistons when pushing one back in. You’ll obviously need to work them in and out a few times to get the seals nicely coated in the silicon lube.

    The pistons coming out separately with no pads in is normal as the fluid is acting on the front pistons first, but they should be all the same when pads are in.

    Phil_H
    Full Member

    If you’re pushing directly on the pistons be careful.
    It’s easy to chip the edge of the piston as I found out the hard way😟

    brads
    Free Member

    What lube are folk using on the pistons ?

    marksnook
    Free Member

    Yeah being super careful not to damage the piston surface! So thanks for all the advice, got the stuck one freed, they are all still being temperamental, should they all come out together as I pump the brake or not? They don’t return into the Caliper without being pushed back in with the spanner. Is that normal?! Sorry about my lack of knowledge. All I ever did to my zees was change the pads as they just worked!

    ta11pau1
    Full Member

    They won’t all come out at the same time with no pads in (ie coming out more than a few mm) as when you pump the lever the fluid will push out whatever is easiest, and the front pistons get the pressure first.

    The pistons won’t go back in on thier own as the nothing forcing them back in. They do retract when you have the pads in as they’re only moving a few mm and the movement is the seals flexing, the pistons aren’t sliding through them.

    Once you’ve pushed them out, used a small brush to put some lube on each one, then worked them all in and out a few times they should move a lot easier. Put the pads back in, wheel back on, pump the pistons out and centre the pads again and you should see each piston moving equally when you pull the lever.

    Lube to use is hunters silicone lube.

    dyna-ti
    Full Member

    +1 Hunters lube.

    With the pads out on E4 calipers, i can push in the piston using 2 thumbs, top and bottom, and it should go in evenly. I guess the slot is about the same size so you should be able to get a thumb onto each side.

    If you are going to the trouble of opening it to remove, might consider putting a new one in.
    Naturally of course it is unlikely to be a problem, but squint, one hard edge is pressing into the piston side and could leave an indentation. A new one is a fiver.
    with the tool ,might as well do the other too.

    How old are they/usage ?. A serviced brake is a happy brake 😉

    marksnook
    Free Member

    Ran out of lube so I gave up for today! Ordered a set of zees last night as a back up so if the hopes don’t start playing ball I got a backup. Tempted to get lbs to sort the hopes then flog them anyway. Like I said my old zee brakes were always there and reliable.
    These v4s are 3 months old! If pistons are sticking after that much time I don’t think they are all that!

    ta11pau1
    Full Member

    My V4’s were fitted in September, have done 500 miles (through one of the worst winters I’ve known) and have only needed a lube now as the rear had a sticky piston or 2. That’s the only maintenance I’ve had to do in the 10 months.

    Took all of 30 minutes to lube and work all the pistons in and out on both front and rear brakes.

    flicker
    Free Member

    My guide r pistons do the same trick (although not at 4 months old) the seal dries out and the pistons stick. I use one of these to push each piston out individually, clean them and use red rubber grease on each piston then push them in and out a few times. Brakes are rock solid with very little lever travel after that.

    At some point over winter I’ll replace the pistons and seals as the black coating has worn off the pistons.

    Onzadog
    Free Member

    The thing with V4 over E4 is the wider gap between pistons as the V4 is capable of taking a 3 layer vented rotor. Are you using single skin rotors with them? If so, this is the reason why the pistons are a bit further out and closer to the wonky zone, especially if pads are low. It’s a long way from fresh pads and a vented rotor to single skin rotor and worn pads. Once you know what’s happening and how to deal with it, it’s not so bad.

    I used to get similar with my V2 occasionally when the pads were low.

    marksnook
    Free Member

    Using floating rotors, pads were getting low to be fair. Kind of makes sense the wider gap causing more piston exposed so more surface area for dirt
    Got some more silicon lube on the way so will have another stab at it tomorrow

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