Home Forums Bike Forum Replacing pistons and seals on Zee calipers

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  • Replacing pistons and seals on Zee calipers
  • cjr61
    Full Member

    Afternoon,

    Ive picked up some Heppe (AliExpress) replacement pistons and seals for my 640 zee calipers. I’ve cleaned up the calipers, a little mineral oil on the seals and around the piston but the piston won’t go in. Is there a knack? Or possibly the curse of cheap pistons and poor tolerance? Thanks in advance

    cjr61
    Full Member

    Did try replacing an old piston with new ring and wouldn’t easily go in either. How much force do they need to go in?

    cjr61
    Full Member

    Some blogs suggest silicon grease but some say mineral oil. Any suggestions here?

    1
    tjagain
    Full Member

    shimano – mineral oil.  You have to get them exactly square to go in.  Try without the seal to see if they go in then

    1
    hammerandcycle
    Free Member

    They need to go in perfectly straight and they should slide in with just finger force.

    twonks
    Full Member

    Do you need / have you got the system open or callipers off the bike so you can displace oil / air as you push them in?

    thols2
    Free Member

    Do you need / have you got the system open or callipers off the bike so you can displace oil / air as you push them in?

    Yes

    cjr61
    Full Member

    Thanks @twonks, yep, calipers off, hoses off, calipers split open. Nothing blocking the ports.

    BoardinBob
    Full Member

    Digital caliper available to measure old diameter Vs new?

    cjr61
    Full Member

    Diameter are the same, got a few in with lots of wiggling. Will persevere!

    intheborders
    Free Member

    My experience is that when pistons need replacing on callipers it’s usually just late to replace them, they need replacing before or what happens is that SLX callipers get bought to replace Saint callipers because the pistons are sh*gged…

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