Hayes Mag service ?- Mtbr.com
Results 1 to 5 of 5
  1. #1
    mtbr member
    Reputation:
    Join Date
    Nov 2006
    Posts
    141

    Hayes Mag service ?

    Can anyone answer the following?

    I just put a new piston and square seal in a front G1 mag caliper. I have 2 questions:

    Does the DOT 4 I used for lubrication on the seal and piston as instructed seap a bit for a short time or am I still leaking a little?

    Secondly, I notice that the outside piston (not replaced) has more travel than the new piston (inside) question is this, Does the outboard piston travel more anyway? or does the new piston need some time to break in ? or do I really need to replace BOTH pistons at the same time?

    Side topic... If the latter why wouldn't Hayes just sell both in one set for replacing the pistons...Really the reason I thought I might be able to get away with one is that thats how they are sold

  2. #2
    Meh.
    Reputation: XSL_WiLL's Avatar
    Join Date
    Nov 2004
    Posts
    17,508
    They might seep a little bit. Clean it up and keep an eye on it.

    Most hydraulic brakes do have a dominant piston. That's just how they are. It is possible that there's just more friction with the new piston and seal though.

  3. #3
    Category Winner
    Reputation: teamdicky's Avatar
    Join Date
    Jan 2004
    Posts
    6,030
    Quote Originally Posted by new2this

    Side topic... If the latter why wouldn't Hayes just sell both in one set for replacing the pistons...Really the reason I thought I might be able to get away with one is that thats how they are sold
    Oh, now you don't think us Charlotte folks can answer questions huh??

    They sell them in onesies because people bend the little post that hold the pad more often than they replace the seals/pistons due to them wearing out.
    I am guessing here.

    How much did you use to lube the piston? I just wet my finger down and rubbed the seal/piston (kind of like an oil filter on a car). Pick up some disc brake cleaner, and make things stay clean down there for awhile.
    WWW.TEAMDICKY.COM

    I get paid 3 every time I post on MTBR.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Nov 2006
    Posts
    141
    Quote Originally Posted by teamdicky
    Oh, now you don't think us Charlotte folks can answer questions huh??

    They sell them in onesies because people bend the little post that hold the pad more often than they replace the seals/pistons due to them wearing out.
    I am guessing here.

    How much did you use to lube the piston? I just wet my finger down and rubbed the seal/piston (kind of like an oil filter on a car). Pick up some disc brake cleaner, and make things stay clean down there for awhile.
    Na, I know you all can usually answer my questions

    I was actually hoping the Hayes guy would have an answer...I lubed it about how you described. Looking at some other threads I think its a new tight seal Vs and old broken in seal causing the one piston moving more than the other. I am going to replace that one as well, rebleed and see if that works. If not I will get another caliper and call it a day.

  5. #5
    Race Technician
    Reputation: Randy@Hayes's Avatar
    Join Date
    Jan 2005
    Posts
    192

    Replacing both will yield best results.

    By replacing both seals and pistons you'll get essentially "like new" piston retraction. If you can find a shop that has just the seals that is all you really need if your piston is in good shape.

    As for the seeping, there shouldn't be any. If you've cleaned up the caliper with isopropyl alcohol after the rebuild and have fluid on the back side of the pads you might have damaged or twisted the seal while putting in the piston. Reclean the piston area and wipe off the backside of the pad, ride for a while and recheck. If you're still getting seepage the seal might be damaged.

    January's brake tip:

    Lubricating and cleaning the pistons and seals is the key to good piston retraction. Brake maintenance is right up there with fork maintenance, take care of them and they will feel like new. Change the fluid once a year minimum, more often if you do alot of dh riding. Relube the piston seals (with DOT 3-4 only) when you replace your pads or if retraction seems to have changed.

    Randy

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.