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  1. #1
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    Reputation: Ray Lee's Avatar
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    Help changing Shimano pads (M485)

    New pads for my girl friends M485's I have the directions and seems easy enough... almost to easy... is says to level the lever and push the pistons back with the reservoir cap off (some oil may spill) like I said seems easy but is there risk of getting air into the system? should I have some extra mineral oil handy?

    Like I said it seems easy just wanted to know if there is anything I should look out for.

    Ray

  2. #2
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    Reputation: SteveUK's Avatar
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    If there is excess fluid (like from over-filling during a previous bleed) then this fluid will be pushed out at the MC when you press the pads back into the caliper. You won't be introducing air into the system.

    If, when you've pressed the pistons back flush with the caliper inteior, you find that the MC isn't topped off with fluid, then you should add fluid so that it is level with the rim of the reservoir, so, yes, it's worth having some brake fluid handy.
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  3. #3
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    Thanks, I am new to hydraulic brakes and it was very easy except that not only did REI (only thing open) not have Shimano mineral oil the child at the desk wanted to argue that all brakes used DOT 4 or 5.1 fluid....

    There is a little free lever play before the pads engage not sure if that just how her brakes are or if I need a few extra drops of oil, it was about 5 drops shy of full.

    thanks again
    Ray

    Quote Originally Posted by SteveUK
    If there is excess fluid (like from over-filling during a previous bleed) then this fluid will be pushed out at the MC when you press the pads back into the caliper. You won't be introducing air into the system.

    If, when you've pressed the pistons back flush with the caliper inteior, you find that the MC isn't topped off with fluid, then you should add fluid so that it is level with the rim of the reservoir, so, yes, it's worth having some brake fluid handy.
    Last edited by Ray Lee; 05-15-2009 at 04:57 PM.

  4. #4
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    "...There is a little free lever play before the pads engage not sure if that just how her brakes are or if I need a few extra drops of oil, it was about 5 drops shy of full."

    Yes, free travel is normal; it translates to the distance that the pads need to move before they contact the rotor. It's the same as any cable brakes, it's just that the different feel is so frictionless prior to the pads engaging that the difference is so much more noticeable.

    This amount of travel is fixed, although most brakes have lever throw adjustment (usually by turning the lever's piston pin with a 2mm Allen key). Some brakes have a mechanical bite point adjustment on the lever, but it's not really possible* to alter it by adding more fluid. What you have is what you've got, so to speak.

    *there are exceptions, but they can bring with them a whole other set of problems.
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