Question on XT brakes

Northwind
Northwind Posts: 14,675
edited February 2009 in MTB workshop & tech
I've just bought and fitted a set of XT M775 brakes, the 08 model, but the feel from the rear lever is noticably different from the feel of the front. It takes more lever movement at the front before the brakes engage. It's not air in the system, or at least I don't think so, since it's not engaging at all rather than just engaging weakly, and the power when it comes is still effective- it's just got a lot of movement before it does anything.

Unfortunately, the manual isn't available through the website and none came with the brakes. I'm wondering if this might be to do with the free stroke adjustment, but both levers have this adjusted fully in.

Any idea what's causing it?

Oh, while I'm at it, can anyone explain exactly how the free stroke adjustment works? My understanding was that it increased the "bounce back" meaning that the pads stand further clear of the rotor when disengaged, helping reduce rub... But as far as I can tell, turning the screw doesn't change that. I'm nervous of turning it too far too...
Uncompromising extremist

Comments

  • nicklouse
    nicklouse Posts: 50,673
    http://cycle.shimano-eu.com/media/techd ... 616345.pdf

    from the web site.

    and give them a chance to settle in.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • supersonic
    supersonic Posts: 82,708
    May just need bedding in. Can be a while before they settle into their stride. Check that both pistons are engaging the rotor at the same time and one isn't stuck (and rotor is true)

    AFAIK free stroke adjustment adjusts where in the stroke the pads engage, but without moving the pads themselves. This is distinct from lever reach which changes the distance from the bars of the lever and therefore distance to that bite point.

    I think it is just a case of bed in until the pads settle and the pistons retract fully. Tune up with the free play so they bite at the same place.
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  • Northwind
    Northwind Posts: 14,675
    Thanks, but that doesn't mention the free stroke adjustment feature at all (I should have thought to check under the duals, the manual's just missing from the M775 page, and on the Oz and USA pages there's a dead link for the manual instead- cheers!)

    So, you reckon they'll just settle then? Cool, I'll forget about it for now then... Do you know more about the free stroke adjust?

    <edit- wrote this before I saw Super's response :oops: All answered now>
    Uncompromising extremist
  • Northwind
    Northwind Posts: 14,675
    Cheers folks...
    Uncompromising extremist
  • nicklouse
    nicklouse Posts: 50,673
    well have a look at how far the pads are actually moving. as often the mis mtch feel is due to more movement that will dial out in use.

    Also check that the rotors are not being moved by the pads as this will cause the pistons to move back more or rub, as well as giving a poor feel.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • supersonic
    supersonic Posts: 82,708
    Ha, I posted that to be met by Nicks post, and your reply to nicks after mine though I hadn't seen it!!!

    I was a bit slow lol
    GT ZASKAR CARBON TEAM

    VOODOO CANZO

    Come and see me at https://www.facebook.com/biketyke/
  • pdid
    pdid Posts: 1,065
    All XT manuals are here:

    http://techdocs.shimano.com/techdocs/bl ... 4085164469

    The page you are after is under 776 brakes here:

    http://techdocs.shimano.com/media/techd ... 648114.PDF

    HTH

    EDIT: full link for XT doesn`t work, just go to MTB and select XT
    Commie Meta 5
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