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  • XT M775 Brake Help – Anyone else had this?
  • oscillatewildly
    Free Member

    thought as the brakes had an extreme winter (cold) and heard bad things about things seizing come cold winters and the likes, that perhaps one of the pistons had seized on the front brake….so had a play, got the pistons out so far, give them an IPA clean, then put some mineral oil in and around the pistons, pushed back in, did the same etc that it would cure my problem – however it has’nt!

    its the lever itself, its catching or should i say it feels gritty on the very first initial tug on the brake, once it gets past that point its fine and smooth, yet the lever itself its almost crunchy/gritty ie. not smooth upon pulling first off for about 2mm of travel of the lever (then pulls in normal)….

    i had a look at the underneath of the brake lever, there seems to be a roller of some sort for when the brake is depressed, so i gave this a clean, thinking thats where the said grit lay…but its still the same??? same crunch inital 2mm of travel on the lever? is there any where else i can lube or anywhere else it could be the problem? its really annoying and actually scared me a bit on some descents, as it feels almost like the the brake isnt going to pull in for a moment, like its seized/stuck?

    i know theres enough folk on here who have them so any input really helpful 🙂 ive been hovering over some cheap formula rx brakes for a while, so will this send me over the edge 😆

    thepurist
    Full Member

    The roller is part of the servowave system – there’s a plastic cover on the bottom of the lever body (near the blade) that comes off with a couple of screws, that’ll expose the roller mechanism a bit better so you can give it more of a clean. There’s a second cover on top of the lever (the bit between the reservoir & lever blade), but to get that off you need to undo the clearance adjustment lever all the way.

    (Parts 8 & 6 on this) – you may also have managed to get grit into the swively bits on the lever blade. Unlikely to have got further into the workings unless you’ve crashed majorly.

    oscillatewildly
    Free Member

    ahh cheers the purist, will have to have a further look into it then, i can only assume its a bit of grit somewhere along the lines, i cant really see what else it can be, defo no crashes involved though 🙂

    cheers again!

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    bigyinn
    Free Member

    If cleaning the roller fails to remove the grittyness, then you can remove the actual lever blade. The roller doobry has a ball and socket joint which is what actually compresses the fluid in the master cylinder, perhaps you’ve got grit in there.
    The only trouble ism to remove the lever, you need to unscrew the hose from the lever to get at a small grub screw (through a small hole near the hose) which holds the main pivot pin in place on the lever.

    oscillatewildly
    Free Member

    cheers bigyinn i will have a look into it further, i have a spare lever that i bent really bad so can have a play with that first before hamfistedly damaging the current one 😆

    cheers again for the help!

    im pretty sure now its just grit in the system some where on the lever, or inside the lever, cant really be much else!

    bigyinn
    Free Member

    I found this out by taking mine apart to straighten a bent lever blade!

    oscillatewildly
    Free Member

    was it a easy job to pull apart and back together? did it need re-bleeding after also biggyin?

    cheeres again!

    bigyinn
    Free Member

    Yes reasonably easy to do, just unscrew the grub screw a bit, don’t undo it completely.

    Re-bleeding prob not a bad idea if your disconnecting the hose.

    But to minimise this need do the following:-
    Take pads out and pump the pistons out a bit BEFORE disconnecting hose.
    Keep hose as high and vertical as possible whilst disconnected.
    Reconnect and then push the pistons all the way back in, should push any air back into the reservoir.

    oscillatewildly
    Free Member

    cheers bigyinn – do you think a squirt of finish line lube in and around the lever may be an easier option? would the lube get in all the nooks and crannys? should get inbetween the grit if theres any there and make it at least smooth?

    ill have a look on the spare knackered one i have to see how easy it is, failing that ill try some lube and then go down the route of dismantling, reason i want to try avoid that is ill forget how it all came apart and end up ko’ing the heads off the grub screws etc 🙁

    bigyinn
    Free Member

    I’d be wary of flushing too much lube around your brakes, the solvents can upset the rubber seals etc.
    I’d have a play with the old lever first so you can decide whether you’re happy to continue in the gritty lever or not.
    Just take the servo wave gubbins out (top and bottom) first then try cleaning it out (cotton bud might be worth a try)

    Oh and use a nice new allen key on the grub screw, less chance of it rounding out!

    oscillatewildly
    Free Member

    ahhh thanks bigyinn, will remove the grub screw for the servowave, maybe where its entered as i have them at the max out setting, if i just remove the screw completely it wont do any damage will it? ie air entering the system etc? ill give everything a good clean i think, the bottom of the lever looks like a likely place to start removing, as the second person responded in this thread, as you can see the roller bit in question easier….maybe easy to access with cotton bud!

    cheers again for your thoughts and input bigyinn 8)

    bigyinn
    Free Member

    The grub screw is ok to take out, but its pretty small and easily lost. But you’ll be fine.

    oscillatewildly
    Free Member

    bigyinn cheeres for the help, a good fettle and clean with cotton buds and some IPA and then a smoothing over of the moving parts with a mix of light lube and oil and shazzzam, working back smooth as can be! i also wound the freestroke in a bit more as i dont know whether it had rattled outwards a bit more, a few quarter turns in of that and without even cleaning it felt alot smoother, so dont know whether that was the cause to some extent also….anyways, cheers for the help as its working like new and smooth as can be now 🙂

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