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Hydraulic brakes, again. . .

bobbydigitalbobbydigital Posts: 249
edited April 2018 in MTB workshop & tech
I bled a rear M675 brake, it feels solid when the bleed block is in place, which is great.

I have centered the disc and caliper. The wheel spins freely. The pads engage the disc equally and do not push on it and move it, so everything seems great but it just isn't.

The lever travel is long before there's any bite, probably 1.5 cm but when it gets there it's pretty solid, no idea what it could be, but I do not want such a long throw before the brake engages, it feels sloppy and unprofessional!

I've rode it for a while like it but no change.

Posts

  • The RookieThe Rookie Posts: 27,747
    So have the pads settled out on the disc are are they still retracting and leaving a gap, if it’s the latter you just need to use the brakes until they adjust out.
  • trekvettrekvet Posts: 219
    Just checked mine and they both ~1.5cm. and I can stop on a dime from 35. As I recall the pads will move back, partially from the distortion of the piston seals, which is how they are designed, and also by being knocked back by the disc, so the straighter the disc (and the less play in the wheel bearings), the less the knock back. Perhaps the lever has a free play adjuster, but I doubt it otherwise chaps would adjust out all the free play then the brake would drag / stay on a bit. If you got the caliper spot on once secured, then just ride.
    The Wife complained for months about the empty pot of bike oil on the hall stand; so I replaced it with a full one.
  • cooldadcooldad Posts: 32,904
    M675 does have adjustable lever travel, but not bite point adjustment.

    Saying that, I have the same brakes, and never found the small amount of lever travel any hassle. Pretty sure all my random brakes have similar.
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  • Okay cool, I will keep using them and see if it improves as there's still a gap between pads and discs from the pads being new.

    I'm coming from motorcycling background and try to get that 5mm of travel feeling :roll:
    Old set of hopes I had were really good for minimal lever travel.

    Yeah I have the adjust on the lever set furthest out, seems to give me a better feel.
  • swod1swod1 Posts: 1,639
    Have you tried pumping the lever as this will position the pads in relation to the disc and should get rid of the lever travel.
  • Yes I've pumped brakes and it doesn't improve, hoping with use that it will.

    It stops very well just I like things to feel a bit more refined.
  • swod1swod1 Posts: 1,639
    Yes I've pumped brakes and it doesn't improve, hoping with use that it will.

    It stops very well just I like things to feel a bit more refined.

    You can adjust the lever reach with an 2mm allen key if you wish.
  • cooldadcooldad Posts: 32,904
    swod1 wrote:
    Yes I've pumped brakes and it doesn't improve, hoping with use that it will.

    It stops very well just I like things to feel a bit more refined.

    You can adjust the lever reach with an 2mm allen key if you wish.

    You don't use an allen key - they have a bloody great knob sticking out to do it.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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    Parktools
  • swod1swod1 Posts: 1,639
    cooldad wrote:
    swod1 wrote:
    Yes I've pumped brakes and it doesn't improve, hoping with use that it will.

    It stops very well just I like things to feel a bit more refined.

    You can adjust the lever reach with an 2mm allen key if you wish.

    You don't use an allen key - they have a bloody great knob sticking out to do it.

    Yes on my XTs they do that but didn't know models down the range had it too.
  • My front one is a 615 that needs allen key but yes the slx has the knob, added weight!
  • 02GF7402GF74 Posts: 1,294
    My front one is a 615 that needs allen key but yes the slx has the knob, added weight!


    Indeed, never could see the sense in that, once reach is adjusted, then that is it.

    Maybe there were issues with the small hex socket rounding off or a marketing feature?.
  • I like the allen key ones, better low key look and like said, you adjust it and that's normally it, unless your fingers grow or shrink a lot.

    I sorted out the rear slx brake,

    I removed the wheel.
    Pumped the brake to move the pistons out.
    Refitted the wheel.

    For some reason it would not self level, even after some bedding in, hard brake, maybe 20 miles in total. Still a little gap between the pads and disc so I reckon I could get it better but I'm happy with it now, there's about 5mm less travel so it's equal to the front brake.
  • swod1swod1 Posts: 1,639
    that sounds fine you want a 1mm or 2 between the pads and the disc other wise they will start rubbing.
  • 02GF7402GF74 Posts: 1,294
    swod1 wrote:
    that sounds fine you want a 1mm or 2 between the pads and the disc other wise they will start rubbing.

    wow what brakes have you got :shock: ? I don't have means to measure but gap between pad and disc on my bikes looks to be typically 0.5 mm or less;

    a 2 mm gap - is that each side? is massive.

    And they only start rubbing if the disc is out of true - you can bend parts of the disc carrier to centre it so there is no rub even with the sub mm gaps.
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