Hope mono M4 trouble!

scotttomo
scotttomo Posts: 531
edited October 2007 in MTB workshop & tech
A couple o days ago i noticed my rear mono m4 started to feel a bit mushy and with near enough half a pull on the lever doing not much atall, which i thought can't be normal? I put this down to wear of the pads and bought a new set (needed spares anyway).
So i took the old ones off and compared to the new ones they dont look excessively worn (similar thickness). So i bled them as i thought air had got in somehow. But they're still quite squishy! I followed the steps in the hope manual atach hose to nipple :oops: , open bleed nipple, pull lever to bars and hold, then tighten nipple, release lever then repeat untill no bubbles appear keeping the fluid in resevior topped up. Can anyone help? As this marshmallow feelin is startin to annoy me :evil: Am i doing anything wrong when i'm bleedin them?
Cheers in advance for any replies,
Scott.
"If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

Whyte 46, i fall off it alot!!

Comments

  • nicklouse
    nicklouse Posts: 50,675
    seals could have gone.

    you have pushed the pistons fully home? before the bleed and kept them in place?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Docgeoffyjones
    Docgeoffyjones Posts: 73
    Are the pistons moving equally? if one moves more than the others this will lead to a mushy brake.
  • scotttomo
    scotttomo Posts: 531
    Ah ha! Cheers :D . That must be where i'm goin wrong Nick, i was bleedin them with the pads and wheel still in :oops:. So keep the pistons in place with some sort of spacer,while 'home'?
    Thanks again,
    Scott.
    "If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

    Whyte 46, i fall off it alot!!
  • nicklouse
    nicklouse Posts: 50,675
    yep that is the idea or you can end up with air pockets in the bores.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • scotttomo
    scotttomo Posts: 531
    Cheers Nick nice one!
    "If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

    Whyte 46, i fall off it alot!!
  • nicklouse
    nicklouse Posts: 50,675
    i am not saying that it will sort the brakes but it is a start. AngyB was saying about winding the lever reach adjuster so that the lever was fully away from the bar helps with the bleed as well.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • scotttomo
    scotttomo Posts: 531
    Fingers crossed :P . If it is the seals is it straight forward? I just dont fancy sendin them out to be replaced as i use my bike to commute till i pass my test :cry: . Wound the levers out when i bled them last, so i'll do it this time too. Thanks again, i'll keep u posted coz i will be doin them in the next hour or so.
    "If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

    Whyte 46, i fall off it alot!!
  • scotttomo
    scotttomo Posts: 531
    Ok so i've bled my rear brake with a block in the caliper to stop the pistons moving. But when i replace the wheel and pads then pull on the lever it takes a couple of 'pumps' untill the pads touch the rotor. Which i suppose is normal as the pistons have to move to the rotor from the 'home' position. Then as the pads seem to be in the right position (bout a mil from the rotor) i pull the lever again and again are mushy. This is startin to do my head in :x . Heeeeeelllllllllllpppppppppp!
    "If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

    Whyte 46, i fall off it alot!!
  • nicklouse
    nicklouse Posts: 50,675
    right it is bled well? and when the pads touch the rotor the rotor is not being bent? As that cangive a mushy feel.

    if the brake feels fine as you move the pads to the disc but only feels bad when you need to re apply it i would say that you still need the pistons to settle, either by use or pump the pads to the disc and then zip tie the lever back to keep the pads in contact, not too much force just enough to hold the brake on, and leave over night. then the brakes just need to get in their "grove" and 1mm sounds a bit much.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • scotttomo
    scotttomo Posts: 531
    Bled well? Topped fluid up at least 6 times in the resevior is that enough?
    Rotor not bendin either. Will take it out tomorrow and see how they fair and i'll report back. Just really annoyin me coz my front brake is solid and has plenty of 'feel'.
    "If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

    Whyte 46, i fall off it alot!!
  • scotttomo
    scotttomo Posts: 531
    Seem to be 100 per cent better now :D . Thanks nick appreciate the help i was at my wits end :x . Anyway i've always wanted to ask you, what is a yorkshire man doing in sweden? :P
    "If i was a slug i don't think i could handle it, i'd just throw myself in the salt pot" -Karl pilkington

    Whyte 46, i fall off it alot!!

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