do i need to bleed my brakes

Anonymous
Anonymous Posts: 79,667
edited April 2008 in MTB workshop & tech
i think i already know the answer to this one (yes) but am hoping someone can convince me other wise.

out today on the bike i was getting thredders with my rear brake. when trying to stop from speed, i would pull the brake lever and the travel seemed excessive and wouldnt result in the rear brake being applied nearly hard enough. but at low speeds it wasnt so bad, also, it was as if i could pump the brake up so the brakes could be applied with less lever travel when stood stil.

so, do i need to bleed the brakes?

the brakes are formula oro k18 fitted with standard 180mm rotors and ebc gold sintered pads. the caliper is correctly aligned, both pistons move an equal amount and the rear disc doesnt bend during operation.

Comments

  • nicklouse
    nicklouse Posts: 50,675
    first check that when you pull the brake that the pads are not twisting the disc. If there is no movement in the disc then yes it is time to buy a bleed kit.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Anonymous
    Anonymous Posts: 79,667
    i kinda figured as much, i have checked and there is no movement in the disc, i take pride in making sure my calipers are always correctly aligned to prolong pad life and prevent the discs rubbing.

    how does a perfectly serviceable brake (the last time i rode the bike)suddenly need bleeding this time (i know it does but cant understand with a sealed system why this would be the case)

    how much should i expect to pay for a bleed kit and would there be any sense in getting a universal kit instead of a formula one?
  • nicklouse
    nicklouse Posts: 50,675
    what i am finding is that most brake benefit with a degas when fitted. as there tends to be air in the fluid which comes out after a few rides but iirc you have had these for a while now?

    does the lever feel sluggish?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Anonymous
    Anonymous Posts: 79,667
    yeah ive had the bike for about 7 months with no problems other than changing some pads.

    the brake lever feels fine, just lever travel was far too long, the blade almost touched the bars and the braking effort was weak at best. as i say, it was improved after a few pumps (fnaar fnaar) but went back to slack next time i wanted to use 'em.

    this only happened today tho and at thetford of all places, hardly alpine braking forces required eh!!
  • nicklouse
    nicklouse Posts: 50,675
    i would get incontact with the supplier as there have been the odd problem with some of the rear lever assys. a new seal assy is provided.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Anonymous
    Anonymous Posts: 79,667
    the brakes are OE so might get in comms with abbey cycles and see if they can take a look.
  • Anonymous
    Anonymous Posts: 79,667
    just found this incase a bleed is necessary in the future, do you think it includes fluid? seems rather cheap but does state it includes everything i need.
  • nicklouse
    nicklouse Posts: 50,675
    any DOT 4 or DOT 5.1 will do and no it does not include fluid. READ the instructions and do not lose the small O rings.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Anonymous
    Anonymous Posts: 79,667
    just reading the instructions on the formula site, looks alot more complicated than my shimano brakes :?
  • skyliner
    skyliner Posts: 613
    Before you start bleeding, express some fliud and check the colour. If it's opaque, a kind of milky yellow,you've got issues with the MC piston assembly and need to get the new ally piston seal body retro fitted under warranty.
    If not, carry on with the bleed and it'll sort it.
    It's nice to be important, but it's more important to be nice.
  • nicklouse
    nicklouse Posts: 50,675
    Now that is something they did not tell me. But it is the expected results of worn seals.

    changed 3 rears as the lever was like i said above "mushy" and slow to return and yes the fluid was milky. but they never said it was a test....
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • clipper
    clipper Posts: 60
    hi , i've recently bled a puro rear brake and the lever is now slow to return compared to the front. there's also a squelching noise coming from the rubber seal where the lever connects to the pump. i bled the brake but didn't notice the fluid was opaque. any ideas? did i mess up the bleed?
  • nicklouse
    nicklouse Posts: 50,675
    maybe. as it seems to be the rear that is having the problems.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • clipper
    clipper Posts: 60
    tried them out at the weekend and the braking power on the rear is fine but the lever is slow to return. have just bled again, very few bubbles came out and the lever is still the same i.e. nowhere near as snappy as the front. could it be anything other than a bleed issue?
  • nicklouse
    nicklouse Posts: 50,675
    shop time for possible warranty fitting of new master piston.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • clipper
    clipper Posts: 60
    They're from Merlin so not as straight forward as wheeling it down the lbs. Is it a tricky job? And would it just require the Formula Oro Master Cylinder Piston Kit on chain reaction?