still got brake problem

gonga
gonga Posts: 225
edited October 2009 in MTB workshop & tech
I have juicy 5's on my trek ex 8 and get a really weird feel to the front.
I have realigned the caliper and cleaned with brake cleaner with no joy.
My brakes were great for the first 50 miles but now the front is hard to use without locking under hard braking on loose surface
The disc is slightly out of true but only just(not enough to bend back) but my rear is the same and that works well. :?
if i push the bike and apply the brake so it just catches the disc it locks at one point on the disc as though its alot more grippy than the rest of the disc :?
I've done around 60 miles since and the issue is still there.
Can a slightly warped disc cause such problems?

Comments

  • supersonic
    supersonic Posts: 82,708
    A warped disc is not desirable, but under moderate braking the pressure from the pads will flex it back. It is more noticable under not braking as intermittent rub.

    How warped is it though?
  • gonga
    gonga Posts: 225
    edited September 2009
    only a fraction,say quarter of a millimetre if that.
    The back is just as warped but that is smooth and predictable.
    If it is a warped disc im not sure if i got i new rotor i'd be able to keep it perfectly true for long :(

    It really grips one area of the disc under any braking pressure.
    I've removed the pads and srubbed the disc with muc off brake cleaner and sanded the top off the pads slightly,still acting the same :?
    I'd try new pads but im puzzled as to why its still bites well on part of the disc and less on other bits.

    could the disc be contaminated?
    can you lightly sand the disc?
    thanks for the help :D
  • nicklouse
    nicklouse Posts: 50,673
    the warp will make no difference.

    with what you say you have done (would have been good in the OP) i would put it down to a faulty dics.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • gonga
    gonga Posts: 225
    nicklouse wrote:
    the warp will make no difference.

    with what you say you have done (would have been good in the OP) i would put it down to a faulty dics.

    thanks. :)

    so would a light sand of the disc be worth a try?
    Im glad if its not the warp thats causing the issue as it looks impossible to keep them perfectly true :lol:
  • Anonymous
    Anonymous Posts: 79,665
    Your disc isn;t catching on your fork or brake calliper is it?
  • steelo
    steelo Posts: 542
    The disc are steel and not prone to being sanded!

    Maybe if you had a bench grinder - but don't!
    Specialized Rockhopper '07
    Trek Fuel EX8 '09
  • Anonymous
    Anonymous Posts: 79,665
    now a surface grinder - that could work, provided you had a properly square mount.
  • nicklouse
    nicklouse Posts: 50,673
    gonga wrote:
    nicklouse wrote:
    the warp will make no difference.

    with what you say you have done (would have been good in the OP) i would put it down to a faulty dics.

    thanks. :)

    so would a light sand of the disc be worth a try?
    Im glad if its not the warp thats causing the issue as it looks impossible to keep them perfectly true :lol:

    change the disc and see if the issue goes.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • gonga
    gonga Posts: 225
    Your disc isn;t catching on your fork or brake calliper is it?

    Hi :D
    no its not rubbing on anything.
    I'll pick another up,should i get new pads aswell?
  • gonga
    gonga Posts: 225
    I have just got my bike back yesterday after evans sent my brakes back to avid for repair.
    The fault was still apparent after much fettling so avid sent me some new elixir 5's(front and back!). :D
    nice result and love the new brakes! :lol:
  • gonga wrote:
    I have just got my bike back yesterday after evans sent my brakes back to avid for repair.
    The fault was still apparent after much fettling so avid sent me some new elixir 5's(front and back!). :D
    nice result and love the new brakes! :lol:

    You had a right result there my friend! :D