Front Brake vibes...

Discussion in 'Maintenance' started by Mr OCD, May 18, 2017.

  1. Mr OCD

    Mr OCD Active Member

    Joined:
    Nov 9, 2014
    Messages:
    2,071
    Likes Received:
    479
    Bit of an odd one this ... my blade has M4 calipers with standard brembo pads, Brembo ORO discs and a Brembo RCS19 MC with braided lines ... they feel superb as expected.

    When braking hard from speed. I.e. motorway to town I get vibration through the front end and I can't work out what it could be... the lever stays constant, as do the brakes and in fact I simply thought it was the road surface through the tyre ... at low speeds it is fine.

    A few months ago the forks were rebuilt, wheel bearings replaced as were the discs and pads and it didn't have this vibration.

    Stripped and cleaned the brakes last night and it is still there.

    Not sure where to go from here? Any ideas?
     
  2. TheRamJam

    TheRamJam Active Member

    Joined:
    Feb 26, 2013
    Messages:
    690
    Likes Received:
    210
    Head bearings maybe
     
  3. Mr OCD

    Mr OCD Active Member

    Joined:
    Nov 9, 2014
    Messages:
    2,071
    Likes Received:
    479
    They were checked as part of the recent work (although not dismantled) and found to be fine with no play / notchyness... ?

    Bikes done 28k btw.
     
  4. blake7

    blake7 Active Member

    Joined:
    Feb 16, 2011
    Messages:
    556
    Likes Received:
    106
    So the vibration on started after the work on the forks and the bearings replaced?
     
  5. Dave dunlop

    Dave dunlop Active Member

    Joined:
    Jan 11, 2015
    Messages:
    1,182
    Likes Received:
    478
    Could be a number of things so it's a process of elimination.... can't see it being the callipers personally, sounds more like something out of balance or something incorrectly tightened so transmitting some bad noise via the bars only under braking.... I would look at headstock first and work your way down! 28K is a great deal of mileage without much or any maintenance, Even look at front wheel assembly, as in the right procedure for how to correctly fit and tighten without restricting fork compression. It might just be that with your old wheel bearings and fork bushes/oil etc were so worn that the feeling was lost within the freeplay limits.
     
  6. Mr OCD

    Mr OCD Active Member

    Joined:
    Nov 9, 2014
    Messages:
    2,071
    Likes Received:
    479

    Calipers, discs, pads, forks, braided hoses are all 2000 miles old ... :) - so no not 28k on the same stuff ...

    Only thing I haven't changed is the head bearings ... idiot here forgot about them but I did check them for play and they were smooth with no play.
     
  7. Mr OCD

    Mr OCD Active Member

    Joined:
    Nov 9, 2014
    Messages:
    2,071
    Likes Received:
    479
    No, not directly after ... it's been about 2000 miles since all the work was done.

    I say vibration, but its more like road noise / feel ... i.e. it doesn't make the bike shake but it is very noticeable...
     
  8. TheRamJam

    TheRamJam Active Member

    Joined:
    Feb 26, 2013
    Messages:
    690
    Likes Received:
    210
    I'd get the front wheel off and refit following the service manual. While the wheel is out, check the wheel bearings for any roughness. Even though they are new sometimes they can fail from time to time. Button everything back up and see if you're getting the same symptons.

    If the problem persists i'd seriously look at the head bearings. You may not feel there is anything wrong while checking the play when the bike is static. But there could be some wear there that is only evident when the front end is loaded up under weight and then it becomes apparent.
     
  9. tuktuk

    tuktuk Member

    Joined:
    Dec 2, 2015
    Messages:
    364
    Likes Received:
    131
    I get this occasionally especially under hard braking. Like a juddering through the forks/bars.

    7k miles on 2013 bike rcs19 and braided lines, not had time to fit m4 calipers yet.
     
  10. Dave dunlop

    Dave dunlop Active Member

    Joined:
    Jan 11, 2015
    Messages:
    1,182
    Likes Received:
    478
    I was referring to the head bearings....28k! They might feel good but under load feel completely different...
     
  11. PeterT

    PeterT Active Member

    Joined:
    May 17, 2011
    Messages:
    997
    Likes Received:
    242
    Head bearings, I had the same issue. Cured by fitting a taper head bearing.
     
  12. Mr OCD

    Mr OCD Active Member

    Joined:
    Nov 9, 2014
    Messages:
    2,071
    Likes Received:
    479
    Cheers all. Will sort the head bearings and go from there.

    Is it a straight forward job?
     
  13. Mr OCD

    Mr OCD Active Member

    Joined:
    Nov 9, 2014
    Messages:
    2,071
    Likes Received:
    479
    Tapered or OEM bearings ?
     
  14. TheRamJam

    TheRamJam Active Member

    Joined:
    Feb 26, 2013
    Messages:
    690
    Likes Received:
    210
    All balls tapered mate
     

Share This Page