Front Brake vibes...

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

  1. Mr OCD

    Mr OCD Active Member

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    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

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    Head bearings maybe
     
  3. Mr OCD

    Mr OCD Active Member

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    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

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    So the vibration on started after the work on the forks and the bearings replaced?
     
  5. Dave dunlop

    Dave dunlop Active Member

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    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

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    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

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    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

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    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

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    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

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    I was referring to the head bearings....28k! They might feel good but under load feel completely different...
     
  11. PeterT

    PeterT Active Member

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    Head bearings, I had the same issue. Cured by fitting a taper head bearing.
     
  12. Mr OCD

    Mr OCD Active Member

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    Cheers all. Will sort the head bearings and go from there.

    Is it a straight forward job?
     
  13. Mr OCD

    Mr OCD Active Member

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    Tapered or OEM bearings ?
     
  14. TheRamJam

    TheRamJam Active Member

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    All balls tapered mate
     
  15. Mr OCD

    Mr OCD Active Member

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    Track day today ... the issue is worse than ever. What the heck is going on. Getting annoyed with it now.

    Even better I sold my spare brake discs to try! :/
     
  16. Mike07

    Mike07 Active Member

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    I think before you start big jobs look at the discs. I had a problem on a mates Blackbird some years ago, similar in some ways Discs had become Varnished with something, you could only tell by running your nail around the disc. only showed up on hard use... Cleaned them with brake cleaner and scotchbrite (it was a b$$** to do.) changed the pads ...solved.
     
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  17. sps170373

    sps170373 Moderator
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    Have you checked the brake buttons are moving freely? I've just cleaned mine and it's stopped a vibey feel I was getting
     
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  18. Mr OCD

    Mr OCD Active Member

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    Yes they are ... the brake buttons are cleaned every wash. They are Brembo ORO discs if that makes any difference which I think are full floating?

    I will be doing this tonight as the disc surfaces aren't as clean as I like. I have a new set of pads waiting to go in anyway.
     
  19. Dave dunlop

    Dave dunlop Active Member

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    I thought you had sorted this issue with new head bearings?
     
  20. Mr OCD

    Mr OCD Active Member

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    New head bearings resolved the issue for about 40-50 miles ... now its back again. I expect disturbing the brakes / alignment was enough to reduce the issue for a few miles but now its back again.

    It's definitely feels like an issue with the brakes. With the wheel on paddock stand you can hear the brakes dragging against the disc, likewise when you push the bike around you can hear the brake discs rotating and feel it through the bars ... if I ride along then pull the clutch in so free wheeling again you can feel the discs rotating.... something isn't right there. But the wheel spins freely enough so clearly the pads aren't dragging!

    Brakes feel powerful and solid with no pulsing.

    So in this case the best thing to do is pull the wheel out, clean up the disc surfaces and install new pads along with checking wheel bearings for any play. Head bearings were checked after about 500 miles once settled in and they are ok.

    I can't see the discs being warped given they have only done a couple thousand miles although were bought used from Daz. They are Oro discs as well so thicker than standard but I wont rule it out just yet.

    Am I barking up the wrong tree?
     

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