Shudder under braking...

Discussion in 'Mechanics Garage' started by snowgoose, Apr 2, 2009.

  1. snowgoose

    snowgoose New Member

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    Hey Gang

    Getting a pretty significant front end shudder under braking and just wondered whether others have encounted the same.

    There is no feedback through the brake lever, so have ruled out warped discs. Also checked discs for spec and both are within 4.5 - 5.0mm. Pads look ok too. Now I am suspecting steering head bearings as there is a distinct notch in the centre when moving bars back and forth. There is no play in the bearings so this would be what you'd expect I guess if some tool had overtightened the bearing adjustment. Does this sound right?

    Cheers

    Snowy
     
    snowgoose, Apr 2, 2009


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  2. derstuka

    derstuka Lord of the Wankers Staff Member

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    Well, since you believe you have ruled out pads and discs being warped, have you checked the front wheel bearings for play? Put the bike on the centerstand, and try to move the wheel fore/aft and lateral, to see if there is any play. Replace if so. What year/model bike to you have boss? Are your fork tubes parallel to each other in the triple clamp (can't see it causing this as much, but worth a shot to look at the forks as well)?

    I had bad/worn headset bearings in my old FZR, but I never felt any shudder in braking before I swapped them out. Not to say it cannot happen. Most times I just felt the slop at low speeds over bumps and such. However, if you notice a notch in the steering head bearings, ( Shimano Indexed Steering as us mtn bikers call it) I would have them and the races replaced for sure.

    Oh, and also check to make sure that your front tire is not cupped/cupping, as this can cause shudder as well. Old Dunlops used to be notorious for cupping. If you had bad headset and/or wheel bearings, this could have caused your tire to wear abnormally as well. If so, worst case you would have to replace the tire to full remedy the problem once the bearings are replaced....if they were bad/worn that is.
     
    derstuka, Apr 2, 2009


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  3. snowgoose

    snowgoose New Member

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    Many thanks Derstuka, yeh have done the old centrestand play check and everything seems fine no movement whatsoever...kinda thinkin maybe I should have a good look at that tire as you've suggested, but as you rightly say with a notch in the center, the bearings are prolly shot anyway. I just wanted to ask to ensure this notch in the center is not normal. It almost feels like it should be there coz its right in the middle.

    I'll do a little more closer inspecting as per your suggestions ... I might just change the pads out to rule out any contaminants, and check the tyre and pressures, have overlooked this, naughty boy.

    Cheers much
     
    snowgoose, Apr 2, 2009


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  4. derstuka

    derstuka Lord of the Wankers Staff Member

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    Yeah, if you are not 100% sure the disc is ok, it could be that your disc is slightly warped and the pad is losing contact then regaining contact....or that your some of your pads are contamintated. You could try block sanding them to make sure you are getting good bite in case they are glazed over slightly.

    Yes, checking tire pressure would be a good thing. Take a look at the brake calipers as well, to make sure (heaven forbid) that nothing is amiss, or missing... :shocked:

    As a remote possibility....see if your forks are adjusted properly (not too soft).

    Good luck mate.... :jason:
     
    derstuka, Apr 2, 2009


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  5. two4one

    two4one New Member

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    A good way to see if your rotors are warped is to crank up to a decent speed (80+), then look to the side and see if your calipers are dancing all over the place. I just replaced a set of bad rotors on my 6th gen due to this same issue. My calipers were moving back and forth and at a very rapid pace causing a lot of shake obviously. Just something to try. For what it's worth you can usually see a warped rotor simply by spinning the front wheel off of the ground also.

    Just my .02.
     
    two4one, Apr 3, 2009


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  6. dizzy

    dizzy New Member

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    You might want to check your pads and discs for contamination such as from leaky fork seals.

    If you have a notch in your steering...your head bearings probably have a divet and should be replaced. Usually it becomes more notable if the bearing preload is too tight...such as right after an adjustment.
     
    dizzy, Apr 4, 2009


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  7. snowgoose

    snowgoose New Member

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    Cheers Derstuka, as it turned out it was the bloody front wheel bearing. Didn't pick it until I dropped a caliper off to look closer at pads, so much for my earlier check when I had wheel off the ground :-(

    But there is still a definite notch in the centre once steering is straight, think I'll go the whole hog and change fork oil, seals, overhaul calipers while Im changin the steerin head bearings.

    Many thanks for the suggestions
     
    snowgoose, Apr 4, 2009


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