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Buell Forum » 1125R Superbike Board » Archives 001 » Archive through August 11, 2009 » Front end vibration « Previous Next »

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Fresnobuell
Posted on Sunday, August 09, 2009 - 11:13 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Well yesterday for the first time I noticed a pronounced vibration from the front end under heavy braking and only from about 5 mph to 0 mph. If I stop normally it's all good, but hard on the brakes it shudders from 5 to 0 mph.

Anyone have a guess why this may be happening?

Incidentally and I hope coincidentally, yesterday I also saved dropping the bike by using the clip-ons and retard strength. The gravel was deeper than it appeared. I don't think I bent anything, but it's of course possible.

I thought I would just throw this out there to see if anyone has any idea of what could be causing this vibration.
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Geforce
Posted on Sunday, August 09, 2009 - 11:23 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Dunno Fresno, but I know when I am coming to a stop the brakes pulse like normal, and when I keep it steady from about 5MPH to stop it seems to catch harder and the front dips a little. Made me wonder if I need to pop the pads off, clean it up and bleed the brakes.
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D_adams
Posted on Sunday, August 09, 2009 - 11:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rotor warpage.
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Spank
Posted on Sunday, August 09, 2009 - 11:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Can't help ya, but I am curious to know the answer as well, mine seems to do the same. Kinda acts like its warped, but mine doesn't vibrate I guess.... More like a pulse. Like you said though, it only happens right before I come to a stop.
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R2s
Posted on Monday, August 10, 2009 - 12:38 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

What kind of pads you using, and is it all the time or just after. they get hot.

My rotors got black deposits on them from over heating the stock pads. Then I got pulsating. The rotors got real ugly looking.

I cleaned them up but it is still there, but mostly under heavy braking. With the EBC's on now they seem to be cleaning up the rotor some. I'm hoping I will not have to get a new rotor.

Are the Buell rotors turn-able, and who can do it.
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Ponti1
Posted on Monday, August 10, 2009 - 08:08 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I had minor rotor warp, which was greatly pronounced every time some brake build-up got on the rotor. So, my pulsing/vibration was happening all the time, and under all braking conditions. It was less annoying for a while each time I scrubbed off the crap on the rotor.

With the new race rotor and latest spec brake pads from BMC installed, I have not had any issues. Then again, it's only been 1000 miles, so time will tell.

I imagine the symptoms you describe could be from a perfectly fine rotor with just some build-up on it, but have not experienced it myself.
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Jdugger
Posted on Monday, August 10, 2009 - 08:20 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The pulsing may be caused by the stock pads glazing. If your rotors aren't turning colors (straw, blue and purple), they aren't getting hot.

Run up to about 70 and shut her down relatively hard to about 20. Do this a few times and see if the pulsing goes away.
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Ponti1
Posted on Monday, August 10, 2009 - 08:55 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

+1 Jdugger, not sure if it was you that last recommended this to me, but it definitely helped. Only difference is I have been going from 90-100+ down to 10-20.

(Message edited by ponti1 on August 10, 2009)
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Luisemilio25r
Posted on Monday, August 10, 2009 - 11:44 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Does it do it only when you brake or all the time? Mine is doing the same. I checked my front tire and it seems to be the cause. Because I use on the highway a lot, i has "squared" and there is an angle on both sides of the tire between the contact patch and the sides of the tire.
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Fresnobuell
Posted on Monday, August 10, 2009 - 12:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

It's definitely not a pulsation, but a vibration. Seems to do it hot or cold and only 5 to 0 MPH. Weird. I have been using the EBC HH pads with good results--however they are getting down to the end of their life.



andrew, do you have the new finned rotor? If so, what are your thoughts on it? How much heavier is it than the stocker? I am considering it possibly.
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Fresnobuell
Posted on Tuesday, August 11, 2009 - 05:08 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Just in from Buell racing:

3.2 lbs stock rotor
3.486 lbs finned rotor
3.692 lbs 6mm rotor.

Difference is 4.57 ozs. from stock to finned. Or an 8.9% increase.

7.87 ozs. from stock to 6mm rotor. Or 15.4% increase.

I wonder how this would affect the gyro aspect of the ZTL?
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Gregtonn
Posted on Tuesday, August 11, 2009 - 06:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Fresno,
Go find yourself a hill that you can coast down at 0 to 5 mph for 200 feet or so while lightly applying the brake.
If you feel the brake lever pulse its a warped rotor.
Other wise the pads probably aren't bedded correctly.

G
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Fresnobuell
Posted on Tuesday, August 11, 2009 - 06:13 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Dunno. everything feels completely normal except 5 to 0 MPH under very hard braking. COuld a warped rotor manifest itself in that manner?

I am thinking it MIGHT possibly be a slightly warped rotor as I did a track day a few weeks ago with sizzling temps.
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