Brake Chatter!!!

[lowd239]

Well I had a close call this past weekend.  I was getting on an onramp and tipped into the turn and realized I was in a bit too hot.  I trail braked into the turn and then the front end started chattering like crazy.  It was chattering so much, I had to stand it up in the turn and ended up lowsiding into a curb.

I was quite lucky since I was wearing my full leathers and only hit the curb at 10mph with minimal damage to myself and the bike.  Even the mirror wasnt broken!

Anyways, I had a similar problem at mid-ohio, trail braking into one of the turns, but I had not experienced the chattering the last time I did a track day there so I thought perhaps it was just my riding style. 

The onramp was concrete that was slightly wavy and I think that may have had something to do with the chatter.  Ive checked the steering stem bearings three times over the past couple months and as far as I can tell they are fine.  Ive also changed brake pads within the last year so I think I have ruled brake pads out.

I should note that I swapped out the front forks on my m900 two years ago for the 05-06 gsxr1000 forks and radial calipers.

Any thoughts on what could have caused the chatter or is it just an inherant issue with the bike that I have to be aware of?   Thanks!

[Ddan]

The usual chatter problem is from uneven deposits of pad material on the rotor, but normally it happens at slow speed to almost stopped.  Try cleaning the rotors with something like Scotch-brite and brake cleaner and then re-bed the pads. While you're cleaning make sure the buttons are all free and the rotor can move on the carrier.

[Norm]

Are you sure it wasn't wheel chatter?

[Howie]

I think what Norm is referring to is some people mistake brake chatter for a different problem. The front suspension can bottom out on braking, causing the wheel to bounce on the pavement.

[lowd239]

I think Im starting to believe that the brakes might be the cause.  I was riding double up yesterday and had to decelerate pretty quickly and noticed a slight chatter as I came to a stop.

I will check the rotor run out to see if it is within spec.  Is there anything else, brake related, that could be the culprit?

[ducpainter]

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

[Norm]

PS: wheel chatter can be caused by about a million different things - 1/2 of which are blamed on the tire guys and the other half on the suspension guys.
I understand some of them, but no one seems to understand all of them. We can go deeper if you like, or if it seems relevent.

[Howie]

You will not find a run-out spec in the official Ducati manual for the front, only the rear.  Since you have a two piece rotor, carrier and blade held together by buttons with spring washers (semi floating rotors) there is movement, so you can't measure run-out without dissasembly.  As stated in ducpainter's link, uneven brake material transfer will cause vibration.  The cure, if this is the cause,is to clean the blades with brake cleaner and a Scotchbrite Pad.  Then sand the pads, go for a ride and bed in the brakes.  While you are at it, clean the buttons and make sure they are not stuck.  If you feel adventurous, are good with a hammer and don't mind hearing your rotors rattle when going slowly, ask Norm about his trick for turning your semi floaters into full floaters.