Rear brake "chatter"

Hi all! Just got finished with a 300 mile loop in the Rockies. I noticed a couple of strange things on my new (to me) bike. When I hit the rear brake and slower speeds (30-40) I get what seems to be chatter. Seems like I've got rubber pads or something. I'll take a look in the morning, but just curious if anyone has had similar issues.

 

Check to see if the pad worn uneven. My did that before pill the calipers and give them a good clean up replace with new pads. Problem go away.........

 

Thanks for the info Scubalong. Everything checked out okay and it hasn't happened since. Strange.

 

Glad it work out for you, never fun when your bike is not running right. Ride safe