Ultegra Caliper Movement

[mrscottyboy]

I recently noticed that my front caliper was getting off center. I used the centering screw to re-center the calipers, but the adjustment needed began to be too much for the centering screw. I then realized that the whole caliper is moving on the mounting bolt. This bolt is very tight, but the caliper can still be moved by hand. Is there a way to lock that bolt/nut down?

 

[KGnagey]

I recently noticed that my front caliper was getting off center. I used the centering screw to re-center the calipers, but the adjustment needed began to be too much for the centering screw. I then realized that the whole caliper is moving on the mounting bolt. This bolt is very tight, but the caliper can still be moved by hand. Is there a way to lock that bolt/nut down?

I suspect you are missing a spacer there somewhere preventing you from tightning the caliper fully. Most brakes have a serated washer behind the calipers. This washer helps prevent movement and is also a spacer. Check to see that you are not bottoming your bolt down down because this washer is missing. Also is this the front or rear break? Front breaks have a longer center post to fit the forks. The rear breaks have a shorter post to fit the mount crossing the seat stays.