Shimano Hydraulic Disc Brake issue
Simply, one of the pistons does not return after releasing the front brakes on my road bike’s Shimano Ultegra hydraulic disc brakes and causes the dreaded brake squeal. Usually the squeal goes away when I lightly pump the brake 3-4. Sometimes it it needs 8-10 pumps. No squeal while applying the brakes, only after releasing them.
I’ve follow all the procedures I know to clean pistons and calipers, including Park Tools’ and other reliable sources. Changing pads and spring clips has not resolved the issue. I’ve tried to determine if the piston is mis-aligned and thus not moving in/out properly but it does not appear to be so.
any practical advice from others who have experienced and resolved this issue?