Thank so much for your reply. I found a rust on the slide pin. So pads propably struggling to move. I'll order new pin and apply very light coat of copper grease ??You have dirty slide pins, or bent pins, stuck piston, or you were way to agresdive on the pads if those pads were brand new as well. New pads need light braking for a couple hundred miles to fully seat the contact surfaces to the rotor. In a car 300 miles is plenty. Rear brakes hardly get used by most people, so expect 500 miles light use.
Thank you for your help, I have inspected today bracket support and can't see any damage. I've applied grease on the pin and spring/clip and will see tommorow if it improved.This side of the pad, rests on the carrier, which is basically just a ledge.
View attachment 378019
What happens over time is, the pads wear a deep grove in it. That grove prevents them from backing-off and moving like they should. Only resolution is to replace the brake caliper carrier. While there might be some way to improvise, you generally don't mess around when it comes to brakes. The rear brake was not designed to STOP the bike... only slow the bike. So if it's being over utilized, this will cause the aforementioned damage.
They call it "bracket support" in this diagram [#10] and, good luck finding one.
View attachment 378020
Inspect your existing one. The damage if present, will be obvious.