JIM77

Hi all, changed pads all round on my 05 STI today. I couldn't get the inside pad out of the back left caliper so i un-bolted the caliper, moved it away from the disc to give me more room to get the pad out. Got the pad out, replaced the caliper, and a 'u' shape piece of metal with a round piece of rubber on one end, sorry i dont know the correct name for this, fitted new pads. I also bled each caliper, in the correct order, as i did each pair of pads. All back together i went for a drive. After 5 miles i stopped to see if the wheels were still on, and all was well. Did another 15 miles, stopped for some tea, and drove home. About 2 miles from home stopped at the supermarket for some bits and bobs. Got back in the car and pulled up to the first junction and could feel the brake pedal was not right. All the way home when i applied the brakes, the corner that i removed the caliper earlier was making a bit of a knocking noise, and i could feel the pedal trying to push itself back up. A bit like the ABS feels like when the wheels are trying to lock. Got home, jacked the noisy corner up and turned the wheel, not a sound. When for another test drive, same noise and vibrating pedal. All after i had done about 40 miles with everything spot on. Has anyone ever come across this before?? Any help or advice will be a great help. Cheers in advance.