96 328is Passenger Rear Brake Issue

[Earl]

This is proving to be a fun issue to try and diagnose....not. Roughly two weeks ago I did my RTABs and on the way home, I was hearing a very faint dragging sound from my passenger rear brake. When I would press on the brakes the dragging would get louder, as if the caliper wasn't grabbing hard enough. I figured I tweaked a hose during the RTAB install or I had a sticking caliper. I replaced the caliper, pads, rotor, and brake hoses. This issue still persists. I removed the hand brake shoes just to rule that out and the noises are still there. I also looked over the hardlines and do not see any kinks or damage to them. At this point I am grabbing at straws to figure out what the issue is. I figure it has to be from the rear tee to the caliper at some point. If it was anywhere before that, I would assume both rear brakes would be having similar issues. Has anyone ever experienced this or may know of what is causing it? 

[Earl]

Going to swap out the master tomorrow and do a full fluid flush to see what happens.

[jc43089]

Moving the trailing arm to do the rtabs could have dislodged a chunk of something in the brake line. Is the little hard line that is attached to the trailing arm new/clean?

Sent from my 831C using Tapatalk

[Earl]

It isn't new but it is nice and clean

[Earl]

Noticed something I hadn't before. I was sitting in my car yesterday after driving it and could hear the pressure relieving in spurts from the caliper and then a simultaneous pressure relief noise coming from the master. 

[KaiserRolls]

Id replace the engine. Just to be sure.

If it was the master, why would it happen on the caliper that's farthest away?

[Earl]

It is something not allowing the pressure to be relieved but the only things that could do that are the master and possibly the ABS. I have never seen something like this and it is frustrating lol

[m42b32]

Maybe try and do a complete fluid flush at all 4 corners? Might help clear out any junk that is causing a blockage? 

[Earl]

I'm just going to swap the master at the same time since it is only removing two lines and two nuts once emptied anyways. I have two liters of ATE Type 200 for doing this already as well. The extra liter is incase I have issues=) 

[KaiserRolls]

I'm just going to swap the master at the same time since it is only removing two lines and two nuts once emptied anyways. I have two liters of ATE Type 200 for doing this already as well. The extra liter is incase I have issues=) 

Just turn your radio up louder so you can't hear any noises.

[Earl]

Did a full fluid flush with no change at all=/ Was about to swap out my master with the one from the compact but that has a 12mm front port and an 11mm rear port instead of two 11mm ports. I should be able to use an adapter to install it to do some troubleshooting as I see nothing else being the culprit=/