I don't know or trust your hose method. I would have to experiment more. Like: reverse your statement and release front first and then try releasing one at a time and like I said, plug the MC off first and all that.. I don't think you are proving anything except you have air in the system. The callipers relax, they don't really retract, they are always almost in contact. Proper bleeding will fix it. You already bypassed an important part of install....you are guilty
Go to the instructions and follow exactly. I read them on the CPP website.
I understand your logic about it all and how could MC air cause it. I don't know, but a theory could be that the spongy is at the plunger stroke and that the air "bubble" stays in the MC or in a "chamber" for only the fronts or rears. I don't know how air manifests itself in a system. If you see a bunch of bubbles when bench bleeding, you will be happy.
