Trying to figure out brake problem with rear disc upgrade

[GregWeld]

I bench bleed the M/C on the bench rather than on the car. It's hard to get all the air out of the M/C sometimes. I use a large phillips screwdriver as the push tool... and that way I can really bottom the plunger. I have a set of lines I use that hook up to the outlets and return to the M/C reservoir and I can SEE that there is not a single bubble left before the install. I cap it -- and leave the lines on - get it bolted up - toweled up - and swap the lines over.

One other thing that is a mistake I've found several times trying to help someone with "brake issues".... Not every M/C is the same line configuration - i.e., some M/C's run the front reservoir to the fronts and some run the front reservoir to the rear. The way I've found to check for this is while I'm bench bleeding it - I plunge slowly while looking for the fluid flow FIRST in which bowl of the reservoir - that reservoir should be to the fronts. If you do this a couple of times - you'll see what I'm talking about - you'll see fluid just a nano second before in one bowl or the other. That wouldn't give you a mushy pedal - I'm just adding this since you're using parts you may or may not be familiar with...

If you bench bled the M/C - and went thru a gallon of fluid - I say you've got a bad M/C and should probably just get a new one.