Jimbro - any updates?
I was looking for more info and ran across this post.
I am also so frustrated with this same symptom I have a hard time working on it anymore and my car is just sitting.
I also have a new brake system, front to back, and have bled repeatedly as you, vacuum, pedal pressure, after sitting for a day, etc., with no improvement.
I have a new combo valve and new master from Inline Tube.
This weekend, after talking with Inline Tube, I fabricated plugs for the master, thinking I may still have air in it, but when plugged, the pedal was rock solid as soon as the slop in the rod was taken up.
I pulled the rear drums off and do not see any problems with my assembly.
Did you ever get an answer about residual pressure in the rear line? When I pulled my rear drums, I noticed "slop" between the pins and the shoes. This tells me there is no residual pressure in the cylinders. I would think the return springs should be pulling the shoes back against the cylinders, and if there was residual pressure, those pins should be tight against the shoes???
I will call Inline Tube and ask them about this, but I was hoping you were having better luck than me.
I think the basic symptom is caused by pressure building slowly in the rear lines, which is consistent with maybe a lack of residual pressure ?? My understanding of the combo valve is it will limit pressure to the front until the rear has pressure. My pedal goes nearly to the floor before the front calipers work, yet there ARE NO BUBBLES. This makes me think the root problem is lack of pressure build in the rear lines.
I wonder if the Inline Tube combo valve is supposed to have a check valve to hold residual pressure in the rear, and maybe it isn't working ?? Does anyone know ? What I have read is that the master for my original drum brake system had check valves built in, but the master for a disc system does not.... so how else can the rear get residual pressure if not from the combo valve? How can I check to see if this is working?
I will try adjusting the rear shoes until they are too tight and see if this makes a difference. Maybe my new shoes are just moving too far still ??
Should I buy a residual pressure valve for the rear line ?
How can something seemingly simple be so difficult ??
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