Still chasing brake issues

[ninescorpions]

Hey guys,
So my saga with brakes continues. I will try to keep this short and to the point (probably won't work):

Original brake condition: Weak pedal...must be pumped several times to get pressures. Lost pressure when parked
Solution: Springs were wrongly installed (top springs that is). Issue fixed.

Next brake condition: trailing brake shoe on the front wheels is dragging the drum creating too much heat.
Solution: Unknown
-Adjusting brake cam cannot fix this (was tried)

-Found that the new cylinder spring was too long (at least on LF).
Trimmed down. Helped condition, but did not solve

-Suspected that the flex hoses needing replacement as they may have not been letting fluid back towards MC and retracting trailing brake shoe via vacuum.
Replaced flex hoses...condition appears to be "slightly" better, but not solved
-Re-bleeding of all four corners. Important note that both rear brake cylinders work perfectly (no drag, pistons are retracted as expected. When opening the bleeder value in the rear cylinders, I get fluid only with sufficient pressure (fluid shoots out). Also note that I have not yet replaced the flex hose on the rear lines. When we bleed the front, we actually were getting only fluid at one point. But after continued bleeding, we get only spitting of fluid and mostly air. Amount of pressure is low (if fluid, it only streams out...does not shoot out). We kept bleeding, but after a while you get the point there bleeding is not gonna solve it. Unable to re-bleed front lines.

Below is what has been replaced in the braking system and by who:

-Master Cylinder (from RN...installed by local auto shop)
-Brake servo (from RN...installed by local auto shop)
-Brake shoes (all) and brake springs (all). (from RN...installed by local auto shop)
-Brake adjusters (from RN...installed by local shop)
-Wheel cylinders (from RN...installed by local shop)
-Brake drums (all) (from RN...installed by me)
-Flex hoses on both LR and RF (from RN...installed by me)

So as of now, only component not "new" are the hard lines. I am coming to the following possible conclusions:

-Master cylinder not working properly or something not installed properly/adjustment?
-Something lodged in hard lines in front and unable to dislodge (perhaps clamping will isolate if this is the case)
-Air leak somewhere that is allowing air in, but not fluid out (not sure this is even possible)
-Is there anyway the master cylinder would need to be bench bled again? (read about this, but not that knowledgeable on it yet)

I cannot find any leaks anywhere in the front lines. After reading a bunch of posts, I was considering to clamp the LF first to see how the RF response to bleeding and then switch to see if I can isolate the issue to one side or the other. If both continue to fail, I was considering to clamp both to see if the issue is back at the MC level. Note that the brake fluid level in the MC is always between min and max (we are monitoring it).

Any advice?

[mearstrae]

Is it a dual or single master cyl? Does it have a shuttle valve block? If it has a shuttle valve it may need taken apart and cleaned. Just a thought... It is worrisome seeing "local auto shop" involved. I hope they know something about old Rovers.

'99 Disco II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S

[ninescorpions]

Dual. The local shop are the best I have available where I am. They are good, but they have made some mistakes simply because they are not that familiar with Rovers. Was talking with lumpydog...thinking to pull the MC and bench bleed it. I need to go get the kit first. I let them do the initial work since I am no where near a mechanic, but learning on each issue I have solved.

[ninescorpions]

Bled the MC and are back in business. Got the fronts done now and brakes are working pretty darn good