Another "brake help" thread...

[BillGrissom]

A few small points. As mentioned, the fill port ("inlet" in post 25 figure) must be exposed when the pedal is released. To insure this, insure that the brake lamp switch is only sensing motion of the pedal and not limiting it, i.e. the pedal should not bottom-out on the switch. That is a common mistake. If the fill port isn't exposed, that causes a "hydraulic lockup" where the fluid is trapped so can build up pressure. The calipers can drag to generate heat, which expands the fluid, to cause even more braking. Most common with a power booster when the output rod tip isn't adjusted properly so the MC piston can't retract enough to expose the fill port. For those with a booster, there is a special tool to measure dimensions to adjust the booster tip ($15 ebay). But, not the problems you describe.

Another point is that, unlike drums, there is no spring to retract caliper pistons. Instead, the square O-ring around the piston is supposed to tilt as the pistons move out and rotate back to retract the pistons when fluid pressure is released. Sounds quirky, but works amazingly well. Less so if the O-ring ages so the rubber gets hard. Problem would be the calipers sticking, which also isn't your issue.

 

[swisswill]

So I spent some time yesterday going back through the brakes. I got into the drums and disconnected the parking brake cable since it’s not connected to the pedal anyway, just eliminate that potential issue. While in there, I cleaned the pads on the backing plate and lubed them up. Cass suggested I replace the hardline from the C/V to the drivers front flex line because it was oriented wrong so I built a new line. I then started bleeding again, but this time I had the dash light to make sure the C/V didn’t somehow trip, and I watched that closely. After all the bleeding, the brake system is now better than it has ever been. I can only assume I did something wrong before which threw off the C/V and created further problems. I do still have a bit of a rear brake sticking issue, but it’s not consistent so I’m not sure what that’s about. Maybe I put another set of springs in the rear. I need to clean the wheels up to verify (with brake dust) to make sure the fronts are actually working but I can say it’s a night and day difference. I really dislike these type of fixes because I can’t point to one specific thing that causes the issue but I’m happy with what I have for now. Thanks for all the help everyone, especially AJ/FormS.

 

[AJ/FormS]

Well, blow thru the old line, both directions. There might be some rust in there. Brake lines often rust out from the inside, and usually at the lowest point, cuz that's where the water collects.
As to sticking
If you noticed the six pads where the shoes sit against, after years of service, they develop ridges that have to be ground off. for just this reason. AND
If you had water in the brakeline that rusted it as bad as I think, then your w/c's could have rust inside the bores as well. Depending how extensive that is, it could be up under the aluminum pistons, causing sticking. Extra springs, even if you could fit them in, are not the answer, just a bandaid.
New shoes, rarely properly fit the drums, new or used. This means that the initial contact patch could be just a fraction of what is should be. which means in the early stage, the rear brakes don't do much. It's gonna take a lotta miles to wear them in.
While wearing in, it's gonna take extra pedal pressure on the fronts to achieve proper deceleration. That extra pressure is simultaneously sent to the back, which usually glazes the shoes, making them LESS able to slow the drums. making you press a lil harder to make the fronts work. Thus the systrm is set up for an even longer break-in period.
Years ago when I worked as an Automotive Tech, we sent the shoes and drums down the street, to have them matched on a special grinder. This eliminated all that break-in crap.
I dunno if these machines still exist cuz so many cars are now rear disc brake.
I have 295s on the back of my car, which allowed me to eliminate the Proportioning valve which allows the back end to brake really hard. I also have a manual trans with an 11/1 360 that compression-brakes really hard. I still burn up rear pads faster than fronts.

One more source of rear brake stiction, I suppose, could be the little residual valve up at the M/C, I defeated mine. My w/c's have springs inside them which do the same thing mechanically.