Time for a New Master Cylinder?

[furyfever]

1968 Fury III 383 w/ 4 drums. I've about had it with the brakes on this car. Ever since I got it earlier this year, I've had problems with one or more of the brakes dragging (drums get too hot to touch and sometimes I can smell them as well). I've replaced both front rubber hoses, rear rubber hose, all four wheels cylinders, all shoes, all springs, drums turned, made sure backing plate pads have no wear grooves in them, applied a little lube on back of shoes, adjusted them every which way possible...from very loose to snug. I've also had the e-brake cables out. I made sure they were freed-up, lubed, reinstalled, adjusted and made sure they're not dragging. Most recently, after replacing everything up front, the front brakes are not getting hot anymore...but the rear drums are still getting too hot after a short 5 mile test ride. In Neutral, car does roll fine though on a very very slight grade in my driveway. After adjusting brakes, I always hit the brake pedal a few times, one thing I've noticed as recent as this AM...on the rears, I adjust the shoes away from the drums...hit the brake pedal a few times and with a rotation or two of the rear wheels (trans in Neutral) shoes start rubbing again...back off some more until there's no rubbing...hit the brakes and they rub again. Extremely frustrating! The only thing left in the system is the Master Cylinder and the Power Booster... I understand there are relief valves in the MC. Is it possible the relief valve for the rear brakes reservoir is plugged? Is it possible to unplug it? (don't know where it is though)...or does one just replace MC? Is there anyway possible the Power Booster could be the problem?

Thanks, Bob

 

[GJS]

Is it possible something got mucked
up in the adjusting apparatus?

Short of that, it seems a pretty good bet that the gremlin is in your hydraulics and likely the fault of the Master Cylinder.

Id just replace the MC ..

 

[Mopars & Missiles]

What you are referring to is a "Residual Pressure Valve", not a relief valve. They are located inside each port of the Master Cylinder. They are intended to maintain a small amount of pressure in the lines to keep the wheel cylinder cups sealed against the bore, IIRC. Here is a couple diagrams to show you where the residual valves are.

 

[65sporty]

When the rear brakes are dragging loosen the line at the master going to the rear and see if they loosen up. If they do replace the master.

 

[fury fan]

As mentioned, residuals keep the wheel cyl seals expanded so they seal. I have heard that modern seals have expanders in them so the residuals are no longer required, and the reman MCs no longer have them. I cannot confirm the accuracy of that, so research for yourself.

 

[67SportFury]

Hi everyone,
I realize this thread was from a few months ago but I was wondering if there was any resolution. I converted my 67 Sport Fury 318 car from manual drum to power drum brakes a couple of years ago
This involved changing the booster, master cylinder, and brake pedal itself. However, I've been stuck with a similar issue with regards to the back brakes. They seem to "stick" quite often and get much hotter than the fronts, to the point of being able to smell them. It feels as if the brakes are not actuating fully as well. Just wondering if anyone else had any success with this problem. My next step is likely to take all 4 drums off and make sure that everything is the right size and fit, because who knows what may have been changed before I bought it.
Thanks for your help!