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1940 President Stuck Master Cylinder

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  • Brakes: 1940 President Stuck Master Cylinder

    This brake project has gone on for waay waaaaaaay to long. Long story short to catch you guys back up...

    Last February-March I lost all brakes. Brake pedal went in, but I had to "pump" it back up. Torn down the entire system and replaced/rebuilt just about everything. New hard lines, New soft lines, rebuilt master cylinder, New shoes, Rebuild cylinders.

    When I rebuilt the master cylinder, I made sure to lube everything inside with new brake fluid. The internal shaft appeared to be in good shape. New springs, ect, ect.

    I added fluid and was going to gravity bleed it. Noticed that the fluid wasn't draining into the lines and decided to gentle push the brake fluid to "force" the fluid into the lines...

    After pushing the brake pedal in and out a couple of times, I noticed that the plunger rod that goes into the mastercylinder would not retract back out. Got me thinking that is what caused me to lose brakes possibly. But when would it not spring back? New springs.. Lubes grommet... Did I miss something? Getting frustrated..

    Thoughts?

    "Spilling a beer is the adult equivalent of a kid letting go of a Balloon."

  • #2
    Your wording makes it sound like the pushrod is not actually attached to the pedal.

    Comment


    • #3
      2 questions: have you replace/rebuilt the MC?
      Have you replaced the soft lines at the wheels and rear axle?

      I've been learning the hard way to just go ahead and replace everything and get it over with.
      PITA, but worth it in the end.

      Case in Point. I had Drum brakes on my Nova. Weak as pond water. step on them and wait to stop.
      I decided to upgrade to front disk (LS Conversion). Still kinda weak, plus i still had the non-power drum setup that was making them drag.
      So decided to do a Power Brake conversion. Replaced MC/combo valve, add booster, etc.
      could not get the rears to bleed at all...
      so 8 hours of beating and banging to get the rear hose off, and voila I now have fluid flow.
      so replaced that, and everthing on the rear axle assembly(brake wise) wheel to wheel .....
      PLUS ONE AXLE THAT WAS BENT.

      After bleeding, I have excellent brakes.
      Only thing left is the hard line from front to back. and next summer I'll get that too. piece of mind.

      OOPS.... I forgot. the emergency brake cable was jammed and I'm in the middle of that.....LOL



      ON the 2R5 i replaced everthing to start with and went with a Jim Turner Kit.
      I'm hoping he turns up at the Chattanooga international next year, cause I need him to diagnose what's going on. I have to pump the pedal, so there is some problem I can't figure out. maybe I used the wrong MC. Not sure.

      Comment


      • #4
        Over the years, I have serviced and repaired brake systems on lots of vehicles. Especially on my Studebaker collection since there are sporadic occasions where they sit for long periods of time. Problem with me is that, since I don't do it regularly, I usually grab a manual and refresh myself regarding the internals before diving into the components with a fist full of wrenches. So, viewing this thread, I thought I would attempt to find a parts breakdown of a typical single chamber master cylinder as used on most of our Studebakers. I hope this pic pastes into this post without having to jump through a lot of hoops.

        Thanks to Bob Johnstone for his diligence in hosting such a wealth of information. ( https://www.google.com/url?sa=i&rct=...70887869135930 )
        I can see the pic on my computer, but as we have seen, some pics will do that and not post to the forum. Let me know if it don't show. As far as I know, if all the components are installed correctly, only two things are needed for the device to perform correctly. That is that the push rod must be adjusted to allow enough travel for the components to produce pressure when activated, and return far enough to "relieve" pressure. Additionally, the tiny vent in the master cylinder reservoir cap (1) must be clear.

        Regarding the "push rod" not coming back out, it looks to require a connected pedal return spring for that function. I'm not certain, that a fresh cylinder with new components...that the return spring (#10) would push the piston & pedal back out on its own? Looking at the drawing, I'm thinking that the piston would have to return back far enough to clear the compensating port (#4) in order to relieve pressure. Hope this helps.
        Last edited by jclary; 10-11-2019, 09:24 AM.
        John Clary
        Greer, SC

        SDC member since 1975

        Comment


        • #5
          Originally posted by Mrs K Corbin View Post
          2 questions: have you replace/rebuilt the MC?
          Have you replaced the soft lines at the wheels and rear axle?

          I've been learning the hard way to just go ahead and replace everything and get it over with.
          PITA, but worth it in the end.

          Case in Point. I had Drum brakes on my Nova. Weak as pond water. step on them and wait to stop.
          I decided to upgrade to front disk (LS Conversion). Still kinda weak, plus i still had the non-power drum setup that was making them drag.
          So decided to do a Power Brake conversion. Replaced MC/combo valve, add booster, etc.
          could not get the rears to bleed at all...
          so 8 hours of beating and banging to get the rear hose off, and voila I now have fluid flow.
          so replaced that, and everthing on the rear axle assembly(brake wise) wheel to wheel .....
          PLUS ONE AXLE THAT WAS BENT.

          After bleeding, I have excellent brakes.
          Only thing left is the hard line from front to back. and next summer I'll get that too. piece of mind.

          OOPS.... I forgot. the emergency brake cable was jammed and I'm in the middle of that.....LOL



          ON the 2R5 i replaced everthing to start with and went with a Jim Turner Kit.
          I'm hoping he turns up at the Chattanooga international next year, cause I need him to diagnose what's going on. I have to pump the pedal, so there is some problem I can't figure out. maybe I used the wrong MC. Not sure.
          Please read the initial post - only two before yours. He states that he "rebuilt the master cylinder" and "new hard lines", "new soft lines", etc.
          Gary L.
          Wappinger, NY

          SDC member since 1968
          Studebaker enthusiast much longer

          Comment


          • #6
            Thank you for the responses. Yes, I have replaced all soft lines and hard lines and rebuilt the MC.

            Thank you for the picture. When I said the "push rod" would not return back out, I was referring to the Piston Assembly, see image #9. My brake pedal has a spring on it, attched to the frame which helps pull it back. The issue I am having is the Piston not returning after being pushed in.

            "Spilling a beer is the adult equivalent of a kid letting go of a Balloon."

            Comment


            • #7
              Originally posted by Okiejoe86 View Post
              Thank you for the responses. Yes, I have replaced all soft lines and hard lines and rebuilt the MC.

              Thank you for the picture. When I said the "push rod" would not return back out, I was referring to the Piston Assembly, see image #9. My brake pedal has a spring on it, attched to the frame which helps pull it back. The issue I am having is the Piston not returning after being pushed in.
              Not meaning to question your skill of assembling the parts correctly, but it might be worth your effort to remove the master cylinder and reconfirm the parts are appropriately assembled. For example, the rubber cup between the piston & spring (not shown in detail)...if it is turned the wrong way, could cause the spring to bind and not move beyond the compensating port to relieve pressure. Also, make sure the check valve is OK on the other end. While your are checking... be sure there is no small bit of trash or build-up clogging the compensating port. If you have installed the correct size parts in the proper sequence, I don't see why it shouldn't operate without sticking or binding?
              John Clary
              Greer, SC

              SDC member since 1975

              Comment


              • #8
                I had an aluminum piston in an old truck swell up with corrosion and stick, brakes would not release. Was a hard to get item so it was all cleaned and new seal fixed it. truck had a big load on it so it had to be done on the spot. Hope the owner ordered new MC. I would have.

                Comment


                • #9
                  I actually remember seeing an incorrect assembly once on an old WW2 dodge truck that a new MC had been ordered for. The new MC was put together backwards and it stuck too....

                  Something to check. If the valve is backwards it may jam.

                  Comment

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