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  • Brakes: Brakes -- No pressure one time...

    Hey guys, I had a scare on the way to a car meet a couple of weeks ago and just wanted to get some ideas of what I need to do. I was almost to the meetup and heading toward a red light when the brake pedal gave almost no pressure. My heart skipped a beat and I hit the brake again -- this time it gained pressure and started to slow the car. Luckily there was almost no traffic and I wasn't going but 25mph anyway, but still... So after the meet, I took the car on a few side streets very slowly and the brakes acted normal again. Perhaps I should have had it towed, but I just went slow on the side roads and made it home uneventfully. The only thing unusual I can think of, on the way to the show, was I came down a really steep hill and hit the brakes pretty hard when the light turned red unexpectedly. I was wondering if perhaps the brake fluid got especially hot because of that and somehow I got a pocket of air for a second? Not sure if that is possible or what. Ordinarily the pedal is on the hard side, not spongy at all. So anyway, would you just bleed the brakes with some all new fluid, or does it sound more like I need to do a rebuild on the master cylinder? Thanks much.
    sigpic

    1950 Commander Starlight Coupe
    Regal Deluxe Trim
    Automatic transmission
    46k original miles, 4th Owner

  • #2
    First order of business is to check the brake fluid level! Brakes normally do not require bleeding unless the system has been open for repair or has had a catastrophic failure. Or to do a routine flush.
    Last edited by 41 Frank; 06-21-2013, 12:09 PM. Reason: grammar
    Frank van Doorn
    Omaha, Ne.
    1962 GT Hawk 289 4 speed
    1941 Champion streetrod, R-2 Powered, GM 200-4R trans.
    1952 V-8 232 Commander State "Starliner" hardtop OD

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    • #3
      Like Frank said. Even if it doesn't look low, check wheels and backing plates for any fluid from a wheel cylinder leak. One little leak can let air in to do just that.
      Dave Warren (Perry Mason by day, Perry Como by night)

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      • #4
        Thanks, I will check it this weekend. Only thing I've done so far is look around for any obvious leaks, and nothing but I will look closer...
        sigpic

        1950 Commander Starlight Coupe
        Regal Deluxe Trim
        Automatic transmission
        46k original miles, 4th Owner

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        • #5
          It will come back to haunt you. What is the history of your MC?
          sigpicAnything worth doing deserves your best shot. Do it right the first time. When you're done you will know it. { I'm just the guy who thinks he knows everything, my buddy is the guy who knows everything.} cheers jimmijim*****SDC***** member

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          • #6
            Originally posted by jimmijim8 View Post
            It will come back to haunt you. What is the history of your MC?

            I only purchased the car last fall, so I have no history to give on the MC. No issues, so I've never looked into the brakes up untill now...
            sigpic

            1950 Commander Starlight Coupe
            Regal Deluxe Trim
            Automatic transmission
            46k original miles, 4th Owner

            Comment


            • #7
              I'm not real clear exactly what happened, Lloyd.

              When you stepped on the brake pedal on that faulty stop, did the pedal unexpectedly go to the floor, or most of the way to floor, only to return to its normal brake-application height from the floor on subsequent brakings?

              If so, that is usually the master cylinder leaking internally, and intermittently. If it does it enough, brake fluid will ooze out around the boot where the push rod linkage enters the master cylinder.

              Peel that boot back a little bit from the master cylinder body and see if it is wet inside with brake fluid. It shouldn't be.

              If it is, the first order of business is to rebuild the master cylinder. BP
              We've got to quit saying, "How stupid can you be?" Too many people are taking it as a challenge.

              Ayn Rand:
              "You can avoid reality, but you cannot avoid the consequences of avoiding reality."

              G. K. Chesterton: This triangle of truisms, of father, mother, and child, cannot be destroyed; it can only destroy those civilizations which disregard it.

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              • #8
                Hmmm, since it only did it that one time, and I was sort of freaked out when it happened, I don't know exactly if it went to the floor. What I remember was that there felt like there was hardly any pressure. Usually it is a very hard pedal. It came back normally and when I pumped it again, there was almost normal pressure, enough to get it to stop. Subsequent to that one time, it has acted normally. I've only driven it one time slowly around the neighborhood since then and the hard pedal I am used to is all I feel. Anyway, I will check under the boot and see if it's wet. Thanks much.
                sigpic

                1950 Commander Starlight Coupe
                Regal Deluxe Trim
                Automatic transmission
                46k original miles, 4th Owner

                Comment


                • #9
                  All I want to add " Isn't it fun having an old car." I love my Champion but there are times I want to take a hammer to it.
                  1942 Packard Clipper Custom Touring Sedan * 1952 Studebaker Champion Regal * 1954 Studebaker Commander Regal Starlight * 1967 Thunderbird Hdtp * 1969 Continental Mark III * 1969 Mercury Marquis convertible * 1972 Buick Riviera * 1973 Continental Mark IV * 1978 Glass Top Lincoln Town Car * 1983 Mercedes 300SD * 1986 Dodge RAM 4WD * 1999 Infiniti Q45

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                  • #10
                    When you rebuild the master cylinder, if the walls of the cylinder are not completely smooth after you hone it, I would replace it.

                    If the thought of rebuilding it scares you then you might check into buying a replacement as they are being reproduced. There are some cheaper replacements out there which I like to stay away from so if you buy one get it from one of the Stude vendors or a good old times parts house.
                    Milt

                    1947 Champion (owned since 1967)
                    1961 Hawk 4-speed
                    1967 Avanti
                    1961 Lark 2 door
                    1988 Avanti Convertible

                    Member of SDC since 1973

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                    • #11
                      As Bob P said, this internal bypass is a very typical response when a master cylinder needs rebuilt. Usually noticed when the brakes are applied lightly.
                      Press the brake pedal and hold firmly. It will probably creep slowly toward the floor.
                      "Burning Bridges...Lost Forevermore"......

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                      • #12
                        One other thing to check. We have discussed this before. Check the vent hole in your Master Cylinder cap. It is vented to atmosphere. It could be that it has accumulated a bit of trash and gunk restricting its ability to breathe. Sometimes they can become momentarily clogged and give the symptom you described. If something popped in that hole and, due to vibration fell back out, that could cause your temporary failure. Make sure that is cleaned out. If it happens again, you might not be so lucky.
                        John Clary
                        Greer, SC

                        SDC member since 1975

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                        • #13
                          Simply put, put in a new master cylinder. Don't even chance rebuilding it for what a new one cost. Definitely go over the complete braking system only after you read of how it functions. jimmijim
                          sigpicAnything worth doing deserves your best shot. Do it right the first time. When you're done you will know it. { I'm just the guy who thinks he knows everything, my buddy is the guy who knows everything.} cheers jimmijim*****SDC***** member

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                          • #14
                            check brake pedal free-play. if not correct, the MC internal bleed hole may not function properly.

                            If you can step hard on the pedal one time and stay on it for sev minutes and it doesn't slowly drift downward then the overall condition of the MC is prolly OK

                            assuming cap air hole is open and fluid level is normal
                            1947 M5 under restoration
                            a bunch of non-Stude stuff

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                            • #15
                              Sounds like classic symptoms of brake fade. Long hill, soft pedal afterword. did you smell pad material burning?

                              I have had it happen twice in my life....once when I ran a 64 Pontiac up to 120 mph and put the brakes on for a crossover on old us 40 when in high school, the other time in the alps in 1970 going down hill in a 59 vw beetle. First time was interesting but not dangerous, second time was a real eye opener and cured me of not using the engine to slow on hills.
                              Diesel loving, autocrossing, Coupe express loving, Grandpa Architect.

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