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Brake Master Cylinder Question????

Discussion in 'The Garage' started by Mudbug1979, Oct 5, 2004.

  1. Mudbug1979

    Mudbug1979 1/2 ton status

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    Will the Master Cylinder off of an 89 Sub work on a 79 K5 with front and back disc's? Mines bad and leaking everywhere and I happen to have this one that is good, so if they will work i'm gonna swap those bad boys out at lunch. Thanks ahead of time.
     
  2. R72K5

    R72K5 Banned

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    make sure fitting sizes are same and that front and rear reservoirs are not opposite of eachother form one m/c to the other and that you dont have too msall of piston diameter,
    for bigger brakes you need bigger piston diameter inside the m/c, IE dont put a 1/2 ton cylinder on a 3/4 or 1 ton

    reservoirs are reverse on 1/2 ton than to 3/4 and 1 ton and wont swap anyways unless you bend the lines to make it work, but thats not a good thing to do
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    IMO just go buy another one.

    The failure rate of used master cylinders is EXTREMELY high, it's the bleeding process that seems to kill them, theory being that when bled, you force the seals further than when in use, which tears them and bleeds off pressure.

    Happened to me, happened to many others here, you can never get a firm pedal after install, eventually one day it completely fails on you and the truck starts rolling, probably at a stop light.
     
  4. Mudbug1979

    Mudbug1979 1/2 ton status

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    Well, I'm tired of changing these things out. This is like the 3rd reman one I have gotten. I'm going to buy a new one this time. For front and rear disc brakes with the rear being a 14b FF, which would be the best application to put on here. I don't mind paying for a better one if there is one that will work better than a stock replacement. It has a brand new booster, so help a brother out. Th /forums/images/graemlins/1zhelp.gifanks.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    To tell you the truth, with the disc/disc setups, there is just too little information on what will work "for sure" in every application.

    Some seem to have no problems with 1/2 ton stuff, some have gone with bigger master cylinders, some have gone with adjustable proportioning valves, etc.

    I haven't done the swap yet, so I can't comment on what's worked for me even. There have been quite a few posts for disk/disk swaps, and search seems to be working pretty well now, so I'd try that route.
     

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