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master cyl help wanted

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  • master cyl help wanted

    My master cylinder looked pretty grungy inside. I didn't want to pump that into the new rear disc brake calipers I just installed so I took it off and disassembled it. Foolishly, I did not keep careful enough track of how the check valves in the outlet ports go together. It appears there are many different ways to assemble them. On my first try the brakes didn't work at all. Now I've got them so it can be driven but is pretty iffy. Can't find a sketch with enough detail. One forum said to remove them for disk brakes, but why did the fronts have a check valve if that would work?
    What is the purpose of these check valves? They are more like restricting orifices than check valves. Is it to keep the slave pistons from retracting too soon?
    Eric Zondervan
    72 240Z
    11 Sierra 4X4
    14 Kia Rondo EX
    19 Audi Q5
    08 Ski Doo MXZ
    16 Triumph Street Triple R.
    2010 Husqvarna 450 Supermoto.
    65 Honda Moped

  • #2
    On my 15/16 master I removed both (duck bill) check valves.

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    • #3
      Took your advice Chris, and removed the check valves. While I had it on the bench I welded the cut ends of some brake lines so I could block the outlets. That let me bleed it on the bench. Worked great as I was able to tip it various ways to get every last bubble out. Put it back on the car with the outlets blocked for a test. It felt like the piston was seized it was so solid. Hooked up fronts only and it was still rock solid. Hooked up the rears and lost a bit of firmness, but quite acceptable. Took it for a road test and all four wheels locked up simultaneously. Next comes the 4 runner front conversion.
      Last edited by zedfoot; 05-14-2015, 08:06 PM.
      Eric Zondervan
      72 240Z
      11 Sierra 4X4
      14 Kia Rondo EX
      19 Audi Q5
      08 Ski Doo MXZ
      16 Triumph Street Triple R.
      2010 Husqvarna 450 Supermoto.
      65 Honda Moped

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