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19mm Master Cylinder Options

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    19mm Master Cylinder Options

    For those that have deleted their brake booster/servo, what master cylinder are you running?

    The preferred setup appears to be a 19/19mm master cylinder with the brake proportioning valve removed.
    I have a 19/20mm one from an early 316 (drum rears), but would prefer to start with a 19/19mm as people have reported success.

    VW Beetle 19mm? - Bolt pattern looks OK, but is a 4 port.

    Tilton 19mm - mounting point are in the 6 & 12 location rather than 3 & 9.

    Before anyone asks: My engine swap doesn't allow adequate room for a relocated/smaller servo (intake plenum & 3" IC piping are in the way).
    Last edited by e30mclow; 08-23-2018, 07:09 AM.

    #2
    Pasting this old thread here in case someone else's search brought them here.



    Looks like old VW is the way to go. I'll post part numbers once I have the plan in place.

    Comment


      #3
      This might help https://www.bimmerforums.com/forum/s...r-Delete/page3

      IG @turbovarg
      '91 318is, M20 turbo
      [CoTM: 4-18]
      '94 525iT slicktop, M50B30 + S362SX-E, 600WHP DD or bust
      - updated 1-26

      Comment


        #4
        Originally posted by varg View Post
        Thanks, a lot of great info there!

        Comment


          #5
          The slightly bigger rear m/c piston is nice, because then you
          can run a limiting valve and actually use the rear brakes.
          A 1:1 master puts more than 70% forward, and there's then
          no way to bias it to the back.

          t
          now, sometimes I just mess with people. It's more entertaining that way. george graves

          Comment


            #6
            A 1:1 master puts more than 70% forward, and there's then
            no way to bias it to the back.
            Couldn't you install the limiter on the single front brake line out of the master before it splits at the tee?

            Comment


              #7
              Yes.
              But it will limit front pressure and let rear rise
              right when you want rear pressures NOT to rise-
              when weight's transferring off the rears and onto the fronts.

              It's a recipe for rear- end lockup under heavy braking

              t
              now, sometimes I just mess with people. It's more entertaining that way. george graves

              Comment


                #8
                Originally posted by TobyB View Post
                A 1:1 master puts more than 70% forward, and there's then
                no way to bias it to the back.

                t
                The original MC has a differential piston sizing. Larger in the front and smaller in the rear. Smaller means that for the same effort, it puts out more hydraulic pressure. Therefore, a stock MC shoots more pressure at the rear and the valve limits it to avoid locking rear brakes.

                When using a same size bores MC, my recommendation is to ditch the valve, or otherwise you will end up with not enough rear braking and will be unbalancing the car's braking distribution.

                Allow me to post the same graphic I have made 15 years ago showing how the OEM valve limits the rear pressure vs the front.

                In red is the linear progression without a valve. You can see a knee, and how the rear brake pressure evolves with the valve.

                Brake harder. Go faster. No shit.

                massivebrakes.com

                http://www.facebook.com/pages/Massiv...78417442267056





                Comment


                  #9
                  Originally posted by Massive Lee View Post
                  The original MC has a differential piston sizing. Larger in the front and smaller in the rear. Smaller means that for the same effort, it puts out more hydraulic pressure. Therefore, a stock MC shoots more pressure at the rear and the valve limits it to avoid locking rear brakes.

                  When using a same size bores MC, my recommendation is to ditch the valve, or otherwise you will end up with not enough rear braking and will be unbalancing the car's braking distribution.

                  Allow me to post the same graphic I have made 15 years ago showing how the OEM valve limits the rear pressure vs the front.

                  In red is the linear progression without a valve. You can see a knee, and how the rear brake pressure evolves with the valve.

                  Just to clarify on this point, if you were locking rear brakes with a factory master (318is, 22/19 master) there is a possibility that the valve is no longer functioning correctly? Currently facing this with my setup on track, fronts seem to not function much at all, rears locking quite easily. (my lines are not back to front)
                  Last edited by jsta1109; 08-27-2018, 06:27 PM.
                  IG: https://www.instagram.com/josh.stacey/
                  Flickr: https://www.flickr.com/photos/133952286@N03/

                  Comment


                    #10
                    Originally posted by jsta1109 View Post
                    Just to clarify on this point, if you were locking rear brakes with a factory master (318is, 22/19 master) there is a possibility that the valve is no longer functioning correctly? Currently facing this with my setup on track, fronts seem to not function much at all, rears locking quite easily. (my lines are not back to front)
                    It is indeed possible.
                    Brake harder. Go faster. No shit.

                    massivebrakes.com

                    http://www.facebook.com/pages/Massiv...78417442267056





                    Comment


                      #11
                      Originally posted by Massive Lee View Post
                      The original MC on the later ABS cars has a differential piston sizing.
                      Fixed that for ya. The earlier m20 cars w/o ABS had a 22/22, and then
                      strangely, early ABS cars seem to have 22/22 as well, switching to
                      the 17/22 roughly around the time of plastic bumpers.

                      I've seen several valve iterations, too, for the different systems.
                      And I've had them fail, too.

                      t
                      now, sometimes I just mess with people. It's more entertaining that way. george graves

                      Comment

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