Dual Master Cylinder

[BWhitmore]

I have installed a Mustang dual master cylinder on my 57 Ranchero.  The Ranchero has stock drum brakes on the rear and new stop n' drop disc brakes on the front.  There is an addjustable proportioning valve in the rear brake line only.  The master cyinder does not have residual pressure check valves in either the front or rear lines.  The master cylinder is new. 

After bleeding the brakes several times and with no air bubbles, I still need to pump the brake pedal.  The rear brake shoes are adjusted up fairly tight.  I have now installed a 10lb residual pressure in-line valve in the rear brake line before the proportioning valve and still have the same problem of having to pump the brake pedal.

I have noticed that there is about 1 1/2" of play in the brake pedal push rod before the push rod makes contact with the rear of the master cylinder piston.  Could this be the problem?  As you know the push rod on a 57 Ford is not adjustble.  Any help with this long term problem would be appreciated.  Thanks. 

[RICH MUISE]

I believe there is suppose to be about 1/8" of play @ the rod, so my guess is that is the problem.
I am just referencing what I've read, not experience.

[gasman826]

Sound advice, Rich.

[57chero]

I installed a maverick master cyl. on mine and had to lengthen the push rod to get the correct amount travel.

[Ford Blue blood]

The push rod is too short, as rich says 1/16th or just a rch less between the push rod and the piston base.

[BWhitmore]

The problem was the push rod.  All is well.  Thanks to everyone for their help.  Happy Holidays

[RICH MUISE]

Way to go! how did you lengthen it?

[gasman826]

Showed it girlie pictures!

[BWhitmore]

I made an adjustable push rod by adding a threaded sleeve to the original push rod. 

[RICH MUISE]

 

[4banger]

I used a adjustalble push rod.  Or, you can put a small filler spacer in the M/C bore. Make sure you bench bleed the master.  Vaccum bleed the wheel cyl. I had the same problem, but is good now. I have frt. disc and back shoes. 10 lb. residule valve to the rear. Dot 3 or 4 fluid. Do not use silicone.