Temporary Master Cylinder use - rear brakes

[dennislbrooks]

I am working on making a 59 GMC fleet mobile at the shop for moving it around and building it for future parts. My plans are disc for the front so I am not rebuilding the oem front brakes. I have replaced the Spicer 45 with a 12 bolt with new drum brakes.

I am putting a 75 vette style dual port master cylinder in it and only want to hook up the rear brakes.


Can I just plug the front port of the master cyclinder -- does it internal bypass or not allow function of the master cylinder at all?

Or will I have to use both ports to send to rear brakes?


This vehicle will not see 5 mph and not be on the public road with only rear brakes.

thanks

[wixthedog]

A plug should work, the combination valve is the piece that shuttles front to rear during leaks. If the plug doesn't work you could run the two lines together at a tee to a single line I bet.

[dennislbrooks]

Yea, I agree either a shuttle valve like on a stock 67 or a proportioning valve that will do the same thing. A plug on the master cylinder front port will just make a hard pedal with no fluid going out to the back port.

With that in mind, I will tee the 2 ports and run a single line back to the rear brakes off the tee. It will probably require little distance on the brake pedal to engage the rear brakes.

Dunno, never done this. My son and fiance live down near you in Cypress.

thanks Mike

[wixthedog]

No problem, I hope it works out. I think you may be surprised with the pedal. Fluid only moves so much in a closed system so the travel may feel the same or even better due to the full pressure of the MC being divided to only two brakes rather than four.

Cypress is just south of me, small world.