Bench bleeding master cylinder?

[lalessi1]

I bought a master cylinder for a 67 Galaxie like the one ROKuberski suggested in the "scarebird adapters" thread. I am having trouble bench bleeding the thing. I have the primary bled and it went "by the book". My issue is with the secondary side. I can't get any fluid to come out of the downward facing forward port when I push the piston in. It will come out of the side port however where the bleeder is located. I assumed that the downward facing port was for a failure mode warning light so I bled the front (smaller) reservoir using the bleeder and assumed I would connect the rear brakes to the bleeder port. The secondary side didn't seem to work like the primary side. I looked at the posted photos and went back and reinstalled the bleeder and attempted to re-bleed the secondary side from the downward port. Now when I push the piston in the fluid is pushed back up into the reservoir like a fountain! Any thoughts?

[ROKuberski]

Lynn,

First off, you can't use the bleed port for anything except bleeding.  The threads are not tapered so you cannot put it an adapter for the brake piping.  That's the port I anticipated using for my brake light switch.  That was when all I had was a photo.  When I got the M/C, it was apparent that I could not use that port. 

I did bench bleed with the M/C in my vice.  I used the rod from the car to push very hard to get the bleeding done.  It did take a while to get all of the air out of the unit.  My M/C came with plastic inserts.  After bleeding, I put the plastic inserts back into the M/C as I took the unit out to mount it on the car. 

As I was doing internet research, I saw where someone else had the issue of the fluid squiring back up through the bottom of the M/C.  The thread I saw said not to worry about it.  However, a while back when I was trying to get power brakes to work, I was furnished with a dual chamber M/C and the first one I had did exactly what you are describing.  I told that to the supplier and he sent me another M/C.  That one did not have fluid squirting up as you saw. 

The bottom port at the front for the smaller chamber is for the rear brakes.  It is this port that has the residual pressure valve built in.  Stick in a small wire gently and you will feel the soft material that's in there.  The side port from the rear, large, chamber is for the front disk brakes.

There are several different M/C's for that car.  I selected the one for disk/drum and non power.  I think the part number for my M/C was shown in one of the previous posts.

Give me a call if you want to.  303-422-9510.

Rich

[lalessi1]

Bench Bleeding Part Dieux.... well after the advice and after I "re-piped" and started over, magically within 10 minutes all was fine. I even "proofed" the cylinder. I never thought of myself as an alarmest now I am having second thoughts about that....

[ROKuberski]

Lynn,

Tr?s bien.  It was good to talk to you yesterday.  Glad that you have had success with the master cylinder and that you got the last of the close out deals on one from Rockauto. 

I wouldn't say you were an alarmist.  Brakes are one of the most important systems on the car.  If they don't work properly, it's going to be a bad day.

Rich

[lalessi1]

Finally finished my brake project! I changed out the master cylinder, replaced the lines from the MC to the main lines with NiCopp. Replaced the rear brake cylinders and installed stainless brake hoses all around. The brake effort was substantially reduced and the pedal is "way up firm and high". I bought the stainless hoses on eBay from Nick Cristman, "Brake Hoses Unlimited". He did an incredible job, custom stuff, 3 days to my door! I bought a funky little double flare tool from Snap-On (see the pic) and new Wagner rear cylinders from Rock Auto. In typical fashion it took me 3 times longer than I figured.  Thanks to ROKuberski and RICH MUISE for their input.