Hello FTE community - long time no speaky-to....

I have disc brakes now on the front - originally retained the existing MC. Worked OK, had to pump once then stopped fine.

Decided to install power dual master cylinder from Performance Online -

link to the actual part:

1948-56 FORD F-1 AND F-100, POWER BRAKE BOOSTER KIT (ZINC)

Installation went great, although a real bunch of work - and a very tight fit.

Bench bled the MC per instructions using method 1 of the instructions - plugging the 2 ports with the appropriate flare plugs, pumping 3/4 - 1" until no more air in bowls, and plunger would not move more than 1/8".

(booster and new brake lines already installed in truck and dry run to fit to MC)

Installed bench bled MC to brake booster, remove one plug at a time and immediately hooked up brake lines.

Bled lines using a technique POL provided leaving one opposite end of vehicle line open to bleed lines. All went well, after air quit coming out, clear clean fluid at all wheels.

When finished, closed off all bleeders... brake pedal "still" goes to the floor as if I still have a line open - but do not. No leaks, no fluid coming out anywhere...?

Have pumped at least two quarts of fluid through this thing.

Anybody out there got an idea of what gives here??

Disc brake conversion worked fine with old MC (although with an extra pump or two on the pedal).

Am now wishing had just stayed with it.

Thanks

 

Did you put the check valves in line? Don't know much about them, but I thought you had to put a 2 and 10 lb. residual check valve in the front and rear circuits on a dual cylinder. Just a random thought.

 

good question dmack.

I saw those check vales on the POL website and their learned about their purpose, so when I was ordering this unit I asked a technical adviser if I needed them for my truck as the MC is lower that the wheel cylinders. He said no, this package is set up to keep the fluid from flowing backwards.

Thanks a million though.

My plan is to start all over again, bench bleeding the MC, etc., etc.

 

It isn't uncommon to install a wheel cylinder/disc caliper upside down (no offense, but an easy check). Easy way to check is the bleed nipple should be at the highest point of the cyl/caliper. If the bleeder is lower than then top of the internal reservoir of the cyl/caliper, there will be air trapped in the reservoir above the bleeder.

Good luck with it.

 

Another good point.

What this is, is a Dana 44 4x4 front axle out of a F-150 Super Cab (leaf spring model) I installed, after cutting both ends off, having the axles modified, welding the "C"'s back on, reinstalling everything just as it came off.

Worked fine with the existing master cylinder, except I had to double pump the pedal to stop - which it then did fine - drove it thata' way for months.

Re the double pumping of the pedal, my thought was that with the existing MC, the fluid was running back out of the wheel cylinders, etc. (no check valves)

I considered the check valves and a proportioning valve, etc., but for a few more bucks I could convert the entire mess with a whole new unit from POL, which, according to them, included a check valve system in the prop valve. (not sure how they could get all that stuff in the prop valve???).

So, I have found on the POL website a trouble shooting guide - first thing I will do... with the MC still installed, plug the ports again, and try the leak down test to see if maybe I somehow screwed up the seals in the plunger while bleeding the system.

Then, go from there ................ not sure where,,,, but.... onward, anyway....

Thanks