Booster question

[route66]

Hey guys, having a problem here. Just installed a M/C and booster off a Mustang II on to a 57 Fairlane. I extended the rod to match the length of the original, factory one. Bleed the brakes without starting the car and was able to get fluid out every bleeder, but the pedal won't pump up. tried it with the engine running and still no luck. We then went back to the bone yard and got a M/C and booster off a 81-82 Mustang since there were no other Mustang II's out there....we got the last/only one. the 81-82 Mustang booster was really close to the size of the other one. Installed it and still the same thing is happening......getting fluid out the bleeders but not getting any real pedal or any power assist with the car running. They wont pump up. Sure could use some advice.....THANKS!

[Ford Blue blood]

Push rod too short?  The pedal should be all the way up, make sure the spring that is around the pedal shaft is engaged to return it to the rest position.  With the pedal all the way up there should be about 1/8" play (less is OK too), any more and you start losing stroke.  Make sure the adjusters on each of the rear wheels (assuming front disc here) are out to where the drum drags ever so slightly.

[BWhitmore]

Also, if the car has front disc brakes ensure that the bleeder screws on the caliper are facing straight up or as close to straight up as possible.  If the bleeders are not straight up you will never be able to bleed all of the air from the system and will constantly have to pump the pedal. 

[route66]

Thanks! I think I have narrowed it down to the proportioning valve. blocked of the rear line coming out of it and had great pedal response. I had no idea that there was a valve in it.....just thought that it was a block to route the fluid. It's my father in laws car. he is doing a frame off resto on it. Aside from buying seals and certain other stuff, we have frankensteined it.

Master and booster.....77-82 mustang
spindles, rotors, and calipers........77 T Bird
steering column.....77 Ford truck
manual rack........Geo Storm
steering column rods and knuckles.......Chevy Aveo
302 engine......92 Ford truck

[Ford Blue blood]

OK, that tells me the rear brakes are not adjusted out as needed. 

[route66]

OK.....here's an update.

Replaced the proportioning valve.

Bought a pnumatic bleeder. (Harbor Freight $24) Worked great.
Sucked fluid back to the rear cylinders and then bled them as normal (pumping the brakes).
Finally got the wheel cylinders to pump up. ( I adjusted the rear shoes as well).

However........after a few minutes, no brakes again!
Repeated the process and got brakes.
Again......after a few minutes....nothing.
Even started the car after we had brakes to see if the booster was working and BOOM.......no pressure to the rear cylinders.

There are 3 connections (all new lines) for the rear line from the proportioning valve back to the rear cylinders.
1.  a union about mid way down the frame.
2. above the axle where the metal brake line connects to the rubber line (brand new line) that goes to the rear end.
3. the "T" fitting where the rubber line connects to the 2 rear wheel brake lines.

I laid newspaper down under the fittings to see if there were any leaks that I could see and.....none

I don't know what would cause the rear lines to loose pressure?

I've eaten ALOT of asprin dealing with this.....doesn't make sense.

Thank you for your input.

[BWhitmore]

Are your front brake caliper bleeder screws pointing straight up?  On some disc brake kits it s possible to mount the calipers backward (left & right).  I had the exact same problem with good pedal for about 1 minute and then nothing.  It turned out I had the calipers switched and the bleeder screws were not facing up.  I reversed (left to right) calipers with caliper bleeder screws facing up- problem solved.

The only other possibilities I can think of is your brake pedal pushrod has too much end play (should be about 1/8") or you have a bad master cylinder.