power brake troubles

[turbodart]

hope someone can help. i am/was in the process of converting my slant six dart to power brakes. all was going well, untill i started the car

first thing i noticed, was the still rock hard pedal.

second thing i noticed, pedal did not return to "at rest" position---it stayed pretty much down, thus causing the brakes to drag. if you put your foot behind the pedal and pull up, the brakes release. needless to say the manifold vacum is definetaly pulling hard on the diaphram of the booster.


i dont happen to have my service manual nearby---actually, im not sure where i put it. i did find an 85 diplomat service manual, and best i can tell from that, the booster is no good as one of the tests says i should see no more than 12" of vacum at the check valve, i have 14-15" of vacum.

also, when you start the car, it pulls the pedal about 1/3-1/2 way down instantly. notsure why it does this either.

any ideas here? im at a loss. these boosters are supposed to be simple right? just a giant vacum cannister.

--chad

 

[OUTLAW]

not that simple as there are a set of check and bypass valves inside besides a diaphram. when you push the pedal only a few 1000/inch a port open up to allow the vacuum to assist the pedal draw action and when you release it closes that port and equalizes the vacuum on that side of the diaphram so the pedal can release. Also if the pushrods are not adjusted correctly it will cause problems (one is it activates brakes without being on pedal).

 

[turbodart]

but the only adjustable part is the rod out of the booster into the master cylinder. that is just suppossed to touch the m/c piston , right? other than that, nothing else i can adjust. i will be prob be just better off finding a new booster---right?

--chad

 

[OUTLAW]

should be a little bit of clearance between the rod and master (very little) and yes rebuilding a booster is a major pain ...time to hit a junkyard