I have installed Auto City cl***ic disc brake conversion on my 1959 Ford Wagon. Everything is new and I left nothing to chance and I have a problem. The brakes are hard and the vehicle just does not stop. I have bleed the brakes for over a hour, adjusted the booster rod. I have flowing fluid to all wheels. Any thoughs since I am stuck. I am thinking there is a restriction in a line or the master is bad out of the box. Just not getting good flow.
Make sure the calipers are on the correct side with the bleeder pointing straight up, if not, switch sides. I had the same problem on my 56.
Remove the check valve from the booster and with the engine running make sure there is vacuum. The valve could be bad not allowing vacuum to the booster. I have had a bad booster act like your problem and a bad master cylinder with the same symptoms.
All checked, great vacuum a the engine in the car came from a power brake vehicle. Also no check valve in the system. Also calipers are mounted up. The odd part is I have flow to all wheels. I am going after a line today I do not like the bend. My thinking is the line does not have great flow.
To rule out the booster: With the engine off, pump the pedal so all the vacuum is out of the booster. With a foot on the brake pedal, start it up. The pedal should drop about an inch. No drop, booster is not working.
Usually the check valve is part of the plastic fitting at the booster. That is why I said pull the fitting from the booster and check for vacuum there.
Those you can unplug while the car is running, an easy test. Look to see where the line is attached to, make sure that is a good vacuum source.
I had a similar problem that I chased for quite a while. The setup for my 55 included a bracket that the booster mounted to so I could use the stock mounting holes. That set it about 4" out from the firewall and went thru a linkage to work the push rod on the booster. I removed the linkage and turned the bracket upside down. It still bolted to the stock holes but it allowed me to connect the pedal directly to the booster push rod. Problem solved.
The problem is present without the engine running. I contacted Auto city and they are sending me a new master. At this time there is nothing left besides the valve. I have felt the vacuum inside the booster and is a good source. They said masters have been know to be faulty. Hope this takes care of the problem.
The line I replaced a bend was not great so I corrected it. I have no pressure without vacuum boost. You press the pedal and it is hard engine not running. When vacuum is supplied the pedal is softer and the pedal will drop but no brake force. And when I bleed either line on the master some times I have great flow other times it very low flow with no air. This is how it is on all wheels some times great flow but no air. The pedal does not pump up and you have to slam the pedal to stop the vehicle. The pedal then starts to drop. It just seems the master is not pushing the fluid.
On that note, see what another master does for you. This is why I like to buy parts that I can get at any parts house, not depending on someone who gets theirs from who knows where.
I had a defective master cylinder once that one of the O rings on the piston had become twisted and would bind.
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