Front Brake Issue

[BBQPorkins]

Hey! I have a 66 Charger that the previous owner installed a piratejack conversion kit in. So it has a Chevy style booster and master. The braking has never been good and I lost the pedal a couple of times. I have replaced the following over the course of a year trying to troubleshoot this garbage.
I have replaced the hoses, calipers, rotors, prop valve and recently the master. I also bought the booster but I haven't installed it yet. The master and booster I re-purchased from Piratejack to try and keep things simple. Right now the issue is after driving about 5 miles the front brakes start to hang. I come home jack up the car and I cannot turn the front wheels by hand. If I release the bleeder a little fluid pops out and both brakes release and I can spin the rotors. Drive it again bring it home fronts still wont spin by hand. Crack the line at the master and both calipers release. Drive it again issue repeats and this time I unbolt the master from the booster and yes the calipers release. Drove it one last time and lifted it and still could not spin the tires by hand...left it set for like an hour and half and low and behold they released on their own... I would believe at this point the pin in the booster needs to be adjusted. I used the booster/master tool to set the pin but the its 1/8 inch or less high off the booster and I would think it would push the piston in a bit on the master. A cannot move the pin in any further and it is not removeable to make any modifications to it. If I try to set the pin on the new booster I didn't install yet the pin on that is too high as well.. What controls the pin? This version of the issue is new since replacing the master 2 weeks ago. Other than junking the whole system and start over what am I missing? I've bled 8qt's of DOT3 through the whole system using a pressure bleeder.

 

[Kern Dog]

First of all, there should be some free play in the brake PEDAL. I'm not talking 2 inches but at least one inch.
If there is no free play, it means that the booster pushrod is likely already under tension, pressing into the master cylinder and effectively causing some "preload".

The threaded nub on the end is adjustable. If it is adjusted out too far, it moves the master cylinder piston forward to where it has pressure already in the system. You need to back off that nub so that at rest, the system has no pressure.
Pedal, not peddle.

 

[MIKESPOLARA]

The typical aftermarket booster has a screw in pin with a nut behind it, is this what you have? If so unscrew the pin completely and remove the nut, you can now screw the pin without nut in farther, all the way until it stops. I had to do that years ago on some boosters

 

[ckessel]

Some years ago I replaced the master on an AMC Scrambler. The car owner sourced it through some AMC specialty outfit and it was "supposed" to be a direct swap. After having the same experience you did, I pulled it back off to check and see if the rod was out too far compared to the bore on the back of the piston. Turned out that whoever made the piston machined the back bore shallower than the original which would then apply the brakes prematurely once it was all bolted together.

 

[RemCharger]

Throw a couple washers between the Mc and the booster, if yours isn't adjustable. Just to try.
Could be your brake light switch holding it from coming back enough.

 

[dvw]

if there isn't enough clearance at the booster push rod. Fab up a spacer that goes between the master and booster.
Doug

 

[pnora]

Sounds like an incompatible master to booster. Simple test to verify its at this point is to do this. When the brakes are locked up just loosen the master from the booster. If the wheels spin that your problem.

 

[RemCharger]

Sounds like an incompatible master to booster. Simple test to verify its at this pint is to do this. When the brakes are locked up just loosen the master from the booster. If the wheels spin that your problem.

He did that.

 

[1 MEAN66]

You are down to two possible problems as I see it. To which you have proved to yourself! If you are a person that likes to put "vice grips" on brakes hoses - to stop leaks while installing other parts, which does work some of the time, BUT IS NOT RECOMMENDED, 1) it can crush the braided part of the hose that is inside the rubber cover that you see on the outside of the hose. 2) what all the others are saying (is much more likely, rod from master to brake pedal arm is too long. If the "pressure" can be relieved by cracking the bleeder, the fluid cannot return to the master cylinder (brakes get warn- it expands) because the port is blocked -rod to long- keeping the internal piston covering the return port., or passage restricted, -crush hoses. You say you changed hoses. And usually, you don't get defective or two bad ones at a time. The simplest diagnosis is just loosening the nuts attaching the master to booster, wheels rotate rod too long. So, if IS adjustable (some are not) adjust it as described. If not adjustable-it is still too long, shorten it. Take your time and make sure it's smooth on the end that goes in the master. I have also seen people drill out the piston in the master. I personally would do neither. If rod is part of master and not removable get the proper master assembly. Most rods do come out. Washers between the master and booster would also work but would look a bit weird besides being a poor solution, brakes should not be "Mickey Mouse'd" Do not over think it, you figured out the problem, just need the fix. Hopefully this just paints a better picture for you, to see why it happens.

 

[BBQPorkins]

Thanks everyone. You've gave me some new things to look at. Hopefully tonight. I kind of walked away to give myself a break on this.

 

[ckessel]

Give yourself a brake.

 

[1STMP]

Are the rears affected? Just curious if
you've checked them.

 

[RJRENTON]

Give yourself a brake.

Is that a brake or is it a break???.....just curious......
BOB RENTON