73 Drum to disc prop valve needed?

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Mopar92

Mopar92

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many years ago I did a disc brake conversion on my 70 Dart. I never changed the prop valve. It’s actually very well balanced. Almost never locks a rear and has a great pedal. However on my 73 Duster... I just can’t get the squish out of the pedal. All new rubber lines. New pads and shoes. Drums are adjusted out. Bleeders are at the top.... new 15/16 master Manual setup. Is there a reason this system won’t bleed well enough to even check bias?
 
It could be. It’s a brand new parts store master... no way that would be bad. Ha. I’ll try another pressure bleed. I did notice 1 drop of fluid on the floor after sitting for a week. It’s not the bleeder. It’s not the banjo. It could be the piston. Again all new but we know how that goes nowadays.
 
Many manual 4 drum systems didn't have a true proportion valve. They had a basic distribution block with the warning switch along with residual pressure valves in the master cylinder. So if you didn't change the master cylinder on the 70 model, the difference between that master cylinder and the master cylinder you have today ( lack of residual pressure ? ) might be where the squish comes from. Just spit balling here since I don't know what year models had a true proportion valve. From what I've read, most owners buy a new aftermarket proportion valve, adjustable type or not.
 
Presence or lack of a prop valve has nothing to do with the pedal "squish" or bleeding the brakes. All that would do is change front / rear braking bias
 
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