Brake pedal goes all the way to the floor when the engine is started

1966 DODGE CHARGER
75,000 MILES • 6.2L • V8 • 2WD • AUTOMATIC
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SAM LEMBO
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We have been trying to fix the brakes for a week and they pump up, but when we start the car the pedal goes all the way to the floor. Brakes have been bled, front hoses replaced, new pads and calipers.

Before I got the car someone installed front disk brakes. They also installed a brake booster and master cylinder. It appears they used GM parts for this. In a mixed brake system shouldn't the rear (closest to the booster) reservoir (for the disks) be larger then the front reservoir (for the drums)? Can anyone recommend the correct part numbers for the master cylinder, booster even calipers and rotors? Part numbers would be great. I have got a feeling the buy cobbled together this brake conversion as cheap as possible. Thanks in advance fr your time and your help!
Apr 25, 2018 at 11:24 AM
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ASEMASTER6371
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Good morning.

Do you have disc in both front and rear?

Do you know if there is a proportioning valve in the system?

Just wondering if they installed all the correct parts.

Roy
Apr 26, 2018 at 5:03 AM
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SAM LEMBO
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Disks in the front, drums in the rear. There is a proportioning valve but I am not sure they installed the right valve, and master for a mixed application. If mixed is a special proportioning valve supposed to be used?
May 11, 2018 at 4:43 AM
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ASEMASTER6371
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It sounds more like you have air trapped in the system. I would suggest a pressure bleeder to force all the air out of the system. You can rent one from a parts store.

Open the rears first and do the fronts last.

Roy
May 11, 2018 at 4:55 AM