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

Tiny
SAM LEMBO
  • MEMBER
  • 1966 DODGE CHARGER
  • 6.2L
  • V8
  • 2WD
  • AUTOMATIC
  • 75,000 MILES
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!
Wednesday, April 25th, 2018 AT 11:24 AM

3 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
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
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Thursday, April 26th, 2018 AT 5:03 AM
Tiny
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?
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Friday, May 11th, 2018 AT 4:43 AM
Tiny
ASEMASTER6371
  • MECHANIC
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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
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Friday, May 11th, 2018 AT 4:55 AM

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