New Brake system has problems, I need help

I have been working on my buddy's 1940 Ford. I set up the brakes using drum rear and disc front from a 1977 Chevy Camaro. The Master cylinder proportioning valve, and booster are from a 1993 Chevy S-10 Blazer. Everything in the system is brand new except for the S-10 parts. I bled out the system with a power brake bleeder until the fluid was clear of bubbles going into my catch jar. I have good pedal when the engine is off but when I start the engine the pedal sucks to the floor or goes to the floor with no resistance at all. I have checked, and the booster will hold vacuum. I have never seen this before. Any help would be appreciated.

Thanks

Mike

 

I am having the same problem...'77 Camaro calipers, master cyl and booster, replaced all with no change. Had proportioning valve with no help. Installed rear residual valve that helped a little.
I have bled many times using all the recommended procedures, had many mechanics check it out...same old poop! ????????????? Frank

 

Get a 1970 Chevelle Manual Master cyl from AutoZone for like $30. Disk/Disk ask for a 1970 Corvette.

I use them straight, just MC, Lines, & Brakes, nothing in between.

 

Is your actuator rod to long and not letting you unapply the brakes with vacuum to the booster?

 

I failed to mention that I also installed the pedal assembly from the S-10. So most likely the actuator rod is not the culprit.

Mike

 

The pedal goes to the floor by itself? If so, it's gotta be a bad booster

 

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Check the adjustment on the rear drums. Are you able to pump up the pedal at all to gain some height? The adjustment may bring the pedal up a bit. But I suspect some geometry problems with the rod that goes to the booster.

Bob

 

I'm thinking the boaster or brake pedal rod adjustment

 

Are the brake pads and shoes engaging the rotors and drums when the engine is on with brake pedal depressed?

 

I spoke with an old master mechanic today. He believes it to be the booster control valve. This requires a new booster. I will let you guys know what happens.

Thanks!

 

Sounds to me like a booster or the booster vacuum check valve. does the pedal come back up by itself or does it stay stuck to the floor? also, do the brakes apply fully when the pedal is down?

 

I second booster control valve.......

 

Yeah. My buddy is tighter than 2 coats of paint. I want him to just pop for a new one from the parts store. He wants to save a buck and waist my time on a junk yard unit. UGH!!! I am going to be so glad when this car is out of my shop!

 

Sounds like a vacuum booster problem. HRP

 

as long as he's buyin the beer, i had abuudy like that tried to tell him to do the math gas goin to junk yard beer wastin time, check around somebody around you might rebuild em

 

Sad fact is I have had the car in my shop since August. It came in needing brakes, a tail pan, the body bolted to the chassis, and bumpers mounted. I have found about 100 other things that had been done in shoe maker fashion. I love this guy like a brother and could not turn him out with an unsafe car. So now I need this thing gone so I can focus on other things like the restoration of my daughters Beetle and about 4 other rods folks want worked on. I don't want to wait more than a day or 2 for parts but in my garage it sits almost one week later still needing a booster.

 

Let it wait outside for a booster.
Tow it back to his place to wait for a booster.

Anybody on the planet can get anything they want next day air.
Get him a booster for the rest of his birthdays and get your shop back