57 Dodge brake disaster

[MoparMike]

I have upgraded the brake system for this car, 66 Chrysler rear end, scarebird disc brake conversion. All new brake lines, new splitter block. The pedal is spongy at best and will go to the floor if pushed hard enough. I have used both a 68 Fury master cylinder, scarebird recommended for the conversation and a master cylinder for a 77 Cordoba. Both were brand new. There is no power booster currently on the car. There are no leaks anywhere, yet the pedal never gets to the point where I would have any confidence in stopping the car. I realize I Frankensteined this system together, but if there are no leaks shouldn't the pedal get firm? I am at a loss for ideas. Any help would be greatly appreciated.

 

[mrs49]

I have upgraded the brake system for this car, 66 Chrysler rear end, scarebird disc brake conversion. All new brake lines, new splitter block. The pedal is spongy at best and will go to the floor if pushed hard enough. I have used both a 68 Fury master cylinder, scarebird recommended for the conversation and a master cylinder for a 77 Cordoba. Both were brand new. There is no power booster currently on the car. There are no leaks anywhere, yet the pedal never gets to the point where I would have any confidence in stopping the car. I realize I Frankensteined this system together, but if there are no leaks shouldn't the pedal get firm? I am at a loss for ideas. Any help would be greatly appreciated.

Bleed,bleed,bleed.

 

[3175375]

I have upgraded the brake system for this car, 66 Chrysler rear end, scarebird disc brake conversion. All new brake lines, new splitter block. The pedal is spongy at best and will go to the floor if pushed hard enough. I have used both a 68 Fury master cylinder, scarebird recommended for the conversation and a master cylinder for a 77 Cordoba. Both were brand new. There is no power booster currently on the car. There are no leaks anywhere, yet the pedal never gets to the point where I would have any confidence in stopping the car. I realize I Frankensteined this system together, but if there are no leaks shouldn't the pedal get firm? I am at a loss for ideas. Any help would be greatly appreciated.

Did you bench bleed the master cylinders before installing them (either one)?

 

[MoparMike]

Did you bench bleed the master cylinders before installing them (either one)?

Both master cylinders were bench bled before installing them on the car. Yesterday, with the 68 Fury master cylinder installed the brakes were bled and rebled until an entire quart of brake fluid had been put into the master cylinder. At no point was the master cylinder run dry. There was nothing but fluid coming out of all the the bleeders.

 

[Davea Lux]

I would start by checking all of the brake system fittings. Brake fittings can suck air if they are not tight and properly seated. If you have a spongy pedal, that usually means air is getting into the system.

Dave

 

[Vinny]

Did you bench bleed the master cylinders before installing them (either one)?

AND, are the bleeder screws at the TOP of the calipers?

 

[MoparMike]

The bleeders are at the top of the calipers....I'm not a complete idiot. Found that one of the new (chinesium) wheel cylinders is no good.

 

[Vinny]

The bleeders are at the top of the calipers....I'm not a complete idiot. Found that one of the new (chinesium) wheel cylinders is no good.

Nice cordial response, bud. You asked for advice, didn't you?

 

[MoparMike]

My apologies. The frustration of losing an entire day going through a system that you completely replaced to avoid this very problem got the better of me.

 

[Just Carbs]

My apologies. The frustration of losing an entire day going through a system that you completely replaced to avoid this very problem got the better of me.

Did the bad cylinder cause the problem?
Can you describe the nature of the defect please.

 

[MoparMike]

After going through the entire system, checking every fitting, every connection the system was still getting air into it. Finally figured out it was it the passenger side rear wheel. Replaced the wheel cylinder and now have brakes. I'm not sure if a seal was bad, it was a manufacturing defect or the line wouldn't seat right in the cylinder. I just know that replacing the cylinder fixed the issue.

 

[wyrmrider]

remember you can change wheel cylinder size if you need more or less rear brake
or a porportioning valve with knob thru the floor in front of the front seat