Rear brakes working intermittently

[C500]

Hi all, have car in brake shop for new rear cylinders for the drums. Guys bleeding them up, and adjusting but working on first pump on the pedal, then not working at all. Car is a 69, have new SSBC booster, new brass distribution block from year one (for disc brake car). Originally drum/drum car. Any ideas on the problem...assuming the distribution block is getting an intermittently stuck valve inside. Can this be fixed or should be replaced? Had it for over a year, so can't return to year one.

[b5blue]

I had air trapped to rear that would not bleed out. I had to buy the brake bleeder tool that forces fluid through the master to clear it. "Motive Products 105 Brake System"

[birdsandbees]

A stock '69 distribution BLOCK has no valves in it that block fluid flow, but only a pressure shuttle spool to turn on that red light to add horror to what you already know is happening! 

[Bronzedodge]

Bad rear hose, collapsed internally?

[b5blue]

How old is the flex line to the axle?

[C500]

All the brake lines are new. The guys have tried the vacuum tool. Seems to be a master cylinder issue I think. Cad goes back Monday to tray and work it out. This is the distribution block I put in from year one

[b5blue]

Yea like me then. The entire lines from new, had to use push fluid through master system. 

[C500]

Yea like me then. The entire lines from new, had to use push fluid through master system. 

A blocked master or faulty valve inside it?

[b5blue]

  Air expands and compresses so I just gave up and pushed fluid from the top. That was 3-4 years ago and when humidity drops I'm gonna flush with fresh brake fluid just because it's eazy-peezy with the rig. (We are still 75-80 degrees and 70-80 percent humid in FL.)
 My "Mighty Vac" tool and the rig ya hook to an air hose for venturous action couldn't overcome whatever pocket of air was trapped in there!  
https://www.motiveproducts.com/

[C500]

 Air expands and compresses so I just gave up and pushed fluid from the top. That was 3-4 years ago and when humidity drops I'm gonna flush with fresh brake fluid just because it's eazy-peezy with the rig. (We are still 75-80 degrees and 70-80 percent humid in FL.)
 My "Mighty Vac" tool and the rig ya hook to an air hose for venturous action couldn't overcome whatever pocket of air was trapped in there!  
https://www.motiveproducts.com/

still no luck, have pushed fluid through, they bleed up fine, but then stop working. No kinked lines... going back to the shop next year

[b5blue]

Have your guys checked the booster to master cylinder plunger rod? There is an adjustable nut on the end that must be set just right.  Too long and the master never resets to "At rest", too short and you never get full action out of the master.

[C500]

Yes,the brake shop did that, I provided the manual and a brand new booster, dual diaphragm

[b5blue]

Darn..Let's see there is the residual presser retainers in the master, if the new wheel cylinders don't need them (Most don't anymore.) that could mess things up. Your certain the flex line to the axle is good?    I'm out of ideas. My 70 is converted to disk up front, I used a Mopar proportioning valve to the rear drums. I've run it manual and converted back to boosted and not had your issue. What master are you using?

[C500]

I'm using a new master from SSBC with their front disc upgrade kit. I'll get the brake shop to check the flex lines, all are new... but ya never know, maybe it's been squished. I wondering if the brass distribution block has issues. It's a new one from year-one, and for disc/drum setup.

[b5blue]

Sounds like the only iffy is that block?     My proportioning valve is adjustable, it restricts flow to the drums. https://www.forabodiesonly.com/mopar/threads/direct-connection-adjustable-brake-proportioning-valve.389010/  They make tiny ones now,

[b5blue]

Is what you installed just like this:  https://therammaninc.com/products/shop_view/Mopar-TA-Disc-Brake-Proportioning-Valve-Metering-Valve-Disc-373

[C500]

This is the one I put in https://www.yearone.com/Product/chrysler-b-body/dtb7

[b5blue]

This might (?) be needed also. It would act like my valve but not adjustable.  https://www.yearone.com/Product/chrysler-b-body/dbhv7#prettyPhoto[part]/0/
Here is a link to what I used and everything I know:  https://www.moparaction.com/2016/03/16/disc-main/

[C500]

Thanks, will look into it later today 

[b5blue]

Good luck!

[Bronzedodge]

https://www.summitracing.com/parts/leb-bpg001?seid=srese1&gclid=CjwKCAiA2rOeBhAsEiwA2Pl7Q1SgwLCDXFSFlp9VYo5r9A6IyaRkxTQQLZt6JrO22tNaE_cNc8ffVhoC3qoQAvD_BwE

[C500]

The brakes shop tested the vacuum.... not enough for the brakes unfortunately, the cam used for the rebuild was a mild street cam too. May be a leak somewhere.

[b5blue]

Damn.