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Mopar Garage => Chassis, Suspension, Brakes, Wheels, & Tires => Topic started by: C500 on December 09, 2022, 07:48:41 AM

Title: Rear brakes working intermittently
Post by: C500 on December 09, 2022, 07:48:41 AM
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.
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 09, 2022, 09:11:24 AM
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"
Title: Re: Rear brakes working intermittently
Post by: birdsandbees on December 09, 2022, 10:16:38 AM
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!  :icon_smile_big:
Title: Re: Rear brakes working intermittently
Post by: Bronzedodge on December 10, 2022, 07:58:59 AM
Bad rear hose, collapsed internally?
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 10, 2022, 10:08:42 AM
How old is the flex line to the axle?
Title: Re: Rear brakes working intermittently
Post by: C500 on December 10, 2022, 01:16:19 PM
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
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 10, 2022, 02:22:37 PM
Yea like me then. The entire lines from new, had to use push fluid through master system.  :scratchchin:
Title: Re: Rear brakes working intermittently
Post by: C500 on December 10, 2022, 03:17:20 PM
Quote from: b5blue on December 10, 2022, 02:22:37 PM
Yea like me then. The entire lines from new, had to use push fluid through master system.  :scratchchin:

A blocked master or faulty valve inside it?
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 10, 2022, 03:30:41 PM
  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/
Title: Re: Rear brakes working intermittently
Post by: C500 on December 19, 2022, 08:03:54 PM
Quote from: b5blue on December 10, 2022, 03:30:41 PM
 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
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 19, 2022, 08:55:21 PM
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.  :scratchchin: Too long and the master never resets to "At rest", too short and you never get full action out of the master.
Title: Re: Rear brakes working intermittently
Post by: C500 on December 19, 2022, 08:58:07 PM
Yes,the brake shop did that, I provided the manual and a brand new booster, dual diaphragm
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 19, 2022, 11:16:08 PM
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?  :scratchchin:  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?
Title: Re: Rear brakes working intermittently
Post by: C500 on December 19, 2022, 11:26:40 PM
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.
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 20, 2022, 09:42:55 AM
Sounds like the only iffy is that block?  :shruggy:   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,
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 20, 2022, 09:53:08 AM
Is what you installed just like this:  https://therammaninc.com/products/shop_view/Mopar-TA-Disc-Brake-Proportioning-Valve-Metering-Valve-Disc-373
Title: Re: Rear brakes working intermittently
Post by: C500 on December 20, 2022, 10:12:24 AM
This is the one I put in https://www.yearone.com/Product/chrysler-b-body/dtb7
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 20, 2022, 12:22:15 PM
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/
Title: Re: Rear brakes working intermittently
Post by: C500 on December 20, 2022, 12:54:22 PM
Thanks, will look into it later today  :cheers:
Title: Re: Rear brakes working intermittently
Post by: b5blue on December 20, 2022, 01:22:19 PM
Good luck!
Title: Re: Rear brakes working intermittently
Post by: Bronzedodge on January 22, 2023, 10:26:39 AM
https://www.summitracing.com/parts/leb-bpg001?seid=srese1&gclid=CjwKCAiA2rOeBhAsEiwA2Pl7Q1SgwLCDXFSFlp9VYo5r9A6IyaRkxTQQLZt6JrO22tNaE_cNc8ffVhoC3qoQAvD_BwE
Title: Re: Rear brakes working intermittently
Post by: C500 on February 23, 2023, 09:37:59 PM
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.
Title: Re: Rear brakes working intermittently
Post by: b5blue on February 23, 2023, 10:37:50 PM
Damn.