Brake booster time.

[Boydsdodge]

I pulled the old booster last week, found that it had plenty of dried up brake fluid and a broken hub. Had the guys at John Stuart brake open up and dissect, then I took cases, stripped off old finish at my shop, then took to local platting shop. Couple days later, platting done, back to Stuart brake, drop off. Wait for call, couple days later I have a rebuilt shiny booster.
Now to reinstall.

 

[1970FuryConv]

Nice work! Great that it could be done locally.

 

[Boydsdodge]

All right, with some slight health delays the booster is back in its place and all hooked up and looking good.

 

[Boydsdodge]

Well this is disappointing.
First nice day in months here, dry enough to take my Imperial for a test drive. The test drive was a disappointment backing out of garage, My new rebuilt booster not doing its thing. Still have a brake pedal like pushing on a wall. Uggghhh.

 

[1970FuryConv]

Are there any vacuum leaks in the hoses to the carb fitting or to the cruise control from the check valve?
Could the hose from the carb fitting be partially blocked?
Is the check valve new as well as the booster?
Is the master cylinder and brake system properly bled?

 

[Boydsdodge]

The vacuum lines were are checked and vacuum up to specs before the pull, all hoses connected.
Master was not changed, very solid pedal.
I will be going over it all today

 

[Big_John]

I've read of a lot of failures of brake hoses causing issues like this. The internal lining breaks down and closes up. There's been a few threads on here about it with the rear line often being the problem.

I would try cracking the bleeders (one at a time) with a helper pushing the pedal.

 

[Boydsdodge]

OK, I'll give the rear line a try. I would not have thought a collapsed line would give a solid pedal feel on power brakes. I figured a collapsed line would feel like power assist but not stop.
Thanks for suggestion. On that idea, is there a listing for a longer rear flex line? my current line is (to me) too short. When car is lifted the line is pulled tight. This is most likely the cause of failed line.

 

[Boydsdodge]

I think I found a longer line. I looked up rear line for 72 Dodge D200. it is 4" longer.
RAYBESTOS BH36664

 

[Boydsdodge]

Booster holds vacuum, as does the cruise control unit. I have assist with the vacuum pump connected. Tracing down any vacuum leaks I can find and repairing or investigating a cure.
Park brake release switch is a good leak of an inch of vacuum per second starting at 15 in hg. Also a leak in the hot air door pull off valve, that one too fast to record.
The HVAC vacuum line from under hood reservoir to dash, leaks at a rate of 5 seconds fro 20 in hg to zero.
I don't see any specs on acceptable leaks for a proper system in the service manual. This being my first car with complete HVAC system and I care about, it would be nice to sort.
It will be easier to tune with out vacuum leaks. A,B, E and C-body cop cars are what I am used to, not many with AC up here or many with system intact.