Brake valves

[john108]

I have a 1968 Charger R/T and presently the Brake system is stock power brakes.  I have read various posts concerning existing drum brakes as well as upgrades to disk.  I am trying to get educated but find myself a little confused.  I have attached a picture of what I think is my proportioning valve or distribution block or???.  I don't know if a second valve also exists.  My terminology may be wrong.  I read many posts but the last thread I read concerning the Brakes was:
http://www.dodgecharger.com/forum/index.php/topic,101591.0.html

The picture posted there and the terminology used is new to me. 

If I were to upgrade, does this valve need to be replaced (possibly with something similar to the one John K posted in the above link) and what other valves need to be added?  I hope someone can anticipate what questions I should ask next and answer them first.
Thank you - John

[John_Kunkel]

That item is merely a distibution block with a warning light switch often called a "safety tee". It does no proportioning or metering.

The combo valve I mentioned in another thread has it all in one unit, easiest way to go IMO.

[john108]

John K
If I interpret you correctly, My system does not have proportioning or metering.

You also made the following 2 statements:

1- There is a difference between the hold-off valve that goes in the front brake circuit and the proportioning valve that goes in the rear brake circuit. The hold-off valve delays brake application until a specified pressure builds in the front circuit, the prop valve limits the pressure in the rear circuit.
I don't think anybody uses the hold-off valve in a retrofit, it's a factory thing.

2-A difference in terminology, the correct term for the rear brake valve is Residual Pressure Valve (RPV), the metering valve (correct terminology) for the front discs is often called the hold-off valve.

Along with a picture of a Metering valve assembly, you made the following statement: For a disc/drum setup the RPV in the factory MC is all you need, no need for an inline RPV.
If you're worried about the front metering valve, just get a factory-style combo valve and you won't need to do a lot of extra line bending/flaring.

Other than replacing brake pads/shoes and master cylinders, I am un-familiar with the newer braking systems and terminology.  Would you please explain what I need or have to do (to this simpleton) when I upgrade.  Is that Metering valve assembly the combo valve you are referring to?  Does it replace the distribution block that I have?  Do I need a special master cylinder?  Is a second valve, required in the system, or optional?
Thank you again.

[John_Kunkel]

The first Mopar disc brake setups had the safety tee, a separate proportioning valve for the rear brakes  and , sometimes, a separate metering valve for the front brakes.

The purpose of the metering valve in the front system is to hold off brake application until a certain pressure is attained in the system; most disc brake retrofits don't use this but, if you want one, the combo valve has it all.

For the most common front disc upgrade, leaving the existing safety tee and adding an adjustable proportioning valve in the rear system is all you really need. At the same time you'll need a disc brake MC with a RPV for only the rear brake system...an RPV in the front system will prevent the calipers from fully releasing. Besides having only one RPV, the disc brake MC has a larger fluid reservoir for the front brakes because caliper pistons move out of there bores as the pads wear and displace more fluid. 

[john108]

John K.
I think I understand now.  Leave the safety tee!  A NEW Master Cylinder (MC) will have a built-in Residual Pressure Valve (RPV) for the line going to/through the safety tee to the adjustable proportioning valve (NEW) that feeds the rear brakes.  The front brakes are still fed through the safety tee but no Residual Pressure Valve (RPV) is required.  I included an updated picture (Updates in RED) trying to show what I believe I understand.
Thank you  --  John

[john108]

Please confirm or correct my understanding.

[John_Kunkel]

You've got it.

[resq302]

The "What is Here" arrow is pointing to the service port / plug where you unscrew that to access the internal moving parts in order to rebuild the distribution block.

[john108]

   Thank You Very Much.