[WANTED] Kelsey-Hayes proportioning valve for A body

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jawbone

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Application is for 68 Barracuda with Kelsey-Hayes front disc and 10 x 1 3/4" rear drum. No junk please. Looking for nice rebuildable unit. Would rather have Mopar unit than a re-pop. Think it resembles this one if not mistaken.

Prop Valve A Body 003 (Small).JPG
 
Thanks. I have seen references to this. Did not know was associated with the 68. Is the first pic with integral proportioning valve a direct fit?
 
early Factory disc/drum system requires both - the big one with many connections (post #1) is actually a distribution valve and does not protortion the pressure. The small one that takes two fittings in post #4 is the proportioning valve and is located about a foot toward the rear of the car from the distribution valve in the line to the back brakes.
 
Application is for 68 Barracuda with Kelsey-Hayes front disc and 10 x 1 3/4" rear drum. No junk please. Looking for nice rebuildable unit. Would rather have Mopar unit than a re-pop. Think it resembles this one if not mistaken.

View attachment 1716055970
Not to sidetrack, but I have one exactly as in the picture. What is the piece at the top circled in red? Thanks.
Proportioning valve.JPG
 
Not to sidetrack, but I have one exactly as in the picture. What is the piece at the top circled in red? Thanks.
View attachment 1716063436
I think the name of that fitting is called a Residual Pressure Valve. It's what designates the whole shebang as being for front disc brakes. The whole brass part below it is divided into two halves. Top part is above the mount bracket, with 1 line into the part you circled and 2 lines out going to the front disc brakes. Bottom part has 1 line in and then 1 line out going to the rear drums. Unless I misunderstand them, the only difference between the disc and drum blocks are the valve on top. I have a diagram drawn on a piece of cardboard and stuck up in the shop showing where each line goes because my CRS makes me forget! :realcrazy:
 
I think the name of that fitting is called a Residual Pressure Valve. It's what designates the whole shebang as being for front disc brakes. The whole brass part below it is divided into two halves. Top part is above the mount bracket, with 1 line into the part you circled and 2 lines out going to the front disc brakes. Bottom part has 1 line in and then 1 line out going to the rear drums. Unless I misunderstand them, the only difference between the disc and drum blocks are the valve on top. I have a diagram drawn on a piece of cardboard and stuck up in the shop showing where each line goes because my CRS makes me forget! :realcrazy:
Residual pressure valves are located in the master cylinder as required. Ie; 4 wheel drum master has a residual pressure valve each located in the port of the master right behind the brass line seat. A disc master has only one residual pressure valve located in rear segment port, you don’t want residual pressure on disc brakes.
the thing you circled is just and adapter to accommodate the brake line. You take the adapter out to get to the guts of the valve.

19A69C43-675B-4F51-9B0A-08CFF810DF30.jpeg
 
Residual pressure valves are located in the master cylinder as required. Ie; 4 wheel drum master has a residual pressure valve each located in the port of the master right behind the brass line seat. A disc master has only one residual pressure valve located in rear segment port, you don’t want residual pressure on disc brakes.
the thing you circled is just and adapter to accommodate the brake line. You take the adapter out to get to the guts of the valve.
4mulas - can you confirm that the smaller valve in line to the back brakes is the actual proportioning valve?
 
Residual pressure valves are located in the master cylinder as required. Ie; 4 wheel drum master has a residual pressure valve each located in the port of the master right behind the brass line seat. A disc master has only one residual pressure valve located in rear segment port, you don’t want residual pressure on disc brakes.
the thing you circled is just and adapter to accommodate the brake line. You take the adapter out to get to the guts of the valve.

View attachment 1716063563
Thanks. I ask because I have two that are identical except for that adapter on top. The one that does not have it simply has the port for the line from the master cylinder to screw into with no adapter.
 
Is this to say the in line proportioning valve (pic in post 4) may operate at a different pressure say for Kelsey-Hayes brakes than the one for later disk with integral valve? I'm trying to make this simple but never is.
 
early Factory disc/drum system requires both - the big one with many connections (post #1) is actually a distribution valve and does not protortion the pressure. The small one that takes two fittings in post #4 is the proportioning valve and is located about a foot toward the rear of the car from the distribution valve in the line to the back brakes.
I don't know about the A-bodies, but on the B/E-bodies the proportioning valve and distribution block were integrated into one unit starting with model-year 1972.
 
I run 7/8 wheel cylinders on rear brakes on my factory disc setup with an adjustable proportioning valve set to full pressure to the rear. Seems to work pretty good.
 
Is this to say the in line proportioning valve (pic in post 4) may operate at a different pressure say for Kelsey-Hayes brakes than the one for later disk with integral valve? I'm trying to make this simple but never is.
Do you need to one in your first picture with the adapter on top? If you do, that's the extra one I have.
 
Do you need to one in your first picture with the adapter on top? If you do, that's the extra one I have.
Hey Rob. That's the million dollar question. At this point I'm not sure if the newer style will work. Posted question regarding operating pressure. Awaiting a response. Did read about installing smaller rear wheel cylinders but not sure if my application is applicable.
 
Hey Rob. That's the million dollar question. At this point I'm not sure if the newer style will work. Posted question regarding operating pressure. Awaiting a response. Did read about installing smaller rear wheel cylinders but not sure if my application is applicable.
Ok. Well, if you decide you need it, I have one. I used the style without the adapter on Vixen. That's what she has now, even though she still has drums all around. I went ahead and upgraded the hydraulics before I pit the discs on the front.
 
I'm trying to make this simple but never is.
just run the 73 and up style from doctor Diff And your disc brake project will be perfect, less complicated, and easier.

pro valve regulates pressure doesn’t care what caliper you use.

I’m doing the same job on my duster right now with Kelsey-Hayes and am confidently replacing my drum brake distribution block with the later style 73 and up proportioning valve..

make sure you have the correct master cylinder. disc/drum
 
Residual pressure valves are located in the master cylinder as required. Ie; 4 wheel drum master has a residual pressure valve each located in the port of the master right behind the brass line seat. A disc master has only one residual pressure valve located in rear segment port, you don’t want residual pressure on disc brakes.
the thing you circled is just and adapter to accommodate the brake line. You take the adapter out to get to the guts of the valve.

View attachment 1716063563
Now that you jogged my memory, I know you are correct about the RPV being in the master cylinder. I got my terminology and brake parts mixed up! E burg or somebody wrote an article back in the day before Al Gore invented the internet, telling how to remove one from a drum brake master cylinder to convert it to use with front discs. You just remove the brake line from the end of the reservoir you want to use for the discs, run the appropriate size sheet metal screw into the hole the brake fluid comes thru and wiggle that little baffle out. Behind it, you will find a spring that looks like one from a ball point pen with a rubber hickey in it. You throw the spring and rubber hickey away and remove the screw from the seat you pulled out and put the seat back in the hole in the master cylinder and let the fitting on the line push it back in place when you tighten the line down. I tried it once on a 74 Duster I converted to big bolt pattern discs. It worked ok, but I wouldn't do it again.
 
Now that you jogged my memory, I know you are correct about the RPV being in the master cylinder. I got my terminology and brake parts mixed up! E burg or somebody wrote an article back in the day before Al Gore invented the internet, telling how to remove one from a drum brake master cylinder to convert it to use with front discs. You just remove the brake line from the end of the reservoir you want to use for the discs, run the appropriate size sheet metal screw into the hole the brake fluid comes thru and wiggle that little baffle out. Behind it, you will find a spring that looks like one from a ball point pen with a rubber hickey in it. You throw the spring and rubber hickey away and remove the screw from the seat you pulled out and put the seat back in the hole in the master cylinder and let the fitting on the line push it back in place when you tighten the line down. I tried it once on a 74 Duster I converted to big bolt pattern discs. It worked ok, but I wouldn't do it again.
Well, I agree, you can remove it - sometimes. For me it’s about 50/50 if the brass bit even comes out. Sometimes they get stuck pretty good. Just removed one on the rear of an oem 74 master for a disc brake car and there wasn’t even one there.
the reservoir size is a lot smaller on a drum master which isn’t ideal for a disc application. A caliper compressing in consumes a lot more fluid than a wheel cylinder Does hence the larger size reservoir for the front circuit on a disc brake master.
 
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