Moparts
A Body disc brake swap - proportioning valve.
Posted By: VITC_GTX
A Body disc brake swap - proportioning valve. - 03/31/13 07:46 PM
1969 Barracuda; I put '73 A body disc brake spindle/calipers on. The rear brakes don't seem to work unless I hit the pedal very hard. Also, after they are activated they don't release very well (drag a lot).
The car still has the original proportioning valve, is it required to change that out when going from older drums to newer discs? If so, is there a drop in valve that I can buy that won't require me to redo the lines (bending lines/new fittings)?
Posted By: maximus
Re: A Body disc brake swap - proportioning valve. - 03/31/13 07:52 PM
You will have to use the valve for the disc brake front and drum rear if that is your new set-up. There should be no or minor bending to accept the new valve. Contact In-Line Tubing in Shelby Township, Michigan. They sell everything you need. Or you can get a used disc/drum valve from a junkyard if you want to go that route.
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 03/31/13 08:45 PM
I put 74 A discs on my 65 dart & kept the OE drum splitter & NO issues. 10" rear drums/alum dual bowl M/C. bowl next to firewall to front discs/forward bowl to rear drums. Likely an issue with the OE prop valve. I'd open it up & see what's stuck or I wouldn't be afraid to gut it & convert it to an open splitter & avoid having to rebend lines.
Posted By: d-150
Re: A Body disc brake swap - proportioning valve. - 03/31/13 08:56 PM
sounds like you still have air in the line
Posted By: Supercuda
Re: A Body disc brake swap - proportioning valve. - 04/01/13 01:35 AM
Quote:
I put 74 A discs on my 65 dart & kept the OE drum splitter & NO issues. 10" rear drums/alum dual bowl M/C. bowl next to firewall to front discs/forward bowl to rear drums. Likely an issue with the OE prop valve. I'd open it up & see what's stuck or I wouldn't be afraid to gut it & convert it to an open splitter & avoid having to rebend lines.
There IS NOTHING in a drum splitter.
NOTHING
You'd know that if you understood how a braking system works.
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 04/01/13 02:09 AM
Quote:
[here IS NOTHING in a drum splitter.
NOTHING
You'd know that if you understood how a braking system works.
Having a bad day there bro 
. HE mentioned having a prop valve which means he's swapping the 4 piston KH brakes out (which have a prop valve) for the 73 single piston ones (very likely if swapping to a big bolt pattern rear) or he's swapping the front drums for 73 A discs & he is mistakingly calling the splitter a prop valve. (re) read his post & get your facts straight before you run your mouth
Posted By: B5 Bee
Re: A Body disc brake swap - proportioning valve. - 04/01/13 02:14 AM
Easy there boys, you're both correct, sort of.
The OP mistakingly called the distribution block a proportioning valve and he mentions he went from older drums to newer discs.
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/01/13 02:36 AM
Yeah, maybe I am using the wrong words. I believe the car was originally 4 drums but I don't know for sure because when I got the car it had the big bolt pattern discs up front.
So if this was a drum car originally then this piece I am talking about is just a distribution block and not a proportioning valve? If that's the case is there any reason in replacing it? What has me baffled is the fact that the rear brakes do not come on at all until I push down VERY hard and then the rear brakes won't release after the pedal is released.
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 04/01/13 02:53 AM
Yes if it was originally 4 wheel drums it would have originally have had a distribution block AKA as a splitter. First thing I'd do is look up under there & see what you have since front discs have already been swapped on by a PO. You have a blockage somewhere.
Posted By: moparpollack
Re: A Body disc brake swap - proportioning valve. - 04/01/13 02:53 AM
I say the calipers pistons are stiff from sitting.
What master cylinder are you using? How old are the lines? I had a car where the lines looked new but the insides were gunked up from old fluid.
Posted By: moparpollack
Re: A Body disc brake swap - proportioning valve. - 04/01/13 03:01 AM
Quote:
Yes if it was originally 4 wheel drums it would have originally have had a distribution block AKA as a splitter. First thing I'd do is look up under there & see what you have since front discs have already been swapped on by a PO. You have a blockage somewhere.
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/01/13 03:26 AM
Quote:
I say the calipers pistons are stiff from sitting.
What master cylinder are you using? How old are the lines? I had a car where the lines looked new but the insides were gunked up from old fluid.
Master cylinder is a rebuilt unit for a disc brake car (73 Duster). I blew out all the lines before I put everything together. I did not try to blow out the splitter though. Maybe something is plugged up in there?
Is the splitter simply a block with no valves, just a fancy tee with one inlet and three outlets?
Posted By: Chris2581
Re: A Body disc brake swap - proportioning valve. - 04/01/13 03:29 AM
FWIW... I put Wilwood HD brakes on the front of my 71 Demon and all I did was change the front brakes over and install one of Ehrenberg's Mopar master cylinders.My Dana already had 10" drums from a B-body on the rear when the car had the OEM 10 front drums and my brakes work great.
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/01/13 03:34 AM
Quote:
Yes if it was originally 4 wheel drums it would have originally have had a distribution block AKA as a splitter. First thing I'd do is look up under there & see what you have since front discs have already been swapped on by a PO. You have a blockage somewhere.
How can I tell if I have a splitter or a proportioning valve?
Posted By: B5 Bee
Re: A Body disc brake swap - proportioning valve. - 04/01/13 04:39 AM
A bad rear brake hose is another possibility.
They sometimes rupture internally creating a flap that will block the fluid flow. Usually it blocks during release making the brake slow to release but can also block during brake apply, and maybe both apply and release.
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 04/01/13 04:48 AM
Quote:
Is the splitter simply a block with no valves, just a fancy tee with one inlet and three outlets?
Yes, a basic T block & a prop is larger/more complicated as it contains valving. I wonder if the rear flex hose has collapsed internally. EDIT I'd jack up all 4 corners & see how much braking you do have. Something ain't right here in the symptoms
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/01/13 06:15 AM
Quote:
Quote:
Is the splitter simply a block with no valves, just a fancy tee with one inlet and three outlets?
Yes, a basic T block & a prop is larger/more complicated as it contains valving. I wonder if the rear flex hose has collapsed internally. EDIT I'd jack up all 4 corners & see how much braking you do have. Something ain't right here in the symptoms
I did remove the rear flex hose and blew compressed air through it. It seemed to have no restrictions at all. I'm wondering if my splitter/proportioning valve is where the blockage is 
Posted By: 383man
Re: A Body disc brake swap - proportioning valve. - 04/01/13 08:13 AM
When I put front disc on my boys Dart I got the right combination valve from an A-body with the disc/drum setup. You have to remember the disc brake combo valve has the prop valve and the metering valve in it plus it has the light switch to turn the dash brake lite on if you lose one side of the master cyl. Of course the prop valve limits the press to the rear brakes on hard braking so the rear wont lock right up with the front down and not much weight at the rear of the car when braking hard. The metering valve keeps the front disc brakes from applying to much on light brake pedal application until the rear drum brakes overcome the spring tension and start to work. Without the metering valve on light brake pedal applying the disc would be doing all the stopping since they have no return springs on disc and they would apply to much before the rear start to work and most likely would wear the pads out to fast. But the few I did I always but the right disc/drum combo (prop and metering)valve on it and everything worked good. It should be the only valve you need since it has the prop and metering valve in it. If the car has a prop valvre in the rear line under the car you could remove it if you put the combo valve in it. I got one of mine of a Duster at a junk yard and another of a disc/drum Duster my brother was parting out. Ron
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 04/01/13 03:01 PM
Quote:
I did remove the rear flex hose and blew compressed air through it. It seemed to have no restrictions at all. I'm wondering if my splitter/proportioning valve is where the blockage is
Next step would be to unscrew the rear line male fitting from the splitter & hit the brake & see what you get for volume (It'd be good to have a piece of brake line to screw in the block to contain the mess into a jar). If restricted then unscrew & check the line in front of the splitter & if still bad that would point to the M/C half & if good there ahead of the splitter then there's a restriction in the splitter. Holler how it goes. I'm thinking M/C
Posted By: Rhinodart
Re: A Body disc brake swap - proportioning valve. - 04/01/13 03:04 PM
On factory single piston disc brake set-ups there are two valves, the distribution block and a metering valve for the rear brakes. The metering valve is just downline of the distribution block. A lot of people just use an adjustable valve.
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/01/13 08:24 PM
Quote:
Quote:
I did remove the rear flex hose and blew compressed air through it. It seemed to have no restrictions at all. I'm wondering if my splitter/proportioning valve is where the blockage is
Next step would be to unscrew the rear line male fitting from the splitter & hit the brake & see what you get for volume (It'd be good to have a piece of brake line to screw in the block to contain the mess into a jar). If restricted then unscrew & check the line in front of the splitter & if still bad that would point to the M/C half & if good there ahead of the splitter then there's a restriction in the splitter. Holler how it goes. I'm thinking M/C
Yeah, I'll break the line loose and see what I find. How much fluid should I expect to come out, tablespoon?
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 04/01/13 10:38 PM
Quote:
Yeah, I'll break the line loose and see what I find. How much fluid should I expect to come out, tablespoon?
way more than you can handle, you'll know if it's clear
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/03/13 04:20 AM
OK, I'll try and make this as short as possible.
I went out to the car and pushed on the brake EXTREMELY hard and I heard and felt a "pop" and the back brakes started working. Bled them and they were working OK, not great but OK. Went out the next day and no rear brakes again. Next I removed the rear line just after the proportioning valve (I checked and I do have one) and I only got a few drips. So I took off the line in front of the proportioning valve and only got a few drops. So I bench bled the master cylinder and put everything back together and bled the brakes. Rear brakes started working again. If fact they worked pretty good so I locked up the shop and left. Well...I went out today and started the car on the lift put it in gear and hit the brakes...no rear brakes again. I got torqued off and walked away.
I'm thinking something is getting unstuck and stuck once it sits for a while.
Posted By: RapidRobert
Re: A Body disc brake swap - proportioning valve. - 04/03/13 04:37 AM
I wonder if the pop was in the rear drum area. Grab a helper see if you can get it to pop again
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/03/13 04:40 AM
I can't get it to pop again. Hard to tell but it seemed like it came from the front (master cylinder or proportioning valve). I was assuming the proportioning valve had a valve stuck and it broke free but I really don't know anymore...
Posted By: nomore65BelvJim
Re: A Body disc brake swap - proportioning valve. - 04/03/13 05:40 AM
Quote:
How can I tell if I have a splitter or a proportioning valve?
The one in my hand is drum/drum, the one mounted to the frame rail is disc/drum. 72 A body.
Posted By: VITC_GTX
Re: A Body disc brake swap - proportioning valve. - 04/04/13 07:00 PM
Quote:
Quote:
How can I tell if I have a splitter or a proportioning valve?
The one in my hand is drum/drum, the one mounted to the frame rail is disc/drum. 72 A body.
Well, I was wrong...again 
. I do have the drum/drum block that you show. I also think I found another issue. One of my wheel cylinders seems to be froze. I can hit the brakes with the hub off and it doesn't move but I have fluid at the wheel cylinder.
More to come...
Posted By: nomore65BelvJim
Re: A Body disc brake swap - proportioning valve. - 04/05/13 05:28 AM
Quote:
Quote:
Quote:
How can I tell if I have a splitter or a proportioning valve?
The one in my hand is drum/drum, the one mounted to the frame rail is disc/drum. 72 A body.
Well, I was wrong...again . I do have the drum/drum block that you show. I also think I found another issue. One of my wheel cylinders seems to be froze. I can hit the brakes with the hub off and it doesn't move but I have fluid at the wheel cylinder.
More to come...
Replace both wheel cylinders, they are cheap. Also get the disc/drum block. 
Posted By: moparmoondog
Re: A Body disc brake swap - proportioning valve. - 04/08/13 03:18 AM
I have a 67 Satellite that was giving me the same issues presently. After a front drum to single piston floating caliper disc brake conversion and a complete front end rebuild, I could do a solid 2 count after releasing the brake pedal before the brakes would release. I even stopped on a hill, applied the brakes, then lifted my foot off of the pedal and the car would NOT move for a full 2 count. after much troubleshooting and talking with my brake vendor and no luck. I swapped out the new 73 & newer combination disc/drum valve back to the old drum/drum block. Completely re-bled the system (Yes, the master cyl 1st!) NOW the brakes release immediately. A new faulty combo valve is obviously the problem. Will be contacting my vendor to inform him what I found. I still need to reinstall a properly functioning combination valve to achieve the proper braking ratio. Now the car heads to the alignment shop to get everything squared up!
Posted By: dragon slayer
Re: A Body disc brake swap - proportioning valve. - 09/19/14 02:11 PM
Quote:
On factory single piston disc brake set-ups there are two valves, the distribution block and a metering valve for the rear brakes. The metering valve is just downline of the distribution block. A lot of people just use an adjustable valve.
Actually can be 3 also, and the rear valve is not a metering valve.
The distribution block feeds front metering valve for the front calipers. It also feeds a line to the rear proportioning valve that lowers the pressure to the rear drums. The meter valve is also called the hold off valve and delays applying pressure to the front brakes until the rear start grabbing.
Later mopar used a single combined valve with all the pieces in one.
Not sure if this was ever fixed, but sounds like MC secondary piston sticking. That is the piston that applies pressure to rear brakes. That would explain poor brakes and also not allowing pressure to bleed off when applied. G
Posted By: skicker
Re: A Body disc brake swap - proportioning valve. - 09/19/14 03:37 PM
I got lucky, when I did the 69 Dart I found an original 74 manual drum-disc prop valve on the parts car I got. I couldn't find any designation or method to identify this valve from one that would be on a power brake car. I used the master cylinder kit that Dr. Diff sells with the 2 bolt to 4 bolt adapter. The rears are typical 10 x 2.5 B body drums. The Dart has incredible brakes in comparison to my Satellite which has almost the same components less the m/c conversion kit. I don't know if it would help your problem but I'll never put another project together without using the m/c conversion kit. I think sometimes when we get parts store reman m/c's that the bore size is incorrect for what we are working on.