Proportioning Valve

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Moparmonster

Moparmonster

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I'm getting to the point where the brakes are gonna go together soon and while I have a stock proportioning valve, I was just pricing new ones for fun. They're ridiculously expensive so I guess that I need to know more before I spend my money.

The car is a '65 Dodge Dart with '73 Dodge Dart front brakes and suspension.

And I mean, do these pieces go bad and need to be replaced? The stock piece I have looks pretty much like this, but the goldish sort of color.

Mopar Replacement 5083808AA
 
I have a '66 Cuda with '73 disks.
It's been running around with NO proportioning valve for years with no problems.

In fact, we did a Ford 8.8 swap with rear disks and it STILL stops fine using the original '73 manual master cyl.
And this is a street car that gets strip time, so it is driven hard and stopped hard and it has never once acted like it wanted to lock the rear prematurely or anything.

Remember, the prop valve is really there to turn on the Brake light as a warning of a hydraulic failure, and you dont have a light to hook it to on a '65, so why do you need the valve??
 
Moparmonster said:
I'm getting to the point where the brakes are gonna go together soon and while I have a stock proportioning valve, I was just pricing new ones for fun. They're ridiculously expensive so I guess that I need to know more before I spend my money.

The car is a '65 Dodge Dart with '73 Dodge Dart front brakes and suspension.

And I mean, do these pieces go bad and need to be replaced? The stock piece I have looks pretty much like this, but the goldish sort of color.

Mopar Replacement 5083808AA
Click to expand...
As mentioned, although called a ‘proportioning valve’ those units are actually more of a distribution block, used to keep the front and rear hydraulic brake systems separate when a dual master cylinder is used. They also house a valve that when it senses a large pressure difference between the front brake hydraulic pressure and the rear brake hydraulic pressure it lights a warning light. That Summit part looks pricy, I bought the same one from In Line Tube probably 5 years ago and works fine, no leaks. I don’t remember it being expensive either. You may want to look there.
 
motorpirate said:
I have a '66 Cuda with '73 disks.
It's been running around with NO proportioning valve for years with no problems.

In fact, we did a Ford 8.8 swap with rear disks and it STILL stops fine using the original '73 manual master cyl.
And this is a street car that gets strip time, so it is driven hard and stopped hard and it has never once acted like it wanted to lock the rear prematurely or anything.

Remember, the prop valve is really there to turn on the Brake light as a warning of a hydraulic failure, and you dont have a light to hook it to on a '65, so why do you need the valve??
Click to expand...
If you just used a 4 way connector you managed to disgard the seperated front and rear hydraulic brake systems and the safety factor that goes with it.
If you are running a single chamber master cylinder you don’t have separate front and rear hydraulic brake systems. That is not the safest brake system for a track car that gets run hard, or even a grocery getter.
For cars that do not have the ‘check brake’ light, it is easy to rig one up.
Install a warning light that is powered when the ignition switch is on. Use a‘proportioning valve’ like shown in the original post. Run the warning light ground wire to the electrical connector on the valve. If there is a large pressure difference between the front and rear brakes, like one side of the system has a leak, the valve will shift making a ground and causing the brake warning light to illuminate.
 
my68barracuda said:
If you just used a 4 way connector you managed to disgard the seperated front and rear hydraulic brake systems and the safety factor that goes with it.
If you are running a single chamber master cylinder you don’t have separate front and rear hydraulic brake systems. That is not the safest brake system for a track car that gets run hard, or even a grocery getter.
For cars that do not have the ‘check brake’ light, it is easy to rig one up.
Install a warning light that is powered when the ignition switch is on. Use a‘proportioning valve’ like shown in the original post. Run the warning light ground wire to the electrical connector on the valve. If there is a large pressure difference between the front and rear brakes, like one side of the system has a leak, the valve will shift making a ground and causing the brake warning light to illuminate.
Click to expand...
It has the '73 dual res master, large res to the front, smaller to the rear.
 
If you have four same-sized tires on it, with disc brakes, you will need some proportioning, especially if you have a hi-compression engine and/or a manual trans.
But it doesn't have to be a factory unit (which incidentally, I have just taken apart and cleaned).
What you can do is use a split block at the front, and an aftermarket adjustable P-valve somewhere in the rear line.
But if you have big-N-littles, depending on the size difference, you may not need any proportioning at all ... or maybe you can proportion with wheel-cylinder size.

BTW;
on a DB equipped A-body, the frontmost reservoir feeds the rear brakes.
This is for two reasons;
1) when the rear brakes go out of adjustment, it will take more fluid to fill the wheel cylinders. and
2) if the rear hydraulic system fails, you will hardly notice it when plumbed this way, except the pedal will be lower.
Whereas plumbed the other way you may have a long stroke in the beginning where nothing happens. Very scary the first time it happens cuz you ,while panicking, may not remember to push the brake pedal waaay further than usual.
If the system is working perfectly, it doesn't matter.
 
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there's nothing to them ......
images?q=tbn:ANd9GcS9wMi9eE6swJsMa-RiC_EtYqxPt9hfDla9og&usqp=CAU.jpg

take it apart, clean it, lube it with silicon O-ring lube, reassemble and done.
If it won't go back together, it's probably because the o-rings are swollen. You can't fix that... or at least I don't know how to .... so I replace them. The round ones are easy to find. But if you have a specialty ring in there, I just grab another valve from the used parts pile, lol, and start over.

As for testing it IDK ...... I test it on the car, lol, after I rebuild it.
 
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AJ/FormS said:
there's nothing to them ......
View attachment 1715809225
take it apart, clean it, lube it with silicon O-ring lube, reassemble and done.
If it won't go back together, it's probably because the o-rings are swollen. You can't fix that... or at least I don't know how to .... so I replace them. The round ones are easy to find. But if you have a specialty ring in there, I just grab another valve from the used parts pile, lol, and start over.

As for testing it IDK ...... I test it on the car, lol, after I rebuild it.
Click to expand...

That's absolutely awesome, this exploded picture. I think that even an idiot like me can rebuild one of those.
 
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