Proportioning Valves and Residual Valves

[Detroit Iron]

I've got a '67 Dart with the Dr. Diff '73 and later 10.95" front discs, and 10" rear drums. The kit came with this proportioning valve: Mopar 1 Piece Proportioning Valve It actually has some proportioning function and it not just a distribution block. I also have this master cylinder with the "standard Mopar" piston size: Mopar Aluminum Master Cylinder Kit

I would like to know if anyone has experience with the addition of a residual valve for rear drum brakes, with the for-mentioned Dr. Diff proportioning valve. I'm wondering if the constant 10lbs of pressure to the rear drums is good, providing better pedal response, or bad... causing drag. https://www.summitracing.com/parts/wil-260-13784

I'm also looking for input from those who have a similar setup, and added an adjustable like this: https://www.summitracing.com/parts/sum-g3905

Thanks for the input!

 

[Professor Fate]

I've got a '67 Dart with the Dr. Diff '73 and later 10.95" front discs, and 10" rear drums. The kit came with this proportioning valve: Mopar 1 Piece Proportioning Valve It actually has some proportioning function and it not just a distribution block.

I would like to know if anyone has experience with the addition of a residual valve for rear drum brakes, with the for-mentioned Dr. Diff proportioning valve. I'm wondering if the constant 10lbs of pressure to the rear drums is good, providing better pedal response, or bad... causing drag. https://www.summitracing.com/parts/wil-260-13784

I'm also looking for input from those who have a similar setup, and added an adjustable like this: https://www.summitracing.com/parts/sum-g3905

Thanks for the input!

The residual valve is in the outlet port of the master cylinder for the rear brakes (front reservoir). It shouldn't have to be "added", it's already there.
That proportioning valve/distribution block will work fine- the only issue with some of the aftermarket reproductions is getting them to seal up properly, especially with stainless lines if that's what you're using.

 

[Detroit Iron]

The residual valve is in the outlet port of the master cylinder for the rear brakes (front reservoir). It shouldn't have to be "added", it's already there.
That proportioning valve/distribution block will work fine- the only issue with some of the aftermarket reproductions is getting them to seal up properly, especially with stainless lines if that's what you're using.

After I posted, I realized the modern master cylinder probably has this residual valve built in. Thank you for confirming that. And wouldn't you know.... what you said about the new proportioning valve sealing up..... I am having a hard time getting one of the ports to stop leaking, and I've got mild steel lines too. Sheesh! Thank you for your input.

 

[Professor Fate]

And wouldn't you know.... what you said about the new proportioning valve sealing up..... I am having a hard time getting one of the ports to stop leaking, and I've got mild steel lines too. Sheesh!

Maybe these will help:
Inverted flare leak fix.

 

[Murray]

The residual check valve maintains a small amount of pressure in the line but not enough to activate the brakes. It is a mall rubber "flapper" piece built into the M/C behind the tapered brass base. A drum/drum M/C will have in the front and rear port. Not for disc brakes.

 

[Detroit Iron]

What size are these fittings?

 

[slantsixdan]

Skip the proportioning valve; instead do like this. Also be aware that the residual-pressure valve was deleted for '73, as its purpose was served by redesigned wheel cylinder seals.

 

[Dana67Dart]

After I posted, I realized the modern master cylinder probably has this residual valve built in

Actually it is the other way around. Modern master cyl are less likely to have the residual valve, due to redesigned wheel cyl as mentioned.

Having the residual in the master and having redesigned wheel cyl will not cause any issues IMHO

 

[Bewy]

The leaking m/c connection. There is as brass ferrule inside the m/c outlet. If there is a res line pres valve, it will be behind the ferrule & consist of a rubber plug & spring.
The ferrule is pushed in against a machined seat in the m/c body. If there is any deformity or dirt between the sealing surfaces, it can leak. So it could be THIS leaking, not the flared tube. To remove the ferrule to check: screw in a sheet metal screw in a couple of turns & pull out.

 

[Professor Fate]

What size are these fittings?

View attachment 1716433652

3/16 line, 3/8-24 threads on the fitting.

 

[Professor Fate]

The leaking m/c connection. There is as brass ferrule inside the m/c outlet. If there is a res line pres valve, it will be behind the ferrule & consist of a rubber plug & spring.
The ferrule is pushed in against a machined seat in the m/c body. If there is any deformity or dirt between the sealing surfaces, it can leak. So it could be THIS leaking, not the flared tube. To remove the ferrule to check: screw in a sheet metal screw in a couple of turns & pull out.

It's his prop valve that's leaking.

 

[Detroit Iron]

Skip the proportioning valve; instead do like this. Also be aware that the residual-pressure valve was deleted for '73, as its purpose was served by redesigned wheel cylinder seals.

Absolutely makes more sense. Thank you.

 

[Detroit Iron]

It's his prop valve that's leaking.

Correct