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Proportioning valve

Aron Gleason

Aron Gleason

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I have disc/drums with a manual drum brake master cylinder. If I go with a master cylinder for disc brakes do I need to get a adjustable prop valve or can I use the factory prop valve? On hard stops it doesn't lock up the brakes.
 
I would start with the factory stuff. Just need to make sure the rears don’t lock up before the fronts under hard panic braking.
 
Oh, not sure what your working on but most of the Mopars don’t have what I would consider a prop valve. If you look it’s more of a distribution block with shuttle to trip the light if one side fails.

On these old cars they usually call another separate device on the rear lines a ‘hold off’ valve. This would be on some factory disc/drum cars. That’s what acts like prop valve and hold off the rears.
 
You need a proportioning valve for a car that was originally equipped with disc brakes.

If you’ve been using disc/drum with a drum brake master you shouldn’t have been. Unless you removed the residual pressure valve from the master, but even if you did that you still didn’t have proper proportioning of it didn’t have the disc pro valve…
 
Last edited:
4mulas said:
You need a proportioning valve for a car that was originally equipped with disc brakes.

If you’ve been using disc/drum with a drum brake master you shouldn’t have been. Unless you removed the residual pressure valve from the master, but even if you did that you still didn’t have proper proportioning of it didn’t have the disc pro valve…
Click to expand...
I need to replace my factory drum master cylinder. I found one for disc/drum and manual brakes.
 
69L48Z27 said:
Oh, not sure what your working on but most of the Mopars don’t have what I would consider a prop valve. If you look it’s more of a distribution block with shuttle to trip the light if one side fails.

On these old cars they usually call another separate device on the rear lines a ‘hold off’ valve. This would be on some factory disc/drum cars. That’s what acts like prop valve and hold off the rears.
Click to expand...
I'm working on a 67 coronet.

20210704_110526.jpg
 
4mulas said:
You haven’t mentioned what car you have and how it was factory equipped which would help you get specific answers. Regardless, you still need a disc brake proportioning valve. Dr diff sells them for $85. Or you can try to find one out of a disc brake equipped 73-76 mopar A body.
Click to expand...
67 coronet. It was originally a 4 wheel drum brake car. Now has disc up front drums rear. Manual brakes.
 
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