View Full Version : adjustable proportioning valve
12-16-2009, 12:36 PM
Do the adjustable proportioning valves do as good a job and cover all the functions of the standard proportioning valve in a disc/drum situation?
12-16-2009, 03:07 PM
The OEM valve is a "combination" valve.
It does proportioning, metering, residual pressure if needed, and the safety shutoff feature.
The metering portion delays the application of the front brakes slightly relative to the rears. This helps on slick pavement, esp. ice.
A residual pressure valve is in the rear outlet of disc/drum combination valve. You could put one anywhere in the rear line.
The safety shutoff feature is a shuttle valve that shuts off fluid flow to the end of the system if a leak occurs in that end. It also closes a switch for a warning light.
Do you need these things? Maybe only the residual valve. The rest are good to have. What you need to think about is whether you need the adjustability. I think you only need it if you have a huge tire size mismatch, at least on a 55-57. A street rod may need it worse. Or a car with a light rear, like a pickup or FWD.
12-16-2009, 03:18 PM
I have 4 wheel disc brakes so I used ONLY an adjustable proportioning valve in my system. It's accessible from under the car....It's made by Wilwood.
12-16-2009, 08:17 PM
I have disc/drum on mine with the usual, universal combination valve. I have the same size tires on all 4 corners. My back brakes lock up first everytime in a panic stop. I don't like it and want adjustability. I am looking at the new CPP MC with the built in adjustments for proportioning and max pressure to the rear. What I don't understand is why I don't need a residual valve with this new MC. Apparently, you can use it with disc/disc or disc/drum and Aaron at CPP told me I don't need the residual valve. Thoughts and/or explanations? :confused0006:
12-16-2009, 08:35 PM
I have 4 wheel disc and an adjustible proportioning valve under my dash that I can adjust while I drive I feel it's a nice item to fine tune the brake system.
12-16-2009, 10:45 PM
Mark, you need a 10 psi residual valve somewhere in the rear plumbing with rear drum brakes/front discs. CPP master or not. But with rear discs you shouldn't have one unless your m/c is below the calipers, then you would need a 2 psi valve.
Not sure why Aaron told you what he told you. He should know better. Maybe he didn't understand what you were asking.
12-17-2009, 12:40 AM
That is what I thought too. I have been reading what I can find on residual valves and the new CPP MC. I don't see anything that says the new MC has residual in it (how could it and be used on disc/disc) and everything I find says to use one with drums. If I go with the new MC, I am putting the residual valve in.
12-17-2009, 11:14 AM
Rick Excellent explaination Thank you
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