Proportion Valve: How it works

A while ago I pulled my drum brakes from the front of my 1975 Ford Bronco and installed disc brakes but I never replaced the proportioning valve. Then when I was removing my factory wiring harness I broke the connector that feeds the brake warning light. So I figured it was time for a new proportioning valve for this Early Bronco.

One of the things that I found when I was getting the proportioning valve was the proportioning valve tool. It was like $6 and it screws into the top of the proportioning valve where the brake warning light switch is. The nub at the end of the tool prevents the pressure differential switch in the prop valve from tripping when you bleed the brakes. Great little tool, make sure to get it too!

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[WinterTires-uvmr]

Believe it or not. I was reading my textbook and could not figure out how metering valve operates until i had to youtube and found your video. Took me less than 5 mins to understand from your vid VS 4 hrs reading and pictures on the books suck.. Thank you!!

[joshuaking]

That boat reference was gold, it all instantly clicked in my head as soon as you used that analogy, love when that happens. Great explanation 🤙🏻

[johnkemple]

The disc brakes take 6 times more pressure to work that the drums!. the meter valve is there to build pressure to a level that the discs will stop before the drums actuate, or the drums would be locked up way before the discs are fully applied. it needs two separate valves because it is a disc/drum valve. the surface area of the pistons in the calipers is far greater then the drum brake wheel cylinders. Thats why the valve to build pressure and delay the drums. Think of it in terms of fluid needed to fill wheel cylinders, on rear vs disc calipers on the front. Even if you had wheel cylinders that were one inch in the rear. a 2 piston caliper would be like 6 inches of surface area each side. Thats why discs are so powerful. They are not more efficient however, that's why you need a valve to delay the front and another valve to stop the rear from locking up!! science is great!

[jdfitz]

Thanks for the great explanation! Working on our Hot Rod Ford County Squire!

[robertclymer]

Great explanations. Hopefully, your chosen part should work fine on my 67 Mustang with front disc/rear drums.

[sonnyskustoms]

Thank you for this video so I just installed a replacement valve and I hope I did the process correctly,
I installed all the lines and tighten then down also put my bleeder safety clip on so it doesn't move as I'm bleeding, next I bleeded from the far right and worked my way to the front I don't have a fancy vacuum bleeder so I did it the old fashion way and I bled them atleast 6 times each brake, is this how your supposed to bleed this proportioning valve and then after put your low pressure light switch back on

[songsfromthelord]

Thanks, Bronco - very informative. You might to do a video on how to reset the proportioning valbe if it is tripped .
And remember Bronco,
God LOVES you. Thanks again for the info 🙂 much appreciated !

[bartprice]

Weep hole: On some proportioning valves, there is a port on the side rear of the valve. It's a weep hole. Fluid comes out if the o-ring seals inside fail. The valve then needs to be replaced.

[chennemeyer]

Excellent, I had no idea there was that much to it. Your a good teacher thanks for taking the time.

[sreville]

Very informative and easy to watch, thank you!

[dq]

Your boat example makes a lot of sense.
A portioning valve is good for panic stops.
A proportioning valve is bad for drifting.

[denny]

I can't find a video or explanation of how these valves work. Sure they tell you what they do but they don't tell you how they do it. My master has the proportioning valve built in, I'd like to know how it's supposed to work.

[jaytrapp]

As hard as you try not to sound too southern...the use of the word "mash" just totally gives it away! Great Video!

[neilmackenzie]

Just one thing, the rear drum brakes are a way more efficient than the front disc brakes, the problem is, drum brakes are very poor at getting rid of the heat caused by braking, and that is disc brakes forte,

[faridbakhshian]

when you screw the plasic knob into the valve for bleeding, do you need to remove it after bleeding or you can fit the warnin sensor onto it ?

[soundssuitessoundssweetsmu]

Nice smooth, informative video, can you tell me where I can find a proportioning valve for a two thousand five Dodge Dakota.

[blakenorman]

I've never ran brake lines before, I just transplanted suspension and brakes from a 87 d150 onto a 47 1 ton dodge getting ready to run new lines
Just wondering why why theres different thread sizes on valve, rear in is 7/16 out is 9/16? Both 1/4 brake line size, front in is 1/2 thread out is 3/8? Both 3/16 brake line, just not understanding the different thread sizes

[Barret_Radtke]

can you use the same valve for all 4 drum brakes? >> "1965 Meteor"

[macpherson]

with this valve can i remove the red and blue inline proportioning valves witch preload the lines, front and back?

[savagebolt]

All this information, but all I want to know - before I rip things apart - is does the valve need to be bled? And if so, how?