Proportion Valve: How it works
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- เผยแพร่เมื่อ 27 ส.ค. 2024
- 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.
This is what I bought: tomsoffroad.co...
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!
tomsoffroad.co...
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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!!
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 🤙🏻
Awesome! Glad that helped
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!
Thanks for the great explanation! Working on our Hot Rod Ford County Squire!
Great explanations. Hopefully, your chosen part should work fine on my 67 Mustang with front disc/rear drums.
Good explanation.
Your boat example makes a lot of sense.
A portioning valve is good for panic stops.
A proportioning valve is bad for drifting.
Sorry, but this example is regarding the pressure meter. You can't compare a boot to a car. As long as you have grip on the rear and you can transfer lateral force (circle of forces) your rear end will remain stable. That's why the proportioning valve is important. Your statements to the proportioning valve are right but the example to the pressure meter is not fitting imho. However the pressure meter will balance the engagement time of front and rear to a more even apply of the brakes which helps to stabilize the car in general. Without it the car would nose dive in the beginning which result of taking load off the rear to the front (less available force in the circle of forces on the rear). This is effect is not described with the boat example.
@@ringonito What you say is correct. I think the purpose of the boat example was just to illustrate that if the front of a boat is moving and hits a wall, then the rear of the boat will keep moving and swing sideways.
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.
Very informative and easy to watch, thank you!
Glad it was helpful!
Excellent, I had no idea there was that much to it. Your a good teacher thanks for taking the time.
+Chuckles yeah man! You bet!
+Chuckles yeah man! You bet!
As hard as you try not to sound too southern...the use of the word "mash" just totally gives it away! Great Video!
Haha! So true
Thank you very good explanation
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 !
Great explanations!
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 ,
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
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 ?
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.
Good info Thank you
can you use the same valve for all 4 drum brakes? >> "1965 Meteor"
with this valve can i remove the red and blue inline proportioning valves witch preload the lines, front and back?
Nice smooth, informative video, can you tell me where I can find a proportioning valve for a two thousand five Dodge Dakota.
Inside the ABS module. Flush it in the method required by Dodge!
DK, ASE master tech since 1978, retired.
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
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?
Can you trip the sensor if there was existing air in the break lines
This might be my problem. Tje brake bleeding has been near impossible and i have no pedal feel
was it?
@@dougroberts364 it was part of it. The other problem was the rod coming out of the brake booster wasn't adjusted properly so it still felt soft after properly bleeding the brakes. We lengthened the rod fractions of an inch and it worked brilliantly afterwards
@@lm7bird680 good to know, thanks. My first experience bleeding brakes with a proportioning valve
I have a 1987 Toyota one ton pickup chassis with a motor home built on it!!! 4 clyinder, automatic trans, rear wheel drive with a proportional valve in the back. The left fronf wheel locks up and skids. With light braking. But the truck does not stop very well!
I put a new master clyinder on because it was leaking.. Also put a new vacuum booster. Still the front break locking up, then put new pads and calipers up fromt!!! Still not stopping. The I just put a new proportional valve and now it still locks up and hardly stops. When I bleed the brakes I get fluid out of the proportional valve. But now I don't get any fluid out of the bleeders on the drum brakes.
What should I do????
Larry
How do you adjust the valve???
RESET the valve and use a tool next time when bleeding
I have a single bowl master cylinder and only can find a proportioning valve that says was designed for a 2 bowl master cylinder. Do you think i could use it still? Im guessing it will work
Is it possible to get 1 of these for a 97' F250? Having a hard time finding 1.
at 2:58 the switch terminal. Does that connect to the negative side of the bulb?
With an addition of hydraulic hand brake on rear wheels, where should the proportioning valve be? Before or after the inline hydraulic handbrake?
That’s a good question, I haven’t installed a hydraulic hand brake, so I’m not sure.
What to use to clean it sir? Mine is wet with oil.
My new proportioning valve doesn’t bolt on in the same spot as the old one ... did you have to buy a new bracket?
Yeah the one I bought cane with a new bracket
I'm in the middle of a full tbp front disc brakes conversion. The instructions are for a different setup. Any tips on how to hook the rear lines to the proportioning valve?
What do you mean? Should be the same as the front
@@NashvilleEarlyBronco The conversion kit has booster with billet master, proportion valve and all the new spindle Hub rotor caliper and bearings. But the paperwork is not very specific on where any of the hard lines hook up to the proportion valve
In other words, it keep you car from "fishtaling." Correct?
Ever do you connect the wire to? I'm rewiring my dash
Yeah, the wire goes to the red light in the dash.
@@NashvilleEarlyBronco great thank you for the reply. Great channel btw
@@NashvilleEarlyBronco one more question if I take that piece out to just study it and understand it better will I then need to bleed the brakes because it will let air in?
Correct
Can this piece be repaired? Or should it be completely replaced?
ali morris I'd say it depends on the car you drive and the type it uses you should replace it
ali morris honda for example
what if i will rear disc conversion on my honda 92-95 civic, do i still need proportioning valve?🤔
Yes because the weight is all up front. Rear tires will loose traction before front, even in slightly heavy than normal braking.
Don't under stand why people say well informed info? Still don't know what "it" is, other than take out break light warning switch, then put 6$ "it" part in?
does 4 wheel disc brakes needs a proportioning valve?🤔
I think so. The way I understand it, if you have a fluid leak it will give you a few extra minutes and signal the dash light.
I did dis brake conversion kit going to bleed brake i didnt know about that tool so now it already shut the front up how do i get it back to center
Oh bummer! I think it resets over a couple hours
i absolutely hate the valves.. i have a 93 jeep and im trying to figure out how in the hell in one brake line there is 2!!! 2!! different flare nut sizes....???!?!??!!... P.S some help would be nice
1:33; 250 lbs per what,sq.ft.?
That was amazing
Are you joking?
I dont like your boat explanation. If all of the braking torque would be on the front axle, and zero on the rear, the car is not gonna spin (oversteer/drift). Because the rear wheels would always stabilize the car in terms of yawing (because there is no locking on the rear, the rear tires will be able to produce lateral forces and thus stabilizing yaw moment). The more you brake, the more load transfers to the front (unloads rear), therefore less braking force is possible to produce on the rear axle and so the rear braking pressure needs to be reduced (more braking force to the front than to the rear). Otherwise, locking of the rear brakes would occur which would cause oversteer/drift/spin.
You are kind of correct. If the rear does not have any brakes (“zero on the rear” as you said), it is unlikely to spin around. But I’ve seen it too many times where the brake bias is too far to the front, the front brakes engage, the inertia of the vehicle lifts the rear of the vehicle, this causes the rear tires to lock up because of the lack of weight, thus drift/spin.
Fair enough, for this scenario you need quite high center of gravity, so I would say trucks, etc., I come from Formula Student, where center of gravity is low and such weight transfer would not be possible. Front wheels lock up way before rear wheels start to lift.
That makes sense. I guess I should have clarified I’m coming from lifted truck point of view. I imagine it’s so different on a low center of gravity. Thanks for the comments, you got me thinking 👍🏼
My 2000 kia sephia has a brake prop.valve built from a block of aluminum vs original/others that are made /of cast mold aluminum- This car did not have ABS an op[tion. Mine has 4 lines go to it and as 1 magocalician had a pic- there is a service screw in the top middle and MUST placed & BE IN Place to keep its bi-directional tiny piston from going left or right during a brake bleed. Who has this GDFRkn screw NO ONE DOES 3 yrs iof replacing all part for ZERO will; not stop car in 4x the distance as before, a front line broke 5r yrs ago < BULShit Bullshit KIA. I have to buy a new valve or someones. is this failed or is the 'screw holder a hidden item?
DONT SAY Pretty SIMPLE. becasue the part you say you use is unavailbel to me,
Get to the point who cares if you changed over to disc brakes.
Lmao you don't have any idea what a p valve does.... its for if you have a lose of pressure it shuts off fluid to the front or rear brakes..
Lmao you don't have any idea what a p valve does....
He really was trying to slam me, but then he realized he couldn’t spell “proportion” so he went with “p valve” and made himself look like a fool.