I have posted several issues on this Proportional Valve | Differential Valve | Brake Controll Valve | Whatever you want to call it. I have heard it called 15 things till Sunday.

I have found many things online about this subject including the Form and no one seems to know the aswer. I am loosing my mind.

I have checked ever single brake line in my F100 Ranger and there all clear. I have replaced my Master Cylinder and it's bench bleed and primed. I have fluid at the front brakes and nothing at the rear.

The only culprate is the Valve in the photo below. This Valve is a cast iron valve (Kelsey Hayes Valve) apparently designed with a piston to close off the low pressure side if there is a falure to sustain pressure the other side. I have found out there is a tool that holds the pin inward during the bleeding proccess to allow bleeding of the brakes. The tool is unessasary as long as you hold the pin in during bleeding. I used a clamp to hold it.

Others have said they have never held the pin in at all to bleed thier brakes. However the Kelsey Hayes bleeding direction spicificlly states to hold the pin in with a combination valve depression tool. But like I said many just hold it in with a block of wood or nothing at all.

I have no fluid to my rear brakes. All the lines are clear and fluid is flowing on the rear brake side into the valve however nothing comes out the out side to the rear brakes. I have tried with the brake line connected and without it connected. Nothing.

I took the vlave out yesterday and cleaned it up. I took off the two nuts on the valve. One housed the pin however there seems to be a plastic part pressure set into that hole. The pin moves freely in and out fine.
The other nut on the valve housed a small spring, washer, rubber washer and small tube. Everything looked fined. I cleaded the entire parts I could access. When I removed the spring, tube, and washers I was able to get some air through the inlet side and feel it comming out of the rear brake side however when I put it all back together and hooked it up, nothing comes out the rear brake side.

I am loosing my mind on this issue. Yes, one could assume just buy a new valve however at $254 how do you know it's bad and is there a way to fix it ? There has to be someone on here that knows more about this than me.

I suppose the only one thing I have not checked is the flow out of the wheel cylinders when I hook it back up. Meaning if they are both clogged however that was ruled out by no fluid comming out the exit side of the valve when I unhooked the rear out line from the valve however I did not do this while depressing the valve pin. I suppose I will try that tomorrow.

Yes, I could also go to the junk yard and try to find another but how will I know if hat one works? Really, I also want to know as much as I can about this valve before I go and just get another. Is there somthing I am missing here?

Please someone help..............Is there a brake expert anywhere.

 

I'm actually having the same EXACT issue lol. And to boot no-one offers one they claim to "bolt-on" without changing lines and such.

 

I have never seen a service procedure for a proportioning valve. If it's not putting fluid out to the rears, the differential valve is locked in one direction, for whatever reason. Your best bet is to replace it; I don't believe they are easily serviceable.

I realize I'm not answering your question, but I can tell you that I have never seen a service procedure for a proportioning valve documented on this website. The proportioning valve is crucial to the braking system and is responsible for your braking system's last line of safety in the event of a brake failure. That being the case, if this were my truck I'd feel safer if I installed a brand new valve instead of tinkering with an old one.

 

Mine looks just like that & I payed right around $70 as I recall for the new one I got off ebay

 

Sounds like your gonna lose your mind!!! haha
Keep it simple! have you tried keeping the bleeder screws open on rear wheel cylinders and keep pumping pedal until it starts to pump out some fluid then go as a regular brake bleed job. It may just need a good boost to get it started...
Next why not bypass the valve on just the rear brakes. Connect your lines after taking off valve and connect them together with a 2$ flared brass union. That will tell you forsure if its the valve or not. You may have to cap the now open ends on the proportioning valve now with flared fittings with no hole for line.
If it is the valve go get a 50$ adjustable universal one from the parts store!

 

Most likely the best advise yet fmc400. Although you say "your not answering my question" you probably are.

Yes, they may not be to serviceable however such a simple primative part they could have been designed as such. There is no real way to get top the piston inside becuase I think the end was pressure sealed so you can't get to it. I wonder if I slamed it on the ground if I could shake it loose.

Yes, I should get a new one however I was unable to find one. I will search tomorrow. I have found some Mark but Ebay is the last place I would look. You were lucky. If you can;t see the inside you have no idea if what you are buying works unless you put it on. A brand new one would be what I would look for unless there is an after market version that mathes the mount holes and plug. But i dout it.

Thanks guys. This has been a real pain in the butt.

 

Good idea 73 however would like the safty of the valve and it's intended purpose. I though about that at one point an scapped the idea because of safty. Not to mention I think the valve does more that just protect you from a failure. I think it also regulates the front and rear pressure as the front does most of the work. Over riding the valve could cause other ramifications to the brakes. Especually at 50 MPH when a kid jumps into the raod. Could not live with myself.

 

I always thought it just allowed a bit more pressure on rear pads to engage at the same speed as fronts. Your issue is you cant even get fluid to the rear. Did you try pumping with open bleeder screws?? What did you change to make it not want to pump fluid out back?? master cylinder, brake line?? Bypass the valve and see if you get fluid or just disconect the line at the back that goes to the rear brakes right at the valve and get a buddy to pump while you watch to see if fluid comes out. Theres lots of ways to do it!!!

 

If you are getting fluid TO the valve but nothing OUT of the valve then by the process of elimination its the valve thats the problem.
If your concerned about installing a used one but don't want to spend the money for a new one because you're not sure, get a used one and install it. If it works then you can locate a new one and replace it.

 

Nc2x4,
I have read about the (cannot find anwhere) tool to move the pin also, only I have read that the tool is used to keep the pin pulled out, instead of pushing it in. I think it depends on the type of truck that you have, mine is a F250 4x4 and I can tell you for sure that on mine, I have to pull the pin out to properly bleed the brakes, I think that allows the fluid to pass to the rear brakes, hope this helps, its worth a try.

Jeff

 

it does just the opposite. limits the pressure to the rears. the idea is, the back has a whole lot less weight that the front. if you use the same pressure as the front they tend to lock up. the proportioning valve solves this problem

 

I was told the other day the master cylinder is what keeps some pressure on rear brake system to allow pads to have some tension. I dont know anything about brakes though thats why i run a chitty 4 wheel disc brake setup with hydroboost from a 2000 superduty and a wilwood adjustable prop. valve because my rear 44 swampers were locking up if I wanted at 60km/h. Fine tuned it to work perfect stopping with awesome power. Little better than 4 wheel drums my truck came with.

 

heres an easy way to understand it. these are not actual numbers just an example. if the master cylinder put out 30psi to all four wheels, the rears would constantly lock up due to a whole lot less weight on them compared to the front. lower pressure is needed at the rear to prevent them from locking up. ie: 34 psi in the front and 24 in the rear. all it does is help keep the rears from locking up.

the master cylinder is what makes the brake pressure to actuate the calipers and wheel cylinders

 

Thats why I just said I plumbed into the rear brakes an adjustable prop. valve to stop rears from locking. Obviuosly the weight transfers to the front when stopping and is why your front brakes due most of the work.
I'm done with this thread...

 

D5TZ2B257B .. Brake Differential Proportioning Valve / Use w/disc brakes / Marked: D5TA-2B524-FA or -FB / Obsolete *

Last MSRP: $283.30 / Dealer net cost: $169.98.

Fits: 1975/79 F100/150 2WD/4WD / 1975/83 E100/150 (Econoline) / 1976/79 Bronco.

Fits: 1975/79 F250 2WD with single piston caliper disc brakes (6200 lb. GVW).

Fits: 1976/79 F250 4WD / 1979 F350 4WD.
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C8AZ2B264A .. Plastic Low Brake Fluid Warning Light Switch / Threads into prop valve / Available from Ford and myriad autoparts stores.

Fits: 1968/79 F100/350, Bronco & Econoline / 1968/69 FoMoCo Passenger Cars / 1970 Maverick/Comet.

The switch is a notorious POS as it develops cracks in its threads. When this occurs, brake fluid seeps out and the low brake fluid warning lamp on the dash comes on...and stays on.

* Ford obsoleted this valve within the past year. There are 55 still available NOS from three Ford Dealers.

If anyone is interested, I'll list the sources.