bleeding with adjustable proportioning valve

I just installed an adjustable proportioning valve on my rear line. I'm getting good pedal pressure/ and fluid flow to the front brake system,..and down to the "IN" side of the adjustable P Valve. But not getting much psi/ or fluid flow from the " OUT" side of the adjustable P Valve. It does not seem to make any difference where the adjustment is set. Just not much flow to the rear brakes. Checked and the valve IS installed correct.
One thing I did notice was..with light pedal pressure, I was getting more fluid flow.....What am I doing wrong ?
Got this from ebay (first mistake) thought its simple enough , should work.

 

Turn knob all the way out.

Don't forget to set your rear shoe drag.

 

You dont need to use it.

 

From the information provided, you have no way of knowing that.

 

I had a PV on my '41 Ford and finally removed it because I couldn't see any difference in braking with it adj. all the way one direction or the other. Maybe I'd see a difference on gravel or snow, with hard braking, but I do neither..

 

You think it's not needed until you have to do a panic stop on the freeway and you crash the car. Why do you think the auto companys would spend millions installing combination valves on every car and truck if they were not needed? The bean counters would have them off the bill of materials in a heart beat. There is a chance you got lucky building your car and it's balanced but it's very unlikely.

If you want to understand, find a big level parking lot and try to make straight panic stops when it's raining or snowing.

 

Ding! We have our winner!

 

x2!

 

I have adjusted it each way..still no fluid. Rear brakes are set fine.

 

Another piece of cheap EBAY crap !!!...going to summit

 

Think I'm going to take this thing apart. just to see why its not working. Does anyone have an exploded/ cutaway view of a aftermarket adjustable proportioning valve ? ( so I know if something was left out of it) just currious

 

I have a speedway adjustable P V on my T-bucket,my brakes bled out normally last week.I haven't adjusted it . as the car isn't running yet.

 

For bleeding purposes, wouldn't you want to turn it all the way in to make the pressure the same on the front and rear brakes?
From Wilwood:
"The adjusting knob is marked with an arrow indicating the direction required to decrease line pressure to the
calipers. The knob rotated all the way out (counter-clockwise) will provide a maximum pressure reduction of
57%. Rotating the knob in (clockwise) will incrementally increase line pressure, up to full pressure."

Bob

 

Actually I have made panic stops. All four wheels lock up just fine without a PV thanks!

 

I'm just saying what I experienced with my car. I'm not advocating using or not using a PV.
I don't drive it in snow but I have, out of necessity, on a trip. I also don't drive like an idiot on the hiway, one car length off the bumper of the car in front of me. Just saying......

 

I just had a similar problem with a customers car. He also bought his off of e-bay. We swithched it out with one from mbm and no problems. Almost seems as someone baough a defective batch and is pawning them off on e-bay?

 

That just doesn't sound right......it's a simple valve as I see it.....turn it all the way in...nothing to the rear...turn it all the way out ...you have what you had before you fitted it.
I have just bought one from Jegs..haven't fitted it yet but I have a 9" in the rear and calipers up front......I need more brake to the front cos those 9" brakes are too good.....the instructions say to start off somewhere in the middle.
In NZ you can not fit one of those to your vehicle where it can be accessed while you are in motion.......wind it down ...no brakes in the rear.....great burnouts!! ...spoilsports.

 

Is this for a drum/drum or disc/drum set up? I'm fighting the brakes on my disc/drum 55 chevy. Am using a Speedway prop valve, finally got some pressure, but it's way at the bottom of the pedal. Hope you get it sorted out. Brakes can be frustrating. Sounds like yours may not be adjusting when you turn the knob.

 

Proportioning valves do not function like "normal" valves, as they limit, but do not totally shut off pressure to the rears

Fixed (factory production) PVs allow full master cylinder pressure to the rears up to a pre-determined split or knee value, then reduce increasing rear pressure to a percentage, typically .27, .43, or .59% of master cylinder or front brake pressure.

Adjustable PVs allow the full pressure split point or knee value to vary from around 100 psi to 1000 psi or greater. The adjustable PVs that I've used or are familiar with, like Wilwood and K/H, have about 10 full turns of the knob, with CW increasing pressure, and CCW lowering the split point.

 

i used a wilwood, set it half way to bleed and all was well.

 

This is what I have on my car and had no problem bleeding brakes.

 

The following information is from the S10 forum but can be found many places on the Internet.

"Re: proportioning valve centering: how do you do it?

These things can be down right irritating.

First you need to know what's inside and how it works.

Fluid from your M/C flows through both ends of this thing. Your front lines through one end, and the rear through another. Inside is a plunger, right between the 2 fluid lines. As long as both front & back hold pressure the plunger stays centered. If you get a leak in, say the rear, the pressure from the front lines push the plunger to the rear (low pressure) and seal off the rear lines and trip the light in the process. The switch is in the center, you can see the wire attached.

Now the trick is to get that plunger to move back to the center. You are getting close by pressurizing the rear but you are putting air in the system and can make for more problems.

After you repair what ever cased the fluid lose in the rear circuit, you then get setup to center the plunger. This works much better with someone inside the truck while you use a wrench on the lines and give instructions.

Turn the ignition on and have your helper watch the brake warning light, if it goes off, stop what you are doing and close off the lines, the plunger is centered!
With the M/C topped up and the lid on, locate where the front line enters the valve, one of those lines entering from teh top, in the second photo. Crack it loose and place a rag over the fitting so you don't spray brake fluid all over yourself and the truck. Now have you helper slowly press the brake pedal down. Listen very carefully for a click. That is when your helper must stop immediately or the plunger will get pushed over center and will block off the front brakes. These valves can be very sticky and may not move with just an easy push of the pedal. If this doesn't work with a few tries, instead of pushing gently, have them stab the pedal, not too hard, but with a good sharp jab. Close the lines and have them press gently, is the light still on? You will need to try to use the brake fluid pressure to move that plunger. If you move it too much you will need to loosen the rear lines and move it the other way. Often you go back and forth until you get the feel of how hard to hit the pedal.

Once you get the plunger centered the brake warning light should go off and you can finish bleeding. When bleeding always go easy with the brake pedal. Remember, you are creating a fluid lose in on of the brake circuits, and one of the proportioning valve's job is to prevent fluid lose by closing off that circuit.

 

The above "information" is about pressure differential switchs, NOT proportioning valves, and is also incorrect about their function.
The switchs shuttle, and turn a dash warning light on, when one brake system's pressure is about 300 psi less, or different, than the other. They do NOT seal off or prevent any pressure or fluid loss.

The switch centering problem described in the text occured in the early days of dual/tandem master cylinders, but was gone for the most part in the '70s.

 

Yeah mine was an MBM knockoff..sent it back to seller. He's going to replace it...not saying the replacement will be any better.. who knows ?

 

My system is disc/drum, ebay MBM knockoff APV . Just sent it back to seller for replacement...hope this one works.

 

"they do not seal off or prevent any pressure or fluid loss" - not according to Master Power Brakes. That's one of their selling points for PV.

 

The above discussion was about differential pressure (or system failure per MPB) switches. I could not find any "selling points for PV" on their web site, but if they state any switch seals off a system, their wrong.

MPB, like some other brake suppliers, are probably good companies, but sadly, do not know or understand how some of their products function. MPB's recommendation of metering with proportioning, and their explanation of residuals, are just two examples.

 

I've used the wilwood ones with great success.
one thing i didn't see mentioned,where is your apv mounted? and where is your m/c mounted? you may be having bleed back from the rear drums and need to install a residual value to them.

 

OP is talking about APV not a Combination Valve, there is a difference!
I to had troubles with most APV making any difference, tossed them now no problems.
You may as Dane says need a combination valve or stand off valve for better braking/handling but you need to get in on a dirt road for testing to see what you have first. JMO

 

My master cylinder is mounted on the firewall. The adjustable proportioning valve is mounted on the frame about 14 inches below the MC.