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Proportioning / Distribution Valve Bleed Tool - HELLO!

68 Sport Satellite

Well-Known Member
Local time
4:57 PM
Feb 10, 2010
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San Jose, CA
Man, you learn something new every day don't you? In all my years of working on old cars and since 2010 when I started resto-modding my Plymouth, I had never heard of a Proportioning/Distribution valve tool being needed to bleed the rear brakes. Well now I have! It keeps the shuttle valve centered during rear brake bleeding to allow the fluid to flow. My car is front disc / rear drum.

This explains why so many of my friends have had trouble bleeding the rear brakes due to the internal shuttle valve. Even the last shop I had work on my brakes was saying they couldn't get the rears to bleed. Could they really not know this either?! Why don't they suppliers include this little doo dad with the valve when they sell it??? This tread should be a sticky in the brakes section.

Found older FBBO thread that mentions it:
Bad proportioning valve?

Here's a nice explanation and photo from the Master Power Brakes site. I also LOVE that this photo below indicates the fitting sizes.
Bleed Your Brakes Easily with our Proportioning Valve Bleeding Tool

Those tools have been around forever. Myself I have never used one nor needed to.
Neither have I.

I must have bled hundreds of both drum/drum and disk/drum systems on everything from 1955 to 2015 cars and trucks and A- never had that problem caused by bleeding, and B- never used or needed that tool. This is the first I have heard of it.

I have, however, had a valve get stuck due to a hard application of the brakes with very little fluid in the reservoir.
That tool is used on cars that don't have self centering valves. Some Fords are that way, and probably others.
My car (like many of us on FBBO) has mostly aftermarket brake parts, including the distribution block since I switched from 4 wheel drums to disc fronts / drum rear. So, I can really benefit from use of this tool. I haven't bled my own brakes previously, but my go-to shop that swapped in my pads and master cylinder told me they had a heck of a time getting the rears to bleed correctly (and I don't think in the end they got it done correctly either or I wouldn't be having pedal issues and working on it myself).
Brake pressure gauges help to determine what pressures you are getting at each corner.

22 5 Q.JPG

I got this setup through Summit Racing.
I’ve heard of this issue but never experienced a problem. Good to know and re-log in the memory bank.
I have guessed that these tools are for GM valves, not sure they would work on Mopar valves. I have an old proportioning valve with the valve stuck was going to cut it open to see what the valve looks like and if it has a notch in the stem to restrict its movement by putting that tool in place.
I have guessed that these tools are for GM valves, not sure they would work on Mopar valves. I have an old proportioning valve with the valve stuck was going to cut it open to see what the valve looks like and if it has a notch in the stem to restrict its movement by putting that tool in place.
I have a non-stock aftermarket disc/drum conversion kit with a Master Power Brakes distribution block. MP confirmed to me that the distribution block supplied with the kit is GM sized and this centering tool will work with it.
I have been fighting my brakes for 6 months , trying to bleed the rear drums first then the front discs and didn't know about this "tool"? Interesting stuff.
The tool cost $17.00 and the shipping is $21.00? Are you kidding me, how could such a small "tool" cost so much to ship?

Proportioning valve center tool.png

Thanks for both items, which I assume you have bought and used on your car. Is the proportioning valve somewhat universal ? The link you attached was for a GM model car? Is that what you used?
I am not sure that tool would work on a standard Mopar valve as the switch has a sealing o ring and that would be sealing brake fluid I guess.
I have seen the Ford/Chev valve stick while bleeding and the tool solves that.
I have the stock Mopar valves on both my cars and never had problems with bleeding them or them sticking.
I know the brake warning lamp works on the GTX as I had a master cylinder go bad and the warning light was coming on when I applied the brakes.
I never used that tool when bleeding brakes either. A few years ago while putting together my Charger, I had a problem with being unable to get fluid to the rear brakes. I re-centered the valve and got it to work finally after a couple hours of messing with it. Last week I got one of the anodized tools to try but found out it won't fit the mopar proportioning valves. Total waste of money unless you have GM cars. The threads are 1/2"-20 on the tool and our PV switches are 7/16"-20. I was able to grind it down a bit and re-thread it to the 7/16-20 but I'm still not sure it will work since there is no seal to keep it from leaking like the switch has.
I would be interested to hear from someone who has had a good experience with this tool.

I have used the tool all be it a home made one and they do work well. It is for GM and FORD style distribution valves/switches that are isolated from the brake fluid by internal O rings.
You are right it will not work on the Mopar style valves/switch.
I centralise the valve and use a vacuum bleeder. This means there is pressure on either side of the valve which keeps it in the centre.
If you are pressure bleeding and use too much force the valve can "shuttle" and jam - then the light is stuck on etc.