1987 Proportioning Valve leak

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1987 Proportioning Valve leak

March 27, 2011, 01:37:26 PM

The front portion of my proportioning valve is leaking. I've not been able to source the piece -- I've tried Ford, Advance Auto, Autozone, NAPA, and a few local shops. Ford identifies the piece as E7SZ-2B091-A.

Haynes calls the piece a combination Proportioning Valve & Shuttle Valve.

The device has a set bolt on the front and the rear, with two inputs on top and two outputs on the bottom. The inputs are sourced from the master cylinder. The front output appears to go to the rear brakes, while the rear output appears to go to the front right brake. The front left brake is driven directly off the master cylinder.

So a few questions:

1) How can I source a new/rebuilt proportioning valve? Or find a rebuilt kit? Or figure out how to rebuild it?
2) Why is the FL brake driven off the master cylinder, while the FR brake is driven off this valve? I suspect it has something to do with preventing a single point of failure.
3) If I can't get a new/rebuilt one, how can I repair the car? I'm thinking that I might have to buy an adjustable proportioning valve for the rear brakes, and somehow "straight through" the FR brake. Details would definitely be appreciated!

Thanks guys,
--Mark

http://www.marksatterfield.com

1987 Proportioning Valve leak

Reply #1 – March 27, 2011, 02:33:26 PM

Is it leaking out the front hex plug in the front there's two orings one on the plug and one on the shuttle in the valve. If you pull the plug it will drain the reservoir.
I looked and looked for one and the answer I got was no one wanted the liability for a brake system. I want to the Jyard and got a fox Mustang on when i went to the smaller mustang booster.
Motorsports sells plugs and guts I got them at Fortes in Framingham Ma.

1987 Proportioning Valve leak

Reply #2 – March 27, 2011, 02:43:52 PM

It is leaking out of the front plug only. The rear plug looks intact.

It looks like the front plug is actually drilled out in the middle and has a washer that is swollen and sticks out of the little hole. I'm not sure why it is configured with the drilled out plug.

Thanks for the Fortes contact, I just sent them an email.

--Mark

http://www.marksatterfield.com

1987 Proportioning Valve leak

Reply #3 – March 27, 2011, 03:00:51 PM

I pulled the prop valve and it leaked out the hole I think in the event of a catastrophic failure it leaks there so you wont continue to drive the car?

1987 Proportioning Valve leak

Reply #4 – March 28, 2011, 10:50:42 AM

Well, further developments...

I called Fortes ( http://www.fortesparts.com/ ), they sell the plug for the front of the proportioning valve, but not the internal gasket that actually performs the proportioning. According to Mike at Fortes, the plug is used when a user wants to put either disk bakes on the back (where no proportioning valve is necessary) or to install an after market proportioning valve (which I really don't want to do, but may be forced to do).

So the front plug has a hole in the middle of it, which means the rubber seal is actually a rubber stopper. The rubber piece is the failed part (the unit is leaking out of the little hole in the middle of the plug). I don't want to take the plug out until I am able to source a new gasket, because I'm sure the rubber gasket is going to just fall apart.

Anyone have ideas on where to get the gasket?

--Mark

http://www.marksatterfield.com

1987 Proportioning Valve leak

Reply #5 – March 28, 2011, 10:59:58 AM

Not sure if it comes with a gasket, http://www.latemodelrestoration.com/item/M2450A/Mustang-Brake-Proportioning-Valve-Plug

1987 Proportioning Valve leak

Reply #6 – March 28, 2011, 11:23:01 AM

Here is the diagram of the shuttle/proportioning valve assembly:

You may get lucky and get a brand new one from these guys:

http://greensalescompany.com/

Your other choice is to gut the proportioning valve part of the assembly, get the solid plug from Late Model, and install a manual proportioning valve in the brake line going to the rear brakes. Not hard to do and is pretty nice as you can set the front to back bias on the brakes. Will also come in handy if you switch to disc brakes in the rear or upgrade to the SN95 five lug.

Darren

1987 Proportioning Valve leak

Reply #7 – March 28, 2011, 11:29:43 AM

There's a oring on the plug and on the piston in the prop valve. I bought a metric and a English set of orings but never went back. It doesn't leak and I'm pretty sure Ive got a bad master cylinder and when I do the cobra brake swap Ill upgrade every thing then. I think the hardest part of the job will be bleeding the brakes if you have another car take it apart go to a good parts store and match up the Oring?

1987 Proportioning Valve leak

Reply #8 – March 28, 2011, 02:04:47 PM

Okay, so I think I know the o-ring you are talking about. Mine is leaking from the nipple to the far left of the image, not the o-ring around the nut. It looks like the rubber nipple touches the plunger, not sure why though.

I'm considering taking the nut off and trying to form a rubber nipple with RTV or something. I'm not sure if this is even remotely going to work, though, because of pressure.

http://www.marksatterfield.com