Propositioning Valve 93

proportioning valve?

Number 5 in this diagram?
View attachment 508080

If you are looking for info on how to modify for a 5 lug conversion then check out this site:
http://sn95brakes.cjb.net/

Taken from that site:

"You will need the FMS part: M-2450-A and an adjustable proportioning valve to complete the modification. The stock PV is housed in the front part of the combination block. This block is under the master cylinder and houses the PV and shuttle valve or pressure differential valve.

Why do you need to modify the valve? Because it is designed for the specific car and brakes that come with it off the assembly line. So if you change to different size brakes, you will need to change the front to rear bias via the proportioning valve. If you do not, then you will not get the most braking capability out of the car. Worst case scenario, you have too much rear bias and the car spins around when the brakes are applied. Not good on a rainy night!

If you have a Sn95 PV, why not use that? For the same reason you are not using your stock PV. It is not setup correctly for the amount of bias you need. The Sn95 valves are setup for the Sn95 car's weight, braking system and bias requirements. If you do find a 94+ car without ABS or 79-86 , you will notice that they are setup for a 2 port master cylinder. You can swap the end nuts on the combination valve and use this fitting as long as you cut and flare the nut from the donor car to make a factory like 3-2 conversion! You will not find those size of brake nuts at any parts store! Alternatively, you can remove the front internals and cap and transfer that to the fox3 combination valve and that will work to the Sn95 bias specs. This may not be the best bias for a fox3 car, but will work. The solution is to defeat the stock PV by gutting the unit and running an adjustable valve.

Okay, so how do you "gut" this proportioning valve? You use a 13/16 wrench and take the front cap off of it. Be careful as once it is loosened, the spring will shoot it out! Then remove the spring, the spring seat and rod. You may need some needle nose pliers to remove the rod from the valve. Do NOT remove the rear spring and rod from the rear of the valve. If you do modify the rear of the valve to work like the FMS M2300K kit or tap the rear for the 3rd port, be sure to install the rod and spring back in there!

Once you are done modifying the stock valve, you need to install an adjustable unit. There are two kinds of adjustable units: knob style and lever style. The lever style is more designed for an in-car application so that you can adjust the bias as the tires and brakes wear down in a race. You want the knob style. To install it, remove the coupler along the passenger side firewall and replace that with the valve. [pic]

When you bleed the brakes, adjust the valve all the way in for the maximum rear pressure. Once done, adjust the valve all the way out, and then in 4 full turns for your initial setting. Adjust in 1 turn increments from there and then half turn increments to fine tune. You will feel the braking and the pedal differ as the bias is changed."

My LX needed a new prop valve a while back...it leaked pretty profusely. I was lucky enough to find a brand new oem one on ebay. I don't think Ford makes them anymore.

propositioning.... sounds interesting!!