Have a brake proportioning valve from 12-1982, build date, F250 2WD
that incorporates the front bleed pin that must be pushed inward when bleeding the brakes.

Also have a brake proportioning valve from 6-1985, build date, F250 4WD
that looks almost identical to the 1982, but has no front bleed pin.

Apparenlty, the bleed pin was eliminated, so the front hold-off metering valve requires no bypass.

Are the 4WD propotioning valves different than the 2WD or was there a design change for the 2WD & 4WD.

 

2B257 = Brake Pressure Differential Valve =

 

The valve proportions the braking front to rear according to how the vehicle is setup. 4wd changes the characteristics/weight bias of the truck, so they would have changed the valve.

 

The valve I would have to agree was different in brake bias between 2wd and 4wd considering the extra weight up front with the secondary axle assembly.


Now as far as the so called "bleeder valve" that was mentioned had to be pressed in. Every one I seen you had to pull out on that valve and even then that as indicated in my '78 Ford shop manual was only pulled out to recenter the rod in the prop valve that activates the brake light on your dash when you have a brake leak.


Personally I have never had to do this as long as the rod is free and not frozen like it is on my '78, just pressing firmly on the brake pedal will recenter it. And as far as bleeding goes, you can bleed without activating that valve. If that valve was one way as it is implied and requires it to be pulled out then you would apply the brakes and it would keep them applied when you release the pedal similar to the way a residual valve does when youre master cylinder is mounted lower than your brake lines.

 

Based on "Number Dummy" data, 1/2 ton & 3/4 ton 1984-1989, 2WD has identical proportioning valve to the 1 ton 1984-1989, 4WD, pn E4TZ 28257-F


1/2 ton & 3/4 ton 1980-1983, pn E0TZ 28257-A
and 1 ton 1980-1983, pn D4TZ 28257-A, with no 2WD or 4WD in description
Again, identical pn used for both 2WD & 4WD.

The Bendix combination valve used after 1971 has a bleed pin that must be pulled out for years 1972-1974. The pin has a **** on the end to grab.
Have a proportioning valve with this feature on my 1973 F250, 2WD.

Have proportioning valve from a 1976 F250 2WD ,FE 360 that incorporates a push in type bleed pin with a rubber bott cap.

According to the brake bleeding procedure this pin must be pushed inward and held inplace with a L-shaped clip with a slotted hole. The slotted hole is placed under a loosened bolt that fastens the proportioning valve to a support bracket.

The proporioning valve from the 1983 ( 12-82 build date) ,F250 2WD has identical bleed pin feature ito the proportioning valve from the 1976 F250, 2WD.

The proportioning valve from the 1985 F250 4WD looks identical to the 1983, except the bleed pin is not incorporated. Apparently the bleed pin was eliminated to simplify the bleed procedure.
Believe the proportioning valve incorporates the hold-off metering section but the center switch must be removed and a special tool threaded into the opening with an end that interfaces with the annular groove on the slide pin to fix it in place to allow fluid flow to front calipers for the bleed procedure.

Since drum brakes develop more torque friction than the disc brakes for equal hydraulic pressure the proportioning valve distributes the correct % of pressure to front disc brakes and rear disc brakes, so the rear brakes will NOT lock up during servere braking.

Apparenty the 1980-1986 are different than the 1973-1979 proportioning valves, since after market only is available for the 73-79. Believe the 1980-1986 are metric fittings.

 

There are 6 different 1973/79 F100/350 Brake Pressure Differential Valves. None are the same as 1980/89.

 

I have a 1978 f250 4 x 4. Discs on the front and drums on the rear.
Currently restoring.
I believe that the proportioning valve is gummed up and blocking fluid to the rear port. I have taken it apart and the centering part was extremely grimey and would not move. Even with this removed, still no fluid to rear exit port.


If I buy a new one, is there an aftermarket valve available that would not require any mods to my brake lines?


Any suggestions are greatly appreciated.


Thanks

 

I have not seen a direct replacement prop valve available new. Best luck is to locate a NOS or a very clean looking used one and hope for the best.


I am doing that on my tuck as the plastic switch broke off in the valve and I have not been able to get the piece out.






~Update~


I should post this I found on ebay.


http://www.ebay.com/itm/PROPORTIONIN...YVROnQ&vxp=mtr


I personally wouldn't use this as I don't see how one valve could be used from a 1/2 ton up to a 1 ton truck and not be different.