factory proportioning valve question

[SteveC]

ok i got to looking at some other posts on here and am getting more confused to the disk brake swap im doing.
The proportioning valve that came off of the 72 looks identical to the drum/drum one and nothing like the one here in robroys post http://www.fordification.com/forum/view ... ning+valve

The truck its self was a 8100 gvw camper special and the ibeams had a d2 casting number so afaik they should be a factory disk brake.

I reliaze that they can look the same but have different internals but its just wierd that they look the same as the one that is coming off of my 67.

no pictures of this unfortunatly and i cant get any till week after this upcoming on due to spring break

[SteveC]

ok guess i never asked a question

basically i aws wondering if the truck would be ok using the piece that came off from the one i got the disk brakes from even though it looks identical to the 67s

[fordman]

if the 72 has disc brakes then it will also have another little valve sitting on the crossmember to help the dist block work right with the disc brakes. so you must use both of the 72 valves to make it work right.

[Banjo]

Ok, I must be confused, I thought Ford didn't install disc brakes on any truck until 74, do I have that wrong? Also, in the referenced "other" post....did someone type you must hold in the little pin on top of the factory prop valve in order to BLEED the brakes properly? As in removing air? I really thought the holding the little pin is was to reset whatever inside to the middle to ensure it won't activate the light. Reason I ask (not to hijack), but have noticed since my disc conversion on my '68 it doesn't stop a dang bit better than the power drums and pretty disappointing. BUT, I didn't hold this little pin in (how could you???) when bleeding.
You do need to make sure you get a proper disc/drum (if that is your combo) prop/combination valve, as the brass drum/drum valve is only a distribution block I think. I "think" the reason is, the factory proportioning/combination valve has some type of checkball pressure valve system inside that maintains some hydraulic pressure on the front discs to enable them to react at different rate than the rear drums, because if you just reused the drum/drum distribution valve, your front discs would lock up fast and you wouldn't have steering while you are white knuckled and waiting for the rear drums to react and assist slowing you down, if I understand it right. Not saying I understand it right either, I could even have that backwards. Clearly, I'm no brake genius, buy trying to help.

[fordman]

disc brakes started on our trucks in 68 with the f250 cs. but the f100 didnt start with discs until 73. the porportioning valve has to be recentered when the light comes on after fixing or bleeding the brakes. i havent heard of a pin on them. just a plug end to adjust or i should say equalize the front and back brake presures. with disc brakes you do have to have the porportioning valve and not the dist block. they work differently and wont work for the other. dist block is for drums and porportioning is for discs.

[SteveC]

thats the weird thing it didnt have that valve at all that is why im confused.. and from the amount of dirt and rust on all the bolts i doubt that they were changed to disks with out the valve.

Ill take a second look around the shop but i know for almost certain that i took every thing from the distribusion block forward as one piece.

[fordman]

look on the back of the crossmember where the brake lines run. that is where you will find the secong block that works with the block to make the discs work properly.

[SteveC]

ill double check when i get back out to the college the frame piece is out there with the rest of the truck.. i just dont remember seeing a valve like that cause the brake line from the passenger side ran all the way over to the distro block so did the drivers side

[fordman]

i have only seen one of these and it was on a 71 f250 cs. it had the regular dist block and then the front lines had a splitter thing for both front brakes. i think it was the regulartor or porportioning of the fluid for the frotn. that is all i can really say.

[SteveC]

its all good i will just have to investigate when i get a chance...... i always seem to get the weird trucks