Where to find a brake pressure differential valve.

[fordhombre]

Welcome back to the world where if it can go wrong...it will. I was wondering if any of you clever guys know where to pick up another brake pressure differential valve. I'm replacing the lines, and thought I'd go ahead and change that out too. I checked locally, and LMC truck...no show. This made me debate whether or not to replace the valve, but a stripped bolt made up my mind for me. I was going to post a picture, but the file is too large, and i don't have photoshop at home.

The valve has a bracket attached to it, that mounts onto the frame. It has two slots on top of it for brake lines, (1 3/8, 1 7/16), and a spot in the middle for the pressure warning light. There is also one slot on the side for another brake line.

Sorry if the description is poor... i would be very very grateful for any information at all! thanks!

[bluef250]

Do you have disc brakes on your truck? If not you are probably describing the pressure differential switch housing. This switch activates a warning light on the left side of the bottom of the dash if either the front or rear brakes do not have pressure. Unless your local Ford dealer can find the housing, probably the best location is a junk yard. In a couple years of watching eBay I haven't seen one there. Also, some of the others in FORDification might have one.

[460 crew]

If you have drums all the way around I might have one laying around off my old brake system.

[FORDification]

I've got several good ones for drum-brake vehicles too. Let me know.

[72hiboy4x4]

I normally take large pic files,also. but when i need to post 'em I just open them in paint and use the strech/skew option (set at 75%) to reduce them enough to post.

works for me!

[fordhombre]

Okay, i just cleaned up my old housing unit and it looks nice and shiny, so it should be okay. But I have run into the problem of not finding the right brake lines.

The problem is the lines have different size fittings on each end. For instance, the fitting on the line is 3/8" at the valve, and 1/2" at the cylinder. The other line is 7/16" at the valve, and 5/8" at the master cylinder. Every place I've checked locally only offers steel lines with the same size fittings on each side... This means the line would either connect at the valve, or the cylinder, but not both. I don't really have the means of flaring a steel end(i'm guessing they're not as easy as copper).

Even LMC looks like it only offers same-size fittings on each side. Are my brake lines, or the pressure switch housing not factory? Can someone shine some light on this for me? Thanks!!!!!!!

[FORDification]

The brake lines themselves are the same size, it's just the external dimensions of the fittings that vary. Since you don't have the tools to flare, here's what I'd suggest: Just cut your old brake line and remove the fitting. Buy the new line and cut the incorrect fitting off, slide the old fitting on the new line, and run it by a local mechanic, who can double-flare it for you in about 2 minutes. Then bend the line and install. You COULD go with adaptors, but that just looks cheesy.

[460 crew]

If you have a Carquest or a CAP Charelston Auto Parts they cary a large assortment.

[fordhombre]

Well, one of the poor 'ol fittings got stripped in the process, so i'll check with carquest and get the correct fitting and line, then hack it off and see if i can't find somebody to doubleflare that line for me.

out of curiosity, can copper lines be used to replace the steel lines. I'm going with steel, but i was wondering about copper. Thanks!

[FORDification]

Absolutely NOT! Copper lines will not stand up to the internal pressure of the brake line. ONLY use steel lines.

[fordhombre]

Guess I really wouldn'ta gotten around much with copper lines then.

[frisky]

I went thru 2 or 3 from a junk yard - the diff valve for disk/drum brakes;
and they all ended up being cruddy and the plastic seals worn out or eat up.

So I bought a new one from Jeff's bronco graveyard (google it) and made a
simple space block to go between it and the original location on the cross member our of some 1" square tube; drill two 5/16 holes and some bolts and that was it. Took more time worrying about it that it did to fab up the block and put it in.

BTW if you have drum/drum the block is not a valve but a manifold with a sensor spool inside to detect uneven fluid flow front versus rear and to flip a switch to turn on a warning light on the dash.

[72hiboy4x4]

and welcome to the archives, everybody!!

[frisky]

Heck, our Trucks are archived!