I just got a 69 camper special, power drum brakes all the way around. Trouble is my brake distribution block tripped when i brought the truck home and I cannot get it "untripped". Stock replacements seem to be as rare, and premiums are to be had online for FOMOCO NOS items. My question, when this block trips is it only a warning? Does it change fluid pressure/flow to the front/rear in any way when it trips? Also, does it "proportion" the fluid to the rear vs front, or is it only an alarm type system to notify the operator of a problem.

Thanks in advance fellas

 

The distribution block "trips" when there's a difference in pressure between the two fluid circuits (front vs rear), which shuts off fluid flow to the "bad" circuit.

While the spool is off-center, it activates the brake warning switch, telling you there's a problem. If you have drums front and rear, this valve doesn't proportion the fluid flow--it's only for warning and to shut off the suspected leak.

Check for your system for leaks. It is also possible that the master cylinder has internal leakage.

 

Did you actually try the possible techniques to reset it? Tell us what you did. A couple of techniques were described in your other thread on the same topic: https://www.ford-trucks.com/forums/1...l#post13529845

It's a warning .... that's why it is red... it is likely only half the system is actually working.

Here. Study this cut-away diagram. The pressure differential valve (piston) is the culprit.:

 

So based on bleeding I think my proven circuit is the passenger front, but that now has a new wheel cylinder and all soft hoses have been replaced. I get almost like a "grabby" feel when bleeding but I get fluid out and the air is out. To reset the system I first followed the book, which just says to turn key to on but do not start and press brakes. I then followed some suggestions on here, first bleeding cracking each system independent and gettin hard on the pedal. I then tried the same scenario at the distribution block, same story. Lastly I popped the switch and tried to slide the rod manually, but no dice. I'm afraid to disassemble because I cannot find a replacement. Furthermore I am not sure what else to check to correct that pulsy symptom when bleeding the front passenger side, I am curious if the dist block is causing that. Brakes now work awesome except the pedal seems to engage late, but it doesn't pull and I can lock the brakes under hard, hard braking. What is your guys input? Brakes are adjusted btw, shoes in good condition and drums look to be just turned. All new fluid and no more air out the lines. Thanks in advance

 

Problem* not proven.

 

Since your truck is a 1969 yr they had the earlier type of distribution block kind of like this one in the picture. Yes, I say your truck must have been sitting for a while which is a killer for the brake system. So, I'd say time to rebuild the whole brake system. Many people think the fluid gets shut off to the leaking part that had the lost of pressure. But truth is not many people have figuered out just how to do it. So they fix the brakes system bleed the whole system with no problem then unplug the trip switch and drive and drive for yrs. In most motor manuals it tells hoe to do it. But due to a lack of flushing the fluid to keep the crap from loads up in the distribution block the then once the sliding differential valve is tripped it gets stuck until reset or removed and taken apart and cleaned taking care of not to miss up the two end o-rings. ..Took me 30 yr to finally get to mine when I re-tubes the brake systems hard & rubber lines. ..orich

The newer type post above was started being used about 74

 

I stand corrected re: shutoff brake fluid flow. Thanks for the correction, Orich.

I found a rebuild kit online (it contained two seals and a copper crushwasher) and followed their instructions. Hardest part was getting it disassembled.

Don't know if I'm allowed to post a link yet. Muscle car research was the name.

 

Aw yes that's where, I got a kit for the 74 P-block type but have not install it yet since doing the 3500lb disc brake front axles cause got to shorten the f hard lines some. Plus was able to clean out the old P block and re-use it so it can wait a while as it's a low on my list of things needing to finish.

The kit for the 74 & up is like only 1/2 a kit not all the needed replace parts
come in this kit so you may have to hunt some at the junk yards. Like a good bleeder valve & rubber boot..

I made up a few hard line plugs and forced the slider rod out using two feet to push on the brake pedal to get it to move. I soak it in braker cleaner and use a soft bore brush for a numer of days to get it cleaned out. Use some fresh clean B-fluid while putting it all back together being careful to center the slider rod. it should go in the same diraction it came out. Let it self bleed by levening the line a little loose and tighten... orich

 

Are you sure it's the block and not just the switch? The switches are a known source for problems.

 

Sounds like you have a restriction in that corner. All metal lines open and not crimped somewhere? Correct length rubber hose? If it's not pulling to one side that tells me pressure making it there but not necessarilly smooth flow. If everything looks cool I'd be tempted to blow out the line if you have compressed air and re-bleed. Brakes are your life buddy.

 

C8TZ-2B257-D .. Brake Pressure Differential Valve / Obsolete

1968/72 F100/250 2WD & F350 with manual or power drum brakes.

GREEN SALES CO. in Cincinnati OH has ONE = 800-543-4959.
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C8AZ-2B264-A .. Brake Pressure Differential Valve Warning Lamp Switch / Available from Ford/autoparts stores.

1968/79 F100/350, Bronco & Econoline / 1968/69 all FoMoCo Passenger Cars.

 

Yikes. In case anyone is wondering - $225.00 plus shipping. I guess I'll keep trying to get the piston out of mine so I can rebuild it.