1967 F250 manual drum/drum to power disc/drum conversion

[asrfixer]

Hi, All. I am still working on my old camper special, finally about to to get it back on the road after a couple of years (it's been really slow going). I have converted it from manual drum/drum to power disc/drum with parts from a 1979 camper special donor truck. I changed the front spindles and suspension out, and added the '79 booster and master cylinder, and a disc/drum proportioning valve. After replacing all lines, and bleeding the system, I still have absolutely no pedal. I should also mention the the front and rear reservoir connections are swapped at this time, though I will correct that soon. I did not change anything about the 1967 brake pedal. Everything bolted up with no modification (drilling / grinding, etc). Can anyone steer me in the right direction? I don't think the res swap should prevent braking action, just cause problems after the disc pads wear some, causing the fluid level to drop quickly. Am I correct in this assumption? Is the pedal throw in this configuration too short? Anybody? Thanks in advance for any helpful advise!

Bam

1967 F250 2WD Camper Special
400 4BBL / C6 trans

[basketcase0302]

Bam,

Did you keep the original pedal assembly on the CS? If so I can tell you my memory of my 79' F-100 actually had an adjustable push rod between the MC and the booster, (very careful here as only 1 turn adjustment is a lot and changes the distance/throw dramatically.

But I'd first get the lines swapped around and get them all bled before trying anything.
Also highly suggest doing a "reset" on the proportioning valve, (will ask for confirmation from another member here) but believe the valve will go into a "default" "failure" mode once it loses all brake pressure and you'll have to reset it, (there's also a particular way to do this).

Is the MC the used one from the donor or did you replace it?

And did the 79' F-250 Dent spindles simply bolt up to the Bump beams, (8 lug correct)?
There had been much discussion on this through the years on the F-350 as well if it was even possible!

[asrfixer]

Thanks for the reply!
I do still have access to the '79 donor, and I replaced the '67 beams and spindles with the '79 parts (8 lug F250), but kept the radius arms, the '79 arms had some difference that made them unusable on the '67, don't remember what it was, though. The MC was a reman replacement for the '79, and the booster was a new unit for the '79. AFAIK, the proportioning valve reset requires pumping the pedal to re-center the piston. I have zero pressure to work with. I will be correcting the line swap problem before I do anything else. If I have to replace the '67 pedal with the '79 pedal, won't that require a good bit of re-engineering? I really do not want to go that route!

Thanks again

Bam

[basketcase0302]

Randy/Jerry/Jamie/Greg/Robert/anybody...
Can any of you please post the link to the proper way to re-center the proportional valve/brake spool, (or proper procedure to do so)?
I'm pretty sure that you'll never get a pedal until this is done, (and I wouldn't doubt you've got a crappy rebuilt MC) as there seems to be so...many of those nowadays! For many years I had a storage unit across from an old guy who rebuilt GM starters, (and pretty sure his eyesight was failing).
THERE IS NO QUALITY CONTROL OVER REBUILT ANYTHING IN OUR INDUSTRY AFAIK!

Shoot me a PM with an email and I can send you some detailed pics of what it took to get my 79' Dent automatic pedal into my 71' F-350, (emails and phone numbers on the forum here pull out spammers and trolls so are forbidden).
And if you pull the booster look closely at the pushrod that hooks to the pedal inside the cab as I'm pretty sure you'll find the 79' had an adjustable pushrod. The end that "snaps" or slides into the booster should have threads, (keeping in mind that adjustment is done in very small increments if you try to adjust it). I can're remember if you could see this from inside the cab or not, (but pretty sure you can't due to a plastic sleeve)?

[asrfixer]

Thanks Basketcase! I pulled the Master Cylinder and looked at the pushrod in the booster. It was not reaching the MC piston end. I adjusted the push rod to within a couple of threads of its limit, and it just did reach the mc piston. I replaced it (temporarily) with a longer cap screw, and adjusted it to just touch the mc piston when I bolted it on. BTW, I cleared up the line reversal I mentioned in my original post. I now have some pedal. I need to do another, more thorough bleed, then I will post my results. I'll pm you with my email addy, I'd like to see your pix

Bam

1967 F250 Camper Special
400/4 bbl / C6

[basketcase0302]

Bam,

Good to hear you've got some pedal!
I sent the pics this AM via email, hope they help.
Forgot to ask the "obvious"...you did bench bleed the MC before hooking up the lines correct?

Still don't discount having a crappy rebuild MC as through the years I've had that bite me in the butt 3 diff times!
Watch for fluid leaking into the cab/or where the MC bolts to the booster/and also where the cap seals against the resevoir, (I'd gotten a few where the resevoir sealing lip was so...pitted that the rubber cap gasket would never seal) yet the lack of quality control by independednt rebuilders push those trash rebuilds out the door for the dime they get on getting paid by "piece work".

[asrfixer]

Basketcase: I did bench bleed the M/C, how ever, I may try another M/C, as I dismantled this one and powder coated the outside of it. It went back together well, and did move fluid when I benched it, but maybe I damaged something when I subjected it to the heat of the oven or during reassembly. Haven't had a chance to work on it in a week, so haven't re-bled the system yet.

Cheers
T

[basketcase0302]

Bam,

Pretty sure you're onto something, (possible damage in the oven curing)?
I'd never powdercoated one so can't say for sure but they do have rubber o-rings on the piston inside the bore of the MC.
I've had the worst luck of anyone trying to get a MC "presentable" having tried every paint imaginable from high heat to gas grill paint and ultimately...
Fluid leaks take my paint off in record time!