1965 F250CS Brake upgrade. I thought...

[Ridemywideglide]

I've looked at many, many posts on here about the brake upgrades and swapping 70's M/C's in and such, and I can't find a definitive answer to my problem, now that I have done the same..

I took the vac boost M/C out of a 1973 F250 4x4 that was drum all the way around. I had to modify the rod (shorten about 1 inch) to fit in the 65. I assumed this was going to be a bolt and go operation but it has been anything but.
Ran 1 new line down to a splitter to separate front/rear. Capped the now extra port for the rear. Replaced all wheel cylinders. Reverse pressure bled the system many times from all wheels.

I can get either 3 brakes that work TOO good (very touchy) or 1 that locks up at the slightest glance at the brake pedal. I've tried adjusting all pads to barely drag, and 4 clicks back out. I've made them extremely loose, nothing gets all 4 wheels working in sync. It' seems the back is the most problematic.
I hooked up the M/C correctly for front/rear.

I'm wondering if there was a bias fixture on the 73 that I didn't get... I've read mostly that 4 wheel drum trucks had no feature like that, but I'm getting issues that suggest it's necessary.
Any ideas?

The old single pot m/c worked the brakes fine, with the exception of having to pump 3-6 times everytime you wanted to stop. It was time for it to go.

[Toyz]

Not sure what you are referring to as "reverse bleeding", and I am not sure what you are referring to as a "capped port". The '73 should have dual residual valves for all drum; they may be mounted in the m/c outlets, or in the combination valve. If you have indeed just utilized one line from the master cylinder, you are totally defeating it's purpose; as well as causing a potentially dangerous under-supply of fluid to feed all brakes. I would highly advise running the combination valve, as it may function to proportion fluid pressure to the rear brakes. If I am understanding your current setup, correct the items mentioned, bleed the master cylinder first, then bleed starting at longest point from master (usually right rear); work from furthest to closest, and you should be well on your way. While you have the master cylinder loose from the booster, check the booster to m/c rod. It normally extends around 5/8" from the mounting face of the booster when engine is off and booster in static position. Use that dimension only as a starting reference, it may be incorrect for your m/c. With that measurement in hand; start the engine and re-measure the same distance. If it has changed, further adjustment to the rod running to the pedal is required, or booster valves are defective.
If dimension remains the same with or without vacuum, install the m/c, and check for adequate, solid (non-fading) pedal. Test drive in a cautious manner, hopefully all will be well!
Paul

[Ridemywideglide]

Ok, I'll try to clarify..

The boosted m/c is a complete take off unit from the 73. Never separated. Bolt on affair..

Reverse bleeding is pressure bleeding from the wheel, to the m/c. Wastes less fluid, works faster/better.

The "capped port"; I came from a single pot m/c which ran down to a "splitter" on the frame that went <input - Front out - rear out> Rear of course goes to another T at the axle. I separated the front from that block, plugged the port, and ran a new line from the front output of m/c to the front line on the frame. Rear out on m/c goes through the stock remaining lines to rear.

I didn't grab anything of the 73 but the m/c. This is my question/problem... I was unaware that there was a combi valve or proportion valve or anything of the sort. Everything I had read said a 4 drum truck did not have this...

I have adequate pedal. As it sits now, I have about 1 inch free pedal (engine running) and the brakes hit hard.. ON the wheels that choose to work that day. It's not a booster problem, and it's not a bleeding problem. If anything the booster is working too good. Just not equal braking between the wheels no matter what I have done.

[F164]

On your MC, the front bowl is for the rear brakes and the rear bowl for the front brakes.

It sounds like you have them plumbed backwards.

Have you driven backwards and hit the brakes 5-6x to let the self adjusters do their job?

[Toyz]

I can't believe "reverse" bleeding would be very efficient if in fact you do have residual valves in your system. That residual 10 psi may well keep from obtaining a good evacuation. Hydraulic systems seem to function better when you "go with the flow". The only time I would apply pressure from slave to master would be if looking for blockage. Since Ford had gone to disc front on the 2wd '73 F250's, the 4x4 application may have some differences from earlier applications.
In the absence of external devices, Ford, and most, drum brake master cylinders do not care which reservoir is which; the pressures are the same, the volumes are adequate for most normal situations. Naturally, if the reservoirs are unequally sized, the larger reservoir should feed the larger wheel cylinders, which are usually the fronts.
Don't rule out either a problem related to the booster installation, or adequate bleeding. Erratic brake behavior usually is either air remaining or incorrect adjustment of some part of the system. You modified the booster rod; this may result in the booster starting off in a boosted position when running; it is also quite possible for the booster valving to be defective or stuck. If you DO NOT have residual valves at both ends, and do not maintain minimal, and equal, shoe, (not "pads"), travel, you may never achieve repeatable performance due to excessive travel of the wheel cylinder pistons to bring the shoes into equal contact with the drums.
At this point I would suggest locating an applicable OEM combination valve; while it may not have optimum settings for your application and usage; it IS apt to be superior to an incorrectly set up (and pricey) aftermarket system, and much easier to install. Just be sure it is also drum/drum! Lacking a dedicated brake pressure gauge setup, a readily available "low pressure" brake lamp actuating switch set up with a test lamp is a good tool to determine the presence and workings of residual valves. I would NOT recommend the use of one for the purpose they are sold for; it's just asking for trouble, IMO. If you find that residual valves are in place in the m/c; there is no need to be concerned as to whether the combo valve also contains them. The ones in the m/c will be inactive as long as the others are working.
People will argue these statements day in and day out; a little research will easily overcome the "it worked for me", and "you don't need that crap" answers.
Paul

[Ridemywideglide]

F164; Yes I have them plumbed correctly. This is where I'm drawing a blank..

Toyz; It's much more efficient as there is no pumping. Air is pushed toward the highest point, the m/c. I have no "valves" in the system unless there is something in the m/c.... "Going with the flow" maybe not, getting the air out, it works much better and faster.
As to the dual chambers, yes I thought the drums front/rear should be equal in pressure requirements. This seems not so. But I also have issues left to right on the front. I have no external devices in the system, which I'm wondering if were in the 73 and what I need.

I did modify the pedal rod, took an inch out to make it fit the pedal. Maybe this screwed up the geometry, but from what I've read it was what I needed to do.
If I said pads, forgive me.. No pads on this truck..
I've done literally hundreds of drum vehicles. Bugs to trucks. This one isn't working as scheduled.... It's this close to being a driver again after 15 years... If I had hair to pull out it'd be gone...

Wheels off, all wheel cylinders move according to pedal. Drums on, they seem to do what they want. I've tried adjusting to "tight" wheel out to compensate, then another wheel gets "tight" on road test. One always locks up, which one depends on how lose I set them. It's a dog chase tail deal with which one it is....

[banjopicker66]

I am having trouble picturing your setup. Would it be possible to post some pictures of your master cylinder, the capped-off port and the splitter?

[F164]

Also, how do you know that the M/C you took off the 73 was the correct one for a D/D system. Just because you took it off a D/D truck doesn't mean it is the correct M/C or that it is good operating condition.

I agree about going with the flow on bleeding the brakes.

[Toyz]

As stated, if you don't have residual valves, you should have! I can assure you Ford and other manufacturers would not have bothered to fit them if not needed. Ford combination valves have many functions which people do not even consider. As far as I am concerned, for truck usage, Ford's system is an improvement over highly touted aftermarket systems, especially in the hands of most home mechanics. If "reverse" pressure bleeding were as efficient as you stated, it would have become an industry standard. Professional pressure bleeding kits I am familiar with do not even include the adapters to fit most cylinders. Since I tend to overdo some things, I have reverse bled individual lines as an easy diagnosis of any potential blockage, valve or otherwise. "air" is quite often pushed from one point to another more distant point; this is the reason manufacturers state to start at the furthest point from the master cylinder as an initial bleed point.
The symptoms you mention are typical of insufficient bleeding, or a mis-adjusted or defective booster. Lack of residual valving just aggravates those situations.
Do yourself a favor and check as I stated before ignoring my advice. As you improperly adjust brake to shoe clearances, the problem will often migrate elsewhere.
BTW, ALL master cylinders utilize valves. A factory shop manual, particularly the diagnostics section, might be of assistance in gaining an understanding of the system, it's components and how it functions.
Paul

[Toyz]

I can assure you most major light truck manufacturers did indeed use the functions of a "combination" valve by 1973. While the FMVSS brake standards mandated for 1968 and newer vehicles did not specify the use of these devices on light trucks, manufacturers became pro-active, as well as competitive, regarding these safety items.
Paul

[chris401]

http://www.brakebleeder.com/products/be ... ke-bleeder

I used the revese bleading unit for a few years. Ours looked like an old metal electric gas can. It used vehicle battery power to pump NEW brake fluid from wheel bleeder valve up to master cylinder where an adapter, in place of cap, directed OLD fluid into a seperate resevuar. Down side was not having all the adapters.

Ridemywideglide: If you replaced shoes check for smaller primary shoe to be in front and larger secondary shoe to rear.

QUESTION: Would a non power master cylinder mixed with a booster cause this issue?

[Ridemywideglide]

If "reverse" pressure bleeding were as efficient as you stated, it would have become an industry standard. Professional pressure bleeding kits I am familiar with do not even include the adapters to fit most cylinders.
Paul

I guess google is a new term for you as well.. I didn't realize there was so much negative mojo going on here...

I know the m/c was correct for the truck, and I know it worked because I drove it before scrapping it. My question was simply, if someone KNOWS if there was a bias valve, combi valve, etc. on the 1973 D/D trucks..


I'll try to get some pics up later today. I haven't had time to mess with it in several months.. As for the plumbing, I can't explain it any simpler.. The old m/c was single pot, thus 1 line ran down to a 3 way splitter at the frame. From there, 1 line went to front axle, where it again hit a 3 way splitter to go to front wheels. The other line from 1st splitter went to rear axle where, you guessed it, there is another splitter to go to each rear wheel.

I took the incoming line for the first splitter, and hooked this to the small pot (front) of new m/c, removed the line coming out of the splitter for the front axle and capped the port on the splitter.
I then connected the large pot (rear) to the existing line left going to the front axle.

[Toyz]

Hmm, you KNOW your system is "more efficient"; yet my brake repairs invariably work and seldom involve "pumping". "Google" your own solution, your statements clarify the source of several of your problems. Might "google" NIASE brake certification around, oh, say, 1975 while you are at it. I KNOW the answers, I STATED the answers while refraining from adding the obvious thought. You KNOW the parts were right , you KNOW the plumbing is correct, you KNOW the system is bled; it appears the only thing you don't KNOW is how to make your brakes work. Take it to Brake-Check, they probably can use a good laugh!
Paul

[LM14]

If you are 100% sure you have a drum/drum master cylinder, you have residual valves built into the master cylinder.

Do you have a firm pedal? Does it maintain it's pressure or bleed off if you keep pressure against the pedal? Do you "chase" the pedal to the floor while trying to keep constant pressure against the pedal?

If you get, and keep, a firm pedal, you have no leaks. If not, start looking for wet spots on lines, connections, plug ports, etc.

You must adjust your brakes correctly to get a good pedal and be sure everything is bleed completely. Jack it all up, manually adjust your brakes at each wheel. Until that very basic requirement is done, you will no be able to tell much of anything.

I believe nearly every vehicle has a proportioning valve in it's system because it's easier to put a valve in than use different sized wheel cylinders. You never need as much rear brake as front brake. Since that pressure is based partially off of the bore size of the master cylinder, you need a valve to control the rear pressure. Another way to do it is using a smaller bore on the wheel cylinder. The smaller bore on the wheel cylinder would give less pressure on that wheel. Are you sure you have the rear cylinder on the rear and front on the front? Big bore front/small bore rear. If the wheel cylinder bore is the same front and read, you will need a proportioning valve.

When you reverse bleed, re you seeing air coming into the MC? Have you tried to vacuum bleed from MC to WC?

SPark

[ICEMAN6166]

i did the 1st mc conversion almost 15 years ago
its still working fine on the same truck, 66 f250 4x4
bought a new 4x4 non power drum\drum mc, cant remember the exact year ,early 70s for sure
cut 1" off the rod
took the "distribution block" from another drum\drum 4x4
plumbed my brake light switch (pressure type) into one of the lines near the mc using a tee - 2 sides fit brake line,3rd is npt for sender.

perfect working non-power 4 wheel drum brakes.

did a few others since and done the same way except the brake light switch, no issues on any of those trucks either.

[Ridemywideglide]

If you are 100% sure you have a drum/drum master cylinder, you have residual valves built into the master cylinder.

Do you have a firm pedal? Does it maintain it's pressure or bleed off if you keep pressure against the pedal? Do you "chase" the pedal to the floor while trying to keep constant pressure against the pedal?

If you get, and keep, a firm pedal, you have no leaks. If not, start looking for wet spots on lines, connections, plug ports, etc.

You must adjust your brakes correctly to get a good pedal and be sure everything is bleed completely. Jack it all up, manually adjust your brakes at each wheel. Until that very basic requirement is done, you will no be able to tell much of anything.

I believe nearly every vehicle has a proportioning valve in it's system because it's easier to put a valve in than use different sized wheel cylinders. You never need as much rear brake as front brake. Since that pressure is based partially off of the bore size of the master cylinder, you need a valve to control the rear pressure. Another way to do it is using a smaller bore on the wheel cylinder. The smaller bore on the wheel cylinder would give less pressure on that wheel. Are you sure you have the rear cylinder on the rear and front on the front? Big bore front/small bore rear. If the wheel cylinder bore is the same front and read, you will need a proportioning valve.

When you reverse bleed, re you seeing air coming into the MC? Have you tried to vacuum bleed from MC to WC?

SPark

I am 100% sure that it came off a 1973 4x4 with drum/drum and it worked fine before I took it off that truck. Only reason I ended up with the truck was a bad rod. Still ran ok and drove fine. Pulled the 360 for a future 390 for the '65.
It has great pedal, actually super touchy compared to what I'm used to with the old single pot non-power. I've adjusted each wheel several times, only to end up chasing a wheel that doesn't cooperate. There is no bleed off, and no leaks.. I did not know there was a prop valve on the '73 this master and booster came off of, as searching here and there I never found mention of one. I just grabbed what I thought I needed. As before, small pot in front hooked to rear brakes, and vise-versa.. The front pot on the m/c does have a larger output port than the rear pot, used an adapter to get down to the line size connector. Maybe that's a thought, but the largest chamber is what's hooked to the front right now.
After bleeding them several times m/c to w/c, and not getting any more air, I thought I'd do what makes sense and push low to high. Since air travels up in liquid, I thought I'd "go with the flow". I've pushed 16oz of fluid from all w/c's up through m/c with no air remaining to be seen. I run 30psi in my pressure bleeder so this happens fairly quickly.
Always adjust wheels to slight drag and back a click. Tried several combinations of drag amount vs back-off clicks. Front seems to be more consistent, but still not there yet. I'll pull the wheels this weekend and double check everything in there just to be sure.

[bruceandersson]

Is it possible that the drums/shoes are the problem? I did not see that you replaced the shoes. If they have absorbed any fluid over the 15 yrs of non-use, they may be grabby. I'd try new shoes and turned drums.