I guess I should clarify, I am thinking that there must be something that I can ADD to my system to give me more pressure/volume to the rear wheel cylinders at least. If this IS an issue than I have no problem accepting that I just plain screwed up and did not think fur enough ahead.

I wouldnt deny myself though all of the stuff I have learned with this truck for nuthin though. No regrets I guess .....Ok maybe some

Anyway I am looking at ways to make my system better, would adding this sort of gizmo give me a better system, I am not giving up on the possibility that there may be a larger bore M.C. out there that will bolt onto my power booster but I do not believe it exists in the 81/86 range of years.

So again the question is what would be the easiest way out of this possible mess.

BTW I did finally get a master cylinder this A.M that I am happy with, I bought it at Autozone but cannot remember their dist. Those Napa Cordones just would not bleed EXACTLY how their directions indicated they would.

This autozone master did EXACTLY what the directions stated would happen during the bleeding process.

I have it mounted on my truck and also decided to run all new seamless lines fron to rear, I had a junction in both lines before this where I spliced new lines in and I just did not want to screw with the chance of their existing a problem.

I do not yet want to try anything further with anything else until I have gathered some more info so its mounted and plugged and can just sit there and wait.

 

I wouldn't have run new lines just yet. Better to change one thing at a time and see how that affects the whole setup. If you go changing multiple things are the same time, it can help compound the issue of, "What went wrong?"

I wouldn't use the product that you posted at the end of page 5 to "add more pressure" to the braking system. It's more than likely a band-aid product at best, and will likely only cover up an issue that still needs resolution.

Is it not possible to go back to an original style braking system that was used on your truck as it came from the factory? This seems like it would be the best course of action to take.

 

Ok, the original cylinder was a single piston 1.5" diameter or 1.767 sq in area X 1.4375" stroke = 2.54 cu in of fluid displaced at full travel.

New MC, dual piston 1.25" diameter or 1.227 sq in area X 2" travel = 2.454 cu in total fluid displaced at full travel - but each eand of it only displaces 1.227 cu in.

Before you started everything did you still have the original wheel cylinders? If so, lets just look at the rears, assuming 1/4 " travel per cylinder (total between both ends) we get at a bore of 1.625" aan area of 2.074 sq in X 1" travel (4 X .25") or 2.074 cu in fluid needed.

Now you have a 1.75" or 2.405 sq in X 1" = 2.405 cu in needed. 2.405 - 1.227 = 1.178 cu in short

What you need is not a pressure booster but a volume booster. My recomendation would be to find smaller rear wheel cylinders. Another option, which is one some British cars used, would be two single circuit master cylinders side by side with a bar connecting them. This way you can probably get a big set of cylinders and balance the brakes by bar position. The only other possibility would be like Rolls-Royce and Citreon do, or some of the infamous Bendix 10 systems, a high presure pump and the "master cylinder" is more of a control valve. The only problem would come if the pump failed, you might not have enough stroke volume to operate the brakes

Rolls-Royce has an unbelievable system, 3 hydraulic systems, LF,RF,RR and RF,LF,LR and LR,RR. The first two are the high pressure with split front calipers and one rear, the third is non-boosted under floor master cylinder and rear calipers.

If you want to mess with it I have one good Bendix 10 pump and HCA, don't know if the anti-lock solenoids are good or not, it runs at 2200 psi through an accumulator and control valve. Google Bendix 10 system, Chrysler used it.

On lines, my F-350 has a 3 section rear brake line and a load compensating valve, Other than having a rusted through line years ago it has worked fine.

 

I could have the wheel cylinders sleeved to prob. a smaller diam. not cheap, will continue gathering info, looked into that Bendix 10 on google, looks like I would be way over my head with that but who knows what the future holds.

Thanks for the offer

 

Nothing is impossible but I have already too much time into what I have done so far to throw in the towel, where there is a will, there is a way, I just have not found my way yet but it is coming, I can feel it

 

On the Bendix 10, pump power is controlled by a pressure switch so that is just a relay and wiring (switch is on the "master cylinder). It is originally a dual-diagonal system so has 4 lines on the bottom.

 

I am starting to see the problem, with the 1986 F-150 master cylinder ( 1.0 Bore ) that I originally had I had more pressure so it did work the brakes, stopped the truck......(poorly)

Now that I have increased the bore size to 1 1/4 I have decreased the pressure but increased the volume.......( maybe just not enough )

Going to a smaller wheel cylinder as you suggested would be like putting that smaller master cylinder in I.E increased pressure......

There is however the possibility that I will not be able to find THE happy medium so where to go next will be the question......

I could not get a good enough pedal with the 1986 1.0 diam master but then again I did not have the residual valves keeping some sort of contact within the wheel cylinders so maybe with residual valves on the original set-up I would be golden.......Me thinks not quite though, I am hesitant to say that would be enough.

More food for thought though and this is very interesting

 

What are your intentions for this truck? I guess you have the old original engine? When I did my 53, I put a 351c with a c4 behind it, and kept the original rearend. It was 3.90 or 3.91 to 1(I forget which one, it was the very old style original dana 44).

I had problems with this setup. The thing would move out like you would not believe, and could light the tires up at will. The c4 was stock, and when it shifted to 2nd under full throttle by itself, it would actually chirp the tires. But, I had problems holding it back at stoplights, and it screamed going down the highway. It needed a lower numbered rearend in it, or a higher stall convertor.

What I am leading up to in all this, if you swapped the rearend out, you would get modern brakes and wheel cylinders at the rear, and a lower numbered rearend for better manners on the highway.

 

Yes, I have thought about this many times, it would be sooo much easier. I may still do this, I am tapped out right now though.

I can hopefully get it operating well enough to take it to a show, make a run to H.D to pick up a light bulb, you know, all that heavy stuff

I have thought that someday I would still like to start a business with it, not sure what, maybe portable welder, maybe hauling, ideally I would like to put a box on the back and haul classic cars around the country, maybe even a tow truck but I am over the half way point in my life and my motivation is diminishing rapidly.

 

I have brakes! I don't know where I left on here but after I put on the third master cylinder from Autozone ( Napa Cardone were all junk ) I have brakes. Let me tell you how it is and maybe I can get some feedback on how to make it better.

Locked up all brakes tight against the drums with the adjusters, I still have yet to adjust the front brakes properly ever, there is evidently a feeler gauge involved to adjust the bottom adjuster and I just havent bothered to check where it is at.

Anyway I locked up all 4 brakes with the adjusters that were simplest to do and bled all 4 wheels, I could tell right away that this new master was reacting differently, things flowed smoother, I was hearing things that I am accustomed to hearing when I bleed brakes.

After done bleeding ( BTW the truck does not run yet so no booster comes into play yet ) I left the front wheels locked up against the drums and un-locked the rear drums and had my wife hit the brake pedal, no movement in the rear, I stuck a 7 foot steel fence pipe inside the spoke on the wheel and tried to move it, no movement.

I went to the front, unlocked them with the adjusters and had my wife step on the brakes, movement still in the front but took some force, readjusted the brakes quickly ( top adjuster only ) and tried again, difficult to move but I could still force it.

I have to have too much drag on the front brakes, and am running out of room on the pedal but getting there.

I don't know what one has to do with the other since there are on completely different lines but unlocking the front brakes away from the drums in the rear not quite so tight, different reservoir, different lines, makes no sense to me.

How will this react with the brake booster helping???? I have a feeling that will make the pedal even lower.

I noticed that if I pumped the pedal a bit the pedal would be higher and I am assuming ( but did not verify ) that all 4 wheels would have been locked up at this point.

Thinking about re-bleeding, dont know if that will help, I was pretty thorough already with the bleeding, any advice to get more pedal room before it sinks would be helpful.

I guess maybe I am running out of pedal again because of there is just not enough room in the pedal to make up for the volume of fluid I need but I can keep working on that.

 

I think you should call it good till you start driving it. If it has new shoes, they need to conform to the brake drums a little bit, so you should leave them dragging some when you adjust them.

If the pedal is hard with no sponginess, then you do not have any air in the lines.

If you want to have a higher pedal, you might want to look at the pedal arm mechanical connection. I don't know what you used, but if you move the place there the master pushrod connects to a lower spot on the pedal arm, it will require less movement of the pedal pad end to make something happen at the pushrod going into the booster. You don't get something for nothing, and it will require more foot pressure to do this, but you have a booster so it probably won't be noticeable.

 

The adjustment takes up some of the travel in the wheel cylinders. Go back to what I said earlier about only having half of the stroke on each piston. I think once you get the fronts adjusted correctly you won't have the drag and will have brakes.

Sounds good, progress is always nice!

 

Thanks guys, this is where I am at now...... I went out there adjusted the front brakes properly as close the book as I could manage, I also loosened the rear brakes just a bit so they would drag just a little bit, no point in having them drag too far because all that material is just going to come off going down the road and then I will be back to square one, got in the truck pushed the pedal down, rear brakes are locked up tight.

I could not move them, I am still pretty big and strong, front brakes not so good, locked down but not tight, I could still manage to strong arm them around, maybe I have a bit of air still left somewhere? I cant say that I run out of stroke, it isnt like it was before when I could feel that piston hitting the end of the master but I would say I am darn close I guess.

Next I pumped the pedal 4 times and held it, all 4 wheels locked up tighter than I could have wished for. No possability of me moving them unless I went with some sort of fulcrum. Good pedal height as well.

The rear brakes need to be centered, now I understand what that means, this will not happen until its going down the road and the brakes are applied a few times, I will then be able to do a true adjustment.

Now I need to work on making it safe, I should not have to pump it at all to get the fronts to lock up.

Trucks got to be safe but maybe I am half way there, I plan to make some phone calls tomm and get some new ideas hopefully.

At least at this point I am not sick to my stomach as I have been the last few days, I can at least get this thing moved around a bit, I need to work on finishing up the last few details this week with heater blower motor, wiper assy and then finally the gauges, Ok maybe a few more things but it is getting closer.

Ill be honest with you guys, I would not hesitate in THE LEAST to drive this today if I could on the road, the brakes are a huge improvement over my fist stint, I am very careful that I do not do anything to jeopardize someone else but the truck will stop and will stop within a reasonable distance. Again much better than that first time with the smaller master cylinder.

 

BTW I am not sure why, maybe because of drum expansion but they want you to adjust the braked with a 0010 thousands clearance at the top and a 007 thous. at the bottom all 4 shoes ( front ) so now there is no drag at all on the front drum. I guess if there were a little drag that would help but then again when they are worn down I guess that means I will be running out of pedal again, is that correct?

Sounds about right to me.

Stupid question I guess but what would increasing the size of the piston between the shoes and the wheel cylinder do, not sayin I am going to do it but seems to me that might help maybe a whole lot.

Simple pin, would not take much to find a longer one maybe from another truck?

Just throwin it out there

I know ZERO about any sort of hydrovac but it keeps getting mentioned to me, cray question again maybe but can I use any sort of hydrovac with my existing master and brake booster.

I understand if you guys just do not know.

 

I bet it wont take you guys a million years to figure out what I just found in the front brake lines whilst cleaning up my tools. Ill give you a hint, drip drip drip.

For once this is a good thing!