Just trying to keep on the front page any more info would be appreciated. Thanks Eric

 

Lets see if I can help. I have had that exact problem on my F6 years ago. No Insult but
I dont allow Hyd. brakes on my property. I had to say that, but the F6 '50 was our
first new truck. Out of respect for my father, my son gave it a total makeover, still 239.
Ok, for years he used it for raking leaves etc. cause its to small for us, and the brakes
always was the big "S". My son did all you did and he came to this : Every thing was
rebuilt all NAPA stuff even the booster. I assume all is in good health OK next the kid
found out that there is two items that has to BE. #1 with a booster, there shall be no
residual check valve in the master cyl. so he took it out. #2 in the booster he bought,
the check valve is in the booster. #3 He found out the original setup had the check
valve in the master cyl. and not in the booster. I dont think it matters the size of
youre cyl or master cyl. cause if theres no air and lining adj is there it has to work.
What I read is you got later 2 cyl rear axle, no problem so in summery residual check
valve is in either the master cyl or in the booster. I bet $10 you have two. Boosters
are quite generic and when they go there gone. On the contrery I have better results
bleeding the system with eng. running , dont pump to the floor, wait 3sec push down
crack booster, again > rt rear lf. rear, rt frt lf. front. My truck put you right out within
one inch of pedal travel. Again take master cyl apart take valve out (at exit port)
If that dont work> booster check valve big nut at fluid exit on booster, some brake
drums on these have slots on the out side to stick a feeler gauge in. On the front of
F series this is important to set the bottom anchors I think .010 good luck I am positive
this will work . Oh son just walked in and read this and he said the master he bought
always comes with a check valve for non power systems problem solved********

 

Ok,

If I get what you're saying....The Master cyl must NOT have a check valve in it (because the vacuum boosters usually have them)?

Mine does have a check valve in the master cyl.

Since I bought my booster "off the shelf" and it's probably a much newer (style) one, it will MOST LIKELY have a check valve in it?

So I should remove the check valve in the master cyl?

 

The booster that is on my truck currently is the same one that was on it before so is the valve usually in the booster or the master cylinder. Would the master cyl to an F8 still have a checkvalve? I was actually told that the way that my pedal would push back that there wasn't a checkvalve in it? Is any of this accurate. I really appreciate all the input. Were you saying remove both checkvalves or is one necessary ? Thanks Eric

 

brakes are designed to work with the proper components. Im not saying that a check valve is not the problem but for the brakes to work properly they need to get the proper volumn and pressure boyh of which will be affected by the bigger mastercylender. I installed a new mastercylender and newer style booster and my truck will stop on a dime. When I was having trailer brake issues it had no problems stopping 20000 pounds of tractor and trailer.

 

So here is what I have found out so far. The system did have air in it but it was in the rear wheel cylinders. Here is the part that makes me kick myself since the wheel cylinders are mounted vertical instead of horizontal and the bleeder valve is in the middle of the cylinder it had air trapped in the upper 1/2 of the wheel cylinder. You have to remove the backing plates and rotate them to get all the air out of both cylinders then re install them. Any how thanks for all the help on here. Eric I'll definatly come back often Big Jobs forever!!!!!

 

I was wondering if any of you have encountered this problem before. Or if anyone has ever seen brakes that couldn't be bled without disassembly of the rearend of the truck. Thanks Eric

 

normally the wheel cylinders are on top and bottom not on the side

 

This thing was alright for about a year and then blew a rear wheel cyl again. Now has anyone installed like a 7 or 8 inch dual diaphram booster with a dual master cyl or even a hydraboost with a dual master cylinder. Would either of these give me as much assistance as the frame mounted booster. I am ready to switch up to something else if possible. I thing the existing booster is pushing back on the pedal to much and as a result my fat bum is shoving to hard on the pedal. I know I am grasping at straws but this thing only has about 600 miles on the rear brakes. Any info would be appreciated, Thanks Eric

 

I ran into the same problem when I went throught my F6. The new rear axle should
not be the problem. I bought my booster from Napa as well as all cyl and master cyl
kits. Boosters basically do the same thing. Somtimes you got to drop ones I can do
anything additude and go to the book. And the book says trucks with boosters do not
use the residual check valve in the master cyl. This valve is already in the booster. So
I took it out of the master cylinder and the brakes work perfect. Somehow I have
always have better luck bleeding the system with the engine running, although the
book says bleed with engine off. I also fill wheel cylinders up before installing just to
give me a little head start. Golden rule the only black magic in hydrulics is air....

 

Big-E
I'll be interested to see if anyone has tried one of the 7 or 8" dual diaphragm booster kits on an F5 or F6 too. It would be the easy way to get a split hydraulic system. I did call one of the manufacturers / dealer some time back to see if it would work and they were no help, wouldn't say. I'm guessing they didn't want to be on record for liability.

The original boosters on the 48-52 F5/6 trucks were only 7-1/2" (about 11" can dia), yet look a lot bigger than the 7 or 8" aftermarket booster kits for F1's. (I'm guessing whoever swapped in the axle on your truck also used the F7 or F8 vac booster if it's 13".)

One potential draw back might be fluid volume? with the aftermarket kits. Using the Corvette style master with a 1" bore vs the stock 1-1/4" F5/6 bore (even the F1 had a 1-1/16" bore). Hmm reading back did you say your master had a 1-3/4" bore? If so, it's from a truck bigger than a F5/6 early F600.

It is frustrating not being able to get an answer in using one of these split system kits for the bigger trucks.

 

My uncle has an 1980 Chevy C-60 Dump Truck that has a dual master cyl that is firewall mounted with an frame mounted booster. I am going to try to adapt this system to my truck with a dual diaphram married to it. Good Luck to me. Eric

 

Good luck, and keep us posted on how it's going. I'd like to see how it's all plumbed.

 

Here I am complaining about problems and never even described my truck to you. So here we go! It is a 51 Ford F-5 with custom cab stainless and Big Job hood spears. It has a 327 Chevy with a 300 horse cam 1.94 valve heads,and Edelbrock Performer intake and a Holley 0-4776 1450 series double pumper. As for the trans its a Clark 5spd crashbox hooked to a Brownie 3 spd auxillary trans backed up by that 2 spd 10 lug no brake having rearend. As for tha paint it is patina green with hand painted door lettering from the 70s. I installed sprayable bedliner in the cab along with Autometer Sport Comp 2 5/8 gauges and the rear seat from a Astro van and have been working on the system C/D player in the glovebox with speakers in the custom kick panels. The bed is a Heil 3 yard dumper that was old when installed on this truck in the early 70s. The bed is actually from Gladding McBean Co in Lincoln CA and was wore out when the previous owner aquired it. This is the coolest Rat Rod I have ever seen. I actually use it for trash duty at my fab shop. Well Enough about the dumpster thanks for the input Eric

 

Hi Eric,


Tell us a little about your front and back brakes.

Do you have dual cyl brakes in the back and single cyl/single piston actuators in the front?


If I remember correctly, my "single" system runs around 700psi when you "mash" down on the pedal.....