I have a 53 F-500 (two wheel cylinders each side in the rear) with stock brakes. When the brake pedal is depressed it goes all the way to the floor. If it is depressed again it feels fine and stops the truck very well and holds very well with no bleed down. If I wait five seconds and try, it again goes to the floor. The master cylinder was leaking bad so I put another on but got the same results. I bled the system till I got clean fluid and no air. I did this myself as I have in the past by pumping the brake pedal up then put a stick on the pedal against the seat to hold it down. I also adjusted the brake shoes out till they drag and back them off a few notches. All these things worked fine in the past. What is going on? Wait, I just had a thought. Should I adjust the linkage going to the master cylinder a little longer? What do you think?
Do you have a remote booster mounted on the frame, or just a straight nonboosted system? Bleeding your rear brakes is a 2 person job - I found this out chasing the same problem you are. Get a helper to work the brake pedal. If you have the frame mounted booster, bleed it. Then have your helper pump up the brake pedal and hold it with as much force as possible Then you can open a rear bleeder as wide open as possible to get a strong stream of brake fluid. Do this several times for each rear wheel and you should be OK. The tube routing for the rear wheel cylinders tends to hold air unless there is a really strong stream of brake fluid exiting the bleeder fitting, and I have found that vacuum bleeding and "one man" bleeding just do not work.
I agree that the only satisfactory way to bleed brakes is with two people. Surely you can find somebody to help. I've even had my 6-year-old work the pedal. I do, however, believe that norvillebob may be on top of your problem. If there is excessive shoe-to-drum clearance, the hydraulic system has to move enough fluid volume to push the shoes out until they contact the drums so that the system can build pressure. With six wheel cylinders in the system to fill, it can conceivably take one full stroke of the master just to move the shoes out to the drums. When you release the pedal, it grabs another lung full of fluid from the reservoir and allows pressure to build on the second stroke as long as you get back on the pedal again before the shoe return springs have had a chance to pull the shoes all the way back.
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Make sure all the bleeder screws are at the top. I have not ever seen this 2 cylinder set up. but is it possible that the cylinders could be bolted on upside down?Also if you put a hose over the end of the bleeder screw and place the other end of the hose in a contanier with brake fluid in it you can loosen the bleeder off and slowly pump the brakes and bleed them yourself. The hose in the contanier will not let air back into system when you let the pedal up because it is in the fluid.
On the old Ford mediums that have two wheel cylinders on each rear, the bottom cylinder is the one with the bleeder on the ones I have seen and worked on. They came that way from the factory. Why? I do not know. But you can bleed the air out doing it the way I posted earlier. If you want to redo things, you can, but you may have to make new axle tee to cylinder lines and do some bending of the line between the cylinders. I thought about doing that until a mechanic with much experience on medium and heavy trucks set me straight on the bleeding procedure.
Danny D
In the event your brake system includes a vacuum booster set-up (Hydrovac), there is a procedure on how to bleed them posted in the Tech Folder in the Large Truck section of the FTE Forum: http://www.ford-trucks.com/forums/89...ke-system.html
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Bob
'48 F6.5 (under development)
'62 641,
'00 F250 7.3L, '09 Fusion
'01 FLHT
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