I have a 74 f250 and I was just wondering if anyone knew if the master cylinder for a all drum setup is different than for a front disc setup. I was told that the disc M/C has two different size reseviors, and the drum M/C should be both the same size. I am not sure if this is right, I am having trouble finding a M/C for a all drum power brake setup, right now I think I have a disc M/C in the truck from the previous owner and I have basically no brakes, when I press the brake pedal I get a hard pedal then it gets soft then real hard again and I have no stopping power, even at an idle. The only other thing I can think of that might be wrong would be the distribution block, maybe that valve is hung up inside?? If anyone has any advice I surely will take it!!! Thanks, Jack

 

I have a '79 F100 with non-power brakes. the front are disc and the back are drums. yes, you are correct the reserviors are different sizes. I know this seems backwards but the small section is for the back brakes and the big section is for the front brakes.

are you brakes line "bleeded"? if not here's what you do. you will need 2 people for this process. all you will need is a cresent wrench.

put one person in the cab and you get under the truck. right by the brakes under the truck there are things that look like big grease fittings. loosen it just a little bit. tell the person in the cab to step on the brake pedal 4 times. every time that they step on the pedal air should be released. on the 4th time they are pressing the pedal loosen the fitting all the way 'til all of the air is gone, NOTE: don't take the fitting all the way out. the brake pedal should go nearly all the way to the floor. tighten up the fitting. do this for all 4 brakes. make sure that you fill up the master cylinder after every wheel or no brake fluid will be added to the brakes.

I hope that this helps, good luck!!!!

 

OK a cresent wrench on bleeder valves that sounds like a good way to strip them. Might I say most bleeder valve sizes 3/8 with a few odd ball sizes every now and again. Use the correct size wrench. Ok secondly the bleeding instructions sound a little off to me. If you crack the bleeder valve and then pump the brakes you will actually suck air in the system. Pump the brakes four or five times keep pressure on the pedal then crack the bleeder valve when the pedal goes all the way to the floor tighten it back up. Watch your eyes fluid will rush out. As DIRT said add fluid after each time and do this on each wheel till air free fluid comes out. Before bleeding you may want to crack each bleeder then tighten it back up just to make sure they come free. And if you have all drum set up wheel cylinders might be leaking a bit.

 

Sorry to make you guys do all that extra typing, but, yes I have bled them, I am gonna do them again tomorrow though, just to make sure that I don't have any lingering air bubbles. Jack

 

One other thing you may want to do is bleed the M/C as well.

 

Thats a good point, but when I hooked everything up the M/C was full of fluid and I never pumped it once the lines were off, I was thinking that the air would probably get bled out during the normal bleeding process?? Oh by the way, i had the lines off due to replacing the cab in case anyone was wondering.- Jack

 

Sounds to me like you have air in the lines mainly but ALWAYS bleed the M/C if you remove the lines. Doesn't take much for an air bubble to develop. Good Luck

 

Yea, thats what my Uncle was saying too, thats why I think I am gonna bleed them again tomorrow, also, I just did some research and as it turns out, my M/C is the correct one for my truck, apparently Ford did some strange things with their braking systems in the 70's lol, I have looked in several places and the only master cylinder for my truck that has the same size reservoirs and is for all drum is for manual brakes, if it is power drum brakes it has the M/C that looks like a disc/drum setup, so I am going to say that I have the right M/C in my truck and move on. I may be wrong about this and please correct me if I am, but I have searched high and low and I can't find a M/C for power drums that has eqaul size reservoirs, only for manual brakes. Anyway, I am gonna bleed the brakes tomorrow and I will let you guys know what I come up with---------Jack

 

I was having brake problems on mine as well. Mine would go all the way to the floor but would catch at the bottom. When you changed the MC did you notice the small adj. screw on the end of the piston plunger going into the MC? Always use a boxed end wrench to bleed brakes. Always pump then hold then loosen bleeder screws.
You are correct about the MC res. too. youll not find one with equal chambers for Power drum brakes.

 

There are certain things that I go to a mechanic for. When my A/C is not working, when I can't get brakes working (after regular work, of course), or if I have a phantom problem it goes to a shop. I've spent too much time and money on crazy problems, I'd just as soon have specialists with tons of expensive tools and people to help them fix my problems.

 

This all depends on your experience level. If my 2003 Powerstroke has a problem, I'll take a look at it, but I usually end up taking it to a shop for repairs. If my 74 F250 has a problem, I'm confident that there's not a mechanic around here that knows more about my truck than I do. It would be a total waste of money for me to take it to a shop. I'm an old dude, and I've been working on old Fords for 33 years. I build my own motors, paint my own vehicles, set up my ring and pinions, and even started building my own automatic transmissions. I know every part that is in/on my truck, including inside the motor and tranny, but I'm almost lost when I open the hood on my diesel?.

Brakes are very simple, there are only a couple of components that can go bad. If you have power drums (like I do on my 74), your master cylinder should have 2 different size reseviors. The master cylinder should be bled, but any air in the master cylinder should bleed out when you bleed the brakes, it just takes longer if the master cylinder is not bled. Sometimes if you don't bleed the master cylinder, you have to pump the pedal like crazy to get it to prime. It sounds like your master cylinder is pumping fluid so I would bleed the brakes completely, remembering to start at the wheel farthest from the master cylinder. Always have the bleeder vavle closed when you let the pedal back up, or you can suck air back int the lines. Let us know what happens after you bleed them again.

 

Ok, I bled the brakes again today and I have a pedal now and the truck acts like it wants to stop lol, just kidding, it actually does stop the only thing is, is that I am just about standing on the brake pedal even at idle. So, now I am after a problem with the power brake booster, I popped the vaccuum line off of it when the truck was off, and it wasnt holding vacuum, then I did it again later and it was holding, so I dunno what the heck is going on with that. I figured I would check the vacuum with the line off and the truck running just to make sure my line wasnt clogged or something like that and I had plenty of vacuum. So I am figuring either the booster or the check valve is bad. When I push the brake pedal it doesnt feel like it has power brakes, it feels like trying to stop a car that has power brakes and isnt running, rock hard. As for the rest of the brakes, I have a wheel that keeps locking up when the truck sits, I actually have to hit the gas to break it lose and it happens all the time, so I am going to pull the drums off the truck all the way around and replace everything, with the way these brakes are, this truck is a deathtrap lol. I really don't know the condition of the drums and pads etc, the truck sat for a long time so maybee the drum linings are rotting or something, it would match everything else on the truck!! So anyway, thats my story for today. Jack

 

yeah, I would replace the booster. that's what is probably wrong with the brake system.

 

but, it could be worn out drums and brake pads. you never know!!!

 

Thats exactly what I was thinking, but I will find out this week when I start taking things apart, oh and another question, do I have to take the front hubs apart to get the drums off? Jack