They're suposed to be self adjusting. IIRC you had to keep pressing/releasing the pedal in reverse to adjust.

I always adjust when doing brakes. You should feel slight drag on the drum without the wheel on if they're adjusted properly. If there's no slight drag then they're too loose as ardwrkntrk said. And your using most of the pedal travel just to make the shoes touch the drum

 

The rear brakes are "self-adjusting" however the mechanism does not work very well. For best results, you should ALWAYS adjust your rear brakes by hand. There is no substitute for doing them yourself.

The brake system on these trucks isn't very complicated. If the pedal goes right to the floor then the first thing to look at is the rear brakes. If they are adjusted correctly and the pedal still goes to the floor it could be the master cylinder or the pushrod nut. If someone swapped the booster and didn't put the nut in the right place the pedal can go right to the floor before it engages the brakes.

If the pedal catches but slowly sinks to the floor then there is either a leak or the master cylinder is shot.

 

it doesnt catch i hit pedal and it goes right down..no leaks keeps fluid well.. ive never messed with drums but my uncle has a 79 f250 ill ask him to come show me and have him help me with the bleeding..update hes coming next week we are gonna take everything off adjust and flush brakes

 

The drums aren't hard. There's a little slot on the back side of the dust shield that you can fit a flat screw driver in I manually then the spur on the adjuster. I you pull a drum off you can see what I mean (make note of what dorection you have to turn it to expand the adjuster. One sside is LH thread but i dont eemember what side. Should be adjusted untill there's a SLIGHT drag when turning the drum.

 

The adjusters only work if you're backing up and stopping hard.
And they didn't really do a good job when brand new,.... 23 years later???

If the rotors are as warped as you say (pulsing) then there is no way that the pistons and pads are even close to touching when your foot is off the brake.

The master cylinder only displaces so much fluid.
What happens if you pump them slowly, at a stop with the engine running?
The shoes will be pulled back by the springs but the pistons will remain extended.
If it is any better, replace the warped rotors.
If it doesn't fully cure the low pedal, then adjust the rears as well.
It may well be that the adjusters are completely seized and you will need to disassemble or replace them.

 

the rears have over half left and where adjusted and cleaned less then a year ago when i put the new parking brake lines on and the pedal still went to the floor not as bad as they do now but ill have to replace the front rotors and bleed everything then if its still doing it ill replace the MC and if its still doing it im gonna scream lol i found 2 brembo rotors new for $57.57 with shipping is that a good price

 

Last time I bought rotors for my truck they were over $200 each....

 

what brand? ive never had to buy rotors for a big truck i wanna be able to stop i live in the blue ridge mountains north carolina its very curvy and high and my aunt also just got a 20 foot camper i wanna be able to take sometimes and the only place to go is over 2 mountains and 45 min away

 

It's been quite a while, I don't recall. But I do usually get jobber pricing.

Of course that didn't include 8 new wheel studs per side, or anything else either...

 

ok new update i just figured something out i was taking out the bench seat but got into the truck to move it.. tried to start it and it was idling rough i went to hit the brake to move it and when i pushed the pedal to the floor the idle started smoothing out everytime i pushed it down it would smooth out so maybe it is a vacume leak anyone have an idea?? o and also if i push down hard on the pedal like if i kick it down i do get pressure for a sec and then it seems to go away

 

well i just thought of this sitting here trying to think of what it may be i remember my buddy took off hose to booster and it put thumb over hole and i had some pressure and i never thought to take off check valve.......?nm went out not check valve its working

 

If it's hard for a second and then the pedal drops the M/C is bypassing.
I'd suggest you replace the Master/Booster as a unit and bench bleed before installation.

 

Very interested to see what you come up with on this. I'm having the same issues. I have horrible brake pedal sag, changed the mc 5 months ago, changed the rabs valve two months ago, flushed the system, changed some parts on the rear breaks along with pads, and I still get the sag, and as well have absolutely no parking brake.

I'm gonna check it tonight and see if I can adjust the rears.

Not sure about the booster nut you're talking about. I do hear a plunge sound coming from the mc area when I brake sometimes too. That can't be good right!?! I did bench bleed it before i put it in.

I'm kind of stumped too, and all I can say is, it's scary when you have your family in the truck! Very nerve wracking!

 

A sinking pedal could be from a bypassing MC, leaking wheel cylinders, air in the lines, or a bad ABS unit. Take a good careful look at where the MC bolts to the booster. Is it damp? If so, the MC is leaking, and there is most likely fluid getting into the booster. As mentioned, adjustment of the rear brakes is critical. Having badly warped rotors is an indication that the front brakes have been working harder than they should.

Replace the pads & rotors, inspect the calipers for leaks around the pistons and for damaged seals, and lubricate the slides and bracket where the pads sit. Go to the back, take the drums off and carefully pull back the boots on the wheel cylinders. If they are frozen or leaking, they need to be replaced. If the shoes are saturated with fluid, they need to be replaced. If all looks well, spray everything down with brake cleaner, lubricate the adjuster and adjust until there is some slight drag. Flush the entire system, brake fluid is hygroscopic, meaning it absorbs moisture from the air.

Here are some more advanced tests:

Get 3 line clamps specifically for clamping off hoses. DO NOT use vice-grips. Clamp off all three brake hoses. Don't go wild making the clamps gorilla tight, you can damage the inner layer of the hoses. Press the brake pedal. This tests the MC and the steel hydraulic lines. If the pedal sinks, there is a leak in a line or fitting, or the MC is bad.

Remove one clamp at a time and repeat. First the rear, then re-clamp, LF, re-clamp, etc. This is a process of elimination. The key is proving that components are good, instead of immediately condemning them. This saves time and money vs throwing parts at the problem and hoping.



Carver- Did you get a reman MC or a new one? I've seen two consecutive MCs be bad out of the box, both Cardone remans. I always insist on new when available.

 

I'm pretty sure it was new. I'll have to look at the receipt though. I have it at home. I don't like reman anything. That's a whole other rant on its own I won't go into here.

How would I tell if it was bad? Is there a specific test to perform on it?