I looked and looked, but time is running out here tonight. So I gotta ask.

79 F250, 4x4, dual piston calipers, 2 1/2" wide rear shoes. The brakes never worked when I bought the truck. Had a pedal when the truck was off, start it up, and straight to the floor. Well we found that, brake line was spewing. Well, got new shoes/pads on the truck, new MC (thought that is what the problem was before i found the leak). The shoes are adjusted perfectly, have checked and rechecked and checked again(too tight if anything now). I can't find any more leaks, and the level in the MC doesn't drop.

My problem now is that when you hit the brakes, you have to pump them up 3 times or so before you get a pedal. The first couple times it goes straight to the floor, then it firms up. Let it sit for 30 sec or so, and it goes right back to it.
If you stand on the pedal (and it doesn't die, but thats a whole other problem), the pedal doesn't fade. It stays firm and about 1/3 of it's travel.
I've bled everything as much as humanly possible.. Cept for the LR wheel cylinder, bleeder is broke off, but bled it at the brake line fitting. (thats where the leak was to begin with). The wheel cylinders aren't leaking.

What else is there? I bench bled the MC before it was put on, but is possible i screwed that up I guess. ?? Any suggestions?

Matt

 

While someone slowly depresses the pedal.
Take the cap off the M/C and see if there is any bubbling in one of the reservoir's when this happens.

It is still probably a bleeding problem.



Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
[i][font color=red]Calgary,Alberta,Canada[/font][i]
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Hate to say it but....sounds a whole lot like there is still air in the system.
One other thing I can think of right now is bad/soft flex lines to the front calipers. If they are real bad they can buldge out and feel a lot like air as the line expands. Only seen this once or twice....but I guess a third time isnt to hard to beleive

Sparky

 

make sure there arnt any leaks in the calipers, lines or dums and bleed your brakes

 

Pull MC off and adjust the rod behind the MC a 1/4 turn longer. Hope this helps.

 

If you have to pump up the brakes to get a good pedal, it sounds like you have a bad master cyclider. Even though its new, doesnt mean its good. It sounds like youve doen a good job bleading the air out of the lines. I've worked in a parts store for alot of years, and beleive me, its not uncommon to get a bad master cyclinder.

 

Well after much screwing around and desperation.. We got it working.. Mostly. Theres still LOW pedal, but it works.. You don't have to pump them up anymore.

Got there by putting the old MC back on after bleeding the heck out of it, and putting on new wheel cylinders.

I think alot of it has to do now with bad hardware (springs) in the back cuasing the shoes to change adjustment after you adjust them out...

We ended up having a BAD vibration after 50mph also.. The driveshaft was the wrong length.. That sucked, had to have it retubed at $160..

Then, getting the distributor unstuck (hammers and pry bars.. and then a new dist)..

Well, it runs now.. Not decently, the carb is shot, but it can be driven back and forth to work!