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Rear Disks now soft pedal**UPDATE(6/7)**... Help!

today i opened up both rear bleeders very very slightly, just enough to get a slight trickle of fluid flowing, and gravity bled mine. Let them do that for 20 to 30 minutes. I closed them up and checked the pedal, and it had much better pedal response. Ill start it up tomorrow to tune the engine, and check the pedal while its running. Im hoping this solved my troubles.
 
robert97dodge said:
Just curious if you push the brakes and the pedal goes to the floor and then you push them again does it have a better pedal or does it go to the floor again? When I swapped to disk in the rear on my old 14BFF I would have to push it and then the 2nd time I got a good pedal. It is because the rear requires more fluid with the disk. With the residual valve it will hold just a little bit of pressure on the lines so that you dont have to pump it.
Click to expand...

With the booster the pedal doesnt really build pressure at all.
 
Citizen Rider said:
today i opened up both rear bleeders very very slightly, just enough to get a slight trickle of fluid flowing, and gravity bled mine. Let them do that for 20 to 30 minutes. I closed them up and checked the pedal, and it had much better pedal response. Ill start it up tomorrow to tune the engine, and check the pedal while its running. Im hoping this solved my troubles.
Click to expand...


Sounds good. Yeah mine feels good until you start the truck.
 
After barely opening them and gravity bleeding the rears. I have an awesome pedal. Even was able to drive it home tonight.
 
You need residual valves on at least the rears. The run out in the rotors pushes the piston back in. The residuals will help prevent that. Other option is bigger bore to get more volume. Problem is the bigger the bore the harder the peddle.
 
i took out the residual valve in my master,and it seems to get better pressure to the rears.it would hold the calipers to the roters a lil too, so that is why i initialy took it out.i still have the stock master from 1972,with no problems with pressure to the brakes.it is different from yours,so maybe different internally also,but im glad you seem to have figured it out somewhat and have a good pedal now.
 
Grim-Reaper said:
You need residual valves on at least the rears. The run out in the rotors pushes the piston back in. The residuals will help prevent that. Other option is bigger bore to get more volume. Problem is the bigger the bore the harder the peddle.
Click to expand...

I havent even driven the truck and the rotors are brand new. This isn't a run out issue. But I'm leaning towards the master cylinder being the problem. I thought it was a 1 5/16 master though (biggest)
 
Cover off, engine off. Just barely crack the rears enough to get a small trickle of fluid comin out, so it drips every 5 seconds or more off the brackets. Let it do its thing for 30 min. or even more if youve had alot of trouble. I let mine sit for about 40 min.
 
Did you end up getting a new master cylinder too or did just the bleeding fix yours? I'll have to try it this week sometime. It was a bit "cold" and windy yesterday and I had some other things to do. I'm still waiting to here from Gabe on how his pressure bleeding went.

I've got a new question now though. IF I were to have a leak that was sucking air into the lines wouldn't I be leaking fluid or eventually loose my pedal completely?
 
I will let you know as soon as I have a chance to try the new brake machine. As far as sucking air in and not leaking, It is possible. I have seen it a few times. It is usually at the fittings.
gabe
 
here is the machine

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So, did you ever get the brakes fixed? If so how did you fix them?

Mike
 
I havn't fixed them yet. I've had the front axle out of the truck for a while now waiting on some parts so the brake job got put on hold a little bit. I dont have a pressure bleeder and really dont wanna go though the hassle of making one becaue I really dont think thats the problem. Theres nothing "different" about this system that it shoudnlt bleed normally. Its actually simplified without the confluence valve. I'm going to try another master cylinder next. Im also really curious if not having the confluence valve has something to do with it. I will try a inline residual pressure valve after the master cylinder.
 
Tell us how you fixed it when you do.

Thanks,
Mike
 
Ok, so I finaly got the truck driving under its own power a little bit and found that the brakes lock up HARD. didn't go tearing up the lawn but feels like the back brakes are locking first at about half pedal travel but I can push the pedal all the way to the floor. I've got an idea but, What do we think now boys???
 
You don't want your rear brakes to lock up first. You want your fronts to lock first and then your backs

Sorry, but I got lost in the posts - Did you replace the proportioning valve?

.
 
Yeah the whole stock combo valve is gone. I'm thinking I need residual pressure valve in the rear and a proportioning valve. I'd like to get a firmer pedal and all i can think is the pads come too far off the rotors.
 
If you have installed rear disc brakes and the master cylinder was designed for a disc/drum set up - your problem may be that your master cylinder does not have a fluid restrictor on the master cylinder. Disc brakes maintain 80psi on the line to prevent the disc cylinders from fully retracting. Your MC may only have one restrictor ( for the front ). See if you can obtain a second restrictor from an old MC. I believe they were installed right at the brake line fitting. When installed and the system rebled you should have plenty of pedal.
 
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