disk brake problem

[a67and77]

Hey everyone, I have a problem with my front disk brakes on my 77. I have a low pedal that won't go away. I have replaced my master cylinder, proportioning valve, put gallons of fluid to bleed it and the fronts still don't work right :'( When I first start up the Bronco there the pedal goes to the floor and seems like after warming up and driving for a bit the pedal firms up and stays that way. No leaks anywhere. Could it be my calipers??? I'm going to go broke on brakes ?:?

 

[Jimmyjames]

Did you bench bleed the MC?

 

[a67and77]

bench bled the mc also. Spent days bleeding the brakes. Don't know what to do besides beating my head on the desk and drink beer ;D

 

[bobby]

did you check the brake booster?

 

[a67and77]

Replaced the booster as well, even adjusted the rod length. I think I'll just get drunk...My 67 has the original brake equipment with no problems.

 

[JTCamp]

Might check the rear brakes. Poorly adjusted rear drums can cause that problem also. Oh yes, and have one more for me <br><br>John

 

[a67and77]

The only thing I havn't done is replace the rear drums...I'll think I'll have a few more beers and some for you ;D ;D Thanks for the help. Hopefully I'll figure this out some day.

 

[hackyrat]

I agree with the rear brakes. As my rear brakes wear on the 76 the pedal free play increases until the rear are adjusted back up again. Pull a rear wheel and check lining before adjusting. My rears last almost forever but a check is easy and good to see lining condition so you don't go metal/metal.

 

[szjobby]

I would check the rear brakes for wear and adjustment, and replace if it needs it. But after that is done, if the problem is still there I would be replacing the front hoses to the calipers, especially if they're still original. And inspect the vacumn hose that goes to the booster, for possible vacumn leaks around the rubber grommet in the booster housing, where the plastic hose end goes in.

 

[ken75ranger]

sounds like a low vacuum problem since it does get better after it runs awhile. When you first start it up have a vacuum gage on it and see what it reads.

 

[2badrotties]

Sounds to me like the disc brakes are never going to work for you. Why not take them off and trade ME for some good old drum brakes. If you really did have all those beers this might not sound like a bad idea at this point ;D ;D ;D

 

[BwoncoHowie]

If the piston size/diameter in the master cylinder is too small, it could cause this issue. I don't have disc on my rig yet but I have heard of people using the wrong MC with the small bore size and having this problem. <br><br>When the brakes work are they overly touchy or sensitive?<br><br>BH

 

[a67and77]

I replaced the rear brakes a few months ago and re-adjusted them yesterday. I replaced the front rubber lines to the calipers about 5 months ago with ss braided lines. I'm thinking that it may be my rears as all of you suggest. Oh, another thing, the fronts work great when I apply brakes going in reverse but not forward. Go figure ?:? Today I'm going to check the wear limits on my rotors and drums causing the pedal travel. Another thing is maybe the parts store gave me the wrong mc for a drum brake set up...Oh, at times when the brakes are working really good they do get touchy and hard.