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Have a '77 with disc front and drum rear. Duff power brake booster and just reinstalled the proportioning valve. I have zero leaks and bled the system per the tech manual to include pulling the front bleed pin of the proportioning valve.
The truck will stop but I have a LOT of pedal movement. The movement is not linkage slop and the push rod is also finely adjusted. If I slam on the brake I do not lock up or halt with a quickness like I should.
I noticed, when bleeding (one man kit) That it took about 13 pumps to fill the little 5oz canister on the right rear whereas the rear left took about only 5. Same thing with the front. Front right about 3 and front left about 10 pumps. Not sure but that seems weird to me.
Vacuum is good and pretty confident I got all the air out so does anyone have some troubleshooting suggestions for me?
-Mike
'77 351w- Explorer EFI, 4R70W, 4-link, lockers, 4.56, 35" MT/Rs with a severe rock addiction. mokin:
Roads? Where we're going, we don't need roads.
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Did you bleed them in the right order? Farthest from MC first?
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The other thing that will do this is the back brakes are not adjusted yet.
If you have self adjusters in the back, back up and hit the brakes a few times to adjust them.
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Bled back right, back left, front right, front left.
Didn't adjust the rears but will do that too. Just thought the front would give me more stopping power regardless of the adjustment of the rears. Guess not. Let you know what happens tomorrow.
Thx.
'77 351w- Explorer EFI, 4R70W, 4-link, lockers, 4.56, 35" MT/Rs with a severe rock addiction.mokin:
Roads? Where we're going, we don't need roads.
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Ok. Adjusted the rear drums. They were pretty bad and even had some of the linkage sitting in the drum on the right side. Fixed all that and now.... I don't go to the floor on the pedal but I have no braking action until the halfway point on the pedal and then I have to really give it a LOT of force to coast to a stop.
The amount of travel past the halfway point is minimal 10 degrees or less I would say.
Basically my brakes feel exactly as they have for the past 8 years. No change with the addition of the proportioning valve or the adjustment of the booster.
HELP! I want brakes.
'77 351w- Explorer EFI, 4R70W, 4-link, lockers, 4.56, 35" MT/Rs with a severe rock addiction.mokin:
Roads? Where we're going, we don't need roads.
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Does the pedal get firmer if you pump it or does it always stay mushy till half way?
How did the rear linings look? Could they be glazed?
Did you just add the duff booster?
I think at this point I would bleed the master cyl and then bleed all the lines again.
What you are describing sounds like air in the lines somewhere, maybe the master cyl.
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They may be somewhat glazed. The booster is a new replacement for the one I removed when troubleshooting this problem 6 years ago so I assume it is good. Plus, I get much more pedal advantage when bleeding the brakes when the booster is getting vacuum.
I bench bled the Master Cylinder but can't hurt to bleed it all again.
I will have to take the truck out again to answer your first question.
'77 351w- Explorer EFI, 4R70W, 4-link, lockers, 4.56, 35" MT/Rs with a severe rock addiction.mokin:
Roads? Where we're going, we don't need roads.
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Chuzie,
Man I feel your pain... I think my Bronco brakes are very similar to what you describe. I have bled them a couple of times and they are still not correct... Okay to drive, but not what I think they should be based on the amount of pedal movement required. Keep us posted.
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Yep. I can drive so long as I keep my distance and keep and eye far enough ahead but the straw that broke the camel's back was at the Gulches a couple months ago when I could not ride a couple of the trails because of my lack of effective brakes. I WILL fix this problem and never be denied because of them again.
'77 351w- Explorer EFI, 4R70W, 4-link, lockers, 4.56, 35" MT/Rs with a severe rock addiction.mokin:
Roads? Where we're going, we don't need roads.
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I'm guessing when you bled your brakes, you pumped them up and bled them at the wheel? Have you tried gravity bleeding? Uncap the reservoir and open the right rear bleeder. Let it drip for 5-10 minutes while keeping the reservoir full. Then move to the next and so forth.
Also do you run braided or rubber hoses?
What master cylinder are you running? The F250 for dual piston calipers has a larger piston and moves more fluid requiring less pedal pressure.
Is there any free travel in the pedal linkage or bell crank assy?
'72 TBA...
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