Brake issues
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Freshman User
Joined: Sep 2015
Posts: 38
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Brake issues
I just bought a 78 f150, and when running, the brake pedal gets sucked in. It releases a bit when the throttle is revved. Plus, the brakes are very weak. I've checked the vacuum hose that connects to the booster (pulled it off) and it has plenty of suction. Brake fluid in the MC is full. No leaks. Any advice? Truck is not driveable. Thanks!
Fleet Mechanic
Joined: Feb 2010
Posts: 1,742
Likes: 5
From: Near St. Joseph,MO
I'm having the same issue with my truck after rebuilding. New MC, new lines, new calipers, new rear brakes. I've bled it three times and all is well, but as soon as it's running and I press the pedal, it stays put.... aggravating
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
That's a sign of a booster not releasing vacuum after it has been applied.
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
That's what mine was doing.... I could barely drive it around the block because the brakes were locking up. Right after a drive, I'd jack it up and it required significant effort to spin. Let it sit a few hours and the applied vacuum would bleed off and act "normal" where I could spin the front wheels with ease.
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
Yep.... Likewise.
Welcome to the club. I wasn't the first member and you certainly won't be the last.
Welcome to the club. I wasn't the first member and you certainly won't be the last.
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Freshman User
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I assume I can just bleed from rear right, and move on up? Anything special about these models?
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5th Wheeling
Joined: Mar 2015
Posts: 30
Likes: 1
From: Metro Atlanta
Does this apply to me as well? I have to stand on the pedal to get the truck to slow down. So, just replace the booster (get the one with MC already attached), and bleed the brakes?
I assume I can just bleed from rear right, and move on up? Anything special about these models?
I assume I can just bleed from rear right, and move on up? Anything special about these models?
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
Does this apply to me as well? I have to stand on the pedal to get the truck to slow down. So, just replace the booster (get the one with MC already attached), and bleed the brakes?
I assume I can just bleed from rear right, and move on up? Anything special about these models?
I assume I can just bleed from rear right, and move on up? Anything special about these models?
Be doubly sure the rod between the booster and the MC is property adjusted.
Bleeding is always RR, LR, RF, LF.
Lead Driver
Joined: Apr 2011
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From: El Dorado, Arkansas
Fleet Mechanic
Joined: Feb 2010
Posts: 1,742
Likes: 5
From: Near St. Joseph,MO
I can see how having the rod too far out would hurt,, it could keep the rear seals from seating and always allowing air to bleed into the chamber. I'll check it and see if that solves the problem. thanks for the link ultra.