brake problem
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brake problem
hey everyone. i need help!! i have a '79 f 150 4x4 supercab with a 400 in it. i am having major problems with my brake system. when i push the brake pedal in to stop, it goes all the way to the floor and you can feel the whole truck kinda pulsate as i eventually come to a stop. so far i have installed a new master cylinder, replace a worn brake line, new pads about 3 months ago. i dont know what else it could be. i was thinking the calipers, but what are the chances of both of them going bad? any info will be greatly appreciated.
thanks
jeff
thanks
jeff
Elder User
Joined: Nov 1999
Posts: 796
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From: Anderson Northern Ca
Brakes gone
Jeff,are you losing any brake fluid?Did you bleed all the air out of the system?Check to make sure there are no leaks at the wheel cylinders.If no leaks are seen and no fluid is lost then my first guess is the master cylinder was not bench bled or is defective and is moving fluig back and forth between the cylinder and the rod boot.Hope this helps.
"bowties in the rearview mirror'
"bowties in the rearview mirror'
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hey nod, yeah, i checked everywhere for leaks and found none. i bled the entire system real good after changing the line.and about the master cylinder, i keep hearing bench bleed. im not exactly sure what that is, but i did bleed the master cylinder according to my chiltons book.i loosened each line and pressed the brakes, closed them and released the brake. i did this until a solid stream ran out. i hope that is bench bleeding.if not please let me know. im dyin here. thanks for your reply.
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From: Boise, ID
chmuraman, it sounds like you need to bench bleed the master cyl. You can do this on the truck to save the trouble of pulling it off.
You new M/C should have come with two little fittings to screw into the brake line ports. You'll need these or something equivalent.
Basically, what you need to do is run hose from the brake line fittings on the M/C into the reservoir making sure they stay submerged in fluid throughout the process. Once your hoses are attached, press the brake pedal slowly a few times until no bubbles come out of the hoses. Reattach the brake lines to the master and bleed the system at the wheel cylinders like you already did. This should purge the air from the master and let you truly bleed the brakes.
You new M/C should have come with two little fittings to screw into the brake line ports. You'll need these or something equivalent.
Basically, what you need to do is run hose from the brake line fittings on the M/C into the reservoir making sure they stay submerged in fluid throughout the process. Once your hoses are attached, press the brake pedal slowly a few times until no bubbles come out of the hoses. Reattach the brake lines to the master and bleed the system at the wheel cylinders like you already did. This should purge the air from the master and let you truly bleed the brakes.
Post Fiend
Joined: Jun 2002
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From: Atlanta GA
I see no mention of rear brakes. Make sure your rear brakes are properly adjusted, bad or improperly adjusted rear brakes will make it seem like stopping takes forever.
If 1979 still uses a centralizer/equalizer valve, you may have to reset it by bleeding the rears right after bleeding the front. It might have automatically cut off the front brakes when there was pressure loss and only your rears are operating. Which could cause a shaking of the truck as the rears grab unevenly.
My biggest question would be were the rotors turned? If you replace just the pads on worn rotors, you are likely to encounter a shake or pulse under heavy braking. Especially if they had a bad groove in them.
If 1979 still uses a centralizer/equalizer valve, you may have to reset it by bleeding the rears right after bleeding the front. It might have automatically cut off the front brakes when there was pressure loss and only your rears are operating. Which could cause a shaking of the truck as the rears grab unevenly.
My biggest question would be were the rotors turned? If you replace just the pads on worn rotors, you are likely to encounter a shake or pulse under heavy braking. Especially if they had a bad groove in them.
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hey everyone, thanks a million for all of the replies. im gonna check the rear brakes and i am going to bench bleed it like mudder explained it. i will let you know the outcome. once again, thanks a bunch for all of the replies. the old beast thanks ya too.
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hello all, well, here is what i did. i went and got a brand new master cyl. benh bled it, bled my system. problem still ther. im goin to try rebo's suggestion and see if that works. if not im gonna have to take and have the rotors turned. we will see
