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Unread 08-25-2013, 06:02 PM   #1
pmm_lord_raven
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87 yj brakes intermittently dragging/seizing

Hey,
I have an 87 yj. I had issues with not being able to drive much over 40mph. I took the front brakes apart and my rotors were warped and pads cracked to hell. I replaced the calipers, and pads, and rotors.
It was still dragging. I went to replace the hoses, and couldn't get them off the lines. So I replaced the brake lines and hoses to both sides. I flushed the fluid but the problem still happens, sometimes when I hit the brakes too many times, it will go from normal to rock hard. Other times right away. But here is the weird part...they were dragging wicked bad today, and when I pulled over I went over the rumble strips the brake pedal went from rock hard to normal, and they stopped dragging. I relubed the caliper pins, and drove it around. It was fine for a little and then same story, dragging again. I went and hit a few potholes and still dragging. Back to rumble strips and they released.
The proportioning valve was replaced 2 years ago along with the rear wheel cylinders, lines, and shoes. I have no freakin clue what my problem is. Any suggestions?

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Unread 08-25-2013, 06:14 PM   #2
jokerchief462
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The fact that they go from rock hard to normal and were dragging I would say the brake booster has failed.

Sent from underneath my Jeep
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Unread 08-25-2013, 06:15 PM   #3
pmm_lord_raven
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I should clarify, when the pedal went normal the brakes did stop dragging. And when the pedal was hard, it didn't take much effort to slow down and stop. I disconnected the vacuum line to the booster, and my brakes still drag. But I did notice something.
20130825_194207.jpg   20130825_214248.jpg  

Last edited by pmm_lord_raven; 08-25-2013 at 08:09 PM..
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Unread 08-25-2013, 10:01 PM   #4
ReDinTX
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Looks like the master is leaking.
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Unread 08-25-2013, 10:58 PM   #5
pmm_lord_raven
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Would that cause the brakes to drag?
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Unread 08-26-2013, 02:32 AM   #6
Mark05059
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change both the booster and the master cyl.
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Unread 08-26-2013, 03:37 PM   #7
ReDinTX
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Quote:
Originally Posted by pmm_lord_raven View Post
Would that cause the brakes to drag?
if theres trash in there that causes the piston to hang up, yea. fluid is turning black cause its absorbing LOTS of moisture because its leaking out which means moisture is getting IN.

Quote:
Originally Posted by Mark05059 View Post
change both the booster and the master cyl.
I agree
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Unread 08-26-2013, 10:16 PM   #8
jbolty
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if the piston in the master can't fully return it will accumulate pressure and start dragging. The same thing happens if the push rod from the booster is adjusted too long.

good time for a dual diaphragm upgrade
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