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Old 08-26-2013, 08:06 PM   #1
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Yj brake system barely builds pressure

So I'm having a brake issue that I'm about to pull my hair out over. I can't get the brake system to build pressure and they only slow the jeep down when the pedal hits the floor. It has a 8.8 rear end with new calipers, fronts have new calipers as well, new brake booster/ master cylinder (which was bench bled). There are no visible leaks in the lines and when bleeding the brakes I get a solid stream at all four corners. The only thing I haven't replaced in the system are the lines and prop valve. With the engine off the pedal will get stiff but not rock hard. Any ideas to why there is a lack of pressure?

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Old 08-26-2013, 08:07 PM   #2
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Oh and the bleeders are on top

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Old 08-26-2013, 08:32 PM   #3
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Gravity bleed a bottle through it???
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Old 08-26-2013, 08:58 PM   #4
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I've gravity bled them and the standard 2 person method starting farthest away from the master and working to the closest and still no pressure. I'm gonna go to the junkyard and try another prop valve before my last resort of redoing the lines
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Old 08-26-2013, 09:04 PM   #5
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There has to be fluid ether escaping out or air in the system to get a soft pedal. I would go through and bleed untill you get a consistant stream of fluid MULTIPLE times. I usually do 3 to 5 times at each wheel with a steady stream. Sometimes air is farther back in the system and it my not spit at you. If that does nothing I would say double check everything in your brake system and try a gravity bleed.
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Old 08-26-2013, 09:09 PM   #6
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The vacuum bleeders remove all doubt about air in the lines. Most shops will do it for cheap.
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Old 08-26-2013, 11:28 PM   #7
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In some of the 8.8 threads they talk about the proportioning valve. Some said they removed the o-ring on the piston in the proportioning valve but no one said which o-ring so it must be the one in the middle. I am in the middle of the swap and still have to install the master and bleed the system. I took the metering rod out of mine and cleaned it up look at the o-ring but left it on.

Some other threads I read said to get a proportioning valve out of another model Jeep with disc brakes and no ABS. That would give you the metering for four disc brakes and no ABS will leave another connection on the body of the valve so you it would be a straight swap.

So I have a few decisions to make. But then a few more threads there was guys locking up 35s no problem with standard equipment in their YJ.

So I have no real answer for your issue just sharing some ideas for you.

I have a problem with the emergency brake cables that came in the kit for ECGS the passenger side is about 1" too long when you get it to the single pull on the drivers side. Let me know how you hooked your up and where you got the cables. Thanks.
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Old 08-27-2013, 08:36 PM   #8
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Well got em working pretty decent (good enough to safely drive it on the street) but I'm still probably gonna try and have a shop do a vacuum bleed. Thanks for the help everyone!
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Old 08-27-2013, 08:39 PM   #9
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And jokercheif ill look into the prop valve swap.....and as far as emergency brake cables, mine are non existent at the moment
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Old 08-27-2013, 08:49 PM   #10
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Yeah that prop valve is my next step.


Still waiting in ECGS to respond with an idea. Called talked to tech support sent pics and measurements.

If I stumble across a prop valve solution I'll post or PM.

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