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brake problem, help diagnose problem

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Old 01-01-2014, 07:03 PM
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Default brake problem, help diagnose problem

So my brakes are ****ty, in order for them to really engage i need to push almost all the way down to the floor. And there is a sweet spot that you hear a whistle while pushing brake pedal down. And if you keep the pedal in the sweet spot something whistles and does not stop til your out of the sweet spot. I thought about replacing brake booster but don't want to buy what i don't need. Anyone have any idea what's goin on? I have good amount of brake fluid, i bleed brakes multiple times. And replaced rotor, caliper and pads.

1998 xj sport
Old 01-01-2014, 08:02 PM
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Replace brake booster.
Old 01-02-2014, 08:00 PM
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Will do. Now, iv heard all the hype about the booster upgrade to a zj one for all the older xjs. So will it do any difference to a 98 xj or is the 98 one good enough not to upgrade?
Old 01-02-2014, 08:11 PM
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Originally Posted by 1998xjspt
Will do. Now, iv heard all the hype about the booster upgrade to a zj one for all the older xjs. So will it do any difference to a 98 xj or is the 98 one good enough not to upgrade?

You are good to go. Replace with OEM but make sure to check the vacuum line first before replacing the booster. Could just be a cheap rubber hose to replace instead of the booster.
Old 01-02-2014, 08:41 PM
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Also verify it is not the vac fitting going into the booster.
Old 01-02-2014, 11:47 PM
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The internal diaphragm is probably cracked.
Old 01-04-2014, 10:54 PM
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Okay so i replaced the brake booster and bled the brakes but when i go to step on brakes it still has to be pushed all the way down in order for braking to really start. I bled it til there was no bubbles. I noticed how the whistle was gone after new booster put in
Old 01-04-2014, 10:57 PM
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Did you adjust the pushrod?
Old 01-04-2014, 11:16 PM
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No, left it how it came, didn't know it could/should be adjusted
Old 01-04-2014, 11:21 PM
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Increase the length of the push-rod to decrease the amount of travel at the pedal.
Old 01-04-2014, 11:32 PM
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How?
Old 01-04-2014, 11:45 PM
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http://www.jeepforum.com/forum/f11/b...ng-rod-291344/
Old 01-05-2014, 03:20 AM
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Adjust up rear brakes b4 touching any thing else then bleed one more quick time....Don't really understand why brakes were bled but its been opened to air know..
Old 01-05-2014, 08:52 AM
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I discod the lines from the master cyl in order to take both master cyl and booster out, then swap cylinder to new booster. Which by removing lines, introduced air into the brake system, so i needed to bled the brakes...right? And okay will do. My helper said when i was bleeding brakes that it got really hard at one point but when i moved to the front it all of a sudden got soft
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