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  #1  
Old October 12th, 2014, 07:09
PMGaming101 PMGaming101 is offline
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Angry Booster upgrade !

So I've been having this problem after upgrading my master cylinder and brake booster on my 1991 xj to a master cylinder and brake booster off a 2000 Grand Cherokee ! I will start driving the Jeep and everything is fine at first then after 15 to 20 minutesof riding the brake pedal starts to get super hard and the brakes start to drag almost like I'm losing vacuum or boost.This is the second master cylinder and brake booster is put in just to eliminate this problem and it has the same symptom as the last, I measured both boost shaft to brake pedal and they were both the same length so it wouldn't be caused by that? the jeep was not doing this before I did the upgrade. and everything that has to do with the system is new Everything!!! - the Proportioning Valve !?
Thanks
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  #2  
Old October 12th, 2014, 08:46
PMGaming101 PMGaming101 is offline
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Re: Booster upgrade !

Anyone?
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  #3  
Old October 12th, 2014, 13:29
PMGaming101 PMGaming101 is offline
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Re: Booster upgrade !

going to sell for a Toyota









never
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  #4  
Old October 12th, 2014, 13:36
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GrimmJeeper GrimmJeeper is offline
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Re: Booster upgrade !

i would swap in a prop valve off a 95 or later. i havent done the later model booster swap but the first year of the dual diaphragm booster was 95 and ive done 6 95-96 booster swaps into earlier xjs with no problem using the original master cylinder off the jeep its going into
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  #5  
Old October 12th, 2014, 16:13
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techno1154 techno1154 is offline
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Re: Booster upgrade !

I think you have a shaft or rod a little too long and causes the breaks to drag which get tighter when the breaks heat up. Did you use the spacer between the booster and the body?
Proportioning valve,...Is it correct and functioning properly i.e. allowing the break fluid to return to the master cylinder when the pedal is released?
Lastly, the break soft line,...could you tell (and this may be difficult) the condition they are in?
I would say you have a problem with fluid return.

Do you by any chance have a residual valve in the line? http://www.summitracing.com/parts/rsd-rv10/overview/
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1996 XJ; 4.0L; AW4; NP231; SYE; D30 and D44; ECTED; 4.10 gears; 30X9.5 -15 BFG/AT/KO; 3" lift; Rusty's LCA; JKS ADJ UCA; Kevins ADJ Track bar; Drawtite Front Receiver; Dual Electric Fans; Dual Battaries.
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  #6  
Old October 12th, 2014, 16:58
PMGaming101 PMGaming101 is offline
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Re: Booster upgrade !

no spacer going to do that next 1/4 inch or so and everything is new down there soft lines everything! - Proportioning valve and - the drum, everything is new !!! when the truck is cooled its fine
thanks guys for the input !!!!!!
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  #7  
Old October 12th, 2014, 16:58
PMGaming101 PMGaming101 is offline
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Re: Booster upgrade !

residual valve nope never seen that !
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  #8  
Old October 12th, 2014, 18:25
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GrimmJeeper GrimmJeeper is offline
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Re: Booster upgrade !

if the spacer is not there and you didn't modify the pedal rod i would bet techno is on the right track. did you use a specific writeup for that year booster or did you just go for it? they're not all the same.

some info here from pete trasborg at http://www.fourwheeler.com/how-to/tr...stem-upgrades/ more googling can help you find the info you need.
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  #9  
Old October 12th, 2014, 18:28
PMGaming101 PMGaming101 is offline
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Re: Booster upgrade !

I just did it lol .spaces tomorrow and I will let you know . And re bleed them good
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  #10  
Old October 12th, 2014, 21:41
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cruiser54 cruiser54 is offline
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Re: Booster upgrade !

That's not a suggested conversion on a 91.

95 and 96 XJ and 99 to 2004 WJs work fine.
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  #11  
Old October 13th, 2014, 06:16
PMGaming101 PMGaming101 is offline
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Re: Booster upgrade !

i got my booster and master out of a 2000 wj but looks like am missing spacer on mine hope this will fix it !
thanks for the input and i got a computer just for this forum starting to look up thing on Google omg !!!!!!
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