• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Booster upgrade !

PMGaming101

NAXJA Forum User
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 !?:flamemad::flamemad:
Thanks
 
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 :dunno:
 
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/
 
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 !!!!!!
 
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 !!!!!!
 
Back
Top