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1991 XJ Brake Booster Leak???

bdenglund

NAXJA Forum User
Location
Texas
Hey fellas,
I have a 1991 Laredo XJ with a brake booster leak i believe. When I hit the breaks to come to a stop i can hear a hiss comming from behind the firewall directly in front of the driver seat. The breaks suck big time also. It had this leak when I bought it and I need to take care of it. It wont even come close to locking up the 31" coopers I have.
My question is; there is allot of talk about the WJ upgrade and 95/96 XJ booster upgrade, is there a difference between the two or are they essentially the same??
Another question, will that leak from the booster affect anything else that has to do with the vaccume system on the XJ??

Thank yall for taking the time,

bdenglund
 
A whoosh sound is correct for power brakes. The booster is a big vacuum reservoir, and when you press the pedal you crack a seal that lets outside air (normal pressure) into the chamber, rapidly filling it with air, which makes it help push the brake rod. So when you press the pedal, whoosh it fills with air.

The 91 booster just sucks. Its small and doesn't help much. I replaced my whole booster and master cylinder with parts from a 95, since it was basically a drop-in swap that did not require any significant modifications that I can recall other than flaring the lines at the MC. Made a big difference, with good rotors and pads I can lock up my 32s if I want to. IIRC the WJ swap is better but requires some additional mods.
 
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