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Booster Upgrade

WJ versus 95 to 96 XJ booster

Actually, the WJ booster is in some ways easier than the 95 to 96 XJ. I've done both.

Perhaps this is true if you are doing the WJ upgrade on a Renix. But for the 91 and up HOs, the 95/96 XJ swap is by far the easiest. Using the 1/4" spacer behind the booster, no firewall mods are required, and the firewall holes are correct for the four booster mounting studs. It's pure plug and play, even with the brake switch wiring. The only thing that's different are the two brake line fittings on the master cylinder you have to plumb in. And if your windshield washer tank is still in the stock location, it may have to be moved forward a bit if you don't make tight bends on the master cylinder lines. A two hour job max, even with bleeding.
 
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Got the 96 booster & mc & prop valve in. Should I use the 91 or 96 prop valve? Also, what do I with all the wiring left from the old system? There are plugs everywhere! And my battery went dead. Any relation to unplugging all the old brake stuff?
 
Should I use the 91 or 96 prop valve?
I don't think there's any difference between them but I don't know about ABS for certain. They are not different for non-ABS. The flared fittings on the new MC are different and will have to be changed.

Also, what do I with all the wiring left from the old system?

Pull the ABS fuses and relays from the PDC box and ignore the wiring
 
The 91 had ABS. I got the proportioning valve with the 96 mc & booster & left it hooked up. I am just going to hook up the lines to the wheels & try it. Thanks for the help everybody!
 
The newer ones will have am electric motor back up.
Its been my experience that while the back up does indeed work it doesnt work that well.
Bracking performance is about the same if you stall and have no vacuum going to a vacuum booster

That pedal feel, though.

To each their own.
 
I did the wj booster and master cylinder upgrade on my 87 and it made a huge difference. But like the other guys have said, you have to do a few modifications to make it work. I think it was worth it though and I'm about to do the same thing to another xj I just picked up.

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What did you do about the prop valve?

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What did you do about the prop valve?

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I kept the original prop valve and then took the brake lines from the WJ master cylinder and had the fittings replaced on the prop valve side. I still have drum breaks in the rear so I didn't want to use the WJ's valve. I can take some pics tonight if you want to see any it.

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I kept the original prop valve and then took the brake lines from the WJ master cylinder and had the fittings replaced on the prop valve side. I still have drum breaks in the rear so I didn't want to use the WJ's valve. I can take some pics tonight if you want to see any it.

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That would be awesome I need to figure out what to do on my MJ.

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That would be awesome I need to figure out what to do on my MJ.

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First I had to bend the pinch seam at the firewall up a little so it could fit the larger booster
c4633567362d81d58c07496abb289632.jpg


Then I took the brake lines from the WJ master cylinder and had the fittings going to the proportion valve redone so they would fit my old valve.
237875e08e576248be2b4cb76f073078.jpg


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The hardest part for me was the brake light switch though. I ground a little too much off the end of the wj pedal rod and that made the brake lights only come on when the pedal was about 70% of the way down (mines an 87 and I think the switch was changed in 90-91 to one that would have made this much easier). A lot of people say to grab the whole pedal assemboly from the WJ and swap that in too - which is what I will do next time. I ended up having to make a bracket that held the switch at the right angle and distance from the pedal arm.
baf3a1acf126ff5982364abf5fa29c12.jpg


I paid about $35 for the booster, master cylinder and the brake lines from pick and pull and $10 to have the fittings replaced at a local shop. Overall, I'd say it's worth it and i plan to do it again.

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Hello,
I have a completely stock '96 XJ. Brakes are completely new front and rear and being a '96 it does have the dual diaphragm booster. Pedal effort is at the upper end of what I would consider acceptable. Booster works, as I've experimented with coasting without engine vacuum and it does make a difference.

I know it's hard to quantify, but how are these pedals supposed to feel?

Thanks.
 
Are XJs any different from most other vehicles when it comes to brake bleeding?

Pedal is firm. Jeep stops very well, just requires a a bit more effort than I would consider normal.

Thanks.
 
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