XJ booster in a FSJ for 4.0 intake clearance - JeepForum.com
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post #1 of 1 Old 06-25-2013, 02:07 PM Thread Starter
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1998 ZJ 
Join Date: Sep 2007
Location: Cannon AFB
Posts: 160
XJ booster in a FSJ for 4.0 intake clearance

I searched and searched around for info on this swap and all I found is "I heard you can do this". Well I did it. I had a custom booster made 15 years ago to clear the 4.0 intake when we FI'd the 258. It recently went bad and I was stuck making a decision to buy a late model intake for a couple hundred or maybe use an XJ booster. Yes I know hydro boost is the way to go but I don't want to spend that kind of money yet.

I bought a 98' XJ booster from advanceauto.com using a coupon, I think I paid half of what most places charge. I then got to work taking off the old setup. I laid them side by side and you can clearly see the difference in length, XJ is twice as long and it's a dual diaphragm design.

I found that the rod length on the XJ was way too long once I got the booster bolted up and hooked up to the brake pedal. I had to unscrew the rod and cut about an inch off the back side, file the threads, and screw it back in. Also I used my stock MC and had to clearance the holes because the studs on the XJ booster are farther apart than the stock FSJ.

Make sure you measure the rod length hooked up to the pedal on the stock booster before removing it. If this measurement isn't correct you can put pressure on the brakes all the time...bad.

I have the same clearance to the intake as I did with the custom booster and WAY more stopping power than I used to. It will stop extremely fast and in a shorter distance now. I really don't feel the need to go hydro boost in the future anymore. Oh and I have 33" tires on it too.

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I hope that link works. I've been having trouble uploading photos from my iPad.

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1978 J10 Honcho Truggy project 401/Tons/???
1983 J10 Honcho Stepside I-6 add a leaf/33"s
1988 Grand Wagoneer 401 4"/34"s
1998 ZJ 5.9 Limited 4.5" LA/33"s
1999 WJ 4.0 Limited
2003 Ram 1500 w/built 12v cummins
2004 Ram 2500 Cummins tow rig
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