mjeff87 Posted October 16, 2007 Share Posted October 16, 2007 I swapped in a dual diaphragm booster out of a 96 XJ over the weekend, and they really do make the difference that people say they do. Altogether I spent about $50, some of which was on fittings to connect the master to the prop valve. If I’d do it again, I would have let the prop valve installed the way it came out of the XJ, which is set a lot higher than the MJ, and extended the lines from the bottom versus extending the lines on top…..because all the output lines underneath are 3/16”, and the input lines are 5/16” and ¼” which meant I had to conjure up a bunch of different adapters. Oh well, it’s in and not leaking, which is all I care about :D Here is the booster/MC/prop valve assembly I pulled out of the XJ ($32 at the U-pull): Image Not Found Here are the two assemblies side by side after I pulled the MJ stuff out: Image Not Found The swap is pretty straightforward, except the end of the booster rod that connects to the pedal. For the brakelight switch to work, you have to drill out the hole in the XJ rod to 5/8” and transfer the switch and all the bushings onto it. You also have to flatten out the end of the rod eye to match the older version rod…..it’s a very precise width that I proceeded to screw up with an angle grinder, and now have the switch shimmed temporarily until I figure out a more permanent solution :thwak: Here’s the stock, old style rod: Image Not Found And here’s how I modified the new rod: Image Not Found Put it all back together, using the stock MJ hard lines from the MC to the prop valve (with fittings). There’s juuust enough room for everything to fit, EXCEPT the washer fluid resivoir. I’m relocating that to the firewall above the HVAC fan, but haven’t done that yet: Image Not Found Shot from the side: Image Not Found Link to comment Share on other sites More sharing options...
Twisty Posted October 16, 2007 Share Posted October 16, 2007 Nice work :brows: Link to comment Share on other sites More sharing options...
Pete M Posted October 16, 2007 Share Posted October 16, 2007 You also have to flatten out the end of the rod eye to match the older version rod…..it’s a very precise width that I proceeded to screw up with an angle grinder, and now have the switch shimmed temporarily until I figure out a more permanent solution :thwak: Been there, done that. It's on the to-do list. :( I was thinking of adapting the older-older style with the push-button switch (like my 86 has). Link to comment Share on other sites More sharing options...
mjeff87 Posted October 16, 2007 Author Share Posted October 16, 2007 That, I think, is going to be the permanent solution....I went back and got the push button switch out of the XJ. Problem is, there's no bracket to attach it under the dash. I'll either have to fab one up or swap the entire clutch/brake pedal assembly out of a newer XJ. That switch-on-the-pedal thingy has officially become first on the list of the stupidest things ever engineered on a Jeep...... :nuts: Jeff Link to comment Share on other sites More sharing options...
offroader461 Posted October 16, 2007 Share Posted October 16, 2007 i did the same thing but instead of using the 87 brake light switch i just put the 95-96 style one in instead...was very simple to do Link to comment Share on other sites More sharing options...
mjeff87 Posted October 17, 2007 Author Share Posted October 17, 2007 How did you locate the switch? On my 87, there's no bracket to mount it to. Did you fab something up? got any pics? Thanks! Jeff Link to comment Share on other sites More sharing options...
mfpdm Posted October 17, 2007 Share Posted October 17, 2007 How weird. I pick up the same thing at the pick n pull down here this past weekend. Had been looking for sometime. Mine wasn't as clean. The XJ I pulled it from look as if it was driven like it was stolen. Mud everywhere and all the windows broke out. I went ahead and pull the pedal to save the switch headache. Now I regret not pulling some of the tubing. I forgot the mj prop valve set lower. I notice that you also pulled the sensor wiring connected to the prop valve. Should I have snagged that too? Nice job by the way. Glad to hear it wasn't too difficult. Link to comment Share on other sites More sharing options...
offroader461 Posted October 17, 2007 Share Posted October 17, 2007 i swapped in the pedal assembly also...wasnt to difficult...4bolts on the firewall and 2 under the dash..that was the easiest way to do it...ill get some pics of it and post them up Link to comment Share on other sites More sharing options...
mjeff87 Posted October 17, 2007 Author Share Posted October 17, 2007 looks like I'm heading back up to the 'yard Saturday to pull the pedal assembly, then. Do either of you know which two color wires you need to splice (there's about 6 of them.....I was gonna use a meter to figure out) mfpdm- after having done this, I would recommend you leave the prop valve where it is and extend the output lines. Took me about three trips to the parts store to get the right fittings needed the way I did it. You also don't need the wiring for the switch, your MJ one is the same and will fit fine. I was just a bit lazy and cut the wires ;) Jeff Link to comment Share on other sites More sharing options...
mfpdm Posted October 18, 2007 Share Posted October 18, 2007 looks like I'm heading back up to the 'yard Saturday to pull the pedal assembly, then. Do either of you know which two color wires you need to splice (there's about 6 of them.....I was gonna use a meter to figure out) mfpdm- after having done this, I would recommend you leave the prop valve where it is and extend the output lines. Took me about three trips to the parts store to get the right fittings needed the way I did it. You also don't need the wiring for the switch, your MJ one is the same and will fit fine. I was just a bit lazy and cut the wires ;) Jeff After reading the MADXJwrite up and your experience, I will leave the prop valve where it is. I looked up the wiring diagram but it only shows two wires and the MADXJ write up doesn't help either. It did say that if you leave your stock pedal, you could use a brake switch from a 93 xj. i swapped in the pedal assembly also...wasnt to difficult...4bolts on the firewall and 2 under the dash..that was the easiest way to do it...ill get some pics of it and post them up I'm curious about how you wired your switch and if your pedal position was the same after the swap as well. :cheers: Link to comment Share on other sites More sharing options...
offroader461 Posted October 18, 2007 Share Posted October 18, 2007 ill take a pic of the wiring tomorrow....MJ is at home awaiting install of the 6" lift...so I'm driving the XJ for now...my pedal position is exactly where it was prior to the swap..just much stiffer and better :D Link to comment Share on other sites More sharing options...
jtdesigns Posted October 18, 2007 Share Posted October 18, 2007 So if any of yous had to write cliffnotes on what all is needed for this swap it would be something I might have to search for at the yard. And, I'd be really thankful. Link to comment Share on other sites More sharing options...
mjeff87 Posted October 18, 2007 Author Share Posted October 18, 2007 not much really....just a '95 or newer XJ dual diapragm booster with master and prop valve, brake pedal assembly, and the brake light switch. Pull the booster/MC/prop valve as a whole assembly, just disconnect the booster rod from the pedal, cut the lower (output) brake lines off the prop valve, and remove the four nuts that hold the booster to the firewall. Then pull it all out as a unit. I'm heading back up Saturday to grab the pedal assembly and swap it in. I'll take some more pics from under the dash when I do. I metered the wires on the brake switch last night....it's the center set of wires that you need to splice into your existing brake light wiring. Pink and white wires..I think. Link to comment Share on other sites More sharing options...
mjeff87 Posted October 22, 2007 Author Share Posted October 22, 2007 What a mess the weekend was. On the way to the junkyard to get the XJ pedal assembly, I blew a brake line (I “tweaked” it when I installed the XJ prop valve). Got the pedal assy and new brake line and spent Saturday swapping them in. Got it done, and the prop valve was leaking :mad:, ended up swapping the MJ valve back in. Got it all in, bled and working, and the brake light switch was out of adjustment….had to bend the bracket just a tad to fix that. MUCH better braking now :D, but my forearms and hands are beat to snot. One thing I wasn’t counting on was the clutch pedal has a different engagement now (it rides higher under the dash now with the newer assembly), and I have to get used to that. I’m hoping that the difference in throw, about ¼”, isn’t too much for either the master cylinder or throwout assembly. Here’s the installed XJ pedal assembly, with the ’96 contact switch rigged up: Image Not Found Under the hood, I had to relocate the washer resivoir to the passenger side firewall. It just fits there: Relocated Image Not Found Overall bird’s-eye shot of the engine bay now: Image Not Found Link to comment Share on other sites More sharing options...
pingpong Posted October 22, 2007 Share Posted October 22, 2007 nice... quick question.. how do you keep your engine bay so clean :nuts: Link to comment Share on other sites More sharing options...
mjeff87 Posted October 23, 2007 Author Share Posted October 23, 2007 I don't like wrenching on greasy #&@*#(..... ;) Link to comment Share on other sites More sharing options...
UNL1MTD Posted October 23, 2007 Share Posted October 23, 2007 nice... quick question.. how do you keep your engine bay so clean :nuts: He must not have the mandatory 2+ oil leaks, like all normal comanches! ;) I swear I will do this upgrade one day, just seems to make so much sense. Link to comment Share on other sites More sharing options...
pingpong Posted October 23, 2007 Share Posted October 23, 2007 I don't like wrenching on greasy #&@*#(..... ;) Then how am I going to catch it on fire when we clearance it for bigger tires :eek: you know I have a new fire extinguisher now ;) Link to comment Share on other sites More sharing options...
ejndssn Posted October 24, 2007 Share Posted October 24, 2007 nice job dude :cheers: would like to know if anyone has done this swap on the 4.0 and are the any pic's Link to comment Share on other sites More sharing options...
mfpdm Posted October 24, 2007 Share Posted October 24, 2007 nice job dude :cheers: would like to know if anyone has done this swap on the 4.0 and are the any pic's Yep it's been done. Will be done on mine when ever I put it back together. Here's a link to some pic's and another write up. Click on THIS. Link to comment Share on other sites More sharing options...
offroader461 Posted October 24, 2007 Share Posted October 24, 2007 did mine on the 4.0....look in my projects page and youll see the final pic....will be doing it on my XJ here shortly also Link to comment Share on other sites More sharing options...
ejndssn Posted October 25, 2007 Share Posted October 25, 2007 just another question i thought that there was a write up on swapping the booster rod between model years so that was a plug & play swap Any thoughts on this :dunno: Link to comment Share on other sites More sharing options...
mfpdm Posted October 25, 2007 Share Posted October 25, 2007 just another question i thought that there was a write up on swapping the booster rod between model years so that was a plug & play swapAny thoughts on this :dunno: The write up on MADXJ I posted above did that because he use a 97 booster with a longer arm. Then found out the 96 booster was a direct swap with the execption of drilling the hole larger and shaving a little off the back of the arm. Or a plug & play if you use the 96 pedal assembly as well. He has both write ups on the link. :cheers: Link to comment Share on other sites More sharing options...
ejndssn Posted October 26, 2007 Share Posted October 26, 2007 now i have to find two at the pic & pull one for me and the other for the wife :brows: she like th XJ and I of course MJ Link to comment Share on other sites More sharing options...
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