86 mj using 95-96 booster/aster cylinder

[ratrapp]

i know the 86 has differences that the 87 ups don't have.i did the booster/master cylinder upgrade on my old 88 but i passed my 86 on to my nephew for his first vehicle.ive already bypassed the leaking load leveling valve.ive got the parts just don't know if anybody has actually done the 86 if there are any slight differences that i need to plan for.

[eaglescout526]

On my 84 XJ I didn’t notice any differences when I used a 92 booster other than the push rod hole being smaller than the Renix years. I drilled that out and it’s worked great ever since. 

[ratrapp]

the 95-96 booster is the dual diaphram and is longer and thicker than the original style over all mj boosters.it worked fine in my old 88 but the 86 seems to e the bastard child of mjs.

[eaglescout526]

Well I know the only thing that really makes 86 the bastard years of both XJ and MJ is purely the TBI set up, from my experiences. I’m confident to say that you shouldn’t have a problem using the later booster in a pre 87 body. From what I know of using the dual booster is that it won’t clear the firewall lip and that the push rod mounts differently to the pedal. Otherwise my knowledge stops there. 
 

86 guys feel free to tell me otherwise if I’m wrong. 
 

Oh and I guess what makes 84-86 odd is the firewall and the 4.0, hood prop, trans crossmember, horns, radiator support, front header and fenders. Really all the comes to mind. 

[coheed]

I'm also curious if the 95-96 one would need any different work in the 86 to swap in. The diaphragm in mine has started leaking and I wouldn't mind a stronger booster. 

[Greenjeans]

I used a 99 XJ booster on my 86 XJ.  You have to measure your 86 brake rod length, cut both of the rods off and weld your 86 rod end onto the 99 booster rod.  The 86 rod connects to your brake pedal a little differently, so you need to weld that part on.  It’s pretty easy.  And the 99 booster has a 1/4” spacer that gets it away from the firewall, you need that.  I used a new/rebuilt master cylinder for a 99 and a willwood adjustable proportioning valve.  

[ratrapp]

the 99 booster is slightly different than the 95-96 booster.I'm using the 95-96 booster.when i did this swap on my old 88 all i did was grind a flat on the rod to accept the older style brake light switch.i was asking to see if anything needs to be clearanced for the booster to clear the firewall or anything else.

[Eagle_SX4]

28 minutes ago, ratrapp said:

the 99 booster is slightly different than the 95-96 booster.I'm using the 95-96 booster.when i did this swap on my old 88 all i did was grind a flat on the rod to accept the older style brake light switch.i was asking to see if anything needs to be clearanced for the booster to clear the firewall or anything else.

According to rockauto the booster did not change from 84-91. I don't think you will have to do any mods on the fire wall to get the 95-96 booster to fit just make sure you have the spacer. I put a 97+ booster in my 87 and it fit fine but I had to shorten then weld the rod. Stick with the 95-96 booster and it will be easier.

[ratrapp]

yeah ive got the spacer,master cylinder and prop valve all together.i had already deleted the load leveling valve in the back.i never could get fluid to come through it.it had sat several years in the woods before i got it.