xj_dummy Posted November 7, 2008 Share Posted November 7, 2008 On the brake booster. What is or what does a single or dual diaphragm brake booster look like? What would my 86 manhce have? Link to comment Share on other sites More sharing options...
johnnyc Posted November 7, 2008 Share Posted November 7, 2008 A double diaphragm booster is about twice the size of a single diaphragm booster. :D All MJs have a single diaphragm booster. The double diaphragm booster didn't arrive in the XJ until 1995. A lot of people have done the XJ or WJ booster swap. I picked up a WJ booster and master from the JY for $20. I'll get it installed one of these days. Link to comment Share on other sites More sharing options...
xj_dummy Posted November 7, 2008 Author Share Posted November 7, 2008 Um Ok? :huh???: What is a WJ and a JY? I'm still trying to learn all of these two didgit letters. Link to comment Share on other sites More sharing options...
pingpong Posted November 7, 2008 Share Posted November 7, 2008 A wj is a grand cherokee from 99? to 2004?. JY is a junk yard also referred to as a PNP which is pick a part Link to comment Share on other sites More sharing options...
xj_dummy Posted November 7, 2008 Author Share Posted November 7, 2008 Hell, I thought the JY was a freakin jeep. Now I really feel stupid. :oops: Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 7, 2008 Share Posted November 7, 2008 Dual diaphram booster (1996 XJ) Image Not Found Link to comment Share on other sites More sharing options...
xj_dummy Posted November 7, 2008 Author Share Posted November 7, 2008 Oh! Is this pretty much a direct bolt on? Link to comment Share on other sites More sharing options...
Eagle Posted November 7, 2008 Share Posted November 7, 2008 Hell, I thought the JY was a freakin jeep. Now I really feel stupid. :oops: It gets really confusing because there IS a Jeep model with those letters -- reversed. The Jeep YJ was the original, leaf spring, solid axle Wrangler. The newer Wranglers with coil springs and solid axles were the TJ models. And now there's the newest series, and I don't pay attention to it because it doesn't offer a 4.0L engine. Link to comment Share on other sites More sharing options...
maddzz1 Posted November 7, 2008 Share Posted November 7, 2008 Oh! Is this pretty much a direct bolt on? There are a couple different double diaphragm boosters. One has a short rod and one has a long rod. You need the one with the short rod. The end of the rod on ours has a flat side on the rounded end of the rod where the brake light switch connects. The double booster is round on all sides. So you need to grind one side flat. If I remember it is the bottom. Then you need to drill out the hole at the end of the rod a little bigger so the sleeve for the brake switch will fit in. I don't remember the size drill bit you need. The fitting that go into the prop valve are an odd size and are hard to find. Your best bet is to cut them off the old brake line that goes from the booster to the prop valve and put them on the new piece of brake line. You will need a double flare tool to flare the brake lines. Do a few practice ones on the old brake line first till you get the hang of it. It is actually really simple and can be done in a few houres. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 7, 2008 Share Posted November 7, 2008 Oh! Is this pretty much a direct bolt on? There are a couple different double diaphragm boosters. One has a short rod and one has a long rod. You need the one with the short rod. The end of the rod on ours has a flat side on the rounded end of the rod where the brake light switch connects. The double booster is round on all sides. So you need to grind one side flat. If I remember it is the bottom. Then you need to drill out the hole at the end of the rod a little bigger so the sleeve for the brake switch will fit in. I don't remember the size drill bit you need. The fitting that go into the prop valve are an odd size and are hard to find. Your best bet is to cut them off the old brake line that goes from the booster to the prop valve and put them on the new piece of brake line. You will need a double flare tool to flare the brake lines. Do a few practice ones on the old brake line first till you get the hang of it. It is actually really simple and can be done in a few houres. xj_dummy; your profile soes not say what year your MJ is. For my 91 is was a direct bolt-on. The only thing I had to do was fab new brake lines from the 96 master cylinder to the existing combo valve. The booster arm was the correct length for my brake pedal and slipped over the existing stud, no mods required. Link to comment Share on other sites More sharing options...
Pete M Posted November 7, 2008 Share Posted November 7, 2008 Some good reading here: http://www.madxj.com/MADXJ/technical/te ... pgrade.htm Link to comment Share on other sites More sharing options...
maddzz1 Posted November 7, 2008 Share Posted November 7, 2008 Oh! Is this pretty much a direct bolt on? There are a couple different double diaphragm boosters. One has a short rod and one has a long rod. You need the one with the short rod. The end of the rod on ours has a flat side on the rounded end of the rod where the brake light switch connects. The double booster is round on all sides. So you need to grind one side flat. If I remember it is the bottom. Then you need to drill out the hole at the end of the rod a little bigger so the sleeve for the brake switch will fit in. I don't remember the size drill bit you need. The fitting that go into the prop valve are an odd size and are hard to find. Your best bet is to cut them off the old brake line that goes from the booster to the prop valve and put them on the new piece of brake line. You will need a double flare tool to flare the brake lines. Do a few practice ones on the old brake line first till you get the hang of it. It is actually really simple and can be done in a few houres. xj_dummy; your profile soes not say what year your MJ is. For my 91 is was a direct bolt-on. The only thing I had to do was fab new brake lines from the 96 master cylinder to the existing combo valve. The booster arm was the correct length for my brake pedal and slipped over the existing stud, no mods required. Don is correct. I forgot it was different for later years. I have an 89 and just assume everyone else does too. Link to comment Share on other sites More sharing options...
xj_dummy Posted November 18, 2008 Author Share Posted November 18, 2008 xj_dummy; your profile does not say what year your MJ is. For my 91 is was a direct bolt-on. The only thing I had to do was fab new brake lines from the 96 master cylinder to the existing combo valve. The booster arm was the correct length for my brake pedal and slipped over the existing stud, no mods required. Well for the year, I'm upgrading my wife's 90xj from the crappy abs system to non abs. So I would like to use that one as a trial and error. My MJ is a 1986 model and the brakes are OK for now. Link to comment Share on other sites More sharing options...
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