This past weekend I swapped in a booster/mc/proportioning valve from a 95-96 Xj into my Comanche. I had removed the load-sensing valve from the rear during a mild lift to add 31's. I had read several posts & a couple of write-ups on this swap, but found a couple areas that I feel I can add a little information on:
1. Connecting the booster rod to the pedal assembly & getting the factory stoplight switch to work.
To accomplish this, you need some sort of tool that will allow you to grind out the hole in the stock 95-96 booster rod. The goal here is to open up the hole enough to get the metal sleeve through it (the one that has the plastic washers on either end of it that goes through the factory stoplight switch) I used an air-driven die grinder with a carbide bit, but I don't see why a dremel tool with appropriate bit wouldn't work. You only need to open the hole up enough to slip the metal sleeve through such that it will slide easily. Next, you need to grind off the end of the rod to make it flat - use your stock rod for a guide. Try to take as little off as possible, then test fit. You want the stoplight switch to 'just fit' on the rod w/ the metal sleeve installed, but not so tight that the rod pushes on the switch & it makes your brake lights stay on all the time. After you do this, disassemble & take your grinder back out. For the rod to activate the stoplight switch, there needs to be some 'slop' in the hole that the metal sleeve goes through. The goal is to elongate the hole on one side only. Take about 1/8" of material off the inside of the hole, BUT MAKE SURE YOU GRIND IT OFF ON THE SIDE CLOSEST TO THE BOOSTER = AWAY FROM THE FLAT SPOT YOU ADDED. After a couple tries & test-fits. I got this to work perfectly. Be patient & take a little off at a time.
Little more info I haven't seen:
2. Hooking up hard brake lines to 'new' master cylinder.
On the Comanche, there are 6 (yes, SIX) lines going into the factory proportioning valve. You eliminate the secondary (emergency) line that goes to the load-sensing valve you took off. That leaves a single line running to the rear. With a little fiddling, this line will comfortably reach the front of the 'new' proportioning valve. I used a double-flare tool (rental) & used the factory nut that Lawn Cher so conveniently left on the stock prop valve. That leaves the two hard lines that go to the front calipers, and of course the two lines that are already connected between the prop valve & the master cylinder. For the front hard lines, I bought a 3/16" double-flare brass tee, connected those two lines to it, and made up a line using the old hard line from the XJ prop valve - you only need enough to reach approximately 2" past the edge of the front of the booster. I used one of the stock nuts from the secondary rear hard line - it fit right into the 3/16 tee, and you wind up with a system with no extra connections to leak.
The stock brake 'idiot light' sensor will work, but you have to pull some of your connector line out of the wire loom to have enough length to reach the switch - I ran mine on the passenger side of the booster & under the m.c.
3. One last note: I got my factory washer reservoir to fit (barely!) by pulling some of the electrical pigtail out of the wire harness, as well as pulling several inches of the rubber washer fluid line out as well. Be careful pulling them out, as you will have to deal with the factory 'electrical rubber tape'. There is Just enough room to fit the reservoir in between the m.c. and the back of the air filter box, kinda back in it's stock location but about 1/2" farther forward. Hook up the electrical plug & the fluid hose before you mount the res. in place by drilling a couple new holes (3/32 I think) up on the fender to hold it in place.
Now my '90 Comanche stops every bit as good as my '99 XJ! :clap:
I HIGHLY recomend this swap if you have a few tools and a little patience. It is well worth the effort.
Thanks again to everyone who did the various write-ups I found researching this project, also thanks to Lawn Cher on this board for the parts - good fella to do business with.
atriot:
1. Connecting the booster rod to the pedal assembly & getting the factory stoplight switch to work.
To accomplish this, you need some sort of tool that will allow you to grind out the hole in the stock 95-96 booster rod. The goal here is to open up the hole enough to get the metal sleeve through it (the one that has the plastic washers on either end of it that goes through the factory stoplight switch) I used an air-driven die grinder with a carbide bit, but I don't see why a dremel tool with appropriate bit wouldn't work. You only need to open the hole up enough to slip the metal sleeve through such that it will slide easily. Next, you need to grind off the end of the rod to make it flat - use your stock rod for a guide. Try to take as little off as possible, then test fit. You want the stoplight switch to 'just fit' on the rod w/ the metal sleeve installed, but not so tight that the rod pushes on the switch & it makes your brake lights stay on all the time. After you do this, disassemble & take your grinder back out. For the rod to activate the stoplight switch, there needs to be some 'slop' in the hole that the metal sleeve goes through. The goal is to elongate the hole on one side only. Take about 1/8" of material off the inside of the hole, BUT MAKE SURE YOU GRIND IT OFF ON THE SIDE CLOSEST TO THE BOOSTER = AWAY FROM THE FLAT SPOT YOU ADDED. After a couple tries & test-fits. I got this to work perfectly. Be patient & take a little off at a time.
Little more info I haven't seen:
2. Hooking up hard brake lines to 'new' master cylinder.
On the Comanche, there are 6 (yes, SIX) lines going into the factory proportioning valve. You eliminate the secondary (emergency) line that goes to the load-sensing valve you took off. That leaves a single line running to the rear. With a little fiddling, this line will comfortably reach the front of the 'new' proportioning valve. I used a double-flare tool (rental) & used the factory nut that Lawn Cher so conveniently left on the stock prop valve. That leaves the two hard lines that go to the front calipers, and of course the two lines that are already connected between the prop valve & the master cylinder. For the front hard lines, I bought a 3/16" double-flare brass tee, connected those two lines to it, and made up a line using the old hard line from the XJ prop valve - you only need enough to reach approximately 2" past the edge of the front of the booster. I used one of the stock nuts from the secondary rear hard line - it fit right into the 3/16 tee, and you wind up with a system with no extra connections to leak.
The stock brake 'idiot light' sensor will work, but you have to pull some of your connector line out of the wire loom to have enough length to reach the switch - I ran mine on the passenger side of the booster & under the m.c.
3. One last note: I got my factory washer reservoir to fit (barely!) by pulling some of the electrical pigtail out of the wire harness, as well as pulling several inches of the rubber washer fluid line out as well. Be careful pulling them out, as you will have to deal with the factory 'electrical rubber tape'. There is Just enough room to fit the reservoir in between the m.c. and the back of the air filter box, kinda back in it's stock location but about 1/2" farther forward. Hook up the electrical plug & the fluid hose before you mount the res. in place by drilling a couple new holes (3/32 I think) up on the fender to hold it in place.
Now my '90 Comanche stops every bit as good as my '99 XJ! :clap:
I HIGHLY recomend this swap if you have a few tools and a little patience. It is well worth the effort.
Thanks again to everyone who did the various write-ups I found researching this project, also thanks to Lawn Cher on this board for the parts - good fella to do business with.
atriot:
