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ok, ive asked a lot of questions, and i have 3 more. instead of making more posts I'm going to try to use this one, and just post questions i have in this.

 

question 1: my MJ has no cat now (PO took it off) and to make it leagal i need one. i know that some CATS had O2 sensors in the CAT. would an 88 mj. reason being is that if its supposed to be there, i need to get the wiring for it.

 

question 2: the picture below is courtesy of Pete (if you want me to take one of my own let me know and ill modify this post ASAP!)

 

the part that the 2 brake lines from the MC go into...whats that called? is it the proportioning valve, or is that in the rear? anyways, i have my stock MJ one, and an XJ one. should i use the stock MJ one, or swap in the XJ one. the XJ one has the front port plugged (like in pete's pic).

 

question 3: the ebrake assembly under the truck is messed up. there is the cable going into the bracket thats attached to the frame, but there is no way to hook the e-brake cables to it. can i use the ebrake hadware from my XJ on this? i know that was a vague explanation, but its late and my hands are shaking. ill take a pic soon to show what I'm talking about.

 

 

like i said before, if i have any more questiosns ill post in here instead of starting a new thread. thanks!! :cheers:

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Anyone can use any of my pics at any time. :D

 

As I understand it:

 

-MJs only have the one O2 sensor

 

-the front valve in an MJ is a combination valve, aka, just a splitter. In an XJ, it's a proportioning valve.

 

Thankth Pete!

 

ok, 1 O2 sensor makes life easier jamminz.gif . now i have to decide if i want to put the XJ prop valve in, or keep the MJ one and use a T to join the split. I'm just running 1 line back to the axle. the height sensing thing-a-ma-jig is gone, and it will not be on the road a lot, and i will not be hauling with it.

 

any recomendations...swap XJ or keep MJ and T it together?

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1. only jeeps with OBD2 use 2 O2 sensors thats 1997 and up.

2. i swaped in a XJ valve on mine and got rid of the rear prop valve

3. i parted out a XJ i know the backet is different but i don't remember about the 1 cable into 2 thing you could probably make it work though.... i just removed my parking brake crap

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question 1: my MJ has no cat now (PO took it off) and to make it leagal i need one. i know that some CATS had O2 sensors in the CAT. would an 88 mj. reason being is that if its supposed to be there, i need to get the wiring for it.

No wiring on the cat for an '88 MJ.

 

question 2: the picture below is courtesy of Pete (if you want me to take one of my own let me know and ill modify this post ASAP!)

 

the part that the 2 brake lines from the MC go into...whats that called? is it the proportioning valve, or is that in the rear? anyways, i have my stock MJ one, and an XJ one. should i use the stock MJ one, or swap in the XJ one. the XJ one has the front port plugged (like in pete's pic).

I don't trust the XJ proportioning valves. The rear circuit clogs up and you have no (or very weak) rear brakes. Plug the front, bottom outlet on the MJ metering block, and run from the "nose" outlet (the one where Pete's pic has a black plug) directly to the hose at the rear axle.

 

question 3: the ebrake assembly under the truck is messed up. there is the cable going into the bracket thats attached to the frame, but there is no way to hook the e-brake cables to it. can i use the ebrake hadware from my XJ on this? i know that was a vague explanation, but its late and my hands are shaking. ill take a pic soon to show what I'm talking about.

If you're asking can you use the "spreader bar" (dunno if that's the official term) from an XJ on an MJ, I would think so but I haven't compared them so I am not certain.

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thanks for the replies so far guys, this will be a huge help when i tear into the MJ again. eagle, why do you recomend that i block the bottom one, and run the line back from the front nose? :cheers:

Grab a tall, cool one and settle in for a lengthy explanation.

 

The MJ has two rear brake circuits. The "normal" circuit feeds out of the nose of the metering block and runs through the rear proportioning valve. If you have no brake problems, the rears are always fed through the rear proportioning valve.

 

The second line, off the bottom of the metering block, is often called a "return" line. It isn't. It's a bypass line. If you lose the front brakes, the same plunger in the metering block that triggers the brake system warning light also opens a passageway that allows fluid to flow through that bottom outlet. That one bypasses the rear proportioning valve and delivers full pressure to the rear brakes at all times.

 

But ... under normal conditions there is NO FLUID flowing through that bottom outlet. Plugging the outlet at the nose and just leaving the line out of the bottom will give you a hard feeling peddle, but you won't have any rear brakes.

 

Don't ask me how I know this.

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On the parking brake issue.

The cable for from the foot pedel to the center feed is different on the MJ than to the center handle on the XJ, they have a differnet way to lock into the frame as they pass throught it under the truck, not hard to swap just little stuff.

The hardware on the threaded rod under the truck is all the same, the 2 nuts on it and the funky cable pulling assembly wedge.

The cables to the back of the trucks are not the same, the ones on the XJ are longer, i had to use some in a pinch on my MJ and had to take up some slack, about 5 inches of it. The PO had cut the e-brake cables to the axle on the MJ.

The brackets under are at different lenghts from each other on the truck, so even if you had the whole assembly from foot pedel to the axles you would have to make it fit, not impossible but with some work it is do able.

I hope this makes sence, i don't have pictures of this avalible but if you need some i might be able to get some taken and post them up.

 

Andy

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  • 4 weeks later...

a few more questions! :banana:

 

i lost the 3 screws that screw into the axle tubes (D44) :roll: . the 1 that holds on the flex line and the T, and the 2 that hold on the brake line clamp (passy side). can anyone tell me the size of these screws so i don't have to make 10 trips to and from the hardware store?

 

thanks!

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there is the cable going into the bracket thats attached to the frame, but there is no way to hook the e-brake cables to it.

 

i parted out a XJ i know the backet is different but i don't remember about the 1 cable into 2 thing

 

If you're asking can you use the "spreader bar" (dunno if that's the official term)

 

Just throwing this out there. I believe the term for the bracket that splits the e-brake cable is called the "equalizer." Hopefully, some common lingo will help us communicate with eachother easier.

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a few more questions! :banana:

 

i lost the 3 screws that screw into the axle tubes (D44) :roll: . the 1 that holds on the flex line and the T, and the 2 that hold on the brake line clamp (passy side). can anyone tell me the size of these screws so i don't have to make 10 trips to and from the hardware store?

 

thanks!

 

My guess is they are 6mm.

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The one that holds down the Tee is long gone on mine (replaced with a hose clamp) and the other ones are so short that it is hard to be absolutely positive, but it threaded into the 6mm thread-tester-thingie at the hardware store but didn't really like the 1/4" ones.

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ok, now that the brakes, and axle are mostly out of the way (thanks again for all the help everybody!!!), i need to tackle somthing else...the rear lights! they don't work. i admit i havent checked the fuse yet, but if its not that, what could it be? is this a common problem with an easy remedy? the fronts work fine; blinkers, highbeams, lowbeams, hazards, driving lights. i suppose i should pul out my multi meter, and start checking the wires to the back to see if they are getting power. I'm assuming that i would be checking volts. anyone know how many go to the rear? thanks.

 

and pete, i think I'm going to use your idea of the hose clamps, and just fill the holes with some RTV.

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Sounds dumb, but for the rear lights ... start by checking the bulbs. If they're good, then follow the wiring harness forward from the rear lights to find the connector where the rear harness mates to the front chassis harness. If all the front lights work and none of the rear lights do, that's the most likely problem area.

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