Eagle

I'm not sure why what I wrote cancels out the aftermarket adjustable proportioning valve but, if that's a deal-breaker for you, so be it. I don't think you can buy a new distribution block for the MJ, and it's unique -- totally unlike the XJ/ZJ/TJ proportioning valve. If you are going to open it up and clean it out, consider opening up the ID on the ports. Cruiser has made some measurements, which should be posted around here somewhere, which showed that for some reason the orifices on the MJ distro block are smaller than on the XJ/ZJ proportioning valve. IMHO it can't hurt to open them up slightly to match the size of the orifices in the XJ/ZJ units.

Confirmed. For the Dana 30, the carriers used are divided into 3.54 and lower numerically, and 3.73 and higher numerically. This is usually referred to as the “carrier break.

That's a good choice, BUT ... pay attention to this from the instructions: By using this proportioning valve, you will lose the warning light that's intended to signal the loss of the front or rear brake circuit. Technically, I think that may be illegal -- but I think most of us know the difference between a firm pedal and the low pedal that results when you lose half your brakes, so I would be concerned about this only if you live in a place that requires annual safety inspections and the inspection verifies that the warning light is present and functional. And this unit is also a work-around if you've swapped in a different brake pedal setup from a different year, and the mechanical switch isn't getting the job done. This allows you to remove the mechanical switch in the pedal assembly and just extend the two wires through the firewall to the pressure switch on the proportioning valve. Also note that two of your hard lines use a 1/2-20 flare nut, and this unit uses all 3/8-16 flare nuts. So you will have to re-make or adapt two of your lines.

So you're looking for what is generally referred to as an "RV" cam rather than a "performance" cam.

Photo of the distribution block: The XJ/ZJ block is also a proportioning valve. The MJ is not. They look similar on the outside but the internals are different.

Rancho has a rear AAL kit that they advertise as 2-1/2 inches for the XJ and the MJ. Since the XJ is spring over and the MJ is spring under, it can't be the same for both vehicles. I called Rancho and talked to their engineers. It's actually 1-1/2 inches of lift in the MJ.

What kind of performance? Low end grunt power, or high RPM horsepower?

You don't have a proportioning valve -- you wrote that you deleted it. Sounds to me like a bad caliper.

The stock setup with auto (225/75-15 tires with 3.55 gears) turns 2100 RPM at 65 MPH in over drive. 31x10.50-15s with 3.73 gears turn 2085 RPM at 65 MPH. In other words, 31" tires with 3.73 gears are effectively exactly the same as a stock automatic. My rule of thumb is that 3.73 gears are about perfect for 30" tires, 4.10s are good for 31" tires, and for anything bigger than 31s you need at least 4.56 gears. If you run a Dana 30 front axle, last I knew the steepest gearing you could buy was 4.88, and those have such a small pinion that's it's rather weak setup. If you use one of the "Dana 44" front axles out of a TJ Rubicon, the bigger pumpkin will allow you to get into deeper gearing -- but it's a low pinion axle. 31x10.50-15s with 4.10 gearing turn 2292 (call it 2300) RPM at 65 MPH. That's not bad for highway work. My frame of reference, for those of you worrying about "burning up" the engine, is the AMC cars these engines were originally designed for. My family was an AMC family. We owned just about every early variation of the engine: 199 c.i.d, 232 c.i.d, and 258 c.i.d. They didn't have over drive in those days, and the models with standard transmission were geared to run 24 MPH per 1,000 RPM. That means 60 MPH was 2500 RPM, and 3000 RPM was a 72 MPH cruise. And the engines easily went well over 200,000 miles. Jeff, a bit more crunching shows me that in overdrive you are turning 1904 RPM at 65 MPH. That's actually below the torque peak for the engine, so it's not a surprise it won't pull long upgrades on the highway. When you lock it out of overdrive, in third gear you're turning 2539 RPM. 4.10 gears will get you to 2205 RPM, which kind of splits the difference. But the torque peak for the 2000 XJ engine is at 3,000 RPM, so you'd still be well below the torque peak. 4.56 gears would get you closer -- 2453 RPM. But that's very close to what you're turning when you just lock it in third gear, so I don't know if you want to live there all the time or not.

If the wire is aluminum, corrosion could very well be the problem. In addition, aluminum is subject to "creep" under pressure -- you torque dow a screw, and over time the aluminum slowly deforms until you no longer have a solid connection. When you re-wire, be sure to use Ox-Gard (corrosion inhibitor) on the wires when you stick 'em into the lugs and torque 'em down.

No need to drive into town. https://www.theupsstore.com/tools/estimate-shipping-cost

I've got a story that I think beats anything the current generation pulls. This goes back to the early 1980s, when I was married to my second wife. I was finally ready to sell my 1968 Javelin, that I had bought new with my Vietnam combat pay. It had the 343 c.i.d. V8 (which was the largest available when I ordered it -- the 390 came out later in 1968), the "go package," limited slip rear axle, several suspension tweaks (I was heavily into autocross and time trials in those days), and a recent engine rebuild. My then mother-in-law lived on a busy road in a town full of gearheads, so we parked it in her front yard with a "For Sale" sign in the window, the price, and my telephone number. Had a call from a guy who said he loved it and really REALLY wanted it. So we made an appointment for me to meet him a the MIL's place at 6:00 p.m. one evening after work. I was there at 6:00. He wasn't. He also wasn't there at 6:15, or 6:30. I had a phone number, so at around 6:45 p.m. I called. His father answered, and said he had no idea where his son was. At 7:00 there was a knock on the door. MIL answered. It was NOT the prospective buyer I had the appointment with, it was a kid who was one of my wife's students (she was a high school English teacher). He was a nice kid, very polite. He took it for a test drive, liked it, gave me a big deposit, and we arranged to finalize the paperwork the following Saturday. He left, and I went home. Around 9:30 that night I got a phone call at home from prospective buyer #1, asking about "his" car. I informed him that it wasn't "his" car, that I had waited over an hour for him and couldn't reach him, and that the car was now sold -- to someone else. The guy went totally bat $#!& crazy over the phone. He kept telling me that I had no right to sell "his" car, that we had a deal (we didn't, we were going to meet so he could test drive it), and he was going to sue me. I finally told him where to go and hung up on him. Ten years later I had another guy pull a similar routine when I was selling a full-size Cherokee with a snow plow. Yeah -- they're out there.

What the [bleep] is "minor" brain bleeding? Prayers that she recovers, quickly and completely.

Also, check your door pillar switches. After 33 years, they're probably not in very good shape.

Oh, yes! I haven't been to Wright's Farm in years.

Here's the diagram for the 1988 fuse panel. Not sure if the '91 is the same.

The factory oil pressure spec is for when the engine is at operating temperature. The spec is 13 psi minimum at idle, and 37 to 75 above 1600 RPM. As a rule, most of the 4.0L engines I've driven seem to run between 50 and 55 psi at 2,000 RPM. What weight oil do you run? Heavier oil will make higher oil pressure, especially when cold.

If you want to sell it, post in the classifieds. You'll have to spell out what you have added to it, because I can't imagine how a SporTruck is worth anywhere near what you have in it.

This is great news!

I would. It's even stronger than the Dana 44. The downside is that it's also heavier and offers less ground clearance than the Dana 44.

Not MJ-related, so moved to The Pub.

Stick with 31s.

It's called a clevis. Part number 5200 0532 Check with EagleScout526 -- they may still be available through the factory parts system.

No. And I'll almost guarantee that using SOS on the plastic chrome-like (it's NOT chrome) finish will quickly destroy it.