AZJeff

Of course, that requires the lower control arm links to be cut off the Libby axle, and leaf spring perches to be welded on. If you have welding skills, or know someone who does, that is an excellent suggestion

If you think the backing plates are corroded to hell, I would sacrifice them and start by using and angle grinder with a cut-off wheel and chop the outside of the area drum where the shoe rides in about 6-8 places around the drum. This cutting will go thru the drum outer wall, and through part of the backing plate, and probably through part of the shoe face. Then squirt in some of the best penetrating oil you can find. Acetone mixed 50/50 with ATF is very good for this. Flood each of the saw cuts as best as you can and let it sit a while. if that STILL doesn’t get the drum to move/rotate, then start cutting on the front face of the drum between the previous saw cuts you made. DO NOT cut far enough inboard so as to harm the axle flange itself. Once the cuts are made, you can now pry off the drum segments to leave just the part of the drum that contacts the axle flange. and start to apply penetrating oil to the joint between the drum hub and the axle flange. At that point, heat, and a chisel between the drum and axle, along with a big hammer should get the rest of the drum off. Then it’s just a matter of removing all the remaining trashed parts.

The variable ratio function is accomplished by having the worm gear (on the shaft connected to the steering wheel) having a varying "thread" pitch. The further away from the center of the thread, the faster the thread pitch becomes.

That is exactly what the track bar is….a pan hard rod by another name!

I gotta ask one question, OP: you are here in the PHX area, and it's already been warm enough to use the A/C in a car. Does your MJ have A/C? I mention this because, although my MJ has the OBD-II control system and instake manifold, and thus is not exactly like yours, my idle will jump up and down slightly depending upon whether the A/C compressor is on or not.

I was never a big fan of the chassis end of the track bar being a sort of tie rod end device. For that reason, I ditch the OEM style track bar and it associated bracket for something that uses a traditional bushing/bolt on the chassis end, even if the vehicle isn’t lifted above factory ride height.

I vote with Cruiser's advice. I am a big fan of "do it once, and do it right", but I don't see the need to "refresh" a head with those compression numbers.

Aside from the nicks in the crank, those striations are going to make the seals job just about impossible using an OEM rubber lip seal. I really don’t understand why they are present if the engine used the normal two-piece rubber Kip-type seal😵‍💫

So did AMC ever use a rope seal on their six cylinder family from which the 4.0 is derived? (Is this crank possibly out of one of those older engines?)

Chances are the aluminum bracket has oxidized around the threads and created a mechanical bond. Drilling, in stages to increase the hole size in the bolt will thin the walls of the now tubular bolt. Then plenty of heat on the aluminum, will cause the bracket to expand and make the bolt easier to turn. Lay a propane torch on that bracket for about five minutes, and that oxide will break down as tha aluminum expands away from the steel bolt.

I am not sure, Pete. That crank has a number of defects in the sealing area, and the photo only shows 1/2 of the total circumference. The other side might be worse! Also, those striations (diagonal lines) on the sealing surface are something I have only seen on shafts that typically also have an oil slinger. It’s not something I have ever seen on a crankshaft before. How did the striations get there? Is a special seal employed with that sort of surface? (I am trying to remember if any of the cranks that used those “rope type” seals had those striations…..)🤔

The lip faces INWARD towards the engine. In other words, the edge of the lip that rides on the crank should be AWAY from the flywheel/flexplate. I assume that you have inspected the crank for nicks or gouges in the area where the seal rides. Any damage to the crank will make the seal ineffective.

That is a VERY nice old engine compartment that looks pretty close to original production in appearance. You can wash all the grime off the engine with engine cleaner and some hot water. A pressure washer works better, but keep it away from anything fragile, like the underhood labels and the like. Once the engine compartment is free of the grime, the source of leaks will be MUCH easier to find. And added bonus is that fasteners that are not covered in oil soaked grit won't grind up your tools when you work on the vehicle.

OK, guys, I have decided to rebuild the engine in my MJ. As my sig line says, it's actually a 4.0 from a 2000XJ, so it's not a Renix system, obviously. I am debating doing a “stroker” when I do the rebuild, but I have some concerns/questions. The first (and most important question) is “will the stroker still meet the emissions standards of a standard (non-stroked) engine?” I am in a part of AZ that requires emissions testing, so I cannot create an engine that won't meet he EPA emissions standards for a 1989 vehicle. Secondly, I have read some stuff on various ways to create a stroker, and the more I read, the more confused I get as to all the possible ways to stroke the 4.0 Is there some website (or is someone here on CC) that can tell me how to create a relatively cost effective stroker? I really am not trying to all out in increasing torque/HP with my rebuild, but I figure if I am redoing the engine, maybe I should try to give it a bit of a bump while I have it apart. Your wisdom is appreciated.

If you are trying to actually RESTORE an MJ to the way it looked the day it left the factory, the OEM connectors are obviously needed. That said, the connectors AMC/Chrysler used in the MJ are not the best for an automotive application. In fact, they are pretty low-rent, as far as connectors go. And I say this as an engineer who used to spec. out connectors for adverse environments For a daily driver or resto-mod vehicle, there are lots of choices for multi-pin connectors that are FAR better than the OEM ones, and I would STRONGLY urge MJ owners to replace original troublesome connectors with something better.

You are doing it all wrong. You are supposed to KNOW to put the nut on first, but forget in your haste to cut the bolt, and then spend the next 10 minutes cleaning up the end of the cut threads with files.

So you are doing this as an exercise in geometry. OK, I can buy that. I know life is quiet in Vernal, but have you run out of other projects for your MJ? How about stuff to fix around the house?😆😜

Lots of people get all wound up about using "correct grade" of bolts for applications that are VERY benign. When I say "benign", I means that oil pan bolts (and valve cover bolts) are examples of fasteners that are under VERY low stress, and, even more importantly, the joints they create do NOT require high clamping forces. An SAE grade 5 fastener is PLENTY strong enough to do the job. In addition, the torque requirements of oil pan bolts are such that, with practice (years of wrenching on vehicles), you can estimate the required torque without the need for fancy tools. (I have been working on cars for 50+ years, and a 4.0 oil pan, using the modern Fel-Pro silicone gasket, gets tightened to "wrist tight" with a 1/4" drive socket/ratchet.) If you are not practiced at judging torque needs on these types of fastener applications, I wouldn't say it's wrong to use a torque wrench to insure proper tightening. And using Loctite is totally unnecessary, if you tighten to appropriate torque spec.

In any XJ/MJ front suspension, pinion angle takes precident over caster angle. ALWAYS. It is stated plainly in the shop manual,. That said, I have to ask: As I understand it, you want to do this theoretical calculation, and use that to set up your arms to match those calculated results. Your premise is that, by doing so, you remove any of the "trial and error" arm length adjustments, correct? Aside from the fact that adjusting arms is not as difficult as you are implying, there is another factor: Your vehicle is 30+ years old. I would not bet that the locator holes in the axle, nor the ones on the frame, and guaranteed to be at factory dimensions. Wallowing of holes, combined with possible bending of chassis and axle locating brackets might change the dimensions from the factory settings. Better yet, the fact that Jeep included lower control arm adjustments tells me that the dimensional consistency on the location of the control arm brackets, either on the axle end, or the chassis end, might not be very tight to begin with. In other words, doing all these theoretical calculations might still not prevent the use of trial and error control arm length adjustments.

The 0331 head is the reference for the design features of the head, and not necessarily the source for the raw casting and/or the casting process control used to create the head. The "TUPY" designation on the later 0331 heads is probably some sort of foundry ID code. When I replaced my cracked OEM 0331 head with a brand new one from Clearwater, I couldn't discern any physical difference between the old head and the new one, other than the new head supposedly was "improved" to prevent the cracking potential. Then again, I wasn't using a 3D scanner to map the profile of ever casting feature, particularly around the rocker bosses, which are the weak point on the early 0331 head. In a nutshell, I believe the TUPY head to be a 0331 design, with some sort of changes that are not visually obvious that reduce cracking potential.

The following link explains the differences in the various 4.0 heads 4.0 head differences I found this link on NAXJA

Having small amounts of foreign material still present on a reworked head would not be totally unexpected. However, gasket material still being present would NOT be acceptable. The only time Ihad an issue was they sent me the WRONG head. (A big block Chevy head won’t bolt up on to a 4.0 block, odd enough🥴). They fixed that right away, all on their nickel. Can you remove the gasket material yourself?

The weld nuts in my frame were mostly trashed, so I opted to drill/tap to 7/16 UNC. It worked out fine, but a word of caution: those weld nuts in the frame are HARD. It took me an average of 10 minutes per hole to drill and tap with cutting oil.

I know of one that is driven daily by a guy who works at the ZF automotive airbag factory a few miles north of my house. Since its AZ, the condition looks good, at least from a distance, and the white paint probably hides the sins of paint fade. Otherwise, I will see a couple per month while driving around.

That rating should be plenty adequate for those fasteners intended job.