Eagle

How do you plan to use your truck? The first item you linked says they are designed for speed, not flex. Are you looking for flex? The simplest solution is to use the factory mounts. That also allows you to use the same shocks. What it doesn't do is increase the suspension travel, but if you're not going to be doing rock crawling that may not matter.

No, it won't. It has less unloaded arch, but it's a stiffer/stronger spring, so the weight of the unloaded chassis and box don't deflect the springs as much as the standard springs.

The MJ in factory configuration has the rear springs under the axle. The thickness of the leaf pack doesn't matter.

The factory service manual tells us how to measure ride height, and there is only one spec for 2WD and one spec for 4WD. Both specs are plus-or-minus 1/2-inch, but there's no mention of one spring type riding higher or lower than another.

I think you are correct on the CPS. I had the same thing happen on the '88 MJ, and it began immediately after the CPS was replaced. Too many other things happening in life to troubleshoot it, so it just sits, but I'm 95% sure that's the culprit.

??? Ratios: 1st = 4.01 2nd = 2.32 3rd = 1.40 4th = 1.00 5th = 0.78 R =3.55 5th gear is less overdrive than the AX-15, which is 0.72.

That's the factory transmission in my 2000 Cherokee. No problems whatsoever. It's one of the sweetest transmissions I have ever driven, and at 72 years old I have driven a LOT of manual transmissions. IMHO it's superior to the AX-15 in every way possible. I especially like the lower first gear ratio, and the fact that it's not at all balky about shifting into second gear (which is a characteristic of both the BA 10/5 and the AX-15).

No, you don't. The math is all done for you in the spreadsheet I posted a link to.

Maybe I'm just old (no question there) and dense (probably little question there, either) but I'm still not certain about your rear axle. "8.8" refers to a Ford rear axle, not a Jeep axle. It's a common swap for MJs, so I'm not saying you don't have an 8.8 -- but I'd just like confirmation that you know you DON'T have a factory Jeep rear axle under there. And if you have a 1998 front axle, what's it out of? Is it high pinion or low pinion?

"I love it when a plan comes together." Colonel John "Hannibal" Smith - The A-Team

??? What is this a response to? 4.10 was a ratio that the factory used with the 2.5L, but the Jeep factory didn't use 8.8" rear axles. We're trying to help you here, but trying to get useful information out of you is impossible. We can't help you if you won't answer questions.

I towed a light car trailer with a light car on it -- once. I towed it with a short wheelbase Comanche. It was a one-time event because I was moving the vehicle for a friend. Short trip, no highway involved. Scariest thing I've ever done. Shelbyluvv mentioned the trailer pushing the tow vehicle off the road, and he wasn't kidding. The MJ is just not heavy enough to be used for this kind of duty on a regular basis. Beyond that, although the back of an MJ has a frame, it's a fairly light duty frame. It carries a decent payload in the bed, but it's not made for pulling heavy loads regularly. A small utility trailer for a lawn machine -- no problem. A car trailer with a car on it? Not a good idea. The shortbed just makes it worse. As to V8s, look through the project discussion area and you'll find that a number of people have done V8 swaps. Cooling is an issue with V8 conversions. Also, the front end of an MJ is unibody -- put a big V8 in there and start pulling heavy loads, and I very much expect that the unibody will get twisted out of shape. Hence ==> Buy a Ford F250 ... or F350. You have to remember that the MJ is a small, might to medium duty pickup. It wasn't designed or built to compete against full-size or even mid-size trucks, it was created to compete against the S-10 and Ranger class of truck.

Buy a Ford F250 ... or F350

What makes you think you need a larger engine? The Jeep 4.0L is known for producing lots of torque.

The rear is an 8.8? Did you change it, or was it done by a previous owner? That pretty well rules out worrying about using Dana-Spicer gears, at least in the rear.

I agree. The CAD on my '88 XJ failed once, a number of years ago. Naturally, I was in a valley trying to climb a hill in a snowstorm to get home. I replaced the vacuum harness, and I have a spare that's still new in the factory packaging, but knowing that there's no downside to eliminating it, my choice today would be to just lock it in the engaged position and not worry about it.

You don't have automatic hubs, you have (as already commented) a central axle disconnect. It's a vacuum-operated sliding collar mechanism on the passenger side, between the differential and the outer stub axle. If you lose vacuum, the slider won't actuate. It can be engaged manually, but doing so requires crawling under the vehicle and removing the vacuum shift mechanism from the housing on the axle. There are no solenoids. It's not operated by electricity.

Here's a link to what I consider to be the most accurate chart of tire sizes and engine speeds with different axle ratios. I'm biased -- it's my spreadsheet. It's more accurate than most on-line calculators because I used actual tire manufacturers' revolutions-per-mile data rather than just calculating tire diameter, which doesn't allow for sidewall deflection when the tire is loaded. https://docs.google.com/spreadsheets/d/1pHFuhGgj6dQDfzyfFJH5z7NCDLW2KX3ABQgAJr3lBvM/pub?hl=en&hl=en&output=html Let's assume that a 4-banger originally came with 4.10 gears and 205/75-15 tires. Well, we can't check that, because I didn't go that small, so we'll use a 215/75-15 as the stock tire. Find the column for 4.10 gears, and we can see that at 70 MPH in 5th gear the engine turns 2705 RPM. So now we want to see what comes close to that with 31" tires. Scroll down to the section for 31x10.50-15 tires. We find that with 4.56 gears, at 70 MPH the engine will be turning at 2713 RPM. That's a difference of just 8 RPM from stock. Not worth even worrying about. That's the difference between new tires and tires that are 50% worn. If you want to jump to 4.88 gears, then we see that at 70 MPH (in 5th gear) the engine would be turning at 2904 RPM. That's faster than stock, but not that terrible. Remember, the 2.5L and 4.0L engines are basically the same design. They both were developed from the original 232 c.i.d. engine that AMC introduced in 1964. Back in those days, cars didn't have overdrives -- they were mostly 3-speed manuals, or basic 3-speed automatics. I had a 1966 Rambler American back then. With stock tires and stock gearing, it turned exactly 3000 RPM at 72 MPH. And those engines typically ran for well over 200,000 miles. So getting your 2.5L up to 2900 RPM at 70 MPH isn't going to hurt it. Just keep your oil clean and fresh.

These are critical questions. You can't go much deeper with gears. You have 4.10s -- if you go with Dana-Spicer gears, there's only one more step: 4.56. You can get 4.88s if you go with aftermarket gears. But a lot depends on what you want to do with the truck and what size tires you run (or plan to run).

The 4-way hazards use a separate flasher from the turn signals. You probably need a new flasher for the turns. You also may have one or more turn lights burned out, which will lock up the standard flasher (unless you have a heavy-duty flasher such as used in the trailer tow option). As to the dash lights, have you tried rotating the headlight knob? It's a dimmer, and all the way in one direction (I've forgotten which way) turns them off completely.

Did the crank position sensor (CPS) get damaged or disturbed during the swap?

Power does not come directly from the battery. You may have misunderstood something you read. The blower has four speeds. The lower three speeds are controlled by different resistors in the resitor pack, but high speed doesn't flow through a resistor. That's why if the internal fuse on the resistor pack blows, you have high speed but no lower speeds. BUT ... the fan doesn't run even on high speed when the ignition is turned off, so the power does NOT come direct from the battery.

An open system needs an expansion tank. If the MAC's aluminum tank had been available when I did my '88 XJ, that's the way I would have gone. But ... it wasn't, so I used a Moroso aluminum surge/expansion tank from a local speed shop. It's also sold by Summit racing. I run it with an overflow bottle:

Relays don't lighten the load on the electrical system. Ultimately, whatever component you're switching uses however much current and power as it needs. What relays do is reduce the current through the switch(es), and if properly located they also reduce voltage drop.

Numbers don't lie. The minimum gain you can get from a SOA conversion is the sum of the axle tube diameter + 2x spring perch offset + leaf pack thickness. A D44 tube is what, 2-3/4"? The spring pack is another 1-1/2". and the perch offset is about 1/2" x 2. That's 5-1/4" ... minimum.