Eagle

Last I knew, nobody offered anything steeper than 4.88 for the Dana 30 because beyond that the pinion got so small it was guaranteed to break. So 4.88 is the limit, and there's probably a reason why the factory never offered that as a ratio.

They won't fit, and they're much too big for a 2.5L anyway. Let's assume you have 4.10 gears and a five-speed. At 60 MPH, the engine would be turning 2700 in 4th gear, and only 2000 RPM in 5th. That's WAY below the power and torque peaks for the 2.5L.

Just a stiff ride. Thought it was because of the angle Nope. That's right about where it should be.

There is a thermal fuse in the resistor pack. If mice build a nest in the blower or the blower box and the nest material gets packed around the thermal fuse, it overheats and does what it's supposed to do -- blows. I lost two in the space of a couple of weeks in my 2000 XJ thanks to the danged mice. One of these days I'll try to replace the thermal fuse in one of the old resistor packs and see how that works. The resistors themselves should be fine.

Out of balance. More likely, the slip joint may be worn out. That was the problem with the 2001 XJ I bought (which doesn't have a CAD, by the way). I had a horrible vibration that started acting up around 50 MPH and got worse as the speed increased. I could crawl under the front, grab the aft end of the front yoke, and both see and feel significant angular movement when shaking the yoke (slip joint) side-to-side. I tossed in a junkyard front driveshaft and it pretty much cured it -- enough to get me through the winter, anyway.

What's wrong with a 90-degree shackle angle? Isn't that what it's supposed to be? With a 90-degree angle, the spring can allow both compression (suspension down travel) and extension (suspension up travel). That's usually what we want -- for the suspension to work in both (vertical) directions). XJs are different. The stock XJ leaf springs are spring-over and essentially flat at static rest, so they bend (making the eye-to-eye distance shorter) in both compression and extension. So the XJ stock set up has the shackle pointing back, and it swings forward whether the suspension compresses or extends. Unless your springs are flat at curb rest, I don't think you need to change your shackle angle.

Please post the explanation so if anyone else encounters it, we'll all know. That's how these forums share information.

'86 was different from '87 and newer. The optional transfer case was an NP 228 (or 229), and that had an unusual control setup. Does your truck have Command-Trac or Selec-Trac?

Dunno if you need an entire new column, but if you don't have the nut I suspect there are probably a few other parts missing, as well. I certainly think replacing the nut (and the missing pieces, if you can get them) would be first step, before undertaking a wholesale replacement of the entire column.

CPS?

Even if you don't machine the block, before reassembly you should lightly hone the cylinder walls. That will clean up any light surface rust that might form, as well as prepare the walls so the new rings will seat.

How are your motor mounts? A broken motor mount would possibly allow the engine to twist enough that the fan hits the shroud.

All years of the XJ had rear sway bars, except that Jeep didn't use it on the XJs with the optional Up Country (off-road) suspension. I don't think it can be adapted to the MJ -- and it's so skinny I think it would be worthless anyway. Monroe makes the Load Leveler shocks, but there isn't one listed for the MJ. This was discussed here awhile back. We pretty much decided that there's no listing because adding load carrying capacity would have the effect of defeating the rear height-sensing proportioning valve. But Monroe does make one that's the right length and end fittings to use on an MJ -- you'll have to go to the Monroe web site and surf through the dimensional listings section to find it.

Yes. Yes. The lowest temperature thermostat you can get away with is a 180-degree. With the 160, the sensor that tells the ECU when to switch from open loop (warm-up) mode to closed loop (normal run) mode never tells the ECU to switch modes. In open loop mode, the air-fuel mix is basically not adjusted by input from the various sensors, it's based on a pre-programmed fuel "map."

The hood is different but I don't think they changed the header panel until 1990. And the '86 hood could probably be modified to fit an '88. The basic hood is the same, it's the latches that changed. Gauge cluster could be made to work, but the '88 used the nylon push-on speedo cable attachment, and the '86 used a metal tab and retainer screw.

My '87 was bought used and came with a factory roll bar and factory off-road lights. The lights were KC somethings -- "DaLiter," "HiLiter," i don't know what the name was but awile back I could find them on the KC web site. Now I can't -- they were rectangular, I think about 6" x 9", not the round lights we see on the KC site today. I refer to them in the past tense because there were horribly rusted, so I chopped 'em off and tossed them. Every MJ I've seen with a factory roll bar has had the same lights, so I'm fairly certain they WERE a factory option.

K-C Da-Liters, IIRC.

CPS

I believe it should work as a standalone. My reason for thining that is that the Mopar Performance Catalog used to offer (and perhaps still does, but these days it's only on-line and I'm old enough that I love thumbing through paper catalogs) an MPFI conversion for the carbureted 4.2L YJs. That conversion was essentially the EFI and underhood wiring harness from a '95 YJ. If it works for the 4.0L, it should work for the 2.5L.

I disagree. The gain will be worthwhile. The throttle body injected version produced 117 horsepower at 5,000 RPM and 135 foot-pounds of torque at 3,500 RPM when it was introduced in the 1986 model year. This was raised to 121 horsepower at 5,250 RPM and 141 foot-pounds of torque at 3,250 RPM for model years 1987 through 1990. The final, multi-port injected version produced 130 horsepower at 5,250 RPM and 150 foot-pounds of torque at 3,250 RPM. If you get the system from a '97 - '00 Cherokee, you'll also get OBD-II, which will allow using a hand-held scanner to read trouble codes.

Firewall part of the project? To go from a '91 to an '01 there's nothing to change about the firewall. Use the cross member that belongs with the transmission and transfer case you'll be using.

Any 1991 or newer Jeep YJ, TJ, XJ or MJ. Chrysler changed from throttle body to multi-port on the 2.5L in 1991. But it's also a Chrysler ignition, so you will need a new ECU and under-hood wiring harness.

VERY bad idea.

The symptoms sound like CPS. That's kind of what my '88 XJ did the second time it wanted a new CPS. The first time it gave no warning at all (or I was just lucky). That time I drove it home, parked in front of the garage, and the next morning it wouldn't start.

You can run 31x10.50-15s on a stock MJ with no lift. I'm running 31s on my stock 1988 XJ with no lift, and the MJ has larger wheel wells in the rear.