Eagle

Dan - Yes, of course it will work. See the last paragraph of my quote above. The Catch-22 is that you must forever remember that you have a 1990 front axle and order anything for the front (rotors, hubs, calipers, brake pads( for the '90. The hub offsets are incrementally different and if you mix '87 calipers and/or rotors on the '90 hub ... they won't rotate. As long as you remember to order the correct parts for the axle, it's just fine. Print out a copy of that listing I posted, it'll help you keep track of what you can and can't interchange. One other factor to remember is that the 90+ rotors are the crappy composite style rotors that warp if you speak harshly to them. If it were my choice, I would try to hold out for an '89 or earlier front axle, or else swap over the parts to enable me to keep using the '87 brakes. I've been a member of the "rotor of the month" club and I didn't enjoy it.

If you get a long or "full-length" (they aren't really full-length) AAL, it goes directly beneath the main leaf, unless your seond leaf is longer than the AAL in which case the AAL goes in the #3 position. You want the leaves to decrease in length in sequence. Don't bother with short, or "half-length" AALs, Those are the ones that have generated the AAL reputation for a stiff, choppy ride. If all you want is to make up the 1" that you're down in the back, I'll suggest the Rancho AAL that's listed in their catalog for the MJ. You'll notice they claim 2-1/2" -- but the same kit is also listed at 2-1/2" for the XJ. This is impossible. I called Rancho awhile back and asked. Spoke with a nice engineer chick, who went and checked with a couple of her colleagues, and the final answer was that it's 2-1/2" in the XJ and about 1-1/2" in an MJ. Perfect for leveling out an older truck, picking up a 2WD if you convert to 4WD, or just adding a bit of extra load capacity without getting into a "lift." Two is enough, but four is better. www.huskyspring.com BTW, MJ u-bolts do not interchange with XJ u-bolts. To further complicate the issue, both are metric. XJ u-bolts are 12mm (a hair less than 1/2" and MJ u-bolts are 14mm (approx. 9/16"). This makes the guys in spring shops go nuts. I've pretty much settled on 1/2" u-bolts from a commercial truck spring shop for both XJs and MJs. That way I don't have to keep two sizes around, and I'm comfortable that a new 1/2" u-bolt is as good as a rusted, bent, battered old 14mm u-bolt out a rusted, bent, battered old MJ. Anything is better than those cheap 7/16" "gold" plated u-bolts you see in the aisles at Pep Boys.

3.55 and 3.54 is normal. The two axles have different diameter ring gears and pinions. The tooth count can't be the same. The gear ratio is the number of teeth on the ring gear divided by the number of teeth on the pinion. Here's why the guy at the yard mentioned knuckles:

Monroe's entire catalog is on-line, last I knew. At the end of the catalog they have two sections that are of interest to us type people. First is the section that lists the shocks by length (extended and compressed) and by what type of fittings are on each end. Using that you can find shock numbers with the length and end fittings you need. Then there's an application listing, in which you look up the shock you just chose for length and it tells you what vehicle it is supposed to fit. Once you know that, you can shop other brands and sources for shock to fit that vehicle.

Budget boost. Rancho full-length AAL in the rear (about $50), and a pair of 1-3/4" coil spacers in the front. Done.

Pete's photo is an MJ valve, with the lower front (rear prop valve) line plugged and the "nose" line feeding directly to the rear axle. If you are swapping in an XJ proportioning valve, you don't plug anything. The two upper fittings are the inlets from the master cylinder and you leave them exactly as they were to the MJ valve. The lower rear outlet and the outlet at the "tail" feed the front brakes and are replaced exactly as they were in the MJ valve ... and as shown in Pete's photo. The line from the rear axle goes to the lower front outlet, the one that is shown plugged in Pete's photo. Run from that port directly to the upper end of the rear axle flex hose; do NOT use the rear proportioning valve when using an XJ combo valve in the front.

www.huskyspring.com

Beyond all doubt, THE best deal in the known universe for weld-on spring perches is your local Mopar dealer. They're in the Performance catalog, part number P4120074. They are slightly longer than the factory perches and also beefier. They are designed for a 3" OD tube but they work well with a D44. You won't believe the price. Most places want around $40 to $50 for a pair of perches that are grossly inferior to these. These sell for about $10 per pair.

I don't recall the tube diameter for a D35 and it's raining outside so I'm not going out to measure one right now. Let's guess it's 2-5/8". The mounting surface of the perch is probably offset from the axle by about 5/16", and when you weld on a new one on top of the axle that's going to be another 5"16" (or so). And then there's the spring pack -- four leaves at 1/4" plus the overload leaf at 1/2" 2.625 0.313 0.313 1.500 ------ 4.750 That's the minimum lift you'll get going SOA. If the axle tube is actually larger, or the perches have their mounting surface farther from the surface of the tube, the amount of lift goes up. So you really should be figuring 5" if you do SOA. If all you want to run is 31s, a 3" lift is MORE than enough. Even a 2" budget boost will be plenty. Remember, 31s will fit a stock height MJ just fine. On factory rims they stuff inside the flares. The rubbing you'll get is on the lower control arms at full steering lock, and a lift does NOT eliminate that.

Real world example. I pulled a decent set of Gabriel gas shocks out of the rear of an XJ I bought for the drive train. The 2WD SWB Comanche I have here needs rear shocks big time, so I thought I could possibly remove the bar pins and get by with them in the MJ. My initial measurements suggested they'd be just about maxed out at rest, but I thought they woud bolt in. So I chopped the end off each bar pin and pushed them out. When I tried to mount the shocks in the MJ, even fully extended they were about 1/2" too short. You can buy new shocks (stock height) from Pep Boys or Auto Zone for $10 each if you're in a bind. Don't even bother fooling around with XJ stuff. Not on the rear, anyway.

Halfway is exactly correct. The "marker" is a post inside the bottle, beneath the cap. Of course, you have to be at least 6'-9" tall AND double jointed to see it ... but that's the marker.

I think the Mopar 8.25 is 3" and the D44 is slightly smaller, but I can't find an actual spec. Measure again -- carefully.

Personally, I would seriously rethink doing the spring over. That's going to lift the rear at LEAST 5" and, as I've posted, I think it'll be closer to 6". Once you get into that much lift in the front, you NEED either drop brackets or a long arm kit, a heavy-duty adjustable track bar, adjustable upper and lower control arms, and probably a stretched front drive shaft. What are you going to be doing that absolutely requires that much lift? I bought my '88 MJ with a 4" lift in it, drove and wheeled it for two years, then I removed the lift aand went back to stock height. I couldn't be happier. Best mod I ever made.

:???: Huh? Where'd you get a front 8.25 axle from? I'm totally confused as to what you're going to do. If you don't install the rear 8.25 as a spring over, then you won't get any lift. So regardless of what you put under the front, you won't need longer springs or shocks.

It doesn't hold a candle to pushing the guidance director's Fiat sedan onto the auditorium stage during the senior class dinner. But go ahead. I hope your principal has a sense of humour. Our guidance director didn't ...

How much would the trailer and boat weigh? And how far do you plan to tow and at what speeds? Without specifics, my guess is a 23-foot boat on a trailer is probably pushing the envelope.

I thought you were referring to leaf pack thickness. It's deceptive referring to perch "thickness," because the perches aren't solid. What counts isn't their thickness, but the distance from the OD of the axle tube to the mating surface of the perch. That's why I expressed it as I did. Another way to envision it would be as if you had the same axle tube with both the old (under) perches and the new (over) perches in place. You would simply measure the distance/height between the upper and lower perch mating surfaces. Then add in the thickness of the leaf pack and you have the amount of lift. And then you can add or subtract as necessary if the axle tube diameter changes. I think we're saying the same thing, it's just a matter of expressing a visual image in words.

on the same note the sum of a lower (spring under axle of different thickness) is the [new axle OD minus the old axle OD] plus the [thickness of the new perch minus the thickness of the old perch] if i'm not mistaken...old thickness has to be taken into account as such. just an observation Nope. When the spring is under the axle, the thickness of the spring pack doesn't matter because regardless of the number or thickness of the leaves, the axle always rests on top of the main leaf.

"Evac" means to evacuate -- which in turn means removing any existing R-12 left in the system. R-12 is a serious greenhouse gas and can be serviced only by licensed technicians. Most states (and I thinkg the Feds) make it a criminal offense to just dump the stuff into the atmosphere. Besides, since the stuff cannot be manufactured any more, the only source for it is what shops can salvage. A tank of R-12 now sells for several hundred dollars. Most shops will at least evacuate your system for free in exchange for any R-12 they can recapture. Once in awhile they might even pay you for it. Once the remaining R-12 has been reclaimed, the next step is to "pull a vacuum," which is done to ensure that there's no residual moisture lurking in there to muck up the new gas. The new kits claim you can then just pump their contents into the system, but most sources I've seen recommend replacing the drier first. That would be done, of course, before pulling the vaccum and refilling the system.

That's sort of what I was thinking. As it stands, I now have no A/C. What's the worst that can happen, I won't have A/C?

Don't forget, when you go from spring under to spring over, the amount of lift is the sum of the axle tube OD plus the distance from the tube to the perch mounting surface (times two, once for under and once for over), plus the thickness of the spring pack itself. And if you're going from a D35 to a Chrysler 8.25, then you also add the difference in the tube diameters. I think that's going to add up to around 6"

Ummm, wrong. 1) The XJ spring perches are spaced differently from the MJ. You'll have to cut them off and relocate them. 2) More like 5" to 6" of lift. No way is it 3" for a SOA conversion. The 8.25 has larger tubes that either a D35 or a D44 so it's probably going to be at least 6" for you.

I'm looking at this conversion for both my '88 XJ and '88 MJ. I know the oil compatibility was a huge problem with the original RC134 conversions, but the kits they sell now imply that the oil in the kits is somehow compatible with the old oil in the R-12 systems. Is this true? Can I just evecuate and refill, or do I really have to pull the compressor and dump all the old oil?

Rear? I think they're 10mm but I don't remember the thread pitch. I'm sure they are metric.

Brakes are a good thing. You can take that to the bank.