XJ curb weights through the years.

Hey guys. So I've owned a lot of XJ's, and I know they got heavier several times, mainly for NVH and safety ratings, but I can't find a definitive list of curb weights for stock XJ's throughout the years.
I need to know fairly accurately, what years got heavier, and WHY. I know in 94+ they started adding side impact beams to the doors, then got a steel hatch, and then some beefier unibody structure, but I want to be sure I know I'm looking for the right year for my application.

Backstory: My current rig is about as built as you can build an XJ, minus axles. I plated the shit out of the uni, braced everything 8 different directions, dropped in a 5.3L, blah blah blah. It's now 5000lbs and while I'm not a weight weenie, all that extra weight in the lower end of the uni, causes the upper to want to separate from itself. At the end of the day, the Jeep does everything I want it to except survive long term, or survive a flop. I figure at this point, 80% of my work into it is in plating/bracing, and when I do inevitably flop, i'll be writing off 80% of the work/money put into it.

For that reason, I started a new build. Started with a first gen Runner SFA frame, built some BJ60 axles (Land Cruiser 60 series, front flipped for driver drop, rear hybridized with mini outer tubes for center pumpkin), stuck in another 5.3L v8, etc. The build is now driveable, but as much as I dig the lines of the first gen runner body, 1. it only comes in a 2 door (and I need 4), 2. It's near impossible to find a clean first gen body, 3. The runner body requires as much, if not more work than an XJ shell, to clear 40's, and 4. the XJ is just the perfect size/shape for what I do.

So the plan may be making a minor detour, and I'm seriously considering chopping the uni-rails off an XJ and dumping it on top of the runner frame. Measured it all up, and it'll almost drop right on.
BUT, I figure if I'm going to do this, I want to keep the top light, and avoid all the Chrysler junk (ie: the Dodge Neon interior introduced in 98, the steel hatch, etc).
I'm trying to decide between a pre 94, or 94-97 shell. Pre-94 I lose a lot of rigidity in the doors, but I'm not sure if that'll matter when it's on top of a frame. Roof rigidity doesn't matter at all, as I'll be chopping it off, tubing it in, and running a soft top.
The whole thing will be exo caged.

So, who knows the actual weight of a pre 94, and a 94-97?

I don't see any mention of a cage? Cages are often incorrectly seen as exclusively a safety modification, but unibody vehicles need them for chassis stability.

Anything with tires that big needs more than a ladder box style unibody.... No matter how much you plate it, it's still lacking 3D strength...

A Caged pig is better than an uncaged jeep missing a couple bits of oem weight.

Yup, and that's part of the problem. XJ is now 5000lbs and it's holding together pretty valiantly, but every few months I notice some new cracks or seam separations developing. I fix them and add more plating/reinforcement, but it's a losing proposition.
I'm sorta thinking that given I'll be framing as well as caging, I could probably safely go with the lightest shell manufactured (85-89) and be fine. Side impact beams aren't doing to do shit compared to the exo, so they may just be superfluous weight/protection.
I never liked the steel hatch. When you pin it on a tree, it just folds and crushes and it's a shit show to repair, and in my area, 98+ parts are worth their weight in gold while pre 96 stuff is reasonably priced.

Just trying to think of anything I might want (with regards to weight/year), even after the frame and cage, as well as knowing what sorta weight to expect so I can properly design the suspension. After this last trip out over the long weekend, I know damned well how big a difference 400lbs makes. I built my suspension for 5000 to 5500 lbs. Loaded up to 5800lbs it rides like shit. Drop off the gear at camp and go back out, and I can fly down the same trails 4-5x faster with zero scary noises, no bottoming, etc. Trying to get the new build right on the first try .

I don't have definitive weight answers, but I can tell you that '95 was the year they introduced the airbag and reinforced the front seat mounts with a cross bar (same design as was carried on from '97-'01).

Another detail worth noting is the change in the engine compartment which I believe came about in '87. I think it is the '86 and down that have a shorter engine compartment with a substantially different radiator support. Since you have already done one V-8 conversion you probably have a much better idea than I do of how much of a difference that may make.

My guess is that your best bet is probably to get an '87-'90 as a start point. The Renix years typically sell for less than the H.O. years (at least in my market) and for your purposes it doesn't matter what system is in there because you are going to change it out anyways. The body is all that you really care about, and AMC probably did a better job on that than did Chrysler.

Anak said:

I don't have definitive weight answers, but I can tell you that '95 was the year they introduced the airbag and reinforced the front seat mounts with a cross bar (same design as was carried on from '97-'01).

Another detail worth noting is the change in the engine compartment which I believe came about in '87. I think it is the '86 and down that have a shorter engine compartment with a substantially different radiator support. Since you have already done one V-8 conversion you probably have a much better idea than I do of how much of a difference that may make.

My guess is that your best bet is probably to get an '87-'90 as a start point. The Renix years typically sell for less than the H.O. years (at least in my market) and for your purposes it doesn't matter what system is in there because you are going to change it out anyways. The body is all that you really care about, and AMC probably did a better job on that than did Chrysler.

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Shit. I didn't know about the engine bay being shorter on the early years. There's JUST enough room in a 94+ to fit the 5.3L comfortably (it looks like it belongs there). That was one of the annoyances I ran into with the runner body. The engine bay just isn't quite long enough, so I stuck it as low and far back into the FW as I could (it's binding on stuff even after lots of hammering) and still had to chop the front rad support out for clearance for the rad/e-fan.

I just compared the motor height in my runner frame compared to both of our v8 xj's, and the motor is low enough in the runner that I'm confident it'll clear a stock hood with room to spare. it's almost 2" lower in the runner frame than the XJ, despite the skinnier frame rails.
That said though, I'm planning on chopping the front of the frame off to widen it out a little because it doesn't have enough width to accommodate the AC pump (which I need for OBA). Once I've done that, I can probably lower the motor anywhere I want, but I think it's probably good now, considering the oil pan is only an inch above the top of the axle tube.

And as for 87-90, I agree and that was my first thought. They're definitely the lightest, by between 300 and 600lbs roughly.
One thing I haven't figured out yet, is how I'm going to do the cage. The whole point of this was to build a platform (frame) on top of which I can just drop a new body in under a days work. A conventional exo would make it a real whore to remove the body, so I'm trying to come up with a design that'll allow me to build the lower half of the cage into the frame, then I'd drop the body on top, and the top half of the cage would bolt in or be welded to sacrificial tabs of some sort. Also, the front of the XJ would probably be chopped off from the firewall forward, so the entire front would be fully caged and enclosed in sheet panels (removable for easy access).

Also, does anyone know roughly what a pair of d30/44 axles, 4.0L, ax15, and np231 weigh? Maybe it's easier to subtract some knowns.

Out of curiousity, did you actually weigh it? A 5.3 iron block ls weighs very similar to a 4.0...so you have over 1000lbs of armor and plating?

JohnX said:

Out of curiousity, did you actually weigh it? A 5.3 iron block ls weighs very similar to a 4.0...so you have over 1000lbs of armor and plating?

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Yup. 5.3 is actually about 35lbs lighter, but the 4l65e balances it out so there is no gain/loss of weight. The weight is all in plating, bracing, bumpers, winch, and roof basket. The stuff I can survive is retarded, but my wheelin' is getting too retarded even for all the beef.
Weighed at 3 separate scales. All within' 50lbs of 5000. It kills me because all that mass results in awesome traction, and with the suspension tuned properly for it, it hooks up and gets me up stuff with zero tire spin, in stuff where much larger rigs on 40+ shoes have trouble. I may not be too concerned about the new build hitting the 5k mark as well for that reason, but I'd like to have as much wiggle room as possible before I start adding bumpers/cage.

The differance between a couple chunks of steel being .120 vs .188 or even .250, will much more than make up for a couple door supports. Think light on the next one.

The engine bay is not really shorter. The front radiator support changed when the 4.0L was introduced and a small dimple was added on the driver's side firewall near the head.

I actually put a 4.0L stroked to 4.7L into an 85 with a 2.5L. I swapped the radiator support and hood, along with massaging the firewall slightly with a BFH.

Also, the core support on late model 2.5s is similar to the old 2.8 style. I just happen to have both out front.

I've read they fit a 5.9 better than a 4.0 when it comes to conversions.