Rear Coil Conversion

My 98 XJ that I purchased last fall has a new 8"Rock Ready lift in it that I intend to replace with a 5 1/2" IRO Critical path kit. I have a ZJ in AZ and really like the articulation of the rear coils, so am wondering if it is worth the expense to convert the rear leafs on my XJ to coils when I swap in the IRO kit. I can't seem to find very much info for this project. I'll probably wheel it a dozen times a year. I don't have much time in the XJ, but noticed right away that the ride is rougher and articulation is less than my ZJ. Any ideas will be appreciated.

You link the rear for traction on climbs, not for articulation or ride. My bastard pack on the XJ rode better than my buddies ZJ. It's easier to get a good rear leaf pack, or tune a rear leaf pack to be good, than it is to switch to a linked suspension. Any decent suspension kit has enough articulation, and any decent rear leaf spring has enough articulation if the shackle angle is good, the bolts aren't too tight, and the shocks aren't too short.

If you're not making climbs that you're buddies are making because your rear leafs allow bounce and axle wrap and won't hook up well enough to make the big climbs, then consider linking the rear. But, not for ride or articulation.

Leafs in the rear help with stability as well in off camber situations.

IIRC the rock ready kit doesn't even come with long arms, it just comes with adjustable control arms (correct me if I am wrong). At 8" lift that would greatly reduce ride quality. Also to get to 8" I am pretty sure they would have to use a leaf spring that has QUITE a bit of arch, which will also reduce ride quality and reduce flex quite a bit.

When you drop it down, if you go long arm and keep your leaf arch and shackle length/angle in check, you should be fine with leafs I would think. Right now I am running stock front arms with maybe 3.5" lift. At maybe 4" out back with leafs only (and a bit of lift from my axle swap). Going from stock to 3.5" lift did make the ride quite a bit rougher but I am thinking alot of that had to do with the CA angles and shackle angle, and the rest of that came from the fact that I went from a tired stock suspension to a new/quality offroad setup.

If you run shackle relocation brackets (or relocate your shackles somehow) so you have a 45* shackle angle you would get more flex (more drop) and better ride quality out of the rear leafs. Add long arms up front and you may get better ride quality out of the front. I plan on adding LAs up front and doing something for my shackles out back and hopefully end up around 4-4.5" lift.

Spring rate and shock valving determine ride quality more than anything else. A tall lift, or a more ached spring, don't mean a harsher ride all by themselves.

Goatman said:

Spring rate and shock valving determine ride quality more than anything else. A tall lift, or a more ached spring, don't mean a harsher ride all by themselves.

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I understand, but I thought (possibly/likely incorrectly) that in most cases a more arched spring would in turn increase spring rate, though it also has to do with # of leafs and many other factors... I was just making a broad comment on what I have witnessed in different rigs I have been in.

And I am pretty sure my shock valving has quite a bit to do with the ride of my suspension, though I'm betting some of the harder shocks i feel are due to stock CAs and [near] vertical shackle angle. But anyway, listen to goat over me any day of the week. you can disregard my comments :rof:

I have the complete IRO long arm kit to install. As I mentioned above, I know nothing about setting up an XJ for best performance. Should I go for different rear leafs? I'm sure I will have to do some serious fender trimming, as it has 36" IROK Super Swamper tires. I also have a set of Bushwacker fender flares to cover up the trimming. The guy had the front ACOS cranked up so that the front was closer to a 10" lift and the rear was closer to 7"s. The HP30 and 8.8 have 488 gears with an ARB up front and a detroit in the rear. Alloys in both. I think I have a good starting rig and drivrline, but I need to finish it off with good articulation and ride.

If it sounds like I'm headed in the wrong direction, now is the time to let me know.

Thanks

if you want to lose that acos cheap ill take it off your hands

tonysinnette said:

Leafs in the rear help with stability as well in off camber situations.

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How so?

Jes said:

How so?

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Some people allow things like the body to get in the way of their designs.



I wouldn't link a full body XJ.

Phil said:

Some people allow things like the body to get in the way of their designs.



I wouldn't link a full body XJ.

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Leaves are definitely easier. Clayton and Rock Krawler both have conversion kits for rear coils on XJ's that would be worth looking at (go Clayton!) if you are serious about it. You can get a better RTI flexage score with the coils, but we all know how important that number really is. If you do a lot of rockbed crawling-type wheeling, they can be nice there, too. I was talking to one of the guys at a fall fling in Moab (Tom from CO with his SWEET orange XJ, rear coilovers, D44s, etc) and he said popping the rear end up and over ledges was proving to be much more difficult for him than with his standard rear leaf bretheren. That is the only wheeling 'drawback' I have heard. All the other drawbacks that come to mind are just about inconvenience. The time it takes, you will need to fab a rear sway bar (maybe?), trial and error tuning, lotsa cutting and welding, etc. Generally, it seems to be more work than a lot of people are willing to justify for the gains is presents.
Finally, as these other fine gents have said, your ride quality can be just fine with the right stuff under the rig. I agree you should go with some different leafs, shocks you like, and make sure your shackle angle is reasonable.
Enjoy your project :looney:

For now, at least, I will stick with leafs. It seems much easier and I could always do the coil conversion next year if desired. There was an XJ on e-bay with the rear coil conversion that I was considering, but it sounds like he may have sold it today. I guess, as long as I have the IRO kit in hand, I might as well put it in. I bought the 5 1/2" lift with the 6 1/2" shackles for the rear. I thought that the ACOS up front would give me closer to 6 1/2-7" of lift, I needed a little more in the rear. At this height, what is the best brand of leaf and shock to use? The kit came with the Doetschtech 8000 pre-runners w/bumpstops. That's the shock I have on my ZJ, but it seems a little firm. The crawling down in AZ is over rocks and the coils perform very good, but there are a lot of wranglers on leafs front and rear. In WI and MN the crawling is more in the woods with logs, and hills with ledges to climb. I will be taking the XJ to Moab in Sept. I'm probably going to start my project in couple of weeks. There is a big trail run in Dresser, WI over Memorial day and would like to have it done be then.

Go wheel it then find out what you want or need to do to make it better.I would take out the lockers to truley find out what you and it can do offroad. Seat time will help you decide upgrades..