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post #1 of (permalink) Old 07-17-2009, 09:29 AM Thread Starter
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CJ-7 axle swap - width recommendations

I am about to start my long overdue build. My currently stock '84 CJ-7 drivetrain will receive the following transplants: '96 LT1 350, SM465, D300, Ford 9" rear, Dana 44 front. I have everything I need for the project except for the t-case adapter, wiring harness, and suspension lift (evaluating now to compensate for V-8 weight).

I am seeking experiences, input, and recommendations on axle width. I've got the donors almost all cleaned up and ready for the chop. Width is obviously connected to my use. My goals are pretty restrained: I don't seek to create a monster Jeep, a buggy, or a rock crawler in the traditional sense since I'm on the east coast. I plan on staying spring-under-axle, flipping the U-bolts. I just seek to create a tough, fuel-injected, what I would classify "semi-modified" Jeep. I don't see myself running anything larger than 33" tires, but might be swayed toward 35" once I see the thing coming together.

In theory I only need to cut three sides; both ends of the 9" rear and the long side of the D44 front, as it's a flat-top version from a J10 pickup. Any recommendations on widths from wheel mounting surface to wheel mounting surface? Others with similar setups or experiences? Has anyone blueprinted a similar setup a reference?

Also, what are your feelings on maintaining the construct of keeping the front slightly wider than the rear, like the stock widths?
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post #2 of (permalink) Old 07-17-2009, 12:17 PM
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Welcome to the board! I'd say you've got the disease, bad.

I'm not a fan of wide Jeeps, because narrow works better here, where I often have to thread my way between trees. When I replaced the D30 with a D44, I narrowed it back to stock narrow-track width, which required shortening both sides. I certainly wouldn't go wider than the later wide-track CJ, which is about 2" wider per side, but that's personal preference. And that would still require taking a couple of inches out of the short side. As long as you stay spring under, the differential has to remain in the stock position. With enough lift there's a little room to move it side to side, but still not much. Not too long ago someone posted a chart of WMS lengths for several axle configurations. Do a search for "WMS" and you should be able to find it.

For 35" tires you're going to need about 4" of lift. At that you're in the neighborhood of what a spring-over will do. If that's really what you want, I think most folks would recommend biting the bullet and going SOA. The ride and handling will be much better than with lift springs, and many of the complications are the same whether you go SOA or spring lift.

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post #3 of (permalink) Old 07-17-2009, 01:17 PM Thread Starter
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I've had the disease, treated it for awhile because of that life thing, but relapsed. I've been building it in my head and acquiring the necessary goods to make it happen for a couple years, including the LT1 that I'd been casually keeping an eye out for and am tearing into soon.

I hadn't really even considered going SOA, to be honest, just because of my desire to not have a monster and some of the experiences I've heard over time. I was playing conservative and thought SUA would be safer; drop pitman arm, t-case lowering at most. I need new springs, regardless, not using the stock even if I were to go SOA. Maybe I talked myself out of it and shouldn't have?

I will look up the WMS>WMS lengths. I really don't want this thing wide. I thought I might be able to retain the short-side length of the donor D44 and base everything off that, resulting in a couple inches wider stance. Like youself I don't want a wide stance. Maybe like stock + a couple months at the gym, just "buff" not over the top.

This weekend I'll compare the short-side on the stock D30 compared to the D44 closer. When I picked this up a couple years ago it all seemed to make perfect sense...then.

What about wider front vs. rear for tracking? Thoughts?
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post #4 of (permalink) Old 07-17-2009, 01:39 PM
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The relative width front to rear is a total mystery to me. I would tend to build it that way because that's the way some engineers who know a whole lot about those things thought it would work best.

Personally, I wouldn't do SOA and stock width - too much height for the width. But I wouldn't even go 3" lift. My CJ is stock height, stock width, rubs 31s a little at full flex, and all that is just fine with me. Look at some pictures of how it sits on my website. One thing, I have the stock heavy-duty springs, which picks it up about an inch I think.

But if you want to run 33s you'll need some lift, but maybe a 1" body lift would clear. I wouldn't go any higher than that with a body lift. Actually, I wouldn't even do that, but . . . Wait around for some more opinions. There are a lot of them here, and mine are often not mainstream.

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post #5 of (permalink) Old 07-17-2009, 02:15 PM Thread Starter
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From the little I know I think the wider front is so the tail tracks the front easier, but who knows. CJs went "wide track" too becauase of litigious influence, too. My CJ7 will have some time on the road as well, so being friendly on the pavement is also important for my project.

I don't plan to do a body lift. I want to possibly go a little wider just to allow for a slight increase in tire width but like you don't want my jeep to be wide. I have stock wide-track now, about 56" wide, and considered 58" and had that recommended as well. But again I need to get back to it and check out the widths of the new donor D44.

I am skittish about SOA just because of the horror stories you can find out there in terms of the slippery slope of other corrections (high steer, etc). My donor D44 is flat-topped, though. Since I'm going to have some bigger torque with the injected 350, wrapping is one of those larger concerns, and the aforementioned road mannerisms. Maybe I'll line everything up comparing stock next to the new donor and it'll influence my desired width so I can get these cut and placed.
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post #6 of (permalink) Old 07-17-2009, 04:28 PM
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My big gripe with 4" spring lifts is that every one I've ever ridden in has had a TERRIBLE ride. I like firm suspension, but the way a CJ hobby-horses on tall springs is just too much for me. On the other hand, a lot of people have said that Old Man Emu springs are much better-riding that any others, and almost as good as stock. If I were to do a spring lift, that's where I'd go.

SOA is a lot more involved that putting perches on top of the axle tubes, for sure. But done right they ride as good as stock, handle well considering the center of gravity, and work very well off road. The key is the "done right" part. There is plenty of experience with them here that you could do it right if you wanted. Too tall for me, though.

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post #7 of (permalink) Old 07-17-2009, 07:16 PM
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I have an '84 and have run stock "wide track" axles, 60" wms and now 64" wms axles. I ran 33's and 36's spring under and now run 36 spring over.

The 60" wms is nice because it still allowed the tires to pretty much tuck under the fenders. The 64" pushed about 1/2 the tread outside of the fender.

In my opinion, your best bet is to figure out what width your front axle would be if you only cut the long side. Why cut twice when you can cut once. You might also be able to cut your rear axle one time as well and just run your drive shaft off center.

As for spring over/spring under, they both have their pluses and minuses. If you ever plan on going bigger than 33's then spring over might be the right thing to do now. However, if you don't intend to go above 33"s, then you might be able to get away with a 2" spring under and a 1" body lift, depends upon how much up travel you want and fender trimming you're willing to do.

Good luck,
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post #8 of (permalink) Old 07-17-2009, 07:41 PM Thread Starter
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Yes on all fronts. I'm not opening nor want to get into the SOA versus SUA setups. Both are successful when done well. I like the clearance, automatic lift, and frankly cleanliness of an SOA setup. I also know that it's way more involved if it's to be done right. Some of this might be confidence in my abilities, etc. I am going to have a heavy duty shop do the chopping for me as they have been around forever and build 4x4s all the way up to a couple literal monster trucks that used to be in my area and the equipment to boot.

I've always heard good things about OME stuff, and the dollars go with it. I need to make sure any non-custom setup will handle the LT1 V8 weight.

Now, on the width, I really don't want to be too wide. It sounds like I'm settling on the 58" - 60" range. This should allow it wide enough for a little more room for tire width, stability, but also keep it mangeable and clean looking. Keeping spring under was just sort of a de facto conclusion knowing that the SOA arrangement was probably something more than I wanted to get into, plus it not being monster height, but maybe I should reconsider. I don't know about chopping one side of the ford 9" rear end, though, it might be too much but it is from a 70s Ford so it's not terribly wide.

Off to the garage now and see what I can figure out about what/how much needs to meet its maker on the chopping block.
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post #9 of (permalink) Old 07-17-2009, 08:41 PM
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I think you need to keep the axles on the narrow side, and you should make an exra 9" ....... I'll keep in my jeep until you need it.......


When you build the 9".... take a lot of pics....it's something I've wanted to put in my CJ5 for a long time. I've just got too much invested (arb locker) in my AMC20 to scrap it........ but when it finally breaks, I'll be seriously sizing up the 9"......

Good luck with your build!
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post #10 of (permalink) Old 07-17-2009, 10:46 PM Thread Starter
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The J10 D44 measured up at 65" WMS to WMS. I had to reassemble one side (it's got large Warn hubs from the donor). I didn't get some reference points from WMS to spring perches on the stock D30 yet to see what that means overall, if I can keep the short side as-is and not be too wide in the end. I am leaning toward 58"-60" max depending on that short side and may center the 9" and run an inch or inch-and-a-half narrower than front like the factory construct.
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