Jeep JKU Build/Advice

[Kramnden]

In my attempt to get back on the trails, I picked up a relatively inexpensive JKU without fully researching which Jeep would be right for my needs. I got a 2011 Wrangler Unlimited Sport rocking a 2" body lift, Smittybilt XRC fenders (for tire clearance I assume), and running on 35" AT's. I ran it in Moab last weekend, hitting Fins and Things and Hell's Revenge. It handled both trails fine, but I can already see where it would benefit from some major improvements (gearing for starters).

Here's what I'd ultimately like to end up with:
Wrangler JKU, with a 3-4" suspension lift (body lift delete in this case) and lockers, on 37's.

I've priced out a handful of "upgrades" that would get me there, but I'm wondering if I'd be better off upgrading to a Rubicon first, and making adjustments from there. Where my Jeep stands now, it seems I'd need to replace the front axle with a D44, replace the dirvelines?, regear, truss the rear axle, upgrade to chromoly axle shafts in the rear, add lockers, and install a proper lift, all to capably run 37's off-road.

If you got through that word salad, here's the ultimate question: upgrade to a Rubicon and build from there, or have fun stashing money away until I can add most of these improvements?

*For reference: 2011 JKU with the weaker 3.8l engine. 150,000 miles. Automatic transmission. Really high gearing (I'm guessing 3.21 but I don't really know how to check that), D30 front axle, D44 rear. Open diff. Fox shocks front and rear, and Metal Cloak steering kit installed. And, because this would be a factor in which route to take, I picked this up for $9,500.*

 

[mbryson]

For that rig/engine, I'd gear to at least 4.88 or 5.13 just to run MTR 35". For 37" and a 3.8 (no experience with 3.8) I'd fudge that to 5.13.

Personally, I'd just stick to the D30 unless a D44 front falls in your lap.

 

[The_Lobbster]

If your goal is 37’s, I believe even the rubicon axles to be too weak. At that point, you might as well build some tons.

One thing to consider, instead of just gearing the axles, get a JK rubicon transfercase, has a 1:1 high still, but a 4:1 low. You could get a better crawl ratio. I saw one for $1500 the other day.

 

[moab_cj5]

I had 5.38's in my 2010 JKU on 37's and it still wouldn't get out of its own way. For 35's or 37's I'd seriously consider one ton axles or trussing some D44's.

 

[Kramnden]

I had 5.38's in my 2010 JKU on 37's and it still wouldn't get out of its own way. For 35's or 37's I'd seriously consider one ton axles or trussing some D44's.

What do you mean by, "It wouldn't get out of its own way?" Were you snapping axles or other axle related parts? Or is it that the 3.8l, even with low geared axles, is a dog to push 37's?

 

[Kramnden]

Or is it that the 3.8l, even with low geared axles, is a dog to push 37's?

Actually, I realize you didn't say anything about the engine, just the axles. Adding trusses would be the plan.

 

[moab_cj5]

What do you mean by, "It wouldn't get out of its own way?" Were you snapping axles or other axle related parts? Or is it that the 3.8l, even with low geared axles, is a dog to push 37's?

It was the most gutless vehicle I've ever owned. I lost OD on the freeway on any incline or over 75 mph.

The 3.8 is way underpowered even with gearing for my taste.

 

[UNSTUCK]

What are your goals? What trails do you want to be able to run? Running Hell's without issue covers a very good chunk of the trails in Moab. Were you dragging your belly/axles a lot? Will 1-2" more lift solve that? Are you not getting as many ducks as you hoped for so far?

Our opinions are just that. What we think may not make any sense to you. I like building jeeps probably more than wheeling them, so if it was mine, I'd likely do some stuff just to do it. Needed or not. Open diffs on stock axles may be perfect for some time while you learn the rig and how to wheel it. It may have plenty of power for you, even it's underpowered for me. Do you like to put the throttle to the floor and bounce up rocks or are you scared to spin a tire? Your style of wheeling will greatly change the build you need to do, which is good, because V8's and one ton axles are not in every recipe.

 

[Kramnden]

What are your goals? What trails do you want to be able to run? Running Hell's without issue covers a very good chunk of the trails in Moab. Were you dragging your belly/axles a lot? Will 1-2" more lift solve that? Are you not getting as many ducks as you hoped for so far?

Great questions. Lemme start with ducks; I've not recieved any, and it makes me sad. 🤣

In all seriousness, I've only owned a few Jeeps in the past, and none have been "built." I've wheeled all of them through Hell's (including a '99 Cherokee with a 2" budget boost and stock pizza cutters), Fins and Things, Poison Spider Mesa (minus this JK), and I took an open diff, D35 equipped TJ on 33's through Steelbender. I've made the silliest obstacles look technical, and taken bypasses when necessary. My goal this time around would be to wheel a more capable setup, while keeping it street legal. 70ish MPH on the freeway would be a plus, too.

Do you like to put the throttle to the floor and bounce up rocks or are you scared to spin a tire?

Although I have bumped up a ledge or two, and spun the tires up some steeper inclines, I'm not usually one to mash the peddle to the floor. Slow and steady, and finding the right lines is the game for me. That said, it's always fun to take more challenging lines, or crawl through more extreme obstacles. I like pushing the limits while still being able to drive home afterwords.

Your style of wheeling will greatly change the build you need to do, which is good, because V8's and one ton axles are not in every recipe.

I don't think this type of build is for me, honestly. I don't possess the mechanical prowess to swap engines or retrofit one tons. Perhaps my build preferences will change as I fully realize the limitations of strengthened D44's, locked, on 37's (35's if I must), and utilizing the stock motor. For now though, that's basically my goal.

My dilemma now is, should I save up for the D44 front axle, lockers, drivelines, regear, lift, etc., because I got a decent deal on this model, or would I have been better off spending a bit more on a Rubicon, and upgrading from there? Then, there's still the 3.8l I currently have VS a newer 3.6l...

Hopefully that makes my goals a bit more clear. I really appreciate everyone input so far.

 

[johngottfredson]

I’m no expert when it comes to fabrication and serious off road builds, but I AM a world expert at losing money on vehicles, so I am comfortable sharing what expertise I have.

If you don’t have the skills for v8 swaps or 1-ton axle swaps, then you need to be fine with low power/performance or high investment. The closer you can get to your final goal with factory components, the less money you’ll lose. As an example, if you swap in Dana 44’s and lockers into your vehicle, when you sell it you will only get a fraction of that money back. Whereas if you paid a little more for a rubicon, you get all that additional purchase price back on the resale.

I also subscribe to the camp of buying desirable models at a slightly higher price as being a better investment than lower tier models at a discount. Nobody is clambering for 3.8 wranglers for a reason. The 3.6 is awesome, will make you happier as an owner, and will pay for itself on the back end.

All of this is moot if you are a DIY rig builder like so many here and can do it on the reasonable, or if you keep your vehicles forever so resale isn’t a concern, or you are just easily satisfied and won’t be in danger of throwing good money into a weaker platform forever.

I would get the 3.6 Rubicon and upgrade/truss the axle housing and be done with it. But I don’t hold vehicles very long, I hate underpowered rigs, and I don’t self-perform my upgrades, so ymmv.

 

[Kramnden]

Sound advice Mr. johngottfredson. If it wasn't obvious before, I was already leaning that way, but I needed a better reason than, "cuz I wanna." I hadn't quite thought about resale either, and to be fair, that's not the goal at all, but I'm no motorhead, and my wrenching skills can only get me so far. It would be both easier and net a better return on investment to purchase the higher tier rig, as you out it.

If anyone else has something to add, feel free to do so, otherwise I'll just let this thread die and poke around the forum for other bits of info.

Thanks everyone!

 

[N-Smooth]

Just gear and lock it and see how you like it. It sounds like you got a great deal so throw a little money at it and re-assess.

If you start breaking 30 parts, then maybe it’s 44 time like you said.

 

[Bart]

No matter what year and model of JK you get, you should sleeve and gusset the axles if you plan to wheel it on 35s or 37s. It's just a given. I like the Rubi axles and lockers because you can direct wire the lockers to switches. Personally I would get a 2012 or newer for the motor/trans. It sounds like you got a decent deal on that one, so why not see where it goes. Yes, the 3.8 is anemic, especially combined with the 4 speed trans, but it does go down the road, and revs to the moon.

 

[mesha]

I live just down the road from you. You should stop by one of these days and we can talk. I am always happy to meet a fellow jeep guy.

When building a 3.8 JK the first things to do are 1-get 5.38 gears or however low you can go. 2-Sleeve and gusset the front axle. After that whatever you do depends on your goals. If you want to end up with 4" of suspension lift and 37s I say go for it and try wheeling on the stock(geared, sleeved, and gusseted) axle. Depending on your wheeling style a JK dana 30 might be fine. I would break one on 37s, but many people I have wheeled with wouldn't. If you are breaking stuff, watch out for a cheap set of rubicon axles and snatch them up when the pop up.

I like the 3.8 motor. Yeah it is slow, but with the right gears it is fine.

 

[N-Smooth]

^^^^Chatting with Davy (Mesha) about it is a great idea.