TJ Rubicon axles in an XJ

Before I launch into this... I'm not looking to start a religious war over which axle is better, just see if anyone else thinks the following is feasible or not.

Basically, there are three things that I'd like to do to my XJ's drivetrain: lockers, beefier axles, and regearing. This would mean three separate sets of work for essentially one final result - well, two really, if the regear & lockers are done at the same time. With that in mind, I'm going to start looking a bit more seriously into swapping TJ Rubicon axles into my XJ. I'll get into the reasons for this in a bit.

According to this thread, the TJ D44 front axle will pretty much drop directly in. Possible driveshaft length issues apart, this should be relatively painless based on the experiences most people seem to have had doing this conversion.

From what I've been able to find on the rear axle, this swap should also be relatively painless assuming that the spring perches swap over correctly. It also has the added benefit of converting the rears to disc brakes at the same time, something else I'd like to do in the eventual future anyway.

Here's my reasoning on this: if the axles from a totalled Rubicon can be grabbed for less than the cost of a buildup (or replacement & buildup in the case of the rear axle), there's pretty much nothing preventing their use - and also has the added benefit of being able to take the thing to a dealer if (God forbid) it's my last resort on getting something repaired.

I understand the issues involved with the HP front D44 in the Rubicon vs. the LP version and so on, and that other axle options are available, but for now I'd prefer to see if this idea sounds reasonable before looking into the Ford 8.8 or similar.

Well.... are 4.11's going to be deep enough for you or are you going to be thinking about upgrading shortly later.... Something thaty ou might consider is buy the axles to sell and built something else.
In any case, if you do get the axles make sure to get all the necessary components to make the lockers work.

it's a good swap if you're keeping 4.10 gears, which I would only do on max 31s.

everything should fit right besides the rear leaf springs. im taking over my dads cherokee in a year(idk how im gunna wait that long) but its gunna have the rubicon front from his rubi and either a pro 60 or d44 in the rear. let me know how everything works out.

Kejtar said:

Well.... are 4.11's going to be deep enough for you or are you going to be thinking about upgrading shortly later....

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For now, that should pretty much take care of things. I'm running 29.5" tires right now on the stock 3.55 gearing and don't plan on going over 31" for the foreseeable future, though I really do want to get 4.11s in there as the performance and MPG hit even on the 29.5-inchers is noticeable. My understanding, though, is that the Rubicon D44s can go up to 4.88 - not that I've seen a gear set for it yet, but it does leave some room for improvement.

Kejtar said:

Something thaty ou might consider is buy the axles to sell and built something else.

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That's a really good idea and one that I hadn't considered initially. Thanks for the tip

tjader said:

everything should fit right besides the rear leaf springs.

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OK... Just so I know we're on the same page, you're talking solely about having to convert the Rubicon rear axle to take leafs rather than coils, correct? Or is there something else I haven't accounted for here? Reason I ask is that if it's going to be much worse than doing a SUA to SOA conversion (which going from coils to leafs strikes me as being about the same) this may throw a wrench into the works.

tjader said:

im taking over my dads cherokee in a year(idk how im gunna wait that long) but its gunna have the rubicon front from his rubi and either a pro 60 or d44 in the rear. let me know how everything works out.

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It's cool I'm not going to be able to do this much before that timeframe anyway, but want to start lining things up now so that I can actually plan for them financially. Besides, a year from now someone may well have done the same swap and have it written up, so the whole shebang could be fairly cookbook by then.

couple things I see, some have been mentioned, so not. switching the rear to leaf spring perches (basically cutting the coil perches off and welding in leaf perches, or going coil in the rear!!), shock mounts?, wiring the lockers (they are electric right?), and the brake bias with rear disc's (8.8 swap guys should know how the xj system works with discs). I thought I read the D44 in the Rubicon was basically a D30 with a larger housing, can anyone confirm? Either way 4.88's should be feasable, maybe deeper if its a real D44 carrier.

Sounds like a nice setup for some pretty decent rated trails. Alittle armor, nice flexy lift, some MT's, maybe a winch and your good. One thing is if you go bigger than 31-32's you will end up wanting to re-gear which on top of the axle price could be more $$.

Whats the going price on Rubicon axles? I would think low availablity = high price. I would probably do this if I found a set of rubi axles at a reasonable price.....of course Im poor, so even reasonable isnt reasonable to me!

casm said:

For now, that should pretty much take care of things. I'm running 29.5" tires right now on the stock 3.55 gearing and don't plan on going over 31" for the foreseeable future, though I really do want to get 4.11s in there as the performance and MPG hit even on the 29.5-inchers is noticeable. My understanding, though, is that the Rubicon D44s can go up to 4.88 - not that I've seen a gear set for it yet, but it does leave some room for improvement.

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I'm not saying that you can't go to deeper gears, but if you end up doing it it not too long after you got the rubi axles you've wasted your $$.

Kejtar said:

I'm not saying that you can't go to deeper gears, but if you end up doing it it not too long after you got the rubi axles you've wasted your $$.

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Got it. And understood - the plan is to do the buildup in stages, run each one for a while, and get a feel for what works and what could use improvement. Regearing's coming ahead of lifting beyond 3.5-4", since there'd be some serious engineering involved in that. Also given that this is likely to remain a DD for the foreseeable future, I'd like to keep it as roadable as possible. But I definitely agree on not spending money on essentially the same job more than once.

if its an XJ D44 you want then I have one that I would trade with ya. I would hate to see you cut all those brackets off the TJ housing.
while a Rubi housing is a little different that a regular 44. as a rubicon 44 your only option is 4.88's. but if you nix the rubi locker and went with say a detroit or ARB, then you can toss in whatever ratio you want. same for the front axle.

Get the TC out of this rubi as well. Can you say 4:1?

Rawbrown said:

if its an XJ D44 you want then I have one that I would trade with ya. I would hate to see you cut all those brackets off the TJ housing.

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Hm... OK, I'll bite: the brackets you're referring to - is that for the front or rear, or both? I'd like to eventually go to D44s at both ends and was thinking that the TJ unit would be the easiest route to take.

Besides, I still have to get down to you for the lift and SYE Hopefully I just sold one of the other fleet tonight, so that may actually happen pretty close to the New Year.

while a Rubi housing is a little different that a regular 44. as a rubicon 44 your only option is 4.88's. but if you nix the rubi locker and went with say a detroit or ARB, then you can toss in whatever ratio you want. same for the front axle.

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That's cool - the plan was to do the lift (RE6030) and SYE, run that for a while, then do the D44s, run them in tandem, and evaluate what to do from there. Quite honestly, if I ever get to the point where I need more than a D44 this thing is probably going to end up being Mad Maxed well beyond the point of being a DD

jeepinxj05 said:

Get the TC out of this rubi as well. Can you say 4:1?

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This is also on the cards for down the road - or if I ever hand grenade the 231. Right now, though, top priority is doing the suspension before I go into partnership with a chiropractor.

the Rubi's lockers are air actuated.. and IIRC they operate at very low pressure.. like 4 psi or something.. just need an air source and a regulator... and the front rubi axle is a "hybrid" of sorts.. to most people its a regular D44... in reality it is a D44 center section with D30 outer shafts, knuckles and hubs.. cant recall if its a Hi pinion or Low pinion... in my opinion it is a good out-of-the-box setup to run 32s or 33s... but then you are pushing the usefullness of the stock gears... some 4.88s and your ready to go...
word to the wise... the stock lockers WILL NOT stand up to repeated abuse with 37" Krawlers...

Not trying to start an arguement and I'm probably wrong but I thought the lockers were electric. I've heard both that they're electric and air. Well, I'll find out at premier night this week.

The brackets he is referring on the rear axle are the coil buckets, sway bar mounts, trackbar mount, and control arms mounts on the rear axle. It is alot of cutting to do but they all have to come off (i thought the leaf perches and swaybar mounts on my 8.8 were a PITA). On the front you shouldn't have to remove anything. Unless you are getting a really good deal on the rear rubicon axle, i would just get one of the built 8.8's that have been for sale on here recently (lockers, gears, bolt-in) for around 800-900 bucks; mountaineermac was selling one recently. If you are getting the rubi axle for less than that then all the power to you, but i'd be surprised if you are.

jeepinxj05 said:

Not trying to start an arguement and I'm probably wrong but I thought the lockers were electric. I've heard both that they're electric and air. Well, I'll find out at premier night this week.

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"Press the dash-mounted rocker switch once and a low-pressure, "air-actuated" pump mechanically locks the rear axle. Press it again and the front locker is engaged."

The Rubi front Dana "44" is a low pinion axle with Dana 30 outers; kinda nullifies the whole point of a "beefy" axle.

I found this ad on eBay for a new Rubi frontend. You get a bare housing with inner knuckles and bolt-in bracketry all for a measly $450. x eventy-billion This means you supply ALL the internals as well as the outters, which can be pulled from your current HP30.

So basically, the only good thing about this axle is the ease of bolting it in... is it really worth it?

Okay.

Folks, as much as I appreciate the points of view on other approaches, did anyone notice the part where I mentioned that "I'm not looking to start a religious war over which axle is better"? It was in the second sentence of the original post.

I am well aware that there are alternatives, but I'd like to look into this one for now. Whether or not I go with it is immaterial; I'm just doing research. And as it happens, I'm doing that research one option at a time. I'm also well aware of the theoretical downsides to this axle, which, based on how and where I wheel, may not necessarily be downsides.

What I basically want is a solid understanding of what may be involved in doing the swap. That's all. The rest I'll figure out when I have enough information to make a decision.

With that in mind, let's keep on the intended topic.

For what you say you want to do with these axles, I think It would be a great swap. Some people question the strength of the front "hybrid" axle, but I have seen a friend with a rubicon with 36 iroks on T.R. beadlocks give these axles imortal hell.How they hold up is something that I don't understand. Are they unbreakable, of course not. but pretty tuff for what they are. Like some one said, the rear 44 might have better options for ease of swap. A 44 from a xj would be easier, because it will bolt in. Because the brackets on the rubicon axle have to be trashed and new spring, shock mounts have to be put on, then a 8.8 might be cheaper in the long run. If you are dead set on the rubicon axles, then go for it.

P.S. About how much are you planning on pay for these axles? I think price will play a big part in deciding if this swap is the most economicaly feasable choice. Plus like someone said before if you plan on a rear gear ever, I know these ring and pinions are fairly high dollar. Just more to think about.Good luck.

casm, I just wanted you to be aware of what you're getting if you go with this front axle. I agree, it's a great out-of-the-box axle and can stand up to 35s, but so can the axle that is already under your Jeep.

why not throw some chromoly shafts, 760 joints and 4.88's in the 30 that you allready have. That would hold up to a 35" tire no problem, and a lot cheaper.