Novak Conversions Jeep Wrangler TJ engine mounts

A Hodgepodge of Questions (Another TJ Rubicon Axle Swap)

That'll Buff

New rattle = louder music
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Texas
Disclaimer: A lot of this is me trying to condense all my research and questions into one place so that hopefully it can be easier to wade through this project.

The Story:
After daily driving on stock 3.07 gears out of a 30/35 combo on 33's for years and having issues with hills and steep trails, I finally figured out I needed to regear (I can be slow on the uptake sometimes I know). I did a good amount of research and planned to get 4.88 gears towards the end of the summer. Randomly I decided to look for gear kits on Facebook Marketplace just to see if there was some deal I couldn't pass up. Well I found one, just not in the way I thought. Only a few hours away was a set of built TJ Rubicon Dana 44s for a very reasonable price. It came with 5.13 gears, stock lockers, locking hubs, chromoly shafts, and more that I could give or take. It even had the stock pumps! This sent me into a spiral of research to know what I was even getting into since this would easily be the biggest single project I've done on The Jeep. Before this I barely even knew that regearing existed, now I'm playing around with gear calculators and learning everything I can about my drivetrain. After multiple searches on this forum turned up as "it bolts right in", I spent half a day and $4350 to bring them home.

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Why Switch?:
As I said above, I have been running the worst axle combo for a very long time, and it was pretty clear that something had to change to keep up with my vision for my Jeep. I could've done the super 30/35 combo, but in parts alone that would cost about as much as the axles I bought. Throw in labor to install the gears and locker at a minimum and its way more than it was worth with this option available. Sure if I went without a locker and chromoly shafts it's much cheaper, but where's the fun in that? Plus now I will finally have a Dana 44 in the rear!

Addressing Concerns Out of the Gate:
Admittedly, I didn't thoroughly research every single part before I bought the axles, so I learned that some of the things included have a less than stellar reputation on here.

Truss: I'll be keeping it pretty much just because I do not have the means to take it off. I fully acknowledge that it does not solve the issues with the front 44 and is largely unnecessary.

Wheel Adapters: I'll be taking these off since they don't fit my wheels, but potentially keeping them for future plans.

Tube Seals: If I take out the axle shafts for some reason, I'll remove these, but for now they'll stay on.

Powerstop Brakes: I know these are just repainted stock calipers, so I don't plan to keep them when the plans for 35's get more serious.

Hopefully this will get some of the initial questions and comments out of the way as I'm sure some of the more experienced people who look this over will bring these parts up if I didn't mention them here.

Extra Parts:
I have already purchased the following:
2X Spicer 5-134x U-Joints (1310-1330 conversion U-Joints, only available in greaseable versions sadly) so I can run my current driveshafts
2X parking brake cables (Raybestos BC96157 and BC96158)
Individual switches for the lockers (generic covered on/off switches)
A 43 tooth speedometer gear since I'll be running a 5.13/33's combo

If there are any other parts that you think I might need, let me know. From everything I've researched this should be all that is needed. I am scavenging the rear soft brake line and breather block from the Dana 35 so I shouldn't have to worry about cutting and flaring brake lines like some others who went from drums to disc.

Removal and Install:
I've watched videos from @hosejockey61 and a couple others on this swap which have been very helpful, but just in case I wanted to double check. For removal, I just take off the following parts on the axle side, in mostly no particular order:
  • Driveshaft
  • Springs
  • Shocks
  • Brake lines (and parking brake in the rear)
  • Steering in the front
  • Track bars
  • Sway bar links in the front, full sway bar in the rear
  • Breather hose
  • Lastly, control arms
Installing the new axles seems to pretty much be just be the exact same process but in reverse. There will be additional steps for things like cycling suspension to make sure things fit, checking driveshafts (more on that later), and bleeding brakes. If someone could link any good threads or videos about cycling suspension I'd appreciate it since this would be my first time doing it. Is there anything in the process I listed that sounds wrong or anything I am missing?

Driveshafts:
Most of the threads I have read about this swap mention two things every time, U-Joints and driveshaft length. For U-joint I have that covered with the conversion U-Joints. It's not perfect, but it is the cheapest option. As for axle length, I haven't seen anything that is definitive one way or the other on if you have to shorten it, just a lot of people mentioning it. I called Adams Driveshaft about the question and he basically could not tell me anything definitive either, but did give me useful advice. For the front, he said that if the driveshaft will not go in when the axle is a full droop, it is too long. Same applies to the rear, but there is more to watch there. Since I have one of his CV driveshafts, I asked him about how much spline should show at a minimum, to which he tentatively said he would get it shortened if it showed less than ~1" of spline at ride height. Currently I have ~2" of visible spline showing and plan to watch the driveshaft when I cycle the axles up and down to see how much they travel. Is there anything else I should be looking for driveshaft wise? Are there other opinions on how much spline should show at ride height? Any reason the driveshafts would compress further inward (get shorter) than at full droop? Current plan is that if there are any issues to just get them shortened instead of ordering entirely new driveshafts. Because of this, when testing the shafts for fitment I will be using the stock 1310 U-Joints since I read that driveshaft shops remove all the U-Joints when shortening and balancing them.

Differential:
Even though I bought these axles a couple of months ago, I haven't been able to pull the covers just yet, but plan to very soon. This will be the first diff fluid change I'll be doing and while it seems pretty simple, I still have a few questions.

1) I've read the multiple gear oil threads, so I don't plan to start a whole new one, just looking for an answer. I plan to use 85W-140 Lucas conventional gear oil currently in both diffs. Are there any issues with using a cheaper brand as long as it meets GL-5? As for synthetic, is it really that bad to use or is that mostly a Jerry-ism? I mainly ask this for any future reference since a quick search at in store stock was mostly synthetics. I know that many places recommend conventional when breaking in new aftermarket gears, but since these are already broken in does it matter as much?

2) What should I use to clean the inside of the diffs? Any particular spray or just wipe them down as best I can and call it good? Any extra precautions around the mounting surfaces since I will be (hopefully) reusing the Lube Locker gasket that is already on there?

3) When refilling, I've seen a bit of deliberation on the correct quantities. FSM calls for 2 quarts (1.89 L) in both front and rear but does not specify Rubicon 44's (not sure how much that matters). On the Wrangler TJ Fluid Capacities & Fluid Recommendations thread it states specifically the front Rubicon 44 needs 1.375 quarts. Someone later calls out the discrepancy between the two sources, but no definitive answer comes from it. Most diff oil changes I've seen are just "fill till it comes out the hole" as a rule of thumb but since these are aftermarket covers and I don't have a factory cover to compare the fill hole too. MetalCloak makes no mention of it being a "high fill" cover so I'm inclined to believe it's the same height. I am probably way overthinking this, but I just want to avoid having oil come out the breather tube or worse. When I do this, it'll be before the axles are put into the Jeep so it will be on level ground with the pinion straight forward.

4) Speaking of the MetalCloak cover, anybody who runs these/has run them have anything to say? I am mainly worried about clearance and plan to watch them as I cycle the axles to test it myself (every Jeep is different and whatnot), but other than one review on their website, nobody including the PO seems to have issues with them.

Rubicon Lockers & Lockers in General:
I was surprised to hear how weak these lockers were, but since I do not have the time or money to put in a better set of lockers, its what I'll live with. I've already read the advice of "lock them when you touch dirt" so I'll be doing that to prolong the limited slip. As for lockers in general, any tips for using them? Precautions? I'm especially curious if there's a way to tell if I should be locking the front or not on an obstacle. I also won't have any way to see if the lockers are locked. I assume I can listen for the pump shutting off and it will feel different the moment I start moving? I've wheeled for so long with completely open diffs that I'm not sure what I'll be capable of now. I will be "relocating" the pumps to the ABS tray since that's empty and found a pretty good video on how to do it, so it doesn't seem hard to do.

Locking Hubs:
Are there any good threads on maintenance/repairs on any of these kits for future reference? Since I didn't install them and have no experience with them, if something does happen I'd like to be prepared and read up on them beforehand. If specifics are needed it is the Yukon YA WU-07 kit.

That should be all the questions I have right now, but I'll update the post if anything else comes up. I'm sure many of y'all are probably just thinking "you're overthinking it, just throw them in," and trust me if could they would be in already. Since I can't start working on this for another week or so, I might as well ask questions. Better to find out I've got something wrong while sitting in the AC rather than under the car. Thanks for reading this massive post and hopefully this will help me or anyone in the future make this swap. Looking forward to the advice I get.
 
I use brake cleaner to swab out my differentials.

But if the fluid doesn't look suspect and there isn't a glittery mess at the bottom I'd scoop out what I could with surgical gloves and send it. Doesn't need to be perfect.

-Mac
 
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The JK adapter spacer thicknesses are weird. Those Warn hubs add about .9something" per side. On mine, I am using 1" front and 2" rear. On a factory JK wheel, this results in an effective 4" backspacing all around.
 
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The JK adapter spacer thicknesses are weird. Those Warn hubs add about .9something" per side. On mine, I am using 1" front and 2" rear. On a factory JK wheel, this results in an effective 4" backspacing all around.

I agree. Only reason I plan to keep them for now is to just have options in the future. That being said if I can find TJ wheels with good backspacing that I like I'd much rather use those than JK wheels for a simpler set up. New wheels and tires aren't in the plans for a while now though, even though they probably should be. BTW great build thread, been reading through it a ton. About half way through now.
 
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Update: I was able to pull the covers this weekend. These are some BEEFY gears!
Front:
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Rear:
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Also to answer a question I had, 1.375 qts seems to be correct for the front diff. I had to stick a bent q-tip into the hole to actually reach the oil, but I measured and it was about a 2" drop. Comparing the Metalcloak covers to a stock front Dana 44 cover, I could tell the fill hole was about 2 inches higher on the Metalcloak, so everything seems to line up. Of course driving it will fully confirm that, but I'm a lot more confident now.
 
Normal thick cut gears to make the Rubicon lockers work with deeper gearing. They were intended for 3.73 and down.

Yep, quickly skimmed through some thread on here (which I need to go back and actually read) about the difference since I was caught off-guard when I first saw them. I assume that if I were to get new lockers and keep these gears, I would buy 3.73 and down lockers again? Are there any differences strength-wise between the two or is it simply the way they make space for the thick cut gears?
 
Yep, quickly skimmed through some thread on here (which I need to go back and actually read) about the difference since I was caught off-guard when I first saw them. I assume that if I were to get new lockers and keep these gears, I would buy 3.73 and down lockers again? Are there any differences strength-wise between the two or is it simply the way they make space for the thick cut gears?

It has everything to do with the carrier break.

If you buy new lockers and also change the gear ratio, then you can buy lockers with standard cut gears.

If you buy new lockers and want to reuse the existing thick cut gears, then you need a 3.73 and down locker to allow the use of thick cut gears for the 3.92 and up gears.

If for some reason you wanted 3.73 and down gears on your existing lockers, then you buy standard cut gears.
 
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It has everything to do with the carrier break.

If you buy new lockers and also change the gear ratio, then you can buy lockers with standard cut gears.

If you buy new lockers and want to reuse the existing thick cut gears, then you need a 3.73 and down locker to allow the use of thick cut gears for the 3.92 and up gears.

If for some reason you wanted 3.73 and down gears on your existing lockers, then you buy standard cut gears.

Good to know for the future, thanks. I have 0 plans to change anything in here until absolutely necessary, which knock on wood won't be for a while. Money better spent elsewhere, especially as I slowly prepare for 35's.
 
its worth mentioning that those spacers might be important, as the spin free hub doesn't fit the standard TJ wheel center bore, and hubcentric spacer/adapters also wouldn't. It will need to be bored out to fit.

Edit: I remember seeing those listed on marketplace, and was tempted, but i already have regeared my 30/44
 
its worth mentioning that those spacers might be important, as the spin free hub doesn't fit the standard TJ wheel center bore, and hubcentric spacer/adapters also wouldn't. It will need to be bored out to fit.

Edit: I remember seeing those listed on marketplace, and was tempted, but i already have regeared my 30/44

I have Pro Comp Kore Series 89's which are lug centric and have push through center caps. They have a bore diameter of 3.27" (83.06 mm). The Yukon website says the wheel bore must be at least 2.77" in diameter for their kit. It's something I'll have to take into account when buying a new set of wheels, but they should fit with the ones I have now.
 
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Need a bit of a sanity check. Front and rear are both installed pretty much the entire way, just some small things left. Ordered a new rear TW DS since my old Adams one doesn't move in and out anymore (my fault) and plan to shorten the stock front one. The rear was shortened by 1.25" (16.75" to 15.5") and the front will be shortened by 3.25" (41" to 37.75"). The rear sounds right to me, but the front seems like quite a bit. Any reason I should be concerned?
 
Need a bit of a sanity check. Front and rear are both installed pretty much the entire way, just some small things left. Ordered a new rear TW DS since my old Adams one doesn't move in and out anymore (my fault) and plan to shorten the stock front one. The rear was shortened by 1.25" (16.75" to 15.5") and the front will be shortened by 3.25" (41" to 37.75"). The rear sounds right to me, but the front seems like quite a bit. Any reason I should be concerned?

FWIW, I just did a tummy tuck on my Rubi and ordered new TW driveshaft; front 38 1/4" & rear 16"
 
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After a small mix up with Tom Wood's mishearing me over the phone and sending a driveshaft that was an inch too long (nobody's fault and when I called they got to work fixing it right away), I am finally done. Drove it yesterday for 2 hours pretty hard while moving back to college and it felt great. Not sure if its the gears or the extra weight down low but The Jeep feels a bit more planted, and having power in 5th gear is something I never thought I'd see. I took it to a 4x4 shop for an alignment before this drive and learned of a few things I need to change if I want to bring it back to spec, some I knew like getting new rear lower control arms, and some I didn't. Since I would not have time to leave my Jeep with them since classes start on Monday, I talked to them about how I did not change any control arm lengths or steering components so how it is is how I've been driving for quite a while. They agreed with me that while my alignment is definitely out of spec, my tires don't show any abnormal wear and it drives fine enough, so I should be okay until I do find the time to either do it all myself or give it to another shop.

All in all, I'm really happy with this upgrade and I cant wait to see how it feels off-road. Everyone who says that gears are one of the biggest changes they made to their Jeep are right, it's a whole new car. I am also super happy that The Jeep didn't feel like it hated being high in the RPM's at all. I got it up to around 3500 RPM at a few points in 5th gear and it felt like it was no big deal. There is a some what I assume is drive line vibration around 80-85+, but it's not 100% consistent so I'll have to figure out what that's all about. I do not spend a much time up that high if I can help it, but this is also Texas so it just happens sometimes.
 
Novak Conversions Jeep Wrangler TJ engine mounts