4.10 TJ Rubicon gearing in 3.07 MJ Dana 44

[thousender]

Hi everyone,

 

I'm currently in the process of swapping a 4.0 into my 87' 2.5L, and (lucky me) the parts truck I bought came with an original Dana 44. I've got some differential vibration issues that are certainly NOT driveshaft, axle shaft, wheel, or drum related, so something internal is unhappy and it's time to upgrade.

 

The problem is that my Dana 44 has 3.07s, and my truck is currently set up with 4.10s and so I need to replace the 3.07s. I'm running 31s and like low gearing to begin with so I'm not concerned about the higher revs I will get. I also don't feel like touching my front diff. Anyways I read that there's a case split at 3.73 and I would need the thick style ring gear, but am wondering if I could use a factory Rubicon 4.10 gearset (there's a set available locally for $150. I know this is probably a no, so then my next question is can I use a Rubicon 4.10 carrier and pinion in my MJ housing? If not, I'm curious to hear what you guys suggest!

 

Thanks in advance, have a great day!

[89 MJ]

I would be skeptical of used gears. They are a wear item after all and if you do not get the pattern set up the same, it will likely make noise.

 

If it were my money, I'd do a TrueTrac in the rear with new Yukon on Spicer gears. The TrueTrac is expensive, but seems to be a great option for a strong limited slip that does not wear out and is still daily drivable.

[Eagle_SX4]

I would stay away from used gears. I put a used set of 4.10's in the front axle of my truck and I am probably going to end up replacing them next year. 

 

I bought new gears and a truetrac for the rear 44 and they are doing great. 

 

Rock auto has standalone thick gear sets for $150. DANA brand.

https://www.rockauto.com/en/moreinfo.php?pk=8529284&cc=1181483&pt=10438

 

 

Just remember that you need a full bearing kit to set up gears properly and it is cheaper to buy the kit than everything separately.

[derf]

X3 on staying away from used gears.  There is a reason shops won't install them.

 

The carrier could work but the locker is a bit janky to begin with.  Add 20 years and it's probably not worth the effort to install.

 

Sure  the carrier would fit.  It probably won't lock at all and the limited slip part of the diff is likely worn out.

 

For my MJ project on 31s I'm going with TrueTracs front and rear.

[thousender]

Thanks for all the input guys, $150 for spicer gears seems like a deal to me, and I planned to put in all new bearings anyways. I looked through rockauto's.selection of gears but somehow missed that set, I'll definitely go that route.

 

As for the limited slip, mine has the factory one. Do they still manufacture clutches for them? My dad's got a TrueTrac in his ZJ and it's awesome, they're just very expensive.

 

Again, thanks for sharing you're knowledge. It's much appreciated.

[Eagle_SX4]

Yes they are still available.

https://www.rockauto.com/en/catalog/jeep,1988,comanche,4.0l+242cid+l6,1181584,drivetrain,differential+clutch+pack,19715

 

[ghetdjc320]

To shed some light on a couple of issues here: 1. The TJ rubicon rear locker is a torsion style limited slip (like a truetrac) when not locked. It’s a fairly low pressure air locker. But if the seals are good and the oil has been kept clean, they are some really nice units. 
2. The TJR uses thick cut gearsets meaning they are using a 3.73 and numerically lower carrier for those 4.10 gears. 
 

Thick cut gears for the D44 are a nice options especially why you already have a carrier/locker you like. As for setting up used gears, it really depends on how much wear the gears have seen. The more wear there is, the more you need to try to exactly match the old pattern. But some extra time with shims may pay out in the long run. If those gears and locker are in truly great shape, they may be worthwhile. Those rear lockers were definitely unique and quite a clever design. 

[derf]

22 minutes ago, thousender said:

Thanks for all the input guys, $150 for spicer gears seems like a deal to me, and I planned to put in all new bearings anyways. I looked through rockauto's.selection of gears but somehow missed that set, I'll definitely go that route.

 

As for the limited slip, mine has the factory one. Do they still manufacture clutches for them? My dad's got a TrueTrac in his ZJ and it's awesome, they're just very expensive.

 

Again, thanks for sharing you're knowledge. It's much appreciated.

Be wary of the SVL gears.  That's Dana's budget line.  They are lower quality than regular Dana gears.  They are harder to set up properly than quality gears.  I won't use SVL gears in any axle again.

 

Speaking of setting up the gears, who is doing the setup?  You or a shop?  If you've never set up gears before I would recommend doing some research on the tools you will need and the process to do it.  Most people can do it but it takes a lot of time to get it right.

[Eagle_SX4]

19 minutes ago, derf said:

Be wary of the SVL gears.  That's Dana's budget line.

I wasn't aware dana had a budget line. Thanks for the info.

[derf]

4 minutes ago, Eagle_SX4 said:

I wasn't aware dana had a budget line. Thanks for the info.

I learned the hard way.

[Eagle_SX4]

I checked my order and I ordered this set from Rockauto. It has been great. Dana Spicer 7060175X. It is not a thick cut set and would require you to get a new differential carrier.

 

https://www.rockauto.com/en/moreinfo.php?pk=4900440

 

[derf]

Also, just as a heads up, you'll see 4.09, 4.10, and 4.11 gears for different axles.  They are close enough to each other they can be used together.  A Dana 30 may have 4.11 (37 ring teeth and 9 pinion teeth) while a Dana 44 may have 4.10 (41/10) or 4.09 (45/11).

 

As long as the ratios are within 1% of each other, it's fine to use them together.

[speeding_infraction]

If you end up using the Rubicon locker, just know that replacement parts are NLA, harder to find then a comanche sport bar or OEM rear bumper. Good luck. 

[DesertRat1991]

18 hours ago, thousender said:

Thanks for all the input guys, $150 for spicer gears seems like a deal to me, and I planned to put in all new bearings anyways. I looked through rockauto's.selection of gears but somehow missed that set, I'll definitely go that route.

 

As for the limited slip, mine has the factory one. Do they still manufacture clutches for them? My dad's got a TrueTrac in his ZJ and it's awesome, they're just very expensive.

 

Again, thanks for sharing you're knowledge. It's much appreciated.

 

 

The ring & pinion has been mentioned, and the rebuild kit for the Trac-Lok LSD, but you should also grab a Master Install Kit:

 

https://www.rockauto.com/en/moreinfo.php?pk=10997268&cc=1181584&pt=2224&jsn=10607

[ghetdjc320]

Personally, I go with revolution gears and koyo install kits. The price is excellent and they have given me zero issues despite some pretty heavy use over the years.