Is there a JK/JL axle bible?

Here's the link to the Mitchell Differential upgrade. They don't mention the machining on the website, but I'm curious. Yoke clearance notches like you mention might make sense because the unit bearing/spindle pilot diameter is smaller on these jeeps than it is on D60s, which usually dictates ujoint size.

If AI is correct (I need to verify)-
-JK (and earlier) unit bearing pilots are 100mm (3.94")
-JL pilot diameter are 110mm (4.33")
-Pre-05 D60 are 114mm (4.48")
-05+ D60 are 5.512"

Jeep JL and JT 1480WJ 4340 Chromoly Front Axle Kit | Mitchell Diff Inc.

They note it is configured for the 32 spline lockers, so it's 32 spline inner and outer just has the bigger joints. But makes you wonder, theoretically generic D60 sized 35 spline 1480 shafts might work too? Are there any JL axle seals that can accept a 35 spline shaft, and are there 35 spline JL lockers yet (I assume yes)? But in general, just grabbing a pair of those 1480 32 spline JL stub shafts seems like it opens the floodgates to basically any off the shelf 1480 inner for custom axle builds
 
Seeing those JL and 99-04 60 pilot numbers reminds me of something I've wondered for a while.

Why doesn't a knuckle to use 99-04 ub on a JL exist? Looking at pics, a synergy or ried might have enough meat to machine the 4 bolt pattern into it, but obviously a new casting would be ideal.

Seems like the benefit of locking hubs would make it sell. I'd imagine converting the rear to 5x5.5 wouldn't be too difficult.
 
Treefrog said:
I was talking about the non rubis. I didn't know the carries were interchangeable for the non-rubi. I would have thought that they would have made them slightly different just because.

I don't know off the top of my head, but I'm sure there are some oddball lockers for the Dana 44 over the years.
Click to expand...

JK D44 carriers are interchangeable Rubi to non and back, but the differential centerline is offset, so axle shaft lengths are different.
 
YotaAtieToo said:
Seeing those JL and 99-04 60 pilot numbers reminds me of something I've wondered for a while.

Why doesn't a knuckle to use 99-04 ub on a JL exist? Looking at pics, a synergy or ried might have enough meat to machine the 4 bolt pattern into it, but obviously a new casting would be ideal.

Seems like the benefit of locking hubs would make it sell. I'd imagine converting the rear to 5x5.5 wouldn't be too difficult.
Click to expand...

I've got a set of Reid knuckles coming in for a JL axle swap video, should be here in the next week, I'll check them out.
 
Tech Tim said:
JK D44 carriers are interchangeable Rubi to non and back, but the differential centerline is offset, so axle shaft lengths are different.
Click to expand...
Neither of those are correct. The carriers use different bearings. The centerline is the same. The difference is the center pin in the carrier itself. On the rubi locker the pin is moved towards the ring gear to give room for the actuator. Thats why the shaft lengths are not typical. As soon as you use a different locker, it changes the shaft lengths
 
If you find the rebuild kits for jk 44s you will see there is 2 versions for the rear 44s. One with sae carrier bearings for the non rubis and one with metric bearings for the rubicons
 
So Mitchell responded. It sounds like they open up the UB pilot hole and then use a machined spacer to recenter the UB
 
Here are the 2 different carrier bearings for the Rubicon 44 and Traditional 44 (works with non rubi JK 44s)

downtofab.com

Dana 44 Front and Dana Super 44 Rear Carrier Side Bearings 2007 - 2018 Jeep JK Rubicon

Product Details: Jeep JK Rubicon Dana 44 front (216 mm ring gear) and Dana Super 44 (226 mm ring gear) rear carrier side bearings These do NOT fit Dana Super 44 rear axles that did not come from the factory with the E-locker 3.307" (84MM) OD 1.969" (50MM) ID Parts Included: (2) differential...
downtofab.com
downtofab.com

Dana 44 Front and Rear Carrier Side Bearings

Product Details: Dana 44 front and rear carrier side bearings These do NOT fit Jeep Wrangler JK Rubicon Dana Super 44 rear axles or Jeep Wrangler JK Rubicon front Dana 44's 1.795" ID 3.265" OD Parts Included: (2) bearing race / cups (Spicer 550225) (25523-N) (2) bearing cones (25590-N) Fits...
downtofab.com

JK Rubi:
  • 3.307" (84MM) OD
  • 1.969" (50MM) ID
Non Rubi
  • 1.795" ID
  • 3.265" OD
The only way the switch carriers would be to machine the non rubi housing for the 3.307" OD bearings if you wanted to use a rubi locker in a non rubi housing. Or you could machine down the bearing surface on the locker for the standard bearings. If you wanted to go the other direction, you would need a spacer, and most likely you would still need some machining as the spacer would be unpractically thin.

This also why all aftermarket 35 spline lockers have different PNs for rubicon vs non. IIRC ARB used to only have one version of the 35 spline (I believe it was the traditional non rubi version RD147). The guts were interchangeable so you could by a 32 spline rubi version and throw the 35 spline side gears in if you wanted 35 splines in a rubi application. Eventually they came out with the RD157. I believe this may be the source of the interchangeability misinformation.
 
The rubicon pinion is offset, but that is the case with the non rubis as well, and AFAIK it is true with any axle with equal length shafts. I believe the tcase output is also not centered, but now I am second guessing myself so I will remeasure when I am back home in a couple of days. Here is screenshot of a JK frame model. The blue plane is a midplane right in the center. All of the crossmember humps are offset from center by about 3/4"

1778710610262.png
 
YotaAtieToo said:
Should ask if they've even looked into mounting the 99-04 D60 unit bearing or 60 spindle on a JL knuckle
Click to expand...
Mitchell's response:

That’s an interesting idea, our primary customer base tends to want to retain as many factory components as possible specifically the lug pattern so I haven’t given that a good look. Although I’m not personally a huge fan of the 99-04 setup with the 30 spline outer stubs and the 1.313 needle bearing compared to the earlier 1.5 needle bearing and 35 spline aftermarket support. I’m currently developing a 35 spline outer setup that retains the factory 5x5 lug pattern and is abs compatible without any programming or manipulation of the computer, but I can’t disclose too much about that just yet.
 
gobi_rubi said:
Neither of those are correct. The carriers use different bearings. The centerline is the same. The difference is the center pin in the carrier itself. On the rubi locker the pin is moved towards the ring gear to give room for the actuator. Thats why the shaft lengths are not typical. As soon as you use a different locker, it changes the shaft lengths
Click to expand...

Sorry, busy this morning, typing too fast and didn't explain enough.

Yes they take different bearing kits. But you can install the JK Rubi locker in a non-Rubi housing using conversion bearings.

When I said diff centerline, I am talking about the center pin. It is (iirc aprox 5/8") offset from the standard D44 diff, which is why Rubi shafts are different lengths from non-Rubi and why you need to change out the shafts to 35 spline if you put a non-Rubi locker (ARB etc.) in a Rubi axle housing.

See your post below:

gobi_rubi said:
Here is fusions 35 spline jk rear axles. It states it works with either version, which wouldn't be possible if the pinion centerline was different.

fusion4x4.com

Dana 44 JK Rear Axle Shafts - Chromoly 35 Spline - Lifetime Warranty

Dana 44 JK 35 Spline Chromoly Rear Axle Shafts - Rubicon & Non-Rubicon with 35 Spline Locker. Fully assembled & lifetime warranty. In stock.
fusion4x4.com fusion4x4.com
Click to expand...

These will fit both a Rubi and non-Rubi housing, but not with a Rubicon locker (for two reasons, one the spline count difference, two the shaft length differences).
 
Tech Tim said:
Sorry, busy this morning, typing too fast and didn't explain enough.

Yes they take different bearing kits. But you can install the JK Rubi locker in a non-Rubi housing using conversion bearings.

When I said diff centerline, I am talking about the center pin. It is (iirc aprox 5/8") offset from the standard D44 diff, which is why Rubi shafts are different lengths from non-Rubi and why you need to change out the shafts to 35 spline if you put a non-Rubi locker (ARB etc.) in a Rubi axle housing.

See your post below:



These will fit both a Rubi and non-Rubi housing, but not with a Rubicon locker (for two reasons, one the spline count difference, two the shaft length differences).
Click to expand...
Ya that all tracks. Ive heard talk of conversion bearings but wasn't aware of any that actually existed
 
I message Darius from Mitchell a fair amount today and he answered alot of questions very promptly. It sounds like a family run company and they seem very knowledgeable. They do offer 1410 shafts for JL applications and they require no mods, but he wasn't sure if they could do custom lengths. If 68" wms-wms works for someone that seems like a good option.

He also said he could source and sell beefier JL inner Cs, but they typically reuse the JL ones when they retube JL axles with 3x.5" tube. He didn't think there was enough meat to bore out the Cs so they just turn down the end of the tubes to 2.75".

I picked his brain about if he sees much ring and pinion failures in the JK and JL 44s. He said most of the failures are on JL axles. He thought they could be setup issues, but seemed to agree that while the JL 44 r/p are supposedly stronger on paper, they seem to not hold up as well as the JK 44 r/p. The improved tooth cut advantage doesn't seem to overtake the smaller size and greatly reduce hypoid distance disadvantage.

He also mentioned he was looking for someone to help prototype a 5x5.5 35 spline (I believe inner and outer) front conversion kit with a bolt on spindle, and that they have rear full float conversion kits for 5x5.5 and 6x5.5. If anyone is interested in that, reach out to them.

I actually feel pretty good about my build after talking to them and hearing from others on this thread. My housing is currently ready to be finished welded, and Im going to add a truss and then do internals. Its a JK 44 center, with 3x1/4" tubes and beefy aftermarket Cs, Rancho knuckles and Teraflex BJs. 72" wide. I have a big rotor kit on my current axle with the j8 MC/booster, but I think I will upgrade to JL calipers. I was planning on RCVs, but trying to reel in the cost so I am going to get 1350 shafts from Mitchell in either 32 spline or 35 spline inners. I think Ill just run stock outers for now since I have my stock set lying around, but may get chromos down the road. This is going on my JK with 37s and some extra hp. May eventually get 38s, but that will be the max for me.

Rear axle will most likely be a 60 (contemplating the Jana 76), but may consider a 9". I have a empty gladiator housing I picked up and will hack the ends off and splice them onto whatever I use. Not sure if it was mentioned but JTs and some JLs use larger Set 80 bearings which makes the shaft diameter near the flange larger making it much less likely to bend.
 
gobi_rubi said:
He also mentioned he was looking for someone to help prototype a 5x5.5 35 spline (I believe inner and outer) front conversion kit with a bolt on spindle, and that they have rear full float conversion kits for 5x5.5 and 6x5.5. If anyone is interested in that, reach out to them.
Click to expand...

No

There are already ~$2-3k kits that use all proprietary parts to do this.

Why reinvent the wheel instead of just making knuckles that use a D60 unit bearing or spindle? You should be able to design one knuckle to take either one I believe.
 
YotaAtieToo said:
No

There are already ~$2-3k kits that use all proprietary parts to do this.

Why reinvent the wheel instead of just making knuckles that use a D60 unit bearing or spindle? You should be able to design one knuckle to take either one I believe.
Click to expand...
I agree but in all honesty why bother with the conversion knuckle even? I think at that point you might as well just run the 99-04 SD 60 or use the whole outers on a fab 9. It would be a neat concept but it seems like way too much work for little gain. He'll you could get some adapter spacers and run a super high bs wheel if someone was dead set on 5x5.5. I dont think the JLs are seeing many ub failures. Some people seemed to go through them on jks but many people were running less than 3" effective backspace if they were running 40s so thats a major reason why.
 
gobi_rubi said:
I agree but in all honesty why bother with the conversion knuckle even? I think at that point you might as well just run the 99-04 SD 60 or use the whole outers on a fab 9. It would be a neat concept but it seems like way too much work for little gain. He'll you could get some adapter spacers and run a super high bs wheel if someone was dead set on 5x5.5. I dont think the JLs are seeing many ub failures. Some people seemed to go through them on jks but many people were running less than 3" effective backspace if they were running 40s so thats a major reason why.
Click to expand...

For the sake of a custom axle, absolutely, no reason at all to use JL c's just to adapt the D60 over.

From a marketing standpoint. It makes sense to me. Bigger parts and gaining locking hubs on a stock axle would be a seller imo. Like I said, there are kits, but they're expensive and AFAIK use all custom parts.

The 5x5.5 is just a necessary change since 5x5 won't clear a D60 hub weather ub or spindle style.
 
But a custom knuckle is still custom parts. And then you need machined ub to actually use 35 splines and cant just run to the auto parts store if you have a failure. The kits use a custom spindle that bolts on just like the ub and the rest of the setup is off the shelf 60 parts AFAIK. Im sure people would poney up just to say that had locking hubs
 
gobi_rubi said:
I picked his brain about if he sees much ring and pinion failures in the JK and JL 44s. He said most of the failures are on JL axles. He thought they could be setup issues, but seemed to agree that while the JL 44 r/p are supposedly stronger on paper, they seem to not hold up as well as the JK 44 r/p. The improved tooth cut advantage doesn't seem to overtake the smaller size and greatly reduce hypoid distance disadvantage.
Click to expand...

Cool details from everyone, and all of that context from Mitchell is great. Particularly this bit ^. I haven't heard much good anecdotal comparison between JK and JL gearset strength after all the changes they made for efficiency. I'm a little surprised, but at the same time makes sense, though it complicates my decision making for an eventual replacement front axle for my WJ lol. I probably won't build an axle this year, but still interesting to weigh the options.

I don't need anything exotic in the strength department, so I was originally leaning toward a basic JK44. Then this thread tipped me toward a JL front because more splines and bigger joints are awesome. But another thing I've learned from this thread is that JK front 44s can be built stupidly cheap with those mystery import parts, while JLs are still a bit more expensive, and now it seems that JL gearsets might actually be weaker. Then there's the fact that my rear is already a non-rubi JK44, decisions decisions.

Just for amusement, here's a quick and dirty bench build price list for a JK front 44 using all new import components (except quality master install):
Housing: $550
Knuckles: $150
Stock Locker: $350
Gears: $100
Master Install: $200
Yoke: $75
Axle Shafts: $175
Unit Bearings: $150
Rotors: $100
Calipers: $125
------------------------
$1,975

Really not bad for a 100% brand new axle, if you have faith in the cheap stuff. Actually cheaper than I can buy take out JL D30s locally :lmao:
 
AgitatedPancake said:
Cool details from everyone, and all of that context from Mitchell is great. Particularly this bit ^. I haven't heard much good anecdotal comparison between JK and JL gearset strength after all the changes they made for efficiency. I'm a little surprised, but at the same time makes sense, though it complicates my decision making for an eventual replacement front axle for my WJ lol. I probably won't build an axle this year, but still interesting to weigh the options.

I don't need anything exotic in the strength department, so I was originally leaning toward a basic JK44. Then this thread tipped me toward a JL front because more splines and bigger joints are awesome. But another thing I've learned from this thread is that JK front 44s can be built stupidly cheap with those mystery import parts, while JLs are still a bit more expensive, and now it seems that JL gearsets might actually be weaker. Then there's the fact that my rear is already a non-rubi JK44, decisions decisions.

Just for amusement, here's a quick and dirty bench build price list for a JK front 44 using all new import components (except quality master install):
Housing: $550
Knuckles: $150
Stock Locker: $350
Gears: $100
Master Install: $200
Yoke: $75
Axle Shafts: $175
Unit Bearings: $150
Rotors: $100
Calipers: $125
------------------------
$1,975

Really not bad for a 100% brand new axle, if you have faith in the cheap stuff. Actually cheaper than I can buy take out JL D30s locally :lmao:
Click to expand...
Except you're using import components. No ****ing way the $550 housing is as strong as OEM, probably both thinner and made of pot metal. Which is fine for the vast majority of jeeps that are only driven to the store, but you're going to actually be using it.
 
tsomctl said:
Except you're using import components. No ****ing way the $550 housing is as strong as OEM, probably both thinner and made of pot metal. Which is fine for the vast majority of jeeps that are only driven to the store, but you're going to actually be using it.
Click to expand...

That's the big question, if you can have faith in the metallurgy. From the labor quality and tolerance side of things, it sounds like they have it pretty well figured out:


wrath said:
After working on more than a dozen JK Rubicons and probably crawling under 60, I never saw a J8 housing under anything other than a Rubicon Recon. Maybe someone somewhere found one under a Rubicon Hard Rock, but I never saw one. I have a 2014 Rubicon X and it's a standard 44. Has anyone actually found a thicker housing/J8 under anything but a Recon?


I purchased a Chinesium eBay JK D44 housing and got it delivered for under $500 a couple months ago. My goal was to cut/turn the Cs and build it to replace the axle under my Rubicant. Dimensions I took it is identical to the housings I have. It came in a giant cardboard box with fancy laser cut cardboard supports, filled with sprayfoam bags, and the whole thing was shrinkwrapped. No idea on metallurgy. Welds look robotic, identical machining for the locker plug and indicator. The main difference I saw were the balljoints appear to come from the same place as Moog but with different boots. I bought a white booted eBay and got a black booted eBay. I cut the balljoints apart because I wasn't going to use them. The other main difference is that the upper bushings are definitely identical looking to stock but definitely aren't. They feel "softer" but my other two sets of 10+ year old ones are maybe dried out?


I also bought a Chinesium Shamazon JK 30 spline front locker. Visually and with my caliper it is identical in every way to the Randy's/Yukon one I bought for four times as much.
Click to expand...
 
gobi_rubi said:
I message Darius from Mitchell a fair amount today and he answered alot of questions very promptly. It sounds like a family run company and they seem very knowledgeable. They do offer 1410 shafts for JL applications and they require no mods, but he wasn't sure if they could do custom lengths. If 68" wms-wms works for someone that seems like a good option.

He also said he could source and sell beefier JL inner Cs, but they typically reuse the JL ones when they retube JL axles with 3x.5" tube. He didn't think there was enough meat to bore out the Cs so they just turn down the end of the tubes to 2.75".

I picked his brain about if he sees much ring and pinion failures in the JK and JL 44s. He said most of the failures are on JL axles. He thought they could be setup issues, but seemed to agree that while the JL 44 r/p are supposedly stronger on paper, they seem to not hold up as well as the JK 44 r/p. The improved tooth cut advantage doesn't seem to overtake the smaller size and greatly reduce hypoid distance disadvantage.

He also mentioned he was looking for someone to help prototype a 5x5.5 35 spline (I believe inner and outer) front conversion kit with a bolt on spindle, and that they have rear full float conversion kits for 5x5.5 and 6x5.5. If anyone is interested in that, reach out to them.

I actually feel pretty good about my build after talking to them and hearing from others on this thread. My housing is currently ready to be finished welded, and Im going to add a truss and then do internals. Its a JK 44 center, with 3x1/4" tubes and beefy aftermarket Cs, Rancho knuckles and Teraflex BJs. 72" wide. I have a big rotor kit on my current axle with the j8 MC/booster, but I think I will upgrade to JL calipers. I was planning on RCVs, but trying to reel in the cost so I am going to get 1350 shafts from Mitchell in either 32 spline or 35 spline inners. I think Ill just run stock outers for now since I have my stock set lying around, but may get chromos down the road. This is going on my JK with 37s and some extra hp. May eventually get 38s, but that will be the max for me.

Rear axle will most likely be a 60 (contemplating the Jana 76), but may consider a 9". I have a empty gladiator housing I picked up and will hack the ends off and splice them onto whatever I use. Not sure if it was mentioned but JTs and some JLs use larger Set 80 bearings which makes the shaft diameter near the flange larger making it much less likely to bend.
Click to expand...

Mitchell Diff is a ****ing awesome company with great people behind it!! I used to use them a lot when I lived in New England and was building Jeeps/crawlers for people. They even took the time to make me a set of shafts and stubs for an oddball Tracker/D44 front axle that one of my customers had under his Samurai. I called everywhere looking for replacements, including Trail Tough who built the axle, and was basically told to pound sand. Talked to Mitchell about it and within 2 days of giving them the measurements they had the axle shafts built and ready to be picked up. :smokin:

I miss doing business with them.
 
gobi_rubi said:
I picked his brain about if he sees much ring and pinion failures in the JK and JL 44s. He said most of the failures are on JL axles. He thought they could be setup issues, but seemed to agree that while the JL 44 r/p are supposedly stronger on paper, they seem to not hold up as well as the JK 44 r/p. The improved tooth cut advantage doesn't seem to overtake the smaller size and greatly reduce hypoid distance disadvantage.
Click to expand...

I would debate that. We see more broken JK R&Ps than JL/JT.

BUT, there could be many reasons for that.

I will ask around our industry and see if others agree or not.



YotaAtieToo said:
For the sake of a custom axle, absolutely, no reason at all to use JL c's just to adapt the D60 over.
Click to expand...

The main reason would be to build to your needs and not overbuild for the sake of overbuilding.
 
Tech Tim said:
I would debate that. We see more broken JK R&Ps than JL/JT.

BUT, there could be many reasons for that.

I will ask around our industry and see if others agree or not.
Click to expand...
My statement was just my own speculation and one guy's data point so maybe its not worth much. When I searched for the failures it seemed like JL failures were more common and they haven't been around as long. It would be interesting to get info from several shops. The jl guys are often heavier and it seems like its more common for them to slap 40s on stock axles so maybe its not a fair comparison
 
JR4X said:
That’s everything I want right there ☝️
Click to expand...
For sure. That is also what made me wonder about the Dodge stuff though. If we are going D60 shafts, is the Dodge outers really more heavy than the JL? Im sure cost would be less.

For something zuk sized, I think that the weight penalty might be too much, for only 35 or 37" tires. 1350 shafts might be good enough, but that limits you to JK/XJ axle width/spacings/spline counts unless Revolution will actually make custom inners.
 
ParadisePWoffrd said:
For sure. That is also what made me wonder about the Dodge stuff though. If we are going D60 shafts, is the Dodge outers really more heavy than the JL? Im sure cost would be less.

For something zuk sized, I think that the weight penalty might be too much, for only 35 or 37" tires. 1350 shafts might be good enough, but that limits you to JK/XJ axle width/spacings/spline counts unless Revolution will actually make custom inners.
Click to expand...
Edit: I need to read better

On a zuk I would think a jk based axle would be good for 40s
 
Last edited:
You must log in or register to reply here.
Top Back Refresh