04 LJ Ls swap with GM NP241C/4L60E

[mdbs14]

Hello all,

I have a 2004 TJ Unlimited LJ and doing a ls swap with a 04 silverado 5.3/4l60e.
I am planning to use the gm np241c a got from a friend's old suburban, because it bolts right up to the 4l60e. Running the Jeep 231j will require for expensive adapter...

What challenges will I run into to get the tcase to work? I have notice that it hangs lower so skid plate is on the way.

Please shine some lights. Thanks in advance

 

[Greg]

A clocking ring may help, but the 241 is physically larger than a 231 so you'll have to pay attention to floor clearance.

Standard 6 Bolt Round Clocking Ring Kit

These Clocking Rings are machined out of 3/8" steel to allow maximum spline engagement, Strength and Durability. All clocking rings are engraved with wide set location for ease of installation. Our clocking rings are precision CNC machined for accurate bore alignment. These 6 hole Clocking Rings...

northwestfab.com

 

[mdbs14]

A clocking ring may help, but the 241 is physically larger than a 231 so you'll have to pay attention to floor clearance.

Standard 6 Bolt Round Clocking Ring Kit

These Clocking Rings are machined out of 3/8" steel to allow maximum spline engagement, Strength and Durability. All clocking rings are engraved with wide set location for ease of installation. Our clocking rings are precision CNC machined for accurate bore alignment. These 6 hole Clocking Rings...

northwestfab.com

Thanks for your reply, Greg. When you say floor clearance, do you mean the skid plate? How much lower does the tcase hangs compare to 231? Is the clocking ring a must? can the skid/fab crossmember be lowered?
I am just trying to figure if its worth fighting to make it work, or just get the adapter to run the 231j.

Thanks

 

[The_Lobbster]

You could run a 231C transfercase as well fairly easily. I had one in my Astro, bolted up to my 4l60E. No need for an adapter with the right unit. It came out of a mid 90's S10 Blazer. I had then used a Jeep liberty cable floor shifter for it.

I believe there's a couple different variations in regards to spline inputs and outputs though, so you have to shop around a bit and do a little research to find out exactly what you want.
JB Conversions makes a sweet slip yoke eliminator though that can use a 1310 (CV or non CV) or 1350 (Flange) output.

 

[Greg]

Thanks for your reply, Greg. When you say floor clearance, do you mean the skid plate? How much lower does the tcase hangs compare to 231? Is the clocking ring a must? can the skid/fab crossmember be lowered?
I am just trying to figure if its worth fighting to make it work, or just get the adapter to run the 231j.

Thanks

No, I mean the floor... the body above the t-case. If you use that clocking ring, you'd rotate the t-case up, so it's not hanging so low.

You can lower the skidplate, seems like most options are 3/4" drop.

 

[jpndave]

I would stay away from the 241C same story on the 231C. A dodge is more like the Jeep. Clocking is different, pattern/rotation is different. Shifter is different. Physically larger case. Available SYE kits are not compatible, etc. etc. etc. Adapt the 231J with a solid SYE, you'll be much better off overall. I understand the appeal of "free or cheap" but in the long run it will be much more costly.

 

[The_Lobbster]

I would stay away from the 241C same story on the 231C. A dodge is more like the Jeep. Clocking is different, pattern/rotation is different. Shifter is different. Physically larger case. Available SYE kits are not compatible, etc. etc. etc. Adapt the 231J with a solid SYE, you'll be much better off overall. I understand the appeal of "free or cheap" but in the long run it will be much more costly.

Looking at the JB Conversions stuff, it shows that their SYE kits are compatible with all 231 variations. Plus, it bolts right up to the GM transmission since that's what it's factory mated to. You can just use a clocking ring if you really want to drop it.

 

[mdbs14]

Looking at the JB Conversions stuff, it shows that their SYE kits are compatible with all 231 variations. Plus, it bolts right up to the GM transmission since that's what it's factory mated to. You can just use a clocking ring if you really want to drop it.

My understanding is that it's already dropped, wouldnt the clock ring be used to lift it upward? Is the clock ring even needed, does it hung that low, I dont think so. Was thinking of just lowering the skip plate until I could bolt on the tcase

 

[jpndave]

Looking at the JB Conversions stuff, it shows that their SYE kits are compatible with all 231 variations. Plus, it bolts right up to the GM transmission since that's what it's factory mated to. You can just use a clocking ring if you really want to drop it.

JB does cater more to those niche market parts. I stand by what I said. The C cases are not worth the headache. I have a LOT of experience with these, I designed adapter kits, SYE kits, etc. in a previous career. I have in my JK, 242 AMG/6L80E with those parts. You can work through most of the issues but it is not worth the headache. GM in their great wisdom made a huge amount of their cases proprietary. Just because both say 231 doesn't mean that things are compatible. You can get the Jeep case adapted by swapping the input gears of the transfer case which are compatible to get the 27 splines if you don't want to ante up for a full adapter kit. Still need to address the speed sensor input though.

The best solution is to SYE the Jeep 231 which is then much stronger and lighter than it has a right to be.

 

[jpndave]

The rotation at least on the C case/adapter is low and clocked way off the Jeep at best and completely different on many. I have had this conversation more times than I want to remember....

 

[glockman]

JB does cater more to those niche market parts. I stand by what I said. The C cases are not worth the headache. I have a LOT of experience with these, I designed adapter kits, SYE kits, etc. in a previous career. I have in my JK, 242 AMG/6L80E with those parts. You can work through most of the issues but it is not worth the headache. GM in their great wisdom made a huge amount of their cases proprietary. Just because both say 231 doesn't mean that things are compatible. You can get the Jeep case adapted by swapping the input gears of the transfer case which are compatible to get the 27 splines if you don't want to ante up for a full adapter kit. Still need to address the speed sensor input though.

The best solution is to SYE the Jeep 231 which is then much stronger and lighter than it has a right to be.

So you are saying an NP231J is stronger than a NP241C?
I'm running the 241C with the NW fab clocking ring Greg posted and a JB conversions SYE. The only issue I've had was sealing the clocking ring to the T case. The speedo output was a non issue because I went with Speedhut gauges.

 

[The_Lobbster]

So you are saying an NP231J is stronger than a NP241C?
I'm running the 241C with the NW fab clocking ring Greg posted and a JB conversions SYE. The only issue I've had was sealing the clocking ring to the T case. The speedo output was a non issue because I went with Speedhut gauges.

I watched hours upon hours of videos when I built my Astro setup that showed how there is multiple variations within each manufacturer. Some GM’s had the wide chain, some didn’t, same with Jeep. Some have the extra planetary gears, some don’t. You really don’t know until you open it up.

Original poster never said what his intentions are for this rig. Frankly, if he’s going to be bouncing it and beating it to heck, he’d be better with a Dana or Atlas anyways. I was just trying to help him avoid having to do a lot of chopping and modding.

 

[Gravy]

Generally speaking a 241C that came behind a V8 motor is going to be better and stronger than a 231J. For the same reasons listed above wider chain and an extra planet.

I cooked a five planet planetary from a 231J in my doubler. I replaced it with a six planet unit from 231C and tacked the planet pins and had no further issues.

The only real benefits to the J case 231 is speedo and you won't have to use a clocking ring (and the 241 is slightly longer) which can affect driveline length and stuff (like in a TJ) but should be okay in an LJ.
A problem is he would have to get the J case to work is the need to swap the input from a 231C to get 27 spline because his original J case will a 23 spline input. (I ran into this issue when I tried to run a J behind a 700R4)

IMO The easiest/ cheapest solution is to run a bit of a drop on your belly pan and run the 241C.
2nd would be a clocking ring (or redrill the trans output flange/ redrill and stud the tcase flange) on the existing 241C that you already have and pound the crap out of the floor so it fits.

There are SYEs for a 241.

It's not terribly hard to use a Novak/ JB/ Northwest transfer case cable shifter with any of these cases.
Or if your cheap like me you can steal the cable shifter out of a junkyard KJ and adapt that works great too (because that's what they modeled the Novak kit from).

The 241 also helps driveline angles whenever/ if you decide to swap a wider axle because the centerline to front output spacing is larger so you get less compound angle. It can cause some tight fitting on a narrow LJ/TJ frame if you try to run a really big exhaust down the driver side, (but pass side seems like a better choice imo)

And just to geek you out more More often than not The Tcase clocking is lower on IFS versions of the same t case. Not only to get better driveline angles to a fixed mounted IFS diff but (in the case of the 42rle auto in the LJ vs a KJ the starter position is swapped left to right so the tcase is clocked to clear the starter)

 

[mdbs14]

I watched hours upon hours of videos when I built my Astro setup that showed how there is multiple variations within each manufacturer. Some GM’s had the wide chain, some didn’t, same with Jeep. Some have the extra planetary gears, some don’t. You really don’t know until you open it up.

Original poster never said what his intentions are for this rig. Frankly, if he’s going to be bouncing it and beating it to heck, he’d be better with a Dana or Atlas anyways. I was just trying to help him avoid having to do a lot of chopping and modding.

My intentions with the rig is mostly street driving, definitely dont want to put money where I don't have to. I have the jeep 231j, a gm 241c which bolts on, and can possibly get another Jeep 231j from a friend with the sye already installed. So between the 3 tcases I am just trying to figure out what to use that will cost me less cash and less headache.

 

[mdbs14]

Generally speaking a 241C that came behind a V8 motor is going to be better and stronger than a 231J. For the same reasons listed above wider chain and an extra planet.

I cooked a five planet planetary from a 231J in my doubler. I replaced it with a six planet unit from 231C and tacked the planet pins and had no further issues.

The only real benefits to the J case 231 is speedo and you won't have to use a clocking ring (and the 241 is slightly longer) which can affect driveline length and stuff (like in a TJ) but should be okay in an LJ.
A problem is he would have to get the J case to work is the need to swap the input from a 231C to get 27 spline because his original J case will a 23 spline input. (I ran into this issue when I tried to run a J behind a 700R4)

IMO The easiest/ cheapest solution is to run a bit of a drop on your belly pan and run the 241C.
2nd would be a clocking ring (or redrill the trans output flange/ redrill and stud the tcase flange) on the existing 241C that you already have and pound the crap out of the floor so it fits.

There are SYEs for a 241.

It's not terribly hard to use a Novak/ JB/ Northwest transfer case cable shifter with any of these cases.
Or if your cheap like me you can steal the cable shifter out of a junkyard KJ and adapt that works great too (because that's what they modeled the Novak kit from).

The 241 also helps driveline angles whenever/ if you decide to swap a wider axle because the centerline to front output spacing is larger so you get less compound angle. It can cause some tight fitting on a narrow LJ/TJ frame if you try to run a really big exhaust down the driver side, (but pass side seems like a better choice imo)

And just to geek you out more More often than not The Tcase clocking is lower on IFS versions of the same t case. Not only to get better driveline angles to a fixed mounted IFS diff but (in the case of the 42rle auto in the LJ vs a KJ the starter position is swapped left to right so the tcase is clocked to clear the starter)

I don't mind dropping the skid if that won't mess up the angles. The 241 doesn't seem to hung down that much lower. I rather not use the clocking ring if I really don't have to.

 

[UNSTUCK]

I’m on the tail end of a very similar swap. I don’t think there would have been any way to get everything to fit right with the body removed. As much of a pain as the body is, for me it needed to be there. If you don’t have one already a 1” body lift will be a huge benefit in getting it all to fit.
Get a clocking ring. They’re under $100 and give you options. Combine that with the body lift and you may not need to drop your belly.
You should also consider building a crossmember to mount your trans/tcase mount to. Gives you more flexibility with your pan and makes life way easy when you want to work under there with out the pan in place.

 

[mdbs14]

I’m on the tail end of a very similar swap. I don’t think there would have been any way to get everything to fit right with the body removed. As much of a pain as the body is, for me it needed to be there. If you don’t have one already a 1” body lift will be a huge benefit in getting it all to fit.
Get a clocking ring. They’re under $100 and give you options. Combine that with the body lift and you may not need to drop your belly.
You should also consider building a crossmember to mount your trans/tcase mount to. Gives you more flexibility with your pan and makes life way easy when you want to work under there with out the pan in place.

I did put small spaces on the skid and the 241c tcase bolts right on the tran. I don't really mind the skip dropped a lil as long as the angle won't be an issue. Here is how things look like.. is the sye needed?

 

[Gravy]

Needed now? Maybe not. But pretty necessary for any future mods. I wouldn't go without it if you have more than 3" lift. Even on a LJ. You could check if it binds at full droop if you like.

 

[DAA]

Still haven't really heard the intended use. But for my relatively mild use of my LJ, a slip yoke would have to go.

I had to put an Atlas in mine to replace the boom-boomed 241OR. Had to sink the mount 1" through my tummy tuck skid. Which still puts it 3" above stock and that's only the small mount area - the rest is still 4" higher than stock. And needed to BFH the heck out of the tunnel. But it's tucked in pretty high and tight and never contacts the body.

And still running the lengthened factory non-CV shaft with no (drive shaft) vibes at 90 MPH.

- DAA

 

[1969honda]

@mdbs14 depending on where you're at I believe when I sold my LS Swap blazer parts to @jpndave there was an early 27 spline gear in the parts bin. If it'll work with your 23J, he may, or may not, be using it in the future since that swap is getting a 6l80 as well.