Jeep Comanche 2wd to 4x4 Swap and Lift Help

[Tonynguy]

Hello i have a 87’ 4.0l 2wd automatic longbed comanche and plan on doing a 4x4 swap and lift. It is currently running a d-35 in the rear. I have a donor d-30 and front drive shaft, aw4, and i believe the np231 with 2wd, 4 part time, 4 full time, N, and 4-lo (top to bottom). I also wanted to throw on a trussed donor 8.25 i have for the rear. I plan on running a rustys 4.5” spring pack lift and was wondering if i could get away with not having to mod my driveshaft. I know if I just did a 4x4 swap id have to shorten the rear driveshaft but if i lifted that much could i get away with keeping stock length and not using  a sye kit or wedges, or a transmission drop kit. Any advice helps thanks a bunch! 

[Pete M]

the lift will need an inch of length over stock 4wd shaft, and the rear axle will need an inch removed.  it's more or less a wash and they cancel each other out.  

 

you won't need a SYE or a drop kit. 

 

edit, so I must be tired because I needed a half dozen edits to get that whole thing right. 

[derf]

Adding a transfer case takes a foot or so out of the rear driveshaft.

 

The 8.25 may have a longer pinion than a Dana 35.

 

If you find a stock 4x4 rear driveshaft for your bed length it will probably work.

 

The stock 2wd shaft will be way too long.  But getting it shortened is easy and not expensive.

[Tonynguy]

28 minutes ago, derf said:

Adding a transfer case takes a foot or so out of the rear driveshaft.

 

The 8.25 may have a longer pinion than a Dana 35.

 

If you find a stock 4x4 rear driveshaft for your bed length it will probably work.

 

The stock 2wd shaft will be way too long.  But getting it shortened is easy and not expensive.

Would i be able to drive it to the shop after the swap to get it shortened? And i think i saw on another post the 8.25 is 1” stouter than the d-35. My only issue is having to give them an exact number i need, if id be able to bolt everything up and drive it to a shop nearby that’d be awesome so they can figure out the correct length i need vs me giving them a wrong number. Also was hoping the lift and me having to shorten would cancel out but don’t know how the 8.25 comes into play too

[Tonynguy]

1 hour ago, Pete M said:

the lift will need an inch of length over stock 4wd shaft, and the rear axle will need an inch removed.  it's more or less a wash and they cancel each other out.  

 

you won't need a SYE or a drop kit. 

 

edit, so I must be tired because I needed a half dozen edits to get that whole thing right. 

You mean shave an inch off the 8.25? couldn’t i just get my driveshaft resized to accommodate the longer pinion on the 8.25? Id have to resize anyways with the lift and 4x4 swap 

[Pete M]

the pinion snout is an inch longer on the 8.25 (over the dana 35) which means if you had a stock 4wd MJ, you'd need to shave an inch off of the driveshaft.

 

lifting an MJ 4.5" means that you'll then need a driveshaft that's 1" longer than stock.

 

but I just noticed you included a "full time" in your listing of the t-case specs.  the 231 doesn't have a fulltime option.  the 242 does though. best to know which you have because it might affect the shaft lengths.   

[derf]

8 minutes ago, Tonynguy said:

Would i be able to drive it to the shop after the swap to get it shortened? And i think i saw on another post the 8.25 is 1” stouter than the d-35. My only issue is having to give them an exact number i need, if id be able to bolt everything up and drive it to a shop nearby that’d be awesome so they can figure out the correct length i need vs me giving them a wrong number. Also was hoping the lift and me having to shorten would cancel out but don’t know how the 8.25 comes into play too

Your 2wd rear driveshaft won't even come close to fitting behind a transfer case.

 

And if you don't have a slip yoke eliminator you can't run without a rear shaft.

 

Measuring for the rear shaft modification is a known thing and easy to do.  Then take the shaft to the shop in a different vehicle, have them shorten it, take it home, and install it.

 

If you find a 4wd rear shaft from a Comanche with the same bed size, it would probably work.  But the 2wd shaft is a hard no.

[Tonynguy]

7 minutes ago, Pete M said:

the pinion snout is an inch longer on the 8.25 (over the dana 35) which means if you had a stock 4wd MJ, you'd need to shave an inch off of the driveshaft.

 

lifting an MJ 4.5" means that you'll then need a driveshaft that's 1" longer than stock.

 

but I just noticed you included a "full time" in your listing of the t-case specs.  the 231 doesn't have a fulltime option.  the 242 does though. best to know which you have because it might affect the shaft lengths.   

are there size differences between the two? i wasn’t exactly sure which one i got with my donor parts. so a stock 4x4 longbed rear driveshaft should work if i lift it 4.5 inches and add the 8.25 in the rear? and if that were true then i would just need to resize my rear driveshaft to that of a 4x4 one? 

[Tonynguy]

3 minutes ago, derf said:

Your 2wd rear driveshaft won't even come close to fitting behind a transfer case.

 

And if you don't have a slip yoke eliminator you can't run without a rear shaft.

 

Measuring for the rear shaft modification is a known thing and easy to do.  Then take the shaft to the shop in a different vehicle, have them shorten it, take it home, and install it.

 

If you find a 4wd rear shaft from a Comanche with the same bed size, it would probably work.  But the 2wd shaft is a hard no.

gotcha darn, hopefully what pete said is right and i can just get mine cut down to stock 4x4 size. any idea what that spec is? 

[derf]

Just now, Tonynguy said:

gotcha darn, hopefully what pete said is right and i can just get mine cut down to stock 4x4 size. any idea what that spec is? 

No idea.  But since you're modifying, you should get the axle and transfer case installed first.  Then measure from the end of the slip yoke on the transfer case to the yoke on the axle.  Then you can have it exactly right with no chance of it being too short or too long.

 

A shop can shorten a shaft in about an hour or two and they know how to work with the measurements to make it right.  They can also swap in new ujoints quick and easy which is entirely worth it.

[Pete M]

your 2wd shaft is likely a 2-piece shaft with a 30 year old rubber isolator inside.   I would just get a brand new one made (sans the isolator).  

 

I don't know the lengths of the 242 vs 231.  might even change depending on year.  The MJ never came with the 242, that was an XJ thing.

[Tonynguy]

14 minutes ago, Pete M said:

your 2wd shaft is likely a 2-piece shaft with a 30 year old rubber isolator inside.   I would just get a brand new one made (sans the isolator).  

 

I don't know the lengths of the 242 vs 231.  might even change depending on year.  The MJ never came with the 242, that was an XJ thing.

it should still bolt up though yeah? just a matter of figuring it all out? i thought i read somewhere on here that one of them was better than the other but i just nabbed them for the low from a 89 xj that was being parted out. also the front driveshaft won’t have to be lengthened? i have the stock one from the 89 cherokee. 

[Caish]

Thats a NP242 case, not a 231,  shouldn't matter since you're going to have to cut a shaft anyway. 

I used a Lincoln shaft on my sons when we added a transfer case to it. 
If you can weld a little its easy,  use apiece of paper wrap it around the shaft for a straight line. 
Use hacksaw or grinder go around the weld, knock the cap out with a hammer. 
Then carefully cut the shaft straight, knock the end back in, its a tight fit so even if your 
cut isn't perfect its going to be straight. Make sure the cups pn both ends are lined up, 

Weld it down and enjoy. 
I've done several over the years, never had a vibe issue, just smooth out weld, if its not great, 

with a grinder..... 

[Pete M]

41 minutes ago, Tonynguy said:

it should still bolt up though yeah? just a matter of figuring it all out? i thought i read somewhere on here that one of them was better than the other but i just nabbed them for the low from a 89 xj that was being parted out. also the front driveshaft won’t have to be lengthened? i have the stock one from the 89 cherokee. 

 

the front shaft will be perfect since the front half of XJ and MJ suspension is the same.   I hope you got the t-case shifter linkage/gate from the XJ.

 

I infinitely prefer the 242!  my Liberty has been in AWD mode since 07.  

[Caish]

Since no one mentioned it. 
Mixing and matching transfer cases can be an issue. 
There is three different lengths of transfer case input lengths. 
Then add in early AW4's  used a 21 spline vs 23 spine on later ones. 
So just a bit of advice. I've been playing with XJ's/MJ's for 15 years... 
So long as both came out of same donor you're golden. 
The OEM drive shaft if its like my sons was, its a rubber isolated shaft, 
Why i went with the Lincoln towncar shaft, it uses the same U-Joints too. 
 

[Tonynguy]

On 5/24/2021 at 5:42 PM, Caish said:

Since no one mentioned it. 
Mixing and matching transfer cases can be an issue. 
There is three different lengths of transfer case input lengths. 
Then add in early AW4's  used a 21 spline vs 23 spine on later ones. 
So just a bit of advice. I've been playing with XJ's/MJ's for 15 years... 
So long as both came out of same donor you're golden. 
The OEM drive shaft if its like my sons was, its a rubber isolated shaft, 
Why i went with the Lincoln towncar shaft, it uses the same U-Joints too. 
 

the transmission, transfer case, transfer case linkage, front axle, and front driveshaft came out of the same donor and the t case was never separated from the transmission. all from an automatic 89’ cherokee 4.0l. the rear axle is the only wishy washy item i have and figuring out the rear driveshaft situation. All i know is it’s a chrysler 8.25 27 spline which i know isn’t the best, but i also read that the d-35’s were 27 spline too so figured a swap wouldn’t be too difficult. plus it’s trussed so definitely stronger than the d-35 regardless. i was just planning on taking the 2wd driveshaft to the shop to have them resize it after i figure out how to take measurements properly and get everything hooked up to do that. 

[Pete M]

the 27 spline is the weaker of the 8.25s (the later model one having thicker shafts with 29 splines), but I'd still take it over the dana 35 any day  

[Caish]

The early D35's with bolt in axles are not as weak as the later C clip axles.

I've ran 31" tires, wheeled them etc, never broke an axle. 

87 XJ. I've seen many had issues, but not me, and was always 

C-Clip axles....