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NP242 to NP231 AMC Swap

GravyDavey

NAXJA Member
NAXJA Member
Location
San Diego, CA
1988 XJ 4.0 AW4 NP242

I'm planning on swapping out my 242 for a junkyard 231 AMC tomorrow. I'll be rebuilding the 242 hopefully over the summer.

My questions is will this 231 AMC with the vacuum switch for a CAD system play nice with the full time Dana 30 on my jeep?

I know this tc doesn't have a true neutral so I guess that means I won't be able to shift on the fly, but will the full time spinning front drive shaft cause problems? I don't detect any movement in the input or rear output shafts when I spin the front output shaft in 2wd, but maybe there's something I'm overlooking.

I don't know what vehicle this 231 came out of but spline count and input shaft length seem to be what I need for my xj. Not sure about the clocking.
 
There's no way to disconnect the front axle from the rear axle while having it disconnected from the transmission. It's only an issue when it's being towed. Even with the disconnect axle, while single axle towing it, the front driveshaft would still be spinning, but the axle wouldn't be. One spider gear is held stationary and all rotation goes through the other one and the disconnected shaft. Far from ideal. Use a rollback carrier if it needs towed and you're fine.
 
1988 XJ 4.0 AW4 NP242

I'm planning on swapping out my 242 for a junkyard 231 AMC tomorrow. I'll be rebuilding the 242 hopefully over the summer.

My questions is will this 231 AMC with the vacuum switch for a CAD system play nice with the full time Dana 30 on my jeep?

I know this tc doesn't have a true neutral so I guess that means I won't be able to shift on the fly, but will the full time spinning front drive shaft cause problems? I don't detect any movement in the input or rear output shafts when I spin the front output shaft in 2wd, but maybe there's something I'm overlooking.

I don't know what vehicle this 231 came out of but spline count and input shaft length seem to be what I need for my xj. Not sure about the clocking.

Google the part number on the red and silver tag. There is also a build date on it.

You will be able to shift on the fly. Later models with the 231 had front axles just like yours does now.
 
It’s a direct swap. No need to worry about the vacuum junk on the case since it does not affect the shifting of it. You don’t have the two piece front shaft so swap in the 231 and be done.
 
Just a follow up. The swap went great, everything seems to work. I just need to allocate a new speedo cable. The old one's threads are too stripped out to reuse.

Thanks again for all the help guys!
 
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