Jump to content

NP242 added length


Recommended Posts

I'm considering an NP242 swap on the MJ. I know that this transfer case is longer than the 231, but by how much? I'm trying to determine if I'll need a new rear driveshaft to make this work. Since I am running ~7'' lift on a stock driveshaft, the added length may make up for the 1/4'' of extra slip yoke thats hanging out. Also, what would I need to do to make the 4wd indicator lights on the dash work? I know that the 231 uses a vacuum switch and the 242 uses electric, as well as adding another light for the full time mode. Also, does this transfer case (same year, matching input shaft) use the same speedometer gear, or would I need to get a short and/or different tooth gear?

 

Thanks in advance.

Link to comment
Share on other sites

you may have too many changes to your truck to be able to accurately predict the necessary driveshaft length. It may boil down to a try-it-and-see. the pinion angle of the rear axle alone can make a huge difference in driveshaft length.

Link to comment
Share on other sites

If you get a renix 242 it should be a direct swap for the most part. The shift gate for the 242 is a little deeper, so you will need that too, or just make yours deeper. The added length is less than half an inch I'd guess. I just did this swap in my Cherokee. Be prepared the 242 hangs quite a bit lower.

Link to comment
Share on other sites

Most 87-90 MJ's came pre-wired for the 242TC. To make the shift light indicator work as it should with the 242 TC you will need to use the 242 TC shift position switch at the TC. Just remove the vacummn switch hookup and screw in the elec one. Behind the TC shift linage bracket bolted to the side of your tranny, or somewhere in that area, is a set of wires (3) that is not plugged into anything. That is the wiring you plug your position switch into. Those wires run up to the 10 wire blue plug near the diagnostic plug in. It's plug & play.

Your speedometer should work just fine, mine did with no changes made.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...