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-   -   Update - NP231 Swap (http://www.jeepforum.com/forum/f13/update-np231-swap-1535531/)

huntsducks70 06-12-2013 10:44 AM

Update - NP231 Swap
 
so i got my driveshaft back last night, shortened, balanced and 2 new 1310s for $80 out the door. i installed from and rear DS and added a 1 1/2 qts of ATF to the tcase and the tranny and took her for a test drive. all i can say is that it is a 100% improvement over driving around in 4wd. the best thing is that i gained 3+ mpg during city driving. not sure if i will see an improvement on the highway, probably not though.

1998 5.2 with 249, i swapped in a 99 case from a 2000 cherokee, spline count and input shaft were a match, went in without a hitch.

http://i963.photobucket.com/albums/a...psa92b9418.jpg

http://i963.photobucket.com/albums/a...ps1b9faeab.jpg

http://i963.photobucket.com/albums/a...ps545d9553.jpg

http://i963.photobucket.com/albums/a...psb0e76103.jpg

OldManTan 06-12-2013 10:52 AM

ready to help me with mine?
hahah jk
congrats!

dnuccio 06-12-2013 10:53 AM

theres no way you gained 3mpg. all the front axle components are still turning, causing the same power loss as full time 4wd does. to benefit fuel economy wise, you would need manual locking hubs to disengage the wheels from the rest of the axle. your gains are probably percieved.

huntsducks70 06-12-2013 01:20 PM

okay, thanks for setting me straight, so if it is not 3mpg, what did you observe when you drove MY jeep? bottom line, i gained the 3mpg (per the lie-o-meter) i am content with this figure and the gain observed is consistent, sorry if you did not experience the same.

oh, and thanks for breaking down the workings of a non full float front axle.

huntsducks70 06-12-2013 01:24 PM

Quote:

Originally Posted by OldManTan (Post 15551953)
ready to help me with mine?
hahah jk
congrats!

i am no expert on the subject, but am willing to assist you with the swap, i could definitely get us through it, i am serious if you get the urge to tackle this.

WhiteOut 06-12-2013 01:32 PM

He is right about the mileage. Hand calculating the mileage is going to show that there is not enough gain to measure (pretty much 0.5 MPG). All provided you drive exactly the same way as before with the exact same conditions.

dnuccio 06-12-2013 01:45 PM

Quote:

Originally Posted by WhiteOut (Post 15552672)
He is right about the mileage. Hand calculating the mileage is going to show that there is not enough gain to measure (pretty much 0.5 MPG). All provided you drive exactly the same way as before with the exact same conditions.

thanks whiteout

98ZJLTD 06-12-2013 02:04 PM

Quote:

Originally Posted by huntsducks70 (Post 15551917)
so i got my driveshaft back last night, shortened, balanced and 2 new 1310s for $80 out the door. i installed from and rear DS and added a 1 1/2 qts of ATF to the tcase and the tranny and took her for a test drive. all i can say is that it is a 100% improvement over driving around in 4wd. the best thing is that i gained 3+ mpg during city driving. not sure if i will see an improvement on the highway, probably not though.

1998 5.2 with 249, i swapped in a 99 case from a 2000 cherokee, spline count and input shaft were a match, went in without a hitch.

I'm getting ready to swap a 231 out of a 2000 xj into my 98 here in a couple weeks, was the linkage much of a hassle to get set up correctly? That's the only part of that project that's making me nervous at this point although I'm sure it won't be as big of deal as I'm thinking its gonna be.

huntsducks70 06-12-2013 02:10 PM

i am going to agree to disagree. i understand all that hand calc stuff, most who confirm the results are within +/-.5mpg of the meter.

you guys may be correct when the delta is a 30/70 split, but my VC was dead and at 50/50 i am experiencing some great results with my 231

huntsducks70 06-12-2013 02:18 PM

Quote:

Originally Posted by 98ZJLTD (Post 15552831)
I'm getting ready to swap a 231 out of a 2000 xj into my 98 here in a couple weeks, was the linkage much of a hassle to get set up correctly? That's the only part of that project that's making me nervous at this point although I'm sure it won't be as big of deal as I'm thinking its gonna be.

i agree as the linkage was a concern for me as well, but in all honesty, it was not that bad. i had my son hold the lever in its most reward position (4lo) and then i took up the slack in the linkage and tightened it up. no pop outs yet and i have done a couple nice 2wd drive burn outs (although they did not satisfy my 11 year old son) and no issue so far. i am keeping my fingers crossed.

let me know if you need more details or pics and i will do my best to assist.

PolkaPower 06-12-2013 02:23 PM

You probably gained the mileage because you don't have a bad VC anymore not because you have 2wd. In working order the 96+ 249 is basically Rwd until the tires slip so it's not pushing power to the front like when the VC goes bad. You also lightened the Jeep by 30 lbs. Now you can fit more fat chicks in there :laugh:

98ZJLTD 06-12-2013 02:51 PM

Quote:

Originally Posted by huntsducks70 (Post 15552885)

i agree as the linkage was a concern for me as well, but in all honesty, it was not that bad. i had my son hold the lever in its most reward position (4lo) and then i took up the slack in the linkage and tightened it up. no pop outs yet and i have done a couple nice 2wd drive burn outs (although they did not satisfy my 11 year old son) and no issue so far. i am keeping my fingers crossed.

let me know if you need more details or pics and i will do my best to assist.

Nice, sounds like It should be easier than I was thinking it was gonna be then. Did you change the plugs for the 4wd indicator on the vic? I can't decide if its worth the effort or not, my vic works fine (for now) and I kinda like having it but if I can manage to get my hands on 2wd cubby I might just go that route instead. I will definitely hit you up if I need anymore details, I'm feeling pretty solid about it at this point t though.

Rich93ZJ 06-12-2013 02:55 PM

Quote:

Originally Posted by PolkaPower (Post 15552917)
You probably gained the mileage because you don't have a bad VC anymore not because you have 2wd. In working order the 96+ 249 is basically Rwd until the tires slip so it's not pushing power to the front like when the VC goes bad. You also lightened the Jeep by 30 lbs. Now you can fit more fat chicks in there :laugh:

^^THIS^^......You probably went from 9mpg to 12mpg :laugh:

huntsducks70 06-12-2013 04:38 PM

Quote:

Originally Posted by PolkaPower (Post 15552917)
You also lightened the Jeep by 30 lbs. Now you can fit more fat chicks in there :laugh:

i stopped dating your sister, so no worries there.

huntsducks70 06-12-2013 04:39 PM

Quote:

Originally Posted by Rich93ZJ (Post 15553045)
^^THIS^^......You probably went from 9mpg to 12mpg :laugh:

damn, you must have a ****ty running rig, mine kicks ***.


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