batafish22 Posted November 11, 2009 Share Posted November 11, 2009 i just picked up my '86 MJ last week, and the transfer case (np207) keeps slipping out of 2H. i then have to slow to a stop, shift into neutral, wait for the tcase to wind down, cycle down to 4L and drive it a bit before trying 2H again. what would cause this? the truck is running a 2.8L V6 and a Torque Flight A904 auto tranny. Is a 23-spline NP231 a direct bolt in? ive tried to find the answer to this question all over the internet, and i can't find a solid answer. this is going to be my daily driver, and my only means of transportation, so i need something that i can take a day, maybe two, drop my 207 and bolt up the 231, and be good to go. any and all help and/or information on the swap is GREATLY appreciated! Link to comment Share on other sites More sharing options...
Geonovast Posted November 11, 2009 Share Posted November 11, 2009 A short shaft 23 spline 231 should go right in, but you may run into a rear driveshaft issue. When I went 4wd (86 AX-5 with a 207) in my 2.5, I had the shaft cut about 1/2" too short, so the yoke didn't go in quite as far as I wanted, but good enough to drive. I've since put in a 93 AX-5 and 231, and the yoke is right where it should be. Also, I believe in 86 the front driveshaft had a flat flange with a CV joint. You'll need to put that yoke on the 231, or get a different front shaft. Link to comment Share on other sites More sharing options...
Pete M Posted November 11, 2009 Share Posted November 11, 2009 I thought all 207s were 21 spline? :hmm: Link to comment Share on other sites More sharing options...
Geonovast Posted November 11, 2009 Share Posted November 11, 2009 I thought all 207s were 21 spline? :hmm: I thought all TF904s were 23 spline? Or am I thinking that all NP 228/229s are? Link to comment Share on other sites More sharing options...
Pete M Posted November 11, 2009 Share Posted November 11, 2009 :dunno: I is confused. Link to comment Share on other sites More sharing options...
Geonovast Posted November 11, 2009 Share Posted November 11, 2009 I'll fix it. A 231 with the same length and spline count input of whatever your 207 is will bolt right in, but still considering driveshaft, flange, and linkage issues. Link to comment Share on other sites More sharing options...
mjeff87 Posted November 11, 2009 Share Posted November 11, 2009 904/909's are 23 spline..... found that out the hard way converting my buddy's YJ from auto (909) to stick (AX5) go figure :roll: Jeff Link to comment Share on other sites More sharing options...
batafish22 Posted November 11, 2009 Author Share Posted November 11, 2009 thanks guys. like i said, i've been looking all over the place, and i couldn't find a straight answer anywhere as to what would work and what wouldn't. i have a deal on a 231 worked out, should be picking it up tomorrow, so it's good to know that it'll for sure work out. i'm still baffled as to what would cause the 207 to lose high range while driving. i thought 2H was a straight through kind of thing, no chain involved, right? :???: :???: Link to comment Share on other sites More sharing options...
Tri_X_Troll Posted November 11, 2009 Share Posted November 11, 2009 In my TJ I could slow down to a crawl and go from 2hi to 4low if I took the transmission out of gear and shifted it while rolling slowly.....the 207 in my comanche does not like this???? Is the 207 not shift on the fly? Link to comment Share on other sites More sharing options...
Geonovast Posted November 12, 2009 Share Posted November 12, 2009 It's not exactly a good idea to shift in or out of 4 lo while moving. At all. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted November 12, 2009 Share Posted November 12, 2009 you probably have a bad bushing on your shifter assembly and it's not getting quite in the proper location for 2H Link to comment Share on other sites More sharing options...
batafish22 Posted November 12, 2009 Author Share Posted November 12, 2009 you probably have a bad bushing on your shifter assembly and it's not getting quite in the proper location for 2H i thought about that, and we completely loosened the shift linkage and cycled it by hand on the t-case itself, and put it all the way into 2H that way, and it still came out. and that's what confuses me, isn't 2H straight through the case? i don't understand why i would lose not just 2H, but ALL high range, but 4Low will work all day, everyday. more likely than not, my small parts loan should be coming through tomorrow, and i'll be getting the np231 (hopefully) tomorrow too, so now i'm just trying to figure this 207 out for my sanity's sake! Link to comment Share on other sites More sharing options...
Geonovast Posted November 12, 2009 Share Posted November 12, 2009 Whatever keeps the shift collar for the reduction unit in 1:1 is probably slipping out. This would put the reduction unit in neutral. I've never personally had a T-case apart, but I'll probably bring my toasted 207(stuck in 2wd) back down to MO with me after thanksgiving to tinker with since I usually have nothing else to do down here. Link to comment Share on other sites More sharing options...
akamcbird Posted November 12, 2009 Share Posted November 12, 2009 Also, I believe in 86 the front driveshaft had a flat flange with a CV joint. You'll need to put that yoke on the 231, or get a different front shaft. my '86 2.8 tf np2o7 had the same/standard style front drive shaft. think its longer than the one in my '90 tho :hmm: here are some pics from the inside of the np 207 if it helps... :dunno: rear section front section Link to comment Share on other sites More sharing options...
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