tacoleman93

I have looked at previous threads stating the difference between the 231 and 242 transfer cases. i am almost positive i have the 231 on my '99. The "part-time" light is also proof of this. I am concerned as to whether or not in slippery conditions (snow, ice, heavy rain, etc.) is it acceptable to opperate the vehicle in 4hi? If so under what speeds? What about turning in 4hi? anything would help, thanks

BajaCrawler

well the part time light means nothing both have it. but your shift plate will say 2hi 4hi N 4lo if its a 231. and 242 says 2hi 4part time 4full time N 4lo. the 231 is much better. I've had my stock ones at freeway speeds in the rain no problems. I think they are rated for 85mph in wet weather. i could be wrong but i tested it too and nothing happened.

tacoleman93

The shift plate says 2hi 4hi N 4lo like you stated. I'm glad to know you operated it at highway speeds because thats what i was concerned about, with my previous owner (mom) driving in "4HI" on any kind of snow on pavement for extended distances

BajaCrawler

well the only reason i had one explode was because the chain was broken. a shift fork was damaged and it had a crack in the side so no oil. other than that for a chain driven case the NP231 is pretty soundproof.

BajaCrawler

but normal highway driving with it not in pieces will work fine.

tacoleman93

well again that's good to know. do you recommend getting the fluid changed? it's probably due after several years, but im also a believer if it ain't broke don't fix it.

BajaCrawler

if you ever do river crossings expect your transmission and t-case to have water in them. so i would occasionally check it and change if it smells burnt or is milky. I'm a firm believer of dont fix what aint broke as well but cruddy fluid might as well be the same as broken.

tacoleman93

well i have yet to experience river crossing so water is likely out of the equation, but normal wear and tear are. Ill check the condition of it in the next day or so.

BajaCrawler

you will either need a 30 somethin mm socket or a huge hex drive forgot what size. but probably the hex drive, newer jeeps had that instead.

tacoleman93

that should be no problem long as it wont all pour out like the oil pan plug would. should it be a red color like tranny fluid?

BajaCrawler

yes it should be red cause it calls for atf +3 or higher cause +3 was replaced by +4. and it shouldn't overflow but no guarrantees. just make sure to take out the upper plug in the middle of the case on back. not the lower one. upper for fill and check lower for drain. Wish they made a sight glass like my dirtbike.

tacoleman93

alright bud, ill let you know what she looks like in the morning thanks again

BajaCrawler

no problem at all. good luck.

tacoleman93

the fluid in my t case, (after finding a hex key that big) was a dark red, not brown. everythings working fine so im not going to mess with it

89Laredo

Not ATF... Dexron.
The AW4 and NP231 both call for dexron II which was replaced with Dexron III.
Just look at your trans drain plug for "DII"

ATF 4 most likely would be fine in the tcase, but it WILL kill a AW4