What exactly does engaging 4hi or lo on a YJ do...

[loudobbs]

I know that the vacuum system pulls the fork in the front axle over to couple the two passenger side shafts and 'engage' the 4wd. Does anything else happen? Is power always going to the front diff via the transfer case or does something disconnect in there as well?

I ask because now, as I have autolockers in both axles - if all that happens is that the fork in front moves over to couple the axles, then I am technically running in 3wd at all times with the locker in there. Which just makes me think about how to treat it in snow. Could be better off leaving it out of 4-wheel.

[Bigbike]

power is only being sent to the rear wheels when is in 2wd. The shift fork in the axle prevents the pass side shaft from spinning in 2wd sorta kinda like manualy locking hubs. It was supposed to increase fuel econmy but it really just fails alot and is dumb, most people just get some TJ or late model XJ shafts and get rid of the stupid 2 piece shaft.

So ya your front axle doesnt have power going to it till you put it in 4wd.

[loudobbs]

Well, my thought was that the pass side axles disengage so that all the power would be sent to the disconnected axle via the spider gears effectively disabling 4wd. However, now that I don't have spider gears but an autolocker instead, that wouldn't work, and power would still be sent to the driver side wheel.

Is that not the case? Is something actually disconnected in the transfercase stopping power being sent to the front diff?

[Bigbike]

There is a two piece axle on the pas side, so even if you have an auto locker the axle is still "disconnected" but ya when in 2wd the tcase is no putting power to the front wheels.

[loudobbs]

There is a two piece axle on the pas side, so even if you have an auto locker the axle is still "disconnected" but ya when in 2wd the tcase is no putting power to the front wheels.

Roger. Don't really get the point of disconnecting that pass side axle then, but I don't get a lot of what else went on in the 90's either, except grunge.

Is there any difference, other than the slip yoke, between the YJ and TJ 231's? I know they ditched the vacuum fork on the TJ.

[Bigbike]

dont quote me but i believe the slip yoke is diffrent from yjs- tjs. but Ive never looked at a yj tcase

[Jeep Creep]

adding to what caleb said, the idea of disconnecting the pass side shaft was to prevent the front driveshaft from spinning, thus in theory increasing MPGs. With the locker in front i think your driveshaft might be turning regardless whether or not the passenger side shaft is disconnect. pull the diaphragm and add washers to the fork shaft so its always engaged, that way you never have to worry about the vacuum system failing.

[Ktmracer419]

i cant help but remember you at various wheeling events, popping the cover to your vac disco xj dana 30 and manually sliding the shift fork over before you went back on the street.

[loudobbs]

i cant help but remember you at various wheeling events, popping the cover to your vac disco xj dana 30 and manually sliding the shift fork over before you went back on the street.

Yeah I woulda sworn I had some tire chirp if I left it engaged. I thought it was used to engage/disengage 4wd by having all the power go to a torque-less axle in front while in 2wd mode.

[Crazy Reid]

dont quote me but i believe the slip yoke is diffrent from yjs- tjs. but Ive never looked at a yj tcase

Quoted anyway because you are correct. The rear seal on the output shaft of a 231 from a YJ to a TJ is different. TJ's hav a hard seal in the rear making the output shaft look "male". THe YJ has a longer case and a rubber seal making the tcase ouput look "female" but is really male.

They may be interchangeable.