Topic: Diff. gear break-in on front axle

[bestos]

New question.  My 500 mile diff. gear break-in period is over.  I know the rear has spun 500 miles, however, has the front?  I am not sure if my 1995 2.5 front drive shaft rotates with 2wd only or not.  I know there is the vacuum disconnect, but how this exactly engages the 4wd, i am unsure.  please someone guide me thru the tunnel as i am changing my rear gear oil this saturday, should i be doing the front yet or no?

ps:  on 3 rainy days i have put the jeep in 4wd to work that front diff, but that has only been for like 20 miles.   little help please.

[BlackYJ]

If you have a vacuum disconnect d30 with an open diff, then the ring gear does not turn unless it is in 4wd.

The passenger side has 2 axles and when you shift into 4wd, the vacuum actuator shifts a fork and connects the 2 shafts together to give you 4wd.  having this design allows the front driveshaft to be disconnected, and therefore does not turn.

[bestos]

ok.  i was unsure.  thanks. i posted same on jeep forums as well.  so basically i have to drive a whole lot more miles in the rain to break that front diff. in?

what if i put my aussie front locker in - it will no longer be open on the front, will the ring spin then.  I was going to wait until break in period is over, but what do you guys suggest.

[Jeffy]

Honestly, if you plan on going on some trails just take it easy.  Yes, the front hasn't been turning but it's difficult to get 500 miles on a part-time setup.

Also, think about how the gears are broken in at the factory.  Gears are typically, set up and run on a machine.  The pattern you end up looking for is to duplicate the same pattern, the gears were run before.  What you're doing is finishing up the peening or hardening process on the vehicle.  When you buy the Jeep off the Dealer lot, the gears have not been broken in, which a lot of people don't know.

If you really want to get the front turning then you could reverse the vacuum lines at the disconenct and remove the front driveshaft.  This will cause the gears to turn without putting stress on the transfer case.

[jagular7]

Why can't he engage the disconnect through the vacuum switch on the back side of the tcase (bypassing), and let the ds rotate with the gears? My TJ spins constantly and I have a front locker also. The tcase won't have any input into the front ds.

[Jeffy]

Why can't he engage the disconnect through the vacuum switch on the back side of the tcase (bypassing), and let the ds rotate with the gears? My TJ spins constantly and I have a front locker also. The tcase won't have any input into the front ds.

YJ's don't have balanced front driveshafts.  If he's lucky, he'll only have vibrations at highway speeds.  If it's really lucky, he'll have none.  Also, since the front only turns periotically, he might start noticing the pinion seal leak a bit.

Second, it's a lot easier to get to the front lines then to try to get to the ones on the transfer case.  The switch is on teh front half of the transfer case over the planetary. Not to mention, there are 4 vacuum lines to deal with there. Disconnecting it completely will cause a vacuum leak and at the manifold.

[bestos]

alright guys, thanks a lot for the info.  i dont go wheeling that much, and when i do, it is light work.  i will do the rear gear oil drain, inspection/adjustment if necessary this weekend and put the front locker in at the same time.  Thanks for your help.