Disco D30 with 242 T-Case?

I'm going to be swapping in an AX15 for my Peugeot, and while I'm at it I thought I might try and put a 242 in as well. Winter time would be much awesomer with full-time.

However, I noticed that 242's in the early (87-90) XJ's had non-disco front axles, is this correct?

If I were to simply swap in a 242 and keep my disco-D30, will that cause any problems? I'd like to keep my front driveshaft from spinning in 2WD.

My understanding of this is no, it won't cause a problem. BUT there is a couple of things you'll have to work around. 1st, there isn't going to be a vacuum signal sent to the axle, (or indicator light) to engage the collar. 2nd, you won't be able to shift from 2wd FT to 4wd FT on the fly, at least with out significant risk of blowing something up in your drive train.

Your options around this would be to either fab up some kind of manual vacuum source, or install a cable that will lock the front axle together.

Instructions can be found here... http://home.earthlink.net/~stevenschreiber/jeep/tech/cabledis.htm to make your own. Or you can buy it already made for you here...http://collinsbros.stores.yahoo.net/4x4psilok.html and probably other places as well.

Either way, you would have to lock the front axle together while stopped. That would allow you to shift from 2wd FT to 4wd FT while on the move.

--Tom

Ok that makes sense, but tell me this. How come, with the front driveshaft not spinning and all, that part time 4x4 can be shifted on the fly?

When you're at speed and the vacuum locks the axle together, it would be the same thing as if you were to run a cable, right? So theoretically wouldn't shifting to full time be the same?

I'll admit it's been almost 5 years since I was driving an MJ (just bought an XJ but won't see it until next month) so the brain could be a bit rusty on the advisibility off shifting from 2wd to 4wd PT on the fly. Plus I'd just gotten up and was only half a wake. Thats my story and I'm sticking to it.

My thought was that there must be a reason they went to the extra effort of putting a solid axle shaft on the 242, when most of xj/mj's were disco 231's.

But, you are correct, functionally the cable operated and the vacuum operated 'motor' are the same. I would still think that you would want to engage the tansfer case first to get all the parts moving at close to road speed before locking the haves of the front axle together.

--Tom

The problem here lies in the fact that the 231 t-cases used with the disco axles had a synchro in them to allow for things to shift without the driveshaft spinning, the 242 does not have this. Thus for shift on the fly operations you would need to get the driveshaft turning before shifting the case. As a side note for others, the later 231's used in non-disco jeeps also lacked this synchro causing the same problem if swapped into a disco jeep.