OEM Transfer Cases

[Bird-o-Prey]

Just a bit off topic here, but also remember, the 119 uses 10W30 instead of ATF. 

[Whuntmore]

My newest Eagle is an '86, so it should have the NP 128 Case.  Now if I took a NP129 case, and bolted it to my '86, could I still shift on the fly? 

would there be a NP129 case on my '84 that would do?  Could I just swap them over?

[MaskNMI]

whuntmore: you can shift (your TRANSFER CASE) on the fly as long as your front axle is engaged, either permanently or with the disconnect axle already connected (this must be done at a stop, or at least with the wheels locked, lol)....

anyway, the axle is not supposed to shift on the fly while it is turning, the shift fork is tiny and there no synchronizing from what I understand...what you get your car to do wheeling in the desert is between you and the coyotes

[IowaEagle]

Both the 129 and 128 cases can be shift on the fly.  It was the axle disconnect that created the stop and shift version.  You either need a non-disconnect front axle; or lock the disconnect axle into the "connect" mode to have shift on the fly.

[Whuntmore]

Ok, but since my 86 eagle is already shift on the fly, and the front end is already set up for this, and I'm not changing the front diff, then the front end shouldn't be a consideration here.   Is this just you guys thinking that my Car isn't already shift on the fly?

I mean maybe there's something I'm missing here, but it seems to me if my car is already 'shift on the fly' and the transfer case I want to change to is also 'shift on the fly' and all I'm doing is changing the case, it should work.

[Bird-o-Prey]

I believe that the 80 & 81 and 86 and later all had the locked front axles.  It was from 82 to 85 (?) that had the select-trac that you had to stop the car and shift.  So, if you have a set up that is already a shift on the fly, changing out the transfer case with either the 128 or 129 will not affect that.  I pulled my 129 out of my 84 wagon, then locked the front axle and installed a 119.  I like the idea of full time AWD.  the difference in MPG is negligible and I don't have to worry about shifting the T-case whenever the road conditions change.  There is another 81 wagon at a local wrecker with a 119 in it.  They want $100 for it, and I am considering getting it to have a spare.

[IowaEagle]

Ok, but since my 86 eagle is already shift on the fly, and the front end is already set up for this, and I'm not changing the front diff, then the front end shouldn't be a consideration here.   Is this just you guys thinking that my Car isn't already shift on the fly?

I mean maybe there's something I'm missing here, but it seems to me if my car is already 'shift on the fly' and the transfer case I want to change to is also 'shift on the fly' and all I'm doing is changing the case, it should work.

Yes, all you are doing is changing transfer cases.  You will retain your shift on the fly capability. 

[rockymtnhigh]

A  229 T-case can be installed in place of the 129 or 128, this way you still have the viscous coupler and you have low range.  You would have to install a shifter to shift from low range to high range. Other than the shifter it's identical to a 129.  These can be found on the AMC Grand Wagoneers behind V-8's, but the bolt pattern are the same as a 129 or 128.

[HappyPappy]

Just a bit off topic here, but also remember, the 119 uses 10W30 instead of ATF. 
[/
  How much damage can you do by using ATF instead of 10W-30?  I just changed mine back to 10W-30 after reading it in the manual. I was under the impression that they all used ATF, in fact that's what was in it when I bought it. Guess that's where all of my winning is coming from, sounds like it's going to explode any day now.

[mudkicker715]

You never mentioned what year or what. Case.

[eaglefreek]

I believe it was mentioned somewhere that the factory later recommended ATF over 10w30.

[eagle503]

To my understanding if you swap for a 229 you need to do something different with the speedometer cable. A 90degree adapter I think.
I found this to be a handy chart.

[mudkicker715]

Just reclock it.

[Whuntmore]

While I was at the Calgary PnP helping El Matador strip an eagle there, a guy who used to be a (long standing) member with our AMC chapter came up and started chatting.  he still owns a few AMC cars.

I told him I had a 129 case I was gonna swap out (get rid of my 128 case) and he suggested that I go with a 208 case from one of the full sized wagons (wagoneer... whatever)

Now, is there such a case as a 208?  Or did he have his numbers wrong, and he really meant a 207 TC?  I've never heard of a 208 case. 

If there is such a beast, would this be a good upgrade?

[eagle503]

Just reclock it.

I have heard this will cause leak issues?
Hear is a link to a page on common t cases it has info on the np 208 mentioned above.
http://www.off-roadweb.com/tech/1005or_common_transfer_cases_guide_high_low_ranges/new_process_gear.html