Transfer case

[Sandeagle]

After reading it seems like my 86 sedan has the 128 transfer case and my 84 wagon has the 129 transfer case. The  sedan has the limited slip front dif and the 84 wagon has the locking front dif. Is this correct. Should I put the wagon front dif in the sedan for over sand travel. I live on an island so more sand than dirt. Block Island off the coast of Rhode Island.

[mudkicker715]

eagles never had limited slip. a locking front diff is just an axle disconnect. has nothing to do with traction

[JayRamb]

86 was the only off year from 81-88.

[Sandeagle]

So is the transfer case always sending power up to the d-shaft and front dif but not to the wheels?

[amcfool1]

no, only when you engage it

[macdude443]

My '86 had the NP 128.  When the rebuilt transmission was installed we put in the 129.  If I recall right, the 128 was an "open diff" design with no viscous coupling(?).

[mudkicker715]

My '86 had the NP 128.  When the rebuilt transmission was installed we put in the 129.  If I recall right, the 128 was an "open diff" design with no viscous coupling(?).

that is correct

[eaglefreek]

Sandeagle, the selectable transfer case in an Eagle works just like any other transfer case in a Jeep or truck. It just doesn't have a low range. When in 2wd, only power is sent to the rear driveshaft. When in 4wd, power is sent to both driveshafts. Some Eagles had a front axle disconnect. The right axle inside the front differential, is two pieces and are locked together when put into 4wd.  The purpose is to have less moving parts while in 2wd to help with MPG. I've heard it is also to help reduce driveline vibrations.

[Sandeagle]

Ok now I understand, I couldn't get why they would have 2 systems to disconnect the same thing. Rolling resistance and part wear. Thank you!

[carnuck]

Also less friction with vacuum front axle in 2wd mode, so slightly better fuel economy. I would put a soft positive traction device in the front if it had a vacuum diff, but it may handle weird in 4x4 on the highway.