transmission swap in 89 yj

[suicide_jockey]

i have an 89 yj with a 4.2litre. i am wanting to swap the 5spd. for an auto.this jeep is not being built for hard core offroad.would like to make it as simple as possable.

 

[Saddle Tramp]

We just had another post on a YJ auto transmission behind the 2.5. The TF 903 was the auto transmission jeep used behind your motor. I’m not sure of all the particulars but you may be able to find a trashed donor in the bone yard. It would be helpful to do it this way so you can get everything you need to complete the swap. Only the “Iron Duke” 2.5 used in CJ around 1980 will not have the right bellhousing pattern, it will be Chevy but all the TF 903/999 after 1976 should work.

 

[carnuck]

Since the OP has a 4.2L (aka 258) the 904 (909 if it's lockup) from a 2.5L motor won't work. They have the same bell pattern as the 2.8 V6 used in Chevs and '84-86 XJs. The trans from a '71 or newer 232/258, 4.0L, 4.2L or AMC V8 (flexplate needs to be changed as the 6 is zero balanced)
Since the YJ has a driver's side front driveshaft, the simplest set up is a 998 from an AMC Eagle/YJ or 999 from an '80 to 83 full size Cherokee with 6 cyl.
The Grand Wagoneers and other FSJs '80 to '83 (J pickups '80 to '88) often have a 727 which will work, but it's a bit wider so using the tcase from an FSJ would be best. (NP208J is the simplest one, followed by NP219. NP229 and NP228 are vacuum shifted to 4x4 and lever shifted to low range)

 

[Saddle Tramp]

Since the OP has a 4.2L (aka 258) the 904 (909 if it's lockup) from a 2.5L motor won't work. They have the same bell pattern as the 2.8 V6 used in Chevs and '84-86 XJs. The trans from a '71 or newer 232/258, 4.0L, 4.2L or AMC V8 (flexplate needs to be changed as the 6 is zero balanced)
Since the YJ has a driver's side front driveshaft, the simplest set up is a 998 from an AMC Eagle/YJ or 999 from an '80 to 83 full size Cherokee with 6 cyl.
The Grand Wagoneers and other FSJs '80 to '83 (J pickups '80 to '88) often have a 727 which will work, but it's a bit wider so using the tcase from an FSJ would be best. (NP208J is the simplest one, followed by NP219. NP229 and NP228 are vacuum shifted to 4x4 and lever shifted to low range)

Carnuck- I’m confused. If the TF 903 was the auto option for the YJ (& CJ) why not just use all the OEM parts from the YJ?

 

[carnuck]

Carnuck- I’m confused. If the TF 903 was the auto option for the YJ (& CJ) why not just use all the OEM parts from the YJ?

903 was used for 4 cyl. It won't bolt to the 6 cyl.
CJ also used TH400s.
In some cases the designator just means a minor change in the trans. The 727 is much heavier duty that the 9XX series (the 999 comes close)
If there is no other YJ Jeep for parts in their area, it's always good to know what else you can use.

 

[suicide_jockey]

thanks for the info. picked this jeep up at a good price, but wanted an auto. had plans in rebuilding it. just wondering what would be easiest swap would be. will be occasional driver for my wife.