Best gearing for 31s on a 2.5L auto

Jan 6, 2019
13
3
Pennsylvania
#1
I'm picking up a 2.5L auto TJ next weekend for a really good deal. I know that itll suck on highways because it has 31s and lots of steel bumpers and armor which will weigh it down. I've heard that they suck at merging on the highway so what gearing do you run with a 2.5 and auto trans on 31s or 33s? (I dont want to rear everybody saying that I shouldnt get it with that motor/trans. I found a cheap crashed TJ with a 4.0 and I'll swap the engine and trans.)
 

Jerry Bransford

TJ Guru
Supporting Member
Nov 9, 2015
8,790
9,754
Escondido California
#2
For the effort and trouble it'd be to swap in that 4.0, even though you said you don't want to hear this, I'd wait to find a good deal with one with the 4.0L already in it. Not to mention you'd also have to get inside the transfer case to swap in a different (larger diameter) input shaft or swap the 231 tcase too.
 
Likes: Chris
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Jan 6, 2019
13
3
Pennsylvania
#4
For the effort and trouble it'd be to swap in that 4.0, even though you said you don't want to hear this, I'd wait to find a good deal with one with the 4.0L already in it. Not to mention you'd also have to get inside the transfer case to swap in a different (larger diameter) input shaft or swap the 231 tcase too.
I'm honestly looking for a big project to do next winter so I might do it just for the hell of it. If I can find all the LS swap pieces for cheap I would rather do that