Gear ratios for a manual SE

StG58

TJ Guru
Supporting Member
Joined
Oct 29, 2015
Messages
6,650
Location
Orygun, the wet side...
So, slapped some 31's on the 99 SE the end of last week, and as expected the performance changed. It's a manual, so it's easy to just grab a lower gear on the street and keep on truckin'. On the trail, it's a little different though.

I was planning on gear and axle upgrades, and Trutracs anyway.

What's the consensus between 4.56 and 4.88's? The math tells me 4.88's. Not much highway driving, the Jeep does get loaded down, and there is always 5th gear to use.
 
I depends if you're ever going to go with a bigger tire. With the 5 speed, it's generally thought the 4.56 is perfect for 33,s and 4.88 for 35,s. Yo can go 4.56, and still be ok if you go to 33,s.
 
So, slapped some 31's on the 99 SE the end of last week, and as expected the performance changed. It's a manual, so it's easy to just grab a lower gear on the street and keep on truckin'. On the trail, it's a little different though.

I was planning on gear and axle upgrades, and Trutracs anyway.

What's the consensus between 4.56 and 4.88's? The math tells me 4.88's. Not much highway driving, the Jeep does get loaded down, and there is always 5th gear to use.

4.88 is what is normally chosen for 33's for the four-cylinder SE and 5-speed so for 31's, the lowest ratio I'd go with is 4.56. Most just stick with the factory 4.10 for 31" tires but since yours is a trail rig, 4.56 would be a good ratio for 31's. But if you think you may get to 33" tires, I'd go with 4.88 but the RPMs will be pretty high with only 31" tires.

I depends if you're ever going to go with a bigger tire. With the 5 speed, it's generally thought the 4.56 is perfect for 33,s and 4.88 for 35,s.
Those ratios are what you'd pick for those size tires only if you have the 4.0L I6 engine. The SE with the 2.5L engine requires a lower ratio than is needed for the 4.0L engine. :)
 
Last edited:
  • Like
Reactions: StG58
4.88 is what is normally chosen for 33's for the four-cylinder SE and 5-speed so for 31's, the lowest ratio I'd go with is 4.56. Most just stick with the factory 4.10 for 31" tires but since yours is a trail rig, 4.56 would be a good ratio for 31's. But if you think you may get to 33" tires, I'd go with 4.88 but the RPMs will be pretty high with only 31" tires.

Those ratios are what you'd pick for those size tires only if you have the 4.0L I6 engine. The SE with the 2.5L engine requires a lower ratio than is needed for the 4.0L engine. :)
Thanks for the input @Jerry Bransford , the choice has been driving me nuts. There's a couple oh hills that I hit on a regular basis that had me in third and hammered out with my TJ and a full load out. A couple of trails as well where 1st is to high for going up, and low range was required. Neither of the last are really technical enough to require low range 4 wheel drive, but the Jeep needed the additional gearing to go up safely. Too bad there wasn't a 2wd low range for those rare times it's needed.
 
  • Like
Reactions: Stinger