Ok so 4 times a year I'll be making a drive from Florida to New York going back and forth to college.

Hopefully this summer I'll be upgrading to 35's. What gears should I get?

I do some moderate mudding in Florida and some decent trail/climbing in NY

Keep in mind I understand mpg's will be low, it's a jeep. But I don't want to be getting a ridiculously low mpg on the highway making the 17 hour drive at 70-80 mph.

Thanks for the help

Trey

 

There is a chart in this post. The whole post has good info. Might help you out..

https://www.jk-forum.com/forums/show...276#post211276

 

5.13s with an auto and 35s. that's what I got and it runs great! if you are concerned about MPG, then 4.88's might be a better choice but these things are bricks regardless lol.

 

Yeah I have an auto, probably going to go 5.13's

 

I've done a ton of reading on this lately because I will have my gears done shortly. I have an auto with 35s and I will be going with 5.13s

That seems to be the most popular choice.

 

I will say 4.88s for auto 4.56 for 6spd. I have a 6spd with 4.88s and 35s and its way to low for 35s if you drive alot on the highways

 

Any other advice?

 

There is no consensus for gearing, just personal preferences. Get whatever is right for you. (auto on 35's, 5.13's are very popular. Arguments can be made for both 4.88 and 5.38)

Mileage will vary drastically, no one can say which ratio will give you the best mileage. (5.38's are better mpg's than 5.13's for me...)

Plug some numbers into the chart mentioned above. If you want the OD Off rpm, divide the number you get by .69. The mid 2k rpm range seems to be where this engine performs the best. (again, open to argument. I get the best freeway performance up closer to 3k. Many like to run lower rpm's.)


Post #33 in this one is a good overview for the pre-2012 auto folks.
https://www.jk-forum.com/forums/show...-vs-5.13/page4

(shows an example of an auto on 35's pumping out a whopping 75 rwhp. That's certainly plenty of power. - if you're going downhill - with a tailwind - )

 

Yeah 5.13's are looking good to me now, just as long as they wont burn up my trans

 

Being under-geared and constantly dropping in and out of OD is what will kill the trans. (and mpg's). Being geared correctly for your tires will keep you in OD, keep the trans temps down, (prolonging the life of the trans), and should improve the mpg's.

Which brings up the debate of lower rpm's vs higher rpm's.

-low rpm's give better mpg's (4.88's)
-higher rpm's keeps you in OD longer before downshifts (5.13/5.38)

Decide what rpm's 'you' need to run to be able to hold freeway speeds without downshifts. Sea level with long flat freeways? Lots of hills, few flat stretches? At altitude with mountain roads? Lift and tires? Armor and winch and carrier? 2door or 4door? (for me, whether I am up in Colorado or down in Texas, 5.38's perform better than 5.13's).


Whichever ratio you decide on, you should also look into a trans cooler. They are cheap and pretty easy to install.