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Any body seen a gear chart for the new 3.6 with 5 speed auto? I will be going with 35's and wonder how the 3.73's will hold up. Will not see rocks as I live in south Louisiana. Also how do the 3.73's do on the highway with 35's? A lot of downshifting?
 

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The final drive is similar to the manual tranny on older JKs so you can go off that.
 

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Noob here, how do you read that chart? I guess if you in the green your OK?
yes. So to run 37's on a 12 automatic I only need 4.56 gears. WTF over.
 

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This chart is dead on and the 3.6 is pretty wicked. I have a 2012 6spd and I still have the crappy 3.21s running 35s!! I'm currently getting 21mpg during my 120 mile / day commute. 70mph leaves me at about 1700rpm. Granted as soon as I need to pass anyone on the highway or go uphill I need to downshift out of 6th but IMO this is what a true over drive should be anyway. In today's cars it sometimes makes no sense, I have a 2012 TL 6spd and I can accelerate uphill in 6th...that's stupid. I always thought a highway overdrive gear should give you the best performance regarding mileage. Anyway, to solve my shitty offroad performance I just swapped in a rock-trac which now gets me low enough off road even with the 3.21s. I think I'm still gonna re-gear when I drop my lockers in but I'm torn between 3.73s or 4.10 (leaning towards 4.10)
 

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I've got 3.73's and 35's and it's real close to being good enough. I want just a little more so am going with 4.56's. I know that I will lose a little mileage, but want some more bottom end. If it's flat in LA, I wouldn't change them.
 

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I have 37's, 3.73's and the shitastic 3.8 and my jeep is fine
 

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The chart for the 3.8 is not quite right. I have 35s and 488s. The chart says I should be running 2756 rpm with manuel transmission. I actually run 3200 rpm at 70 mph.
 

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I don't get this chart. My jk came with 3.21 and an auto and 32" tires stock. By this reasoning I should not be able to do anything with my gear set.
 

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2012. 35's 3.73 Auto and procal for the shift points.....no problems. much better than my old 07. i'd try it first before swapping gears

and no constant downshifting. I do have KM2 35's though so they're more like 34's....or 33.75's....rides perfect for me
 

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I don't get this chart. My jk came with 3.21 and an auto and 32" tires stock. By this reasoning I should not be able to do anything with my gear set.
That's about right imo. I wouldn't want that setup for anything...Certainly get you a trans cooler asap.
 

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That's about right imo. I wouldn't want that setup for anything...Certainly get you a trans cooler asap.
You're used to the 3.8L. My wife's '12 with the auto, 3.21s and 33s runs great. The 80 additional h.p. makes a huge difference.

That said, I am going to 3.73s, because I can.
 
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