35's, 3:21's and an auto
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JK Newbie
Joined: Jun 2011
Posts: 43
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From: Draper, Utah
Originally Posted by planman
I believe 3.73 is lowest numerical gearing in an automatic. 3.21s are only available with 6 speeds.
3.73s with 35s is doable if you run a Superchips Flashpaq performance tune and always run with your overdrive turned off. On the highway, you'd run the same rpms as you would with 5.38 gears--which is recommended for Rubicon automatics with 35" or larger tires.
3.73s with 35s is doable if you run a Superchips Flashpaq performance tune and always run with your overdrive turned off. On the highway, you'd run the same rpms as you would with 5.38 gears--which is recommended for Rubicon automatics with 35" or larger tires.
JK Enthusiast
Joined: Nov 2011
Posts: 190
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From: Richmond Virginia
I believe 3.73 is lowest numerical gearing in an automatic. 3.21s are only available with 6 speeds.
3.73s with 35s is doable if you run a Superchips Flashpaq performance tune and always run with your overdrive turned off. On the highway, you'd run the same rpms as you would with 5.38 gears--which is recommended for Rubicon automatics with 35" or larger tires.
3.73s with 35s is doable if you run a Superchips Flashpaq performance tune and always run with your overdrive turned off. On the highway, you'd run the same rpms as you would with 5.38 gears--which is recommended for Rubicon automatics with 35" or larger tires.
JK Enthusiast
Joined: May 2010
Posts: 462
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From: Lowell, AR
Originally Posted by j33p4life
2008.......
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JK Enthusiast
Joined: May 2010
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From: Lowell, AR
Originally Posted by Cervelo
2012 JK auto 3.73 would still need the Superchip?
There have been several 2012 auto owners with 3.73s run 35s and report that re-gear really isn't needed.
JK Jedi Master
Joined: Jan 2008
Posts: 11,463
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From: Austin <--> Colorado Springs
No, you don't 'need' a tuner with any specific engine/tire combo. The added hp/torque/shift points/functions/etc can be very nice to have though, depending on what you have and your personal tolerance.
But, you will definitely want some way to recalibrate for the taller tires. Whether that is a programmer (ProCal) or a tuner (Superchips, Hypertech, etc), is up to you. With an Auto, if you can swing the added money for a tuner, it is the better way to go.
But, you will definitely want some way to recalibrate for the taller tires. Whether that is a programmer (ProCal) or a tuner (Superchips, Hypertech, etc), is up to you. With an Auto, if you can swing the added money for a tuner, it is the better way to go.