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2012's and gearing upgrade

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Old Sep 17, 2011 | 01:27 PM
  #1  
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Default 2012's and gearing upgrade

For those with a 2012 Rubicon w/4.10's running 37'' or larger tires, do you still have the desire to run lower (5.13-5.38) gears? Or is the extra torque/hp of the 3.6 enough to keep you happy (for the most part) with 4.10's? Thanks
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Old Sep 17, 2011 | 02:57 PM
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Originally Posted by planman
Even guys with Hemi's installed regear to at least 4.88s for 37s. So yes, 37s will need a regear on 2012s.
I think it all depends on the ratios in the transmission being used. Are these guys with the Hemi swaps using the stock 4 speed??

The overdrive in the 5 speed auto is taller than in the 4 speed. I haven't heard of anyone running larger than 35s on a '12 yet but these guys say the 4.10s are fine.
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Old Sep 17, 2011 | 08:34 PM
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Originally Posted by tempeyeep
For those with a 2012 Rubicon w/4.10's running 37'' or larger tires, do you still have the desire to run lower (5.13-5.38) gears? Or is the extra torque/hp of the 3.6 enough to keep you happy (for the most part) with 4.10's? Thanks
Might be too early in the life of a 2012 for someone to have a need for steeper gears than 4.10's after they plunked down what they just paid for a 2012 Rubicon. Could be wrong, maybe someone has that need, otherwise, probably wait for the 2012's to show up on used car lots first.
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Old Sep 18, 2011 | 08:25 AM
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well, before you go regearing a 2012, make sure someone has worked out programming for 2012 Limp Mode
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Old Sep 18, 2011 | 09:11 AM
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Originally Posted by jeeeep
well, before you go regearing a 2012, make sure someone has worked out programming for 2012 Limp Mode
I surprised that didnt come up earlier in the thread.
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Old Sep 18, 2011 | 12:31 PM
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I'm assuming the programming issue is only affecting the automatics as it sounds like the computer used Diff speed to aid in shifting or will it affect teh 6-speed as well? How much does a pro-Cal go for. I'l probably get one regardless so I can recaliberate my speedo after teh 35's go on.
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Old Sep 18, 2011 | 12:41 PM
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Originally Posted by jesse0920
I'm assuming the programming issue is only affecting the automatics as it sounds like the computer used Diff speed to aid in shifting or will it affect teh 6-speed as well? How much does a pro-Cal go for. I'l probably get one regardless so I can recaliberate my speedo after teh 35's go on.
They cost around $150. I've used them on my 2011 and 2011 Rubicon's.
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Old Sep 19, 2011 | 04:00 AM
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The gear sets for the 2012s are going to be a lot more accepting because of the larger torque band. The automatics are going to be closely aligned with the manual transmissions of past years and the acceptable rpm range for cruise speed of the Pentastar will begin 10-15% lower. 2012 Owners can look to the manual gear chart in the FAQ regardless of whether they have a manual or automatic transmission. I'll be updating the chart once I can put rubber to the road with a 2012 while on paper the sweet spot for efficiency/performance appears to be much broader.
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Old Oct 17, 2012 | 09:03 PM
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Jpop: I'm running 38" (37.7) on my 2012 jku, auto, would like to know your opinion on my gear choice? My Rubicon is my DD, I live in Oregon so it's a mix of hilly roads, flat ground and altitude of sea level to 4000'. I love wheeling but I would put my self in the moderate range as far as wheeling! Mostly camping, fishing, hunting & trail riding! Not a big fan of carnage, but don't mind watching someone else do it ;-)! Any ways I read a lot of you post and would like your feed back ;-)

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Old Oct 17, 2012 | 09:09 PM
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Jpop: leaning more towards better economy, and I have 3.73 ;-( now! I'm tired of my auto searching for the wright gear to get into?

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