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Old 12-24-2011, 08:22 AM   #1
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'12 Regear thread

Merry Christmas Eve yall.

this thread is solely for all '12 JK/JKUs that have already been regeared, if possible. Any advice that can be given will be extremely helpful to those looking for guidance. Me personally, I will be regearing my JKU with 315/70/17 Duratracs TWICE! Why? So I can help give feedback to all the other Jeepers out there. Sounds stupid right?! Parts and labor are free or next to nothing so I thought it would be a good write up to get some real world numbers. First will be 4.88s running the 35's and swapping to a set of 37's. Then ill break it down and do 5.13 with both sizes.

Ive seen a few on here that have done 4.56. Whatcha think?

Yall have a safe holiday weekend and enjoy time with the fam.
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Old 12-24-2011, 10:05 AM   #2
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Is 4.88 the norm with 35s? Are you auto or manual?
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Old 12-24-2011, 10:08 AM   #3
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Not sure of a norm yet. I've got auto in this one.
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Old 12-24-2011, 01:36 PM   #4
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With the different gearing on the '12s, 5.13s would be too low for anything much below a 40 inch tire. If you do the math, you can go a size or two higher on gears with the '12s and be good.

For instance, 35s with either tranny would be decent with 4.10s and geared fairly low with 4.56s turning aroundd 2700 rpm at 70 mps. 4.88s and 35s are turning a tick over 2900 at 70 on my '12 with an auto.

Honestly, I kind of wish I wouldn't have gone so low on mine. I have plans to go to 37s, but am on 35s now as I took the tires and wheels off my '09 that I traded in. I also pull trailers and even pull an teardrop offroad on occasion so wanted the lower gearing. However, with the power of the 3.6, 4.56s would have most likely been plenty of power even with the 37s and given better highway manners. Also, the first gear on the auto is much lower than the old 4 speed which also really helps with higher gears.

This has me curious though. My '09 Rubi with the 4:1 t case and my '12 with the 2.72: tcase feel from my butt-meter to have very similar crawl ratios. I'm going to have to figure out the math...
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Old 12-24-2011, 01:45 PM   #5
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my plan is to run 4.56 in the wifes dd with 35's. only problem now is waiting for someone to come out with them.
Yukon said early next year...

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Old 12-24-2011, 01:58 PM   #6
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Ok, for kicks.

'07-'11 First gear automatic ratio of 2.84:1
'12 First gear automatic ratio of 3.59:1

'07-'11 Rubicon with 4:1 t-case - 4.10 gears has crawl ratio of 46.57 / 4.88 gears has crawl ratio of 55.43.

'07-'11 non Rubi with 2.72:1 t-case - 4.10 gears has crawl ratio of 31.67 / 4.88 gears has crawl ratio of 37.69

'12 Rubicon with 4:1 t-case - 4.10 gears has crawl ratio of 58.87 / 4.88 gears has crawl ratio of 70.07.

'12 non Rubi with 2.72:1 t-case - 4.10 gears has crawl ratio 40.03 / 4.88 gears has crawl ratio of 47.65.

Comparing this, on the low end, the '12s don't require near as deep gears. On the highway, the auto also has lower overdrive, comparable to the manual (the manual tranny OD was actually raised for '12 slightly), so higher gears can be used there as well.

I think the norm for '12s will be much higher gears that in previous JKs.
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Old 12-24-2011, 01:59 PM   #7
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my plan is to run 4.56 in the wifes dd with 35's. only problem now is waiting for someone to come out with them.
Yukon said early next year...

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Huh? The gears are the same as all other JKs so all ratios are already available.
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Old 12-24-2011, 03:19 PM   #8
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So you guys are saying 4.88 should be the best for 37" tires? I might go 38" toyos and was thinking 5.13 gears.
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Old 12-24-2011, 04:07 PM   #9
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Depending on use, 4.56 or 4.88s would be a good choice for 37s.
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Old 12-24-2011, 04:13 PM   #10
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Originally Posted by AppSt59Dave View Post
Merry Christmas Eve yall.

this thread is solely for all '12 JK/JKUs that have already been regeared, if possible. Any advice that can be given will be extremely helpful to those looking for guidance. Me personally, I will be regearing my JKU with 315/70/17 Duratracs TWICE! Why? So I can help give feedback to all the other Jeepers out there. Sounds stupid right?! Parts and labor are free or next to nothing so I thought it would be a good write up to get some real world numbers. First will be 4.88s running the 35's and swapping to a set of 37's. Then ill break it down and do 5.13 with both sizes.

Ive seen a few on here that have done 4.56. Whatcha think?

Yall have a safe holiday weekend and enjoy time with the fam.


Are you installing the 35s before any regearing? That info may be helpful also. I am assuming you have 4.10s in your auto.
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Old 12-24-2011, 04:26 PM   #11
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Huh? The gears are the same as all other JKs so all ratios are already available.
I have been unable to source any for the front 44 at this time. if you know of any please let me know.


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Old 12-24-2011, 04:33 PM   #12
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Quote:
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Are you installing the 35s before any regearing? That info may be helpful also. I am assuming you have 4.10s in your auto.
I've been running 35s for a couple of weeks. My auto has 3.73. I guess im in the minority since I don't have a Rubicon like most I see people posting about
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Old 12-24-2011, 05:49 PM   #13
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I have been unable to source any for the front 44 at this time. if you know of any please let me know.


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You haven't looked too hard. This is the first place that came up on a google search. EVERY company that makes gears makes the ones you want.

http://www.drivetrain.com/parts_cata...ar_pinion.html

Contact Marcus from RiverCityOffroad on this forum and he will get you all set up.
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Old 12-24-2011, 07:08 PM   #14
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Regeared a 2012 4 door automatic with 35" Toyo's (34.5") to 4.56 and it was perfect, I wouldn't go any higher or any lower on the gear.
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Old 12-24-2011, 07:10 PM   #15
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IIRC rpms where at 2600 at 70mph, I'll have to double check that.
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Old 12-25-2011, 11:30 AM   #16
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Good to know. Good thing that I haven't ordered any parts yet. ,iChat do comparison on 4.56 versus 4.88 with 35s and then info with 4.88 & 37s. Looks like Craftsman took a shit in my living room floor with all the new tools. Now, time to plan the next steps!
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Old 12-25-2011, 08:00 PM   #17
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So you guys are saying 4.88 should be the best for 37" tires? I might go 38" toyos and was thinking 5.13 gears.
I would definitely run 4.88s for this in a auto 12' 5.13 would be too much unless you never drive on the interstate.
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Old 12-25-2011, 08:02 PM   #18
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I have been unable to source any for the front 44 at this time. if you know of any please let me know.

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Call us Wednesday, we should be able to get them no problem for great prices!
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Old 12-26-2011, 10:43 AM   #19
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I would definitely run 4.88s for this in a auto 12' 5.13 would be too much unless you never drive on the interstate.
So you like the 4.88 even for the 38" Toyo MT tires on a 2012 auto?
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Old 12-26-2011, 11:01 AM   #20
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I personally would if i spent a 90% of my time on the road. If you have any plans of going bigger go 5.13.
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Old 12-30-2011, 06:56 PM   #21
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Huh? The gears are the same as all other JKs so all ratios are already available.
Actually I believe the guy was referring to the trans ratios, They are different in the 12s.
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Old 12-31-2011, 12:24 PM   #22
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Actually I believe the guy was referring to the trans ratios, They are different in the 12s.
No, go back and read again. He said he wants 4.56s but coudn't find any. Does'nt really matter though as a vendor already posted regarding it.
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Old 12-31-2011, 01:44 PM   #23
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My 2012 Rubicon auto has Goodrich 37's with 5:13's.

Turns about 2700RPM at 70Mph.

Mabye just a hair short for alot of freeway driving, but I like the acceleration.

Havent had a chance to go wheeling, yet but the gears seem about right to me.

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Old 01-05-2012, 06:29 AM   #24
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Ok...we have to retract our statement about the 4.56 gears...apparently there was something wrong with a batch of gears...so according to our supplier the 4.56 is out of production for some reason. We apparently got the last 4.56 set our guys had for the 2012 install in Nov...sorry guys, still good in all other gear ratios: 4.10, 4.88, 5.13, 5.38(44 only)
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Old 01-18-2012, 09:32 PM   #25
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This question was asked already in the thread but I didn't see a direct answer to it. To run 35's, do I necessarily have to re-gear my JKU Sport 6 speed? I don't think I should make the step all the way up to 4.88 but would running 35's warrant that in any way? Just a new Jeeper kinda lost in the situation

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