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Old 03-18-2014, 11:08 PM   #1
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Re-Gear for Bigger Tires

I was just wondering how many of you have re-geared your Wrangler's after getting bigger wheels? If you did what did you go with?

I have read several threads about people putting 35's on their base Jeep's but it seems like that they would be dog's if you has the stock 3.21's.

If you have re-geared to run 35+ wheels what did you choose and why? What would you change?

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Old 03-18-2014, 11:47 PM   #2
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I chose 4.56 gears to replace the 3.21s in my 2012 manual JK sport when I did the 35" tires. I had considered 4.10s but 4.56 gives me the option of going to 37s in the future. 1st gear winds out sooner than I'd like but freeway RPMs are just fine. It's a good combination for a daily driver.

For the record, 3.21 gears with the stock 32" tires was inadequate. I almost never ran in 6th gear on the freeway. The RPMs were almost too low to maintain speed unless you were going downhill. The mileage was about the same on the freeway between 5th and 6th gear.

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Old 03-19-2014, 12:51 AM   #3
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Derf: did you have any issues with it going into limp mode after gear swap? Did you use a ProCal?
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Old 03-19-2014, 01:34 PM   #4
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Derf: did you have any issues with it going into limp mode after gear swap? Did you use a ProCal?
None whatsoever. But I have a manual transmission. The limp mode really only affects automatic transmissions.

I use a Bullydog programmer to retune the engine. It has the capability to set the gear ratio and the tire size the same way as a ProCal. I had the programmer before I did the gears and tires so as soon as we were done with the gears, I programmed them in. The next week when I got the tires, I did the GPS thing to figure out exactly what to set the tire size to and programmed it in. If I had a ProCal, I could have done the exact same thing with it.
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Old 03-19-2014, 01:53 PM   #5
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Thanks for the info. I have an auto, so I need to research it more before I regear.
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Old 03-19-2014, 02:09 PM   #6
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I have 4:10s with my jeep from factory, I upgraded to 35s and have no problems. I like this setup, plenty of power and good response.
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Old 03-19-2014, 02:12 PM   #7
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With the 3.8L and 6spd MT and running 3:73 gears with 35's & superchips (87 tune).

6th gear is basically useless at highway speeds and really the difference between 5th and 6th is only 500 RPM. Would I love to re-gear? Absolutely, to 4:88's! is it a really necessary? NO, it is bearable for street and wheeling.
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Old 03-19-2014, 02:13 PM   #8
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If mine had come with 4.10's I think 35" tires would have been fine as well. Especially with the supercharger.
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Old 03-19-2014, 03:28 PM   #9
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Thanks for the info. I have an auto, so I need to research it more before I regear.
Just use one of the many ways out there to reprogram for the gears and tires. Have it ready to go when you do the install and you'll be fine.
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Old 03-19-2014, 05:16 PM   #10
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2014 JKRU auto with 4.10 gears. I didn't regear and have no regrets. I calculated it out, and 35s with 4.10 gears are about the same ratio or maybe still lower than the 3.21, if I remember correctly.

I think 3.21s on 35s at altitude or in a really hilly terrain might require a regear.
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Old 03-19-2014, 05:40 PM   #11
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Quote:
Originally Posted by derf View Post
I chose 4.56 gears to replace the 3.21s in my 2012 manual JK sport when I did the 35" tires. I had considered 4.10s but 4.56 gives me the option of going to 37s in the future. 1st gear winds out sooner than I'd like but freeway RPMs are just fine. It's a good combination for a daily driver.

For the record, 3.21 gears with the stock 32" tires was inadequate. I almost never ran in 6th gear on the freeway. The RPMs were almost too low to maintain speed unless you were going downhill. The mileage was about the same on the freeway between 5th and 6th gear.
Agreed. For a JKU with 35s, my personal advice would be 4.56s if you are running "stock" or 4.88s if you are running heavy (steel all around, skids, winch, lightbars, etc etc etc.) Calculating the RPMs isn't the only consideration. Lifting increases drag, so that robs power, armor adds a heap of weight, etc. RPMs should not be your only consideration when regearing.
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Old 03-19-2014, 05:53 PM   #12
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Ok so I just bought a 2014 JKU Sahara that dealer had a mopar 3" lift and 35s put on . Didn't know to ask on re gearing . It's a 6 speed manual , so far I haven't had it in 6 gear more than once .
I can run 60 at a bit over 2500 rpm in 5 th gear . Any ideas as to whether they re geared it or it's stock?
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Old 03-19-2014, 05:55 PM   #13
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Guaranteed it's stock. Dealers generally don't mess inside the axles. If it's at 2500 at 60 in 5th, its not regeared.
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Old 03-19-2014, 06:21 PM   #14
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3.6 jku with 6 speed and 3:73 in hilly Pennsylvania on 35's and heaps of extra weight. Shifts are still quick until 4th then it lacks power. Still good torque off the line though. 6 gear is good on flat land only. 4:56 I think would be perfect.
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Old 03-19-2014, 07:20 PM   #15
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Sounds like 4.56 or 4.88 gears with 35" tires is ideal for a JKU with lift and armor; recommend programming computer for new gears just prior or immediately after re-gear to prevent tranny from going into limp mode with an auto trans. Thank you all for the insight on re-gearing my JKU.
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Old 03-19-2014, 07:35 PM   #16
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3.6 with 3.73 gears and automatic. Does fine everywhere. would like a little more oomph going 80 up a hill but oh well.
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Old 03-19-2014, 07:46 PM   #17
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I'm mainly concerned in preventing the jeep from going into limp mode after re-gearing. I understand 2012's and newer have this issue. Anyone who has re-geared with ratios other than factory #'s, please chime in. Thanks.
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Old 03-19-2014, 07:49 PM   #18
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I regeared from 3.21 to 4.88 with no issue, but I'm driving a 2010 standard trans

I didn't procal it right away, no troubles

after I procal'd it, no troubles
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Old 03-19-2014, 09:09 PM   #19
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I regeared my '12 jku 6 speed on 35's from 3.21 to 4.56. I used a flashcal for the gears and tires. I think it's perfect for a DD.
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Old 03-19-2014, 09:35 PM   #20
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See I wish I would have got the Standard Trans but I ended up with an automatic. I wanted a 2 door (sorry old school that way) but it was impossible to find a sport S with a standard. I should have just spent the extra $$$ and get the Rubicon but oh well, hindsight is 20/20.
I have a buddy who can help me regear, he rebuilds old euro muscle cars but I hate to drop another 500 for a new set of ring and pinions. I may just wait a while and add a 2.5" lift for now and keep rolling the 31"x17. I guess i can switch out to Nitto to get more mud traction. I guess she is new so I will wait a year or so to blow her out and void my warranty

I still wish i had my old YJ and this would bee a moot point.
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Old 03-19-2014, 09:37 PM   #21
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@Derf, would you recommend the Bullydog over the Procal? I have a 2014 Sport.
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Old 03-19-2014, 09:40 PM   #22
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Quote:
Originally Posted by foxsat71 View Post
Sounds like 4.56 or 4.88 gears with 35" tires is ideal for a JKU with lift and armor; recommend programming computer for new gears just prior or immediately after re-gear to prevent tranny from going into limp mode with an auto trans. Thank you all for the insight on re-gearing my JKU.
Not recommend, it's a must. Jeep will go batsh!t if you don't put the correct gears into the ECU right away. Limp mode sucks rhino peepee.
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Old 03-19-2014, 10:22 PM   #23
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@Derf, would you recommend the Bullydog over the Procal? I have a 2014 Sport.
The Bullydog has been fine. I got one of the first ones shipped and I did a bit of a writeup here: Real world experience with the Bully Dog tuner in my 3.6

I like having the ability to run the economy tune which you don't get with a ProCal. But if you want to save the money and just tweak the gears and tire size, the ProCal is a great option.
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Old 03-19-2014, 10:27 PM   #24
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Thanks again everyone; I appreciate the help.
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Old 03-19-2014, 10:32 PM   #25
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Other than lack of power will 3.21 with 35 s cause any issues.
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Old 03-19-2014, 11:17 PM   #26
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It's a little harder on stuff but not much. Auto trany might heat up a bit more. It'll use a bit more gas.
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Old 03-19-2014, 11:17 PM   #27
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Other than lack of power will 3.21 with 35 s cause any issues.
A small amount more wear on the clutch or torque converter. That's it tho
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Old 03-20-2014, 12:04 AM   #28
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Other than lack of power will 3.21 with 35 s cause any issues.
You have to ride the clutch a lot more with a manual so it will wear out faster. But other than that, not much.
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Old 03-20-2014, 02:33 PM   #29
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2014 JKU 35's and 4:88's.....Love it!
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Old 03-20-2014, 09:42 PM   #30
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2014 JKU 35's and 4:88's.....Love it!
What tranny?

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