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Old 08-04-2012, 04:33 AM   #1
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Gear ratio 3.21, what to do

I recently bought a 2012, wrangler, unlimited, altitude, automatic, with a 3.21 gear ratio, didn't do my homework. I plan on putting a 4" lift with wheels and 35" tires. Can I live with the 3.21 a while with the 35's or will it be unbearable, undrivable? Can I pull my boat with 3.21 gears and 35's? Should I re gear to 4.10 or 4.56 for mainly on-road use, boat pulling, light off-road, no rock crawling? What all will I have to change to go from a 3.21 to a 4.10 or 4.56? Just registered with wrangler forum today. Look forward to it

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Old 08-04-2012, 12:29 PM   #2
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You will hate it after you put the 35's on it. I put 33's on my 12' w/3.21 and it seriously lost alot of the off the line power. Youd better plan on regearing for towing w 35's. btw welcome to the fourm, use the search function and no matter what question you have it has no doubt been asked/answered 100 times before! lol

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Old 08-04-2012, 12:33 PM   #3
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Ive heard several people say that with the 3.21's, 33s-35's and the AEV procal the 3.21's are very liveable with the AUTOMATIC trans...with the manual not so much. If you have 3.21's you will have to get diffs for 3.73 and lower and lower...i call them diff's some call them carriers. I myself wouldnt reccomend pulling wiht htose gears and 3's if you have any sort of inclines to do.
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Old 08-04-2012, 01:04 PM   #4
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if I regeared I was thinking about 4.10 or 4.56 sound right for what i am doing
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Old 08-04-2012, 03:00 PM   #5
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I just put on a 3" lift with 305/70/17s with 3.21s. (33.9"). Returned 35" Toyos prior to install after doing what you just did- joining here and realizing I had a problem. It is live able with what I have, but with the AC on its a dog. But very drive able otherwise. Can't help but think that 35s would push me over the edge. Absolutely no way you're towing with 3.21s and 35s. I've yet to come across someone with a manual who hasn't lost 6th gear. I won't do 35s without a trip to my local gear shop. There are people who are perfectly fine with this combo- its not all doom and gloom, but for towing......
Search "3.21" on the forum search function and "gear chart." tons of threads. The gear chart lists exactly where you'll be. Kind of up to you to decide between gears. Personally I am fine with higher revs; I'll be going with 4.56s. 4.10s are probably the safest bet.
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Old 08-04-2012, 03:20 PM   #6
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There's a really cheap set of factory 3.73s front/rear for sale in the classified section right now. Just sayin'..
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Old 08-04-2012, 03:31 PM   #7
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Good point. You can also randomly find them on craigslist. Not sure this is something I'd buy used. Of course I have a few people to call today....
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Old 08-04-2012, 03:41 PM   #8
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Quote:
Originally Posted by WXman
There's a really cheap set of factory 3.73s front/rear for sale in the classified section right now. Just sayin'..
Ya... But if I were to pay the labor to install gears 3.73's would not be the answer
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Old 08-04-2012, 03:54 PM   #9
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Quote:
Originally Posted by WILLIAMHALE1 View Post
I recently bought a 2012, wrangler, unlimited, altitude, automatic, with a 3.21 gear ratio, didn't do my homework. I plan on putting a 4" lift with wheels and 35" tires. Can I live with the 3.21 a while with the 35's or will it be unbearable, undrivable? Can I pull my boat with 3.21 gears and 35's? Should I re gear to 4.10 or 4.56 for mainly on-road use, boat pulling, light off-road, no rock crawling? What all will I have to change to go from a 3.21 to a 4.10 or 4.56? Just registered with wrangler forum today. Look forward to it

Since your main uses are light offroad and pulling a boat...why go 35s with a lift? Looks?

Jack up both rear tires. Put in neutral. Count driveshaft revolutions for one tire revolution when rotating driveshaft by hand. Less than 3.5 = 3.21. More than 3.5 = 3.73.
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Old 08-04-2012, 03:58 PM   #10
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Ya... But if I were to pay the labor to install gears 3.73's would not be the answer
It would be a few hundred less than paying for NEW 4.XXs plus labor. It might be a great option for a lot of people who don't plan on 37" tires.
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Old 08-04-2012, 06:23 PM   #11
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I'd drive it first and then decide- you can't ever go back, but you can always go forward!

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Old 08-04-2012, 06:44 PM   #12
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Originally Posted by WXman
There's a really cheap set of factory 3.73s front/rear for sale in the classified section right now. Just sayin'..
For a daily driver and 33s this is a great gear. If you plan on 35s I would go 4.10s. A hardcare off-road person would want 4.56s with 35s. IMHO
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Old 08-04-2012, 07:45 PM   #13
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I don't know if this will help you or not, but I have 33's and 4.56 gears on a 2009 and on the interstate at 80mph I get 10mpg. I went with 33's because they would be easier on my drivetrain and I only do light wheeling. If I could do it over, I'd go with 4:10's,
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Old 08-04-2012, 09:16 PM   #14
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regear

hi, i have seen in 4 wheel magazine 4.11 gears for about $495 for a set of
front and rear, then the fun starts when you go to install, i am sure you can find
a shop that can install for you, shop around or google in ur area. all the best
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Old 08-06-2012, 02:06 PM   #15
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Originally Posted by Flingit1200s View Post
I don't know if this will help you or not, but I have 33's and 4.56 gears on a 2009 and on the interstate at 80mph I get 10mpg. I went with 33's because they would be easier on my drivetrain and I only do light wheeling. If I could do it over, I'd go with 4:10's,

2012's are a totally different animal...with the new engine and auto trans gearing.
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Old 08-06-2012, 02:25 PM   #16
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I have 2012, 3.21 and 35's (Automatic transmission) and it is fine. It's not going to break any land speed records, but for daily driving it's fine. I have no problem getting up to speed on an interstate on-ramp, and maintaining highway driving speeds. If I had to guess, I'd put the 0 - 60 in the 8 - 9 second range (haven't timed it), which is a very average acceleration speed.
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Old 08-06-2012, 02:39 PM   #17
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I don't know why the "Email This Thread" option isn't coming up but someone posted this yesterday on a towing thread:
Well, I tow an 18' Trophy fishing boat with mine, it weights in at 3500. I'm not sure why everyone here thinks that the 3.21 is so awful. I have a 2012 JKU Sahara with 3.21, 33" tires and I have no problems pulling or stopping with my Jeep. I can go 70 MPH no problem. I will clarify that the trailer has brakes. I've had boats all my life and I have towed with other vehicles and to tell you the truth, it feels the same. Just know that you are not going drag racing when pulling a trailer.

To me, people that preach on higher gears as being an absolute necessity are probably repeating what everyone else says here. It's not that bad. I'm not saying higher gears don't have their benefits I'm saying chill a little bit. Don't knock it till you try it.

It's like boats. People will say if it ain't a Boston Whaler or Grady White it's got to be a piece of shit boat. Really?

If I didn't mind the extra fuel usage and my engine screaming on the highway while cruising at 70, I would have gotten higher gears. For now I'm happy with my 3.21 doing a comfortably 2000 RPM at 70 while getting 21MPG highway (not towing). Just a thought.


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Was from "Muddernuker".

But notice he has 33s.
As someone kind of said above- why not a 2.5" lift & 33" MTs? Based on the above post you should avoid gearing issues and possible drive-shaft issues seen on 4" lifts. You'll get extra lift and can still add a MT 33" tire. If you're not planning on taking it off-road you'll spend a lot more money for a 4" lift/35s and the extra clearance won't do you much (practical) good. It will look good though.
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Old 08-07-2012, 07:05 AM   #18
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Thanks for sending that to me. good info. But Ive already have my mind made up on the 35 nitto mud grappler with 20 Fuel Throttles, I know what your going to say about the 20" but I like the look, Ill get them dirty dont worry. When I say light offroad i mean I will be running old, rutted, logging trails and good hills, and some mud, no rock crawling or 4' deep mud holes. After researching everything I am going to change differentials anyway to a Detroit trutrac, limited slip,front and back. I don't like the idea of having 4 wheel drive that's not 4 wheel drive. It sounds like to me from what you sent 4.56 will be to low of a gear. 4.10 or is it 4.11 will be what I need. O.k. Ive heard conflicting story's about the lift. I heard you need a 4" lift to run 35's then I seen one that said it had a 2.5" lift.
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Old 08-07-2012, 09:00 AM   #19
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I have 2012 Unlimited Sport with 35" and currently undergoing 2.5 Max Rock Krawler lift. I have no complains as far the power goes. My MPG on highway (400 miles +) was 17.1 MPG. NYC traffic i got 13.1 MPG and on average i do see around 15.5 MPG.

I was thinking too to re-gear but purely for better MPG if possible but getting different reviews and posts. Again, as the power goes, I have no issues there. Even my brother in law when he drove my jeep he said that its accelerating better thank his 2011 Toyota 4 runner (the most expensive trim available).
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Old 08-07-2012, 09:42 AM   #20
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do you have 3.21 and i guess 35's will fit under a 2.5 lift
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Old 08-07-2012, 09:44 AM   #21
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i just seen a post with a 2012 unlimited, 4 door,, w/4.10 gears,35's, he said he was getting 18-20 on the highway still
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Old 08-07-2012, 12:20 PM   #22
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You can fit 35s on most 2.5" lifts. The manufacturer of your lift can tell you. (There is a "lift review" thread if that helps). You may get some occasional rubbing under heavy flex. You can always trim your fenders a little. I have a 3" lift and 35s would be no problem.
Enjoy and welcome to the forum.
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Old 08-17-2012, 10:33 PM   #23
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I have a 2012 Rubicon 2DR with 4.11 and manual transmission. Added 4" Rubicon Express lift, CV Drive shafts, and 35"X17"X12.5 Toyo's, bumpers, winch, and rock rails. I am in Ouray, CO as we speak for a first time out, and this thing will not pull itself over a small hump in 2 or 4 Hi. I killed the engine 4 times trying to get up a small hump in a dirt road. Had to put it in 4 Lo to get it moving. It maybe because it is a manual, but with 35's, and 4.11 is basically a dog. I think I will have to change to either 4.88 or 5.13 gears to do anything off road except for 4 LO, and it should then be good for rock crawling.
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Old 08-18-2012, 09:39 AM   #24
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Quick reference gear chart (courtesy of member XJ Knight). As I understand it, you should look to be in the "green" section.Click image for larger version

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