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Discussion Starter · #1 ·
So I am looking to regear from the 3.21 stock that I have, and would like to know what everyone went to, if you had 3.21's or even 3.73s.

I am bit confused on what gear set to buy, but I am looking at either 4.10s or 4.56s....if you have other opinions, let me know.

I drive mostly highway, and would like to maintain some sort of gas mileage (I know, I know, its a jeep), but I see the regear as drastically reducing that.

Can you all give input on the gearing you went to, and why, and what set up you have to give me an idea of what I could be seeing?

I have a 2014 Sport, 3.21 gears, 315 DTs, and a leveling kit.

I would love to do the regear myself, using a friends garage and lift. Between me, my father and my friend that has the garage, I dont see this being a problem.

Just need some real experience on what gear to choose and either steering me away or towards doing it myself. Also what specific brand you chose and what I would need for the 3.21 carrier if it make a difference.

Thanks!
 

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http://www.4ws.com/jeep-wrangler-jk-gear-and-install-kit-package-front-rear.html

Checkout this link for the gear package. You'll want to choose the master overhaul kit. Theres also a link at the bottom for the dana30 carrier.

As for gear choice, I'm in the same boat with my 08 manual trans between those two gear choices. For me, with the 3.8, the suggestions I've received were to go with 4.56 gears. I've read from others on the forums with the 3.6 that 4.10s seems fine with 35s. The 4.56 are about $100 cheaper than the 4.10s.

Hope that helps a little
 

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Don't do it in your garage. Pay a professional. In the first to say wrench on your jeep yourself, but a regear is a job for the pros.

I recently went from 3.21 to 4.56 and have been super happy so far, but I've got the 3.8l motor, so that doesn't help you out too much.
 

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You can do the regear yourself. But proper gear set-up is the most critical portion of the job (pinion depth, ring gear backlash...).

I've done many myself. On my first one (non-Jeep), that particular axle was a real ^#&@* to dial in backlash because of the design. So I took my sweet time until my patterns were spot-on.

If you do not have a LOT of patience and a LOT of time alotted to do this correctly, no matter what, then pay someone to do it for you.
 

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Don't do it in your garage. Pay a professional. In the first to say wrench on your jeep yourself, but a regear is a job for the pros.

I recently went from 3.21 to 4.56 and have been super happy so far, but I've got the 3.8l motor, so that doesn't help you out too much.
What size tires you running vacca? I'm running 33s
 

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I have a 2012 sport. So I have the same engine as you. I'm running 315/70R17 Duratracs. I have 4.56 gears. I'm also running a BullyDog tuner both to tell the computer about the gears and tires but I also run the Economy tune on the engine.

I routinely get 17.x MPG on the freeway. And that's with a stubby winch bumper, flat fenders, and a tire carrying rear bumper. So weight and aerodynamics are not my friend.

I have enough power in overdrive to get up mild hills without downshifting. But I'm not running the engine too high when cruising at 70-75.

If I had known I was going to be moving from the low flat lands to the high elevation mountains, I would have opted for 4.88's. I would like them better here.

As far as installing the gears, have a pro do it. The pinion crush sleeve is a bear if you don't have the right tools. And getting the right shims figured out is a painful process if you don't have the right tools and experience.
 

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OP, I have the same engine and tires but with 3.73s. With the 3.73s its not ideal but livable. I will be going to 4.88s since I do more city driving, but you will be fine with 4.56 and be happy with the decision. ** I would do 4.56 if I did more hwy driving.
 

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I have 33" dura tracks went from 3.21 to 4.10. 4.56 would have been wy too much for me. Highway driving with an automatic is fine now but runs much higher than I thought they'd be. I would have no problem running 34 or 35 inch tires with this setup. If you are looking for 35's or more than you'll want to consider the 4.56 but for 34 or 33 i would stick with the 4.10
 

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4.56s are the ideal gear ratio for your setup. Definitely pay a professional gear shop to get it done. Make sure they have lots of experience with JKs and warranty their work.
 

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Thanks vacca, makes me feel a little easier if i go with 4.56s
They changed the 6 speed when they changed engines. The overdrive with the 3.8 is different than the overdrive with the 3.6. With the 3.6 you get more reduction. the 2011 and older overdrive is 0.84:1. The 2012 and newer is 0.79:1.

In my 2012 with the 6 speed I get closer to 2500 RPM at 70. Maybe just a hair over. I have 4.56 gears and 315/70R17 Duratracs. The 2012+ automatic runs around 2650 RPM with the same combo at 70.
 

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Discussion Starter · #15 ·
Wow thanks for all the input guys....

I think that after reading the comments, a 4.56 May be the way to go, but I am still debating doing it myself or not. I can just save so much money if I do it vs the labor hours...

Any other success or failure stories from people that have done the install themselves?
 

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Wow thanks for all the input guys....

I think that after reading the comments, a 4.56 May be the way to go, but I am still debating doing it myself or not. I can just save so much money if I do it vs the labor hours...

Any other success or failure stories from people that have done the install themselves?
I did it myself with a guy in the Jeep club I was in at the time. He was a professional with the tools needed to do the job right and has done a bunch of gear installs. I was the extra set of hands giving him the assistance. He did the important parts.

He had a full machine shop so we were able to take the old bearings and machine them so they could be used as setup bearings. That's important on the pinion since the shims go between the head of the pinion and the pinion bearing. If you don't have setup bearings that are ever so slightly machined out, you have to press the bearing on and off every time you change the thickness of the shims. And pulling a bearing off with a puller has a good chance of damaging it. With the setup bearings, you can slide the bearing on and off by hand the 3-4 times you need to adjust the shim pack.

Setting up the rest of the shims wasn't excessively difficult since they are placed by hand between the case and the carrier bearing. No setup bearings needed. Once the shims are in place, you paint the marking compound on the gear, rotate the gears to make a pattern, look at it, figure out what adjustment needs to be made, make the adjustment, and try again. Checking the backlash is also needed and you need to have a good dial indicator to do that. It's not difficult but it's not a tool most people have lying around.

By far, the biggest issue was the crush sleeve on the pinion. It goes between the two pinion bearings and puts the right preload on the bearings so they run properly. It takes upwords of 300 foot pounds of torque or more on the pinion nut to crush the sleeve. We had a 3/4" drive ratchet with a 6 foot cheater bar on it. Even then, it took everything we had to get it to crush the sleeve to the point where the preload was right. I've heard of kits that replace the crush sleeve to make this part easier but I can't say if they're worth it or not.

Honestly, it's not outrageously difficult work. But if you don't have the tools and the experience, it's quite a bit more challenging. It's better to have someone who has done it before giving you a hand if it's your first time. Because if you don't get the gears set up right, they will fail prematurely and you'll have to go through the pain all over again.

You'll need a bearing press, a quality bearing puller that can pull bearings without damaging them, a dial indicator, and a very heavy duty set of sockets for the pinion crush sleeve. If you don't already have these tools, it's not hard to spend as much on buying them as you do paying for someone else to do the work.

Quite frankly, having a professional do it and give you a warranty on the work they do is just about always worth it. It's often preferable to do your own work to save money. But for a few things, gears especially, the extra money you spend paying someone else to do the work is very much worth it.

But if you really want to do the work yourself, it can be done.
 

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X2 on everything DERF said. I'd definitely lean on the "don't do it" side unless you have a good amount of mechanical experience and a fully stocked garage. Rotating tires or changing brake pads does not count. My husband is a gear head and we still had to buy a decent amount of stuff. Bearing press, bearing puller, backlash measure-er thingie. (There is a technical name). We made a diff. spreader. Crush sleeves are a NIGHTMARE. Let me put it this way (short version)- my rear axle got thrown into my truck and taken to the local shop It is a difficult, time consuming job that is incredibly important to get right. Probably one job I'd leave to the pros.
 

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Crazy question here, can the stock 4.10s out of the D44 front axle be put in the D30? I assume a different carrier would be needed...
 
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