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Unread 10-24-2013, 05:17 AM   #1
Zrider1967
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How unhappy would I be with 3.21 axle ratio?

I've been going back and forth between getting a Wrangler sport and modifying it my self or getting a Rubicon X. A couple days ago I settled in the Rubi, but yesterday I found a 2013 sport S with just over 1000 miles (yes... 1k!) for $25k. It's got all the bells and whistles I would get on a new one, except the 3.73 axle. If I do go with the sport instead of the Rubi, I plan on putting a 2.5" lift and 35" tires on it. According to a chart I found on this forum, that is right at the limit of tire size for the 3.21 axle (1720 rpm @ 70 mph). Will I be happy with that? It will be 90% street, but not a daily driver. Any offroading that I do will be mud, dirt trails, and some sand (not much rock crawling here in central Illinois...). What are everyone's thoughts?

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Unread 10-24-2013, 05:23 AM   #2
bhoch
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I have the 3.73 gears in my '12 JK sport. I have 33's (well, 305/70/16.. so sort of 33's) and a 2.5" RK lift. I would not be happy with 3.21 gears. I'm boarder line happy with the 3.73 and have 4.56 gears (and 35's) on my short list of next years mods. Mine is an auto, and not sure if you are looking at manual or auto. It's also my DD.
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Unread 10-24-2013, 05:24 AM   #3
SLADE
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I wouldn't consider owning one with 3.21's and stock tires. Unless you are planning on regearing, don't get one with 3.21's.
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Unread 10-24-2013, 05:27 AM   #4
14Sport
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Quote:
Originally Posted by SLADE View Post
I wouldn't consider owning one with 3.21's and stock tires. Unless you are planning on regearing, don't get one with 3.21's.
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Unread 10-24-2013, 06:02 AM   #5
metaldemon7
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I have the 3.21 gears with Rubicon take offs. It works well that way. I can use Sixth gear on the my way to work at 50-55 here in PA. I am getting a built Dana 30 with gussets, CV axles, and C-bracing. Right now it has 5.13 in it, because the friend I am getting it from has 37" tires & an Automatic 3.8 Liter. I will regear it, and the 44 in the back with 4.56's when I move up to 35" tires. I will do it myself, because I can borrow the Dana tools I need.
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Unread 10-24-2013, 10:14 AM   #6
bbbradley
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If the 3.21 gears are so bad, why are they still offered as the standard gear set on many Wrangler models?
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Unread 10-24-2013, 10:42 AM   #7
Yendor
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They do 3.21s for fuel mileage, with the "31" and "32" inch tires, that are really 30, and 31".

Even with the stock sport s 17 inch wheels and tires the 3.21 sucks. I'd really be hating it with tires any bigger.
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Unread 10-24-2013, 11:09 AM   #8
quadna71
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The 3.21 gears are fine on our automatic 2013 Sahara - getting between 21 and 22mpg on the highway with cruise around 70mph. We do plan on lifting and putting on bigger tires though so see 4.56 gears in our future. To summarize - 3.21 is fine for stock tires but any increase in tire size will warrant deeper gears to keep you happy.
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Unread 10-24-2013, 11:15 AM   #9
SLADE
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Quote:
Originally Posted by bbbradley View Post
If the 3.21 gears are so bad, why are they still offered as the standard gear set on many Wrangler models?

Because of the way MPG ratings are calculated and the fact that most people don't know any better.
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Unread 10-24-2013, 11:23 AM   #10
Bringbackmikey
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Where's this chart? I gotta figure out what gears are on mine and thinking of lifting/bigger tires.
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Unread 10-24-2013, 11:27 AM   #11
SLADE
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Quote:
Originally Posted by quadna71 View Post
To summarize - 3.21 is fine for stock tires but any increase in tire size will warrant deeper gears to keep you happy.

Not for everyone in all locations. 3.21's may be OK for flat landers on the highway, but I wouldn't consider buying one without 3.73's.
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Unread 10-24-2013, 11:29 AM   #12
SLADE
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Quote:
Originally Posted by Bringbackmikey View Post
Where's this chart? I gotta figure out what gears are on mine and thinking of lifting/bigger tires.

Keep in mind, that this chart only calculates RPMs at 70MPH. There are many factors left out.


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Unread 10-24-2013, 11:48 AM   #13
invest2m4
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I have a light 2013 2 door with 35's and 3.73. It sucks. I only use 6th gear on flat road and above 70. The engine just doesn't have the power at the lower rpm to pull larger tires. I run around 2000 rpm at 70 and it's no good. A rubi with 4.10's would be perfect though!

I guess if you have an auto it is less of an issue. It just won't use overdrive. When I get into hilly areas on the highway, I have to get my rowing skills on.

Final comment, 3.21 + standard transfer case + 35's = worthless off road for anything above mild. I'm swapping to a Rubi case next weekend. Although, I'd recommend that regardless of the gears.
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Unread 10-24-2013, 11:52 AM   #14
Godholio
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With 35s you're probably going to want to regear anyway, so the only factor in 3.21 vs 3.73 is that the 3.21 front differential is different and requires more money to regear.
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Unread 10-24-2013, 11:52 AM   #15
panthermark
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It all depends on where you live and how you use the vehicle.

If you are going to stay on stock wheels, have a 2 door, and live some place fairly flat, 3.21's are fine on the +2012 auto's.
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