2012 3.73 vs 3.21 - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > JK Jeep Wrangler Forum > JK General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 07-26-2011, 12:03 PM   #1
Jeeper
 
Join Date: Jun 2011
Location: NY
Posts: 20
2012 3.73 vs 3.21

It seems everyone wants the 3.73 gearing over the 3.21 why?
What are the advantages of the 3.73 over the 3.21?
Are there any advantages of the 3.21 over the 3.73?

Im not sure what mine came with but maybe i should verify what im getting very shortly and change it before its too late depending on what everyone says

Thanks

__________________
2012 JKU Sahara
Auto ǀ 3.73 ǀ 430N ǀ Connectivity ǀ
Ordered 07/27 ǀ D1 08/02 ǀ KZ 08/11 ǀ 8/17 Here
Rosh77 is offline   Quote Quick Reply
Old 07-26-2011, 12:12 PM   #2
..shall not be infringed!

WF Supporting Member
 
Up Hill Bill's Avatar
 
Join Date: Jun 2011
Location: Up the hill, CA Northcoast
Posts: 4,284

__________________
2012 JKU Rubicon
Sahara Tan
Auto
3.73


Up Hill Bill
Up Hill Bill is offline   Quote Quick Reply
Old 07-26-2011, 12:13 PM   #3
Jeeper
 
Trunz150's Avatar
 
Join Date: Nov 2010
Location: NY, NY
Posts: 359
More low end power...thats all i know of they sh ould just do away with it
Trunz150 is offline   Quote Quick Reply
Old 07-26-2011, 12:14 PM   #4
Jeeper
 
Redjeepmormon's Avatar
 
Join Date: Oct 2010
Posts: 622
Is your jeep going to be mall terrain or all terrain? If it's the first one, it shouldn't really matter. Honestly go for the 3.73 you'll be happier
Redjeepmormon is offline   Quote Quick Reply
Old 07-26-2011, 12:20 PM   #5
The Bad Guy

WF Supporting Member
 
daggo66's Avatar
 
Join Date: May 2009
Location: NJ exile living in Baltimore
Posts: 22,066
Quote:
Originally Posted by Trunz150 View Post
More low end power...thats all i know of they sh ould just do away with it
You want to do away with more low end power?
__________________
Tom

"I've got two things in this world, my balls and my word and I don't break them for no one."
daggo66 is offline   Quote Quick Reply
Old 07-26-2011, 12:25 PM   #6
Jeeper
 
Trunz150's Avatar
 
Join Date: Nov 2010
Location: NY, NY
Posts: 359
Quote:
Originally Posted by daggo66 View Post
You want to do away with more low end power?

NOOOOOOOOOOOO SILLY DO AWAY WITH 3.21 SO EVERYONE HAS MORE LOW WEN POWER!!!
Trunz150 is offline   Quote Quick Reply
Old 07-26-2011, 12:25 PM   #7
..shall not be infringed!

WF Supporting Member
 
Up Hill Bill's Avatar
 
Join Date: Jun 2011
Location: Up the hill, CA Northcoast
Posts: 4,284
Quote:
Originally Posted by Rosh77 View Post
It seems everyone wants the 3.73 gearing over the 3.21 why?
What are the advantages of the 3.73 over the 3.21?
Are there any advantages of the 3.21 over the 3.73?

Im not sure what mine came with but maybe i should verify what im getting very shortly and change it before its too late depending on what everyone says

Thanks
Use this gear calculator to see for yourself:

Gear Ratio Calculator

Auto = Dodge NAG-1
Stick = NSG370
T'fr Case = 2.72 (or 4.00 - Rubicon only)

Enter your tire size:

Experiment with rear axle ratios....
__________________
2012 JKU Rubicon
Sahara Tan
Auto
3.73


Up Hill Bill
Up Hill Bill is offline   Quote Quick Reply
Old 07-26-2011, 12:28 PM   #8
MTH
Fun Killing Ninja
 
MTH's Avatar
 
Join Date: Oct 2010
Location: North Carolina
Posts: 8,542
The numerically higher the number, the higher your engine RPMs will be at a given speed.

Thus, 3.73 will spin more RPMs at 70 mph than 3.21 will at that same speed. Maybe around 200 RPMs more or so at highway speeds.

The result is that 3.73 will produce more power at your wheels for that same speed than will 3.21. However, because you are revving a little higher, your gas mileage (in theory) will be slightly lower.

Relatedly, if you ever get bigger tires, you will want numerically higher gear numbers to help turn them.

In short, if you can get 3.73s, get them. The Rubicon offers the option of 4.10, but you've ordered a Sahara so that's immaterial to you.
__________________
Mike
2010 JKU "Mountain" Edition
TeraFlex 2.5" Coil Lift : Old Man Emu Nitrocharger Shocks : 33x12.5R15 Goodyear DuraTracs : 15x8 Black Rock 909s : Other Stuff . . .
MTH is offline   Quote Quick Reply
Old 07-26-2011, 12:49 PM   #9
Jeeper
 
Stallion289TX's Avatar
 
Join Date: Jul 2011
Location: Richmond, TX
Posts: 236
Quote:
Originally Posted by Rosh77 View Post
It seems everyone wants the 3.73 gearing over the 3.21 why?
What are the advantages of the 3.73 over the 3.21?
Are there any advantages of the 3.21 over the 3.73?

Im not sure what mine came with but maybe i should verify what im getting very shortly and change it before its too late depending on what everyone says

Thanks
I did not know much about gearing few weeks ago but I have learned a lot from the experts on this website and I have done extensive research on Axel gearing (Trust me, I went back and forth 5 times between 3.73 and 4.10). Please keep in mind that (the higher the number, the lower the gearing - for instance, 3.73 is lower than 3.21)

a) 3.21: Axel gear will have to turn 3.21 times in order for your wheels to complete 'one' revolution - obviously less gear turn will be accompanied with less engine rpm which in turns consumes less energy.

b) 3.73: Axel gear will have to turn 3.73 times in order for your wheels to complete 'one' revolution - since it turns more than 3.21, it will make more torque available for each 'one' wheel revolution. The lower the gear, the higher your rpm will be which in turns will consume more energy (fuel).

Please keep in mind that, if your driving habits require constant passing power, I would go with the lower gearing because with the 3.21, you will end up causing the gear to shift-down more frequently in order to support your passing habits. You will also appreciate the lower gearing when towing and driving up hills. I took the 2011 Cherokee for a long test drive and I thought that it would have been almost perfect with lower gearing (it only had 3.07). I initially was going for the 3.73 but I realized that the mpg is not great to begin with and that losing 1 - 1.5 mpg on highway with 4.10 won't make be poorer (I mean, you can't say 'oh, if I had went with higher gearing, I could have made it to the next exit!). Again, the whole mpg thing will vary based on how you drive your Wrangler. I won't tell you which gear to go with because; like 'Up Hill Bill' says 'It is your Jeep.'
__________________
2012 Jeep Wrangler Rubicon
Tan All Over - Auto - 4.10's
Ordered: 7/19
Delivered: 9/16
Mods: Quadratec Floor Liners (I really can't think of any mods that the Rubi needs)
Stallion289TX is offline   Quote Quick Reply
Old 07-26-2011, 12:55 PM   #10
Ex Navy man
 
rics1997's Avatar
 
Join Date: Oct 2010
Location: Bristol, Tn
Posts: 4,767
You will regret 3.21. Not sure why Jeep even uses them especially in the JKU. If all you plan to do is drive to the mall and own it for looks, then 3.21 is alright until you try passing someone.
__________________
2010 Dark Charcoal Pearl Jeep Wrangler Sport S Automatic
4.88 Yukon w/Trac-Lok rear and Eaton ELocker Front - Synergy Gussets - B&M 70264 Trans Cooler
BDS 3" lift - BDS Fox 2.0 Racing Shocks
XHD front Bumper - Trektop NX - Goodyear MT/R w/Kevlar 35X12.5X15 on MB Chaos 5 Wheels - Thrush Turbo Muffler

Become a WranglerForum Supporting Member!
rics1997 is offline   Quote Quick Reply
Old 07-26-2011, 12:59 PM   #11
MallCrawler

WF Supporting Member
::WF Moderator::
 
kjeeper10's Avatar
 
Join Date: Feb 2011
Location: Connecticut
Posts: 33,866
Quote:
Originally Posted by Up Hill Bill
__________________
2007 Rubicon/Rock Krawler TR 2.5 coils/rear TB/Rancho 9000 31/32XL shocks/Teraflex monster TB/Synergy highsteer,tie rod, ball joints/Hankook MT 315-75-16 on Level 8 ZX's/MC front SB links/Rancho geo brackets & shocks/Fox ATS stabilizer/Adams front DS/Artec front armor w/ Currie upper bushings=Frankinjeep from hell.

Lifting your JK? Read this!!



Click HERE to become a WranglerForum Supporting Member!
kjeeper10 is online now   Quote Quick Reply
Old 07-26-2011, 01:11 PM   #12
Jeeper
 
IowaRaider's Avatar
 
Join Date: Jun 2011
Posts: 537
Quote:
Originally Posted by rics1997 View Post
You will regret 3.21. Not sure why Jeep even uses them especially in the JKU. If all you plan to do is drive to the mall and own it for looks, then 3.21 is alright until you try passing someone.
Probably would regret it but my guess is the 3.21 will do much better with the 3.6 and that's why the 3.73 is an option now with the tow package vs included with the 3.8.
But mostly I agree with Bill
__________________
2012 Wrangler Bright Silver Sport S 6 spd
IowaRaider is offline   Quote Quick Reply
Old 07-26-2011, 01:28 PM   #13
Jeeper
 
07XMan2Door's Avatar
 
Join Date: Nov 2010
Location: colorado
Posts: 1,680
Mine came stock with 3.21's. They worked just fine when I was on the freeway, in 6th gear, going downhill, will a horrific tailwind. Other than that they totally sucked & I did a re-gear immediatley. Runnin 5.13's with 35's & am lovin it!!

It's a jeep not a race care, lower gearing is your friend.
07XMan2Door is offline   Quote Quick Reply
Old 07-26-2011, 01:44 PM   #14
Moderator

WF Supporting Member
::WF Moderator::
 
jkjeeper06's Avatar
 
Join Date: Jul 2010
Posts: 3,403
I currently have 3.21 gears. I only have 31 inch tires but it is bogged down on power all the time. My clutch is wearing way too fast. It'll be gone by 40k I think it's because of the gears because I am easy on clutches(180k out of my last cars clutch) I'm gonna run 4.56 and 32 inch tires. It may be a bit overkill but I'll get more power and it'll be easier on the new clutch I'll have to get soon. In short look at the price. Get a quote on just getting a 4.10 or 4.56 gear swap and if it isn't much more than the 3.73 jeep, buy it with the 3.21 and switch them
jkjeeper06 is offline   Quote Quick Reply
Old 07-26-2011, 01:53 PM   #15
MallCrawler

WF Supporting Member
::WF Moderator::
 
kjeeper10's Avatar
 
Join Date: Feb 2011
Location: Connecticut
Posts: 33,866
Quote:
Originally Posted by 07XMan2Door
Mine came stock with 3.21's. They worked just fine when I was on the freeway, in 6th gear, going downhill, will a horrific tailwind. Other than that they totally sucked & I did a re-gear immediatley. Runnin 5.13's with 35's & am lovin it!!

It's a jeep not a race care, lower gearing is your friend.
Where u been?
__________________
2007 Rubicon/Rock Krawler TR 2.5 coils/rear TB/Rancho 9000 31/32XL shocks/Teraflex monster TB/Synergy highsteer,tie rod, ball joints/Hankook MT 315-75-16 on Level 8 ZX's/MC front SB links/Rancho geo brackets & shocks/Fox ATS stabilizer/Adams front DS/Artec front armor w/ Currie upper bushings=Frankinjeep from hell.

Lifting your JK? Read this!!



Click HERE to become a WranglerForum Supporting Member!
kjeeper10 is online now   Quote Quick Reply
Old 07-26-2011, 06:37 PM   #16
Official WF thread de-railer
 
Mr. Sinister's Avatar
 
Join Date: Jul 2010
Location: Fair Hill, Maryland
Posts: 3,702
Having seen the power curve of the Pentastar, it makes the bulk of it's power higher in the RPM band. That being the case, I'd go with the 3.73 at a minimum. Personally, I'd opt for the 4.10, or even do a set of 4.56 gears after purchase. I'd be willing to bet this engine will love some gear and you'd notice a big difference in usable power.
__________________
My battle with Chrysler over getting my Jeep repaired under warranty: http://www.wranglerforum.com/f33/ins...ml#post3467156
Mr. Sinister is offline   Quote Quick Reply
Old 07-26-2011, 06:47 PM   #17
Official WF thread de-railer
 
Mr. Sinister's Avatar
 
Join Date: Jul 2010
Location: Fair Hill, Maryland
Posts: 3,702
__________________
My battle with Chrysler over getting my Jeep repaired under warranty: http://www.wranglerforum.com/f33/ins...ml#post3467156
Mr. Sinister is offline   Quote Quick Reply
Old 07-26-2011, 06:48 PM   #18
Ex Navy man
 
rics1997's Avatar
 
Join Date: Oct 2010
Location: Bristol, Tn
Posts: 4,767
Quote:
Originally Posted by IowaRaider View Post
Probably would regret it but my guess is the 3.21 will do much better with the 3.6 and that's why the 3.73 is an option now with the tow package vs included with the 3.8.
But mostly I agree with Bill

The 3.6 makes most of it's power at higher RPM's. At the wheel it is only making about 5 more horse over the 3.8 at normal driving speeds looking at the Challenger dyno numbers. Again anyone getting 3.21's will regret them on a wrangler no matter what motor you get. That includes a Hemi.

I would rather get the 3.73 and wonder if 3.21 would have been enough then to get the 3.21 and regret it which I guarantee will happen. Shoot, I got 4.88 and regret not getting 5.13's
__________________
2010 Dark Charcoal Pearl Jeep Wrangler Sport S Automatic
4.88 Yukon w/Trac-Lok rear and Eaton ELocker Front - Synergy Gussets - B&M 70264 Trans Cooler
BDS 3" lift - BDS Fox 2.0 Racing Shocks
XHD front Bumper - Trektop NX - Goodyear MT/R w/Kevlar 35X12.5X15 on MB Chaos 5 Wheels - Thrush Turbo Muffler

Become a WranglerForum Supporting Member!
rics1997 is offline   Quote Quick Reply
Old 07-26-2011, 09:35 PM   #19
Jeeper
 
IowaRaider's Avatar
 
Join Date: Jun 2011
Posts: 537
Quote:
Originally Posted by rics1997 View Post
The 3.6 makes most of it's power at higher RPM's. At the wheel it is only making about 5 more horse over the 3.8 at normal driving speeds looking at the Challenger dyno numbers. Again anyone getting 3.21's will regret them on a wrangler no matter what motor you get. That includes a Hemi.

I would rather get the 3.73 and wonder if 3.21 would have been enough then to get the 3.21 and regret it which I guarantee will happen. Shoot, I got 4.88 and regret not getting 5.13's
I agree that's why I ordered the 3.73 on my 2012.
__________________
2012 Wrangler Bright Silver Sport S 6 spd
IowaRaider is offline   Quote Quick Reply
Old 07-27-2011, 12:36 AM   #20
Jeeper

WF Supporting Member
 
Join Date: Jun 2011
Location: Massachusetts
Posts: 118
I drove a friends with 3.21s and the 3.8. It was not responsive AT ALL.

Chris
Bloke is offline   Quote Quick Reply
Old 07-27-2011, 05:17 AM   #21
Jeeper
 
Join Date: May 2011
Posts: 2,216
3.21 is a dead rear, plan on lots of downshifting going up hills, passing, etc. Even a 3.55 would have been a better choice. After reading thousands of posts in the Jun 2 thread, I'm going to be certain my Rubi comes with a 4.10 rear when I pull the trigger.
demarpaint is online now   Quote Quick Reply
Old 07-27-2011, 08:47 AM   #22
Jeeper
 
Join Date: Jul 2011
Location: Broken Arrow, OK
Posts: 2,305
I think another benefit of the 3.73 would be that they come with the 3.73 and numerically higher carrier, so you won't have to change carriers for different gears later.

I can't think of a single valid and universal reason to have 3.21's in a Wrangler. There are only two things I can think of that even come close, but in practice are either invalid or inconsequential. The first is that numerically lower gears are more efficient than numerically higher gears. This is invalid in practice on the Wrangler because the wheels are downstream of the gears and they are so large that the lower gears lose more in mechanical advantage than they gain in efficiency. The second it temperature. Numerically higher gears usually run hotter than numerically lower gears. In some cases this can lead to reduced life or failure, but it has been proven that you can run much lower gears in the Wrangler without issue.
__________________
2012 Silver Sport S, Silver, 6 speed, soft top, 3.73s, LSD, PCG, Infiniti, deep tint windows, Pro Comp 1028 wheels, 33" Duratracs, Smittybilt bumpers and steps, KC fog lights, Mopar slush mats and fuel door.

Happiness is a belt fed weapon.
oilwell1415 is offline   Quote Quick Reply
Old 07-27-2011, 08:52 AM   #23
MTH
Fun Killing Ninja
 
MTH's Avatar
 
Join Date: Oct 2010
Location: North Carolina
Posts: 8,542
Quote:
Originally Posted by oilwell1415 View Post
I think another benefit of the 3.73 would be that they come with the 3.73 and numerically higher carrier, so you won't have to change carriers for different gears later.

I can't think of a single valid and universal reason to have 3.21's in a Wrangler. There are only two things I can think of that even come close, but in practice are either invalid or inconsequential. The first is that numerically lower gears are more efficient than numerically higher gears. This is invalid in practice on the Wrangler because the wheels are downstream of the gears and they are so large that the lower gears lose more in mechanical advantage than they gain in efficiency. The second it temperature. Numerically higher gears usually run hotter than numerically lower gears. In some cases this can lead to reduced life or failure, but it has been proven that you can run much lower gears in the Wrangler without issue.
^^This.

I have 3.21s in a 4 door. Thank the Lord I have a manual trans, so I can rev it to where it's useful. But still, I can't even ponder 33s without having to think of regearing, so that's kind of frustrating. I also need to downshift to 5th on most hills on the highway.
__________________
Mike
2010 JKU "Mountain" Edition
TeraFlex 2.5" Coil Lift : Old Man Emu Nitrocharger Shocks : 33x12.5R15 Goodyear DuraTracs : 15x8 Black Rock 909s : Other Stuff . . .
MTH is offline   Quote Quick Reply
Old 07-27-2011, 09:26 AM   #24
Jeeper
 
07XMan2Door's Avatar
 
Join Date: Nov 2010
Location: colorado
Posts: 1,680
Quote:
Originally Posted by kjeeper10 View Post
Where u been?
Been working & playing as equally as possible. How ya been Ken?? How's that nice Black Rubi??
07XMan2Door is offline   Quote Quick Reply
Old 07-28-2011, 11:27 AM   #25
Jeeper
 
Join Date: Jun 2011
Location: NY
Posts: 20
I found out it was the 3.73 i ordered. It wasnt on the build sheet but dealer confirmed thats what I would be getting.
__________________
2012 JKU Sahara
Auto ǀ 3.73 ǀ 430N ǀ Connectivity ǀ
Ordered 07/27 ǀ D1 08/02 ǀ KZ 08/11 ǀ 8/17 Here
Rosh77 is offline   Quote Quick Reply
Old 07-28-2011, 11:34 AM   #26
Jeeper

WF Supporting Member
 
JBall's Avatar
 
Join Date: Jul 2011
Location: Brisbane, CA
Posts: 82
Quote:
Originally Posted by Rosh77 View Post
I found out it was the 3.73 i ordered. It wasnt on the build sheet but dealer confirmed thats what I would be getting.
What is on the build sheet? If you want the 3.73 I'd make sure it is on the build sheet.
__________________
'12 Sport S, Bright White, 5-Speed Auto, 3.73 Rear Axle
JBall is offline   Quote Quick Reply
Old 07-28-2011, 12:48 PM   #27
Jeeper
 
Join Date: Jul 2011
Location: Richmond Va
Posts: 34
I have an 08 2 door and have the 3.73 gears and I'm getting over 20 mpg average since I bought it a couple weeks ago. I definitely wouldn't want any higher a gearing.
GOJEEP007 is offline   Quote Quick Reply
Old 07-28-2011, 02:55 PM   #28
..shall not be infringed!

WF Supporting Member
 
Up Hill Bill's Avatar
 
Join Date: Jun 2011
Location: Up the hill, CA Northcoast
Posts: 4,284
Quote:
Originally Posted by Rosh77 View Post
I found out it was the 3.73 i ordered. It wasnt on the build sheet but dealer confirmed thats what I would be getting.
Careful!

What does the build sheet say? If it says 3.21, that IS what you are getting. If it doesn't list a gear option, it isn't a build sheet!

Lots of people have had dealers confirm 3.73s but are getting 3.21s according to their build sheet. And, the build sheet IS what you will get.
__________________
2012 JKU Rubicon
Sahara Tan
Auto
3.73


Up Hill Bill
Up Hill Bill is offline   Quote Quick Reply
Old 07-28-2011, 10:04 PM   #29
Jeeper
 
JohnT11's Avatar
 
Join Date: Jul 2011
Location: Florida
Posts: 297
Quote:
Originally Posted by Up Hill Bill View Post
Careful!

What does the build sheet say? If it says 3.21, that IS what you are getting. If it doesn't list a gear option, it isn't a build sheet!

Lots of people have had dealers confirm 3.73s but are getting 3.21s according to their build sheet. And, the build sheet IS what you will get.
Exactly. The factory doesn't care that you should be getting 3.73s. It sees 3.21 on the build sheet and builds the vehicle according to that.
__________________
John
JohnT11 is offline   Quote Quick Reply
Old 07-29-2011, 06:25 AM   #30
Jeeper
 
JohnT11's Avatar
 
Join Date: Jul 2011
Location: Florida
Posts: 297
Milous just confirmed in the other thread that you do not automatically get 3.73's with the towing package this year. You have to specify them. Not sure why.

__________________
John
JohnT11 is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
2012 Wrangler information thread Milous JK General Discussion Forum 1605 07-17-2013 01:45 PM
2012 Wrangler Details ndrugby JK General Discussion Forum 64 07-17-2011 11:17 AM
3.21 vs 3.73 XNeoJesterX JK General Discussion Forum 1 04-26-2011 05:46 PM
3.21 vs 3.73 Axle Ratio..what's the difference? CF2010 JK General Discussion Forum 6 09-11-2010 02:39 AM
Looking for 3.73 Gears cremaley Classifieds Archive 2 08-03-2010 03:59 PM


logo carid shop wrangler parts carid fender flares custom wheels store avs deflectors at carid
» Rates
Get low rates on auto insurance in Canada!

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 10:43 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC