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Old 08-20-2013, 11:20 AM   #1
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gear ratio - 3.21 vs 3.73

looking for info on hows real world drivers that have put lifts and bigger tires on , comparing anyone who has the stock 3.21 compared to the 3.73. been driving pickups for 30 years but never had anything with 3.21 gears.. everything ive had either 3.73 or 4.10. with no issues.. looking to order with 3.73 or buy on the lot with 3.21s....dont want to kick myself later.......... thanks

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Old 08-20-2013, 11:29 AM   #2
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you're going to regret 3.21s especially if you're going to be putting 35s on. here's the thing. if you know you're going to build a rig... 3.21s are a way to save money.

if you have no plans to crack open the axle and build... then i'd recommend getting the 3.73s, cannot get the 4.1 unless you buy a rubi as i understand it

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Old 08-20-2013, 11:32 AM   #3
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3.73s. Unless you're concerned about the POSSIBILITY of losing .5 MPG then get 3.73s. People will say 3.21s are fine; and they are stock. But any tire size above 33s and you will have a performance change. At that point it becomes subjective as to whether or not it is enough to bother you. Why bother- get 3.73s. I began kicking myself from about the day I put on my lift and tires on over 3.21s.
http://www.wranglerforum.com/f33/3-2...st-209000.html
Even if you have to wait a little and pay more....do it. A re-gear is $1000-$1500. (3.73s aren't foolproof- people do still re-gear with 3.73s and larger tires too- just not as often.)
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Old 08-20-2013, 11:41 AM   #4
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If you are ordering, and you know you will put bigger wheels on.....get the 3.73's. Case closed.
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Old 08-20-2013, 11:44 AM   #5
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3.73 allows for a higher tow rating on the 4-door. So that alone makes it worth it to most and an added benefit for resale.
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Old 08-20-2013, 08:46 PM   #6
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I'm pretty green and don't know better so here I go...

I traded in a 2011 Challenger with the same Pentastar for a 2013 Sport, 6 speed, 3.23 gears and I've been very happy so far. I've stalled it out a few times (I've driven sticks on and off for 20 years) so I've learned to give it more gas when starting off (I wonder if it has anything to do with hill assist), but I enjoy the overall performance. Because I am a tight wad I LOVE 6th gear- even at 35 mph, just cruisin' along. I'm averaging a little over 23mph and have driven over 3,000 miles. It took me 42 years, but I am now a Jeeper.
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Old 08-20-2013, 11:50 PM   #7
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321's will put you below the power band with a 35, 3.73's are better. It would be like strapping a 39 on to your pickup geared at 4.10 and expecting it to move down the road if you get 3.21's in a jeep with 35's.
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Old 08-21-2013, 02:02 AM   #8
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i really wanted the 3.73 gears when i got my jeep. but none of the ones in my area had it. only way i could've gotten it was to order a jeep and have it built with the premium tow package. i found a jeep off the lot at a dealer in town that had all of the other features i wanted... minus the gear ratio. so it came down to, can i live without the 3.73 gears and go with the stock 3.21 gears?? with the price it was on the lot, i saved a couple grand as opposed to ordering one. so i figured to buy the one on the lot. and if i really really really want/need the 3.73 over the stock gear set, then a few years down the road ill either pay to have it re-geared or buy a new axle with the lower ratio. otherwise im happy with what i got.
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Old 08-21-2013, 06:00 AM   #9
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not really saving anything by buying on the lot , was worried that the v-6 did not have enough power with the 3.21 for bigger tires. getting a price to order the way i want today. thanks guys
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Old 08-21-2013, 06:09 AM   #10
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I had 3.21s and now have 3.73s. I've run 33s and 35s and much prefer the latter.
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Old 08-21-2013, 07:02 AM   #11
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Quote:
Originally Posted by ESP View Post
I had 3.21s and now have 3.73s. I've run 33s and 35s and much prefer the latter.
^^ there you have it!
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Old 08-21-2013, 07:25 AM   #12
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When you pull the trigger to change from 3.21 to 3.73 how did you do it? What I mean is did you do it yourself or take it to a dealer or local shop? I have been checking around and it looks like you need a bit of experience as well as tools to do that job right. I am in the same boat with 3.21's and want 35's sometime in the future. I am wondering where to go and how much do I expect to pay because I can't do this myself.
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Old 08-21-2013, 07:28 AM   #13
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Quote:
Originally Posted by Captain Ed View Post
When you pull the trigger to change from 3.21 to 3.73 how did you do it? What I mean is did you do it yourself or take it to a dealer or local shop? I have been checking around and it looks like you need a bit of experience as well as tools to do that job right. I am in the same boat with 3.21's and want 35's sometime in the future. I am wondering where to go and how much do I expect to pay because I can't do this myself.
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Old 08-21-2013, 07:46 AM   #14
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Quote:
Originally Posted by Captain Ed View Post
When you pull the trigger to change from 3.21 to 3.73 how did you do it? What I mean is did you do it yourself or take it to a dealer or local shop? I have been checking around and it looks like you need a bit of experience as well as tools to do that job right. I am in the same boat with 3.21's and want 35's sometime in the future. I am wondering where to go and how much do I expect to pay because I can't do this myself.
You shouldn't pay anyone to change your gears from 3.21 to 3.73 nor should you change your gears to this ratio. Depending on your set up and tranny, if you decide you want to upgrade your gears then go with 4.56 or 4.88s. Gear sets are around $1200-1500 for a shop to install. They should be handled by a professional whether that's you or a shop.

Quote:
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I had 3.21s and now have 3.73s. I've run 33s and 35s and much prefer the latter.
To clarify on my own post:

The 3.21s were with a 2010 and 3.8 engine with 33s, 35s
The 3.73s are with a 2013 and 3.6 engine with 33s.

You can drive on 35s with 3.21s. You may want to upgrade but you may not.
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Old 08-21-2013, 07:49 AM   #15
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well said sir!
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Old 08-21-2013, 08:15 AM   #16
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I have the 3.73 in my 2014 Sport along with LSD and I still get great mileage (as high as 23 hwy) and acceleration. I have no regrets.
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Old 08-21-2013, 10:04 AM   #17
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part of any gear discussion is objective. look at the chart for your motor and transmission type, that's the math part. charts are color coded to tell you what is optimal, what is ok and what is substandard based on math.

the other part of any gear discussion is highly subjective, and that's why people think it's confusing.

either way, regearing in the aftermarket (DIY or buddys or shop) is significantly more expensive than ordering a Jeep with the gear ratio you (subjective) think you will want or the gear ratio the math says is optimal (within reason, since factory gears only go down to 4.10:1)
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Old 08-21-2013, 10:10 AM   #18
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Love my 3.73

Quote:
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I have the 3.73 in my 2014 Sport along with LSD and I still get great mileage (as high as 23 hwy) and acceleration. I have no regrets.
Don't know what tires and wheels this guy is running, but even when my 2013 JKU was stock, on it's best day, going down a hill, I might be able to get 23mpg.
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Old 08-21-2013, 10:37 AM   #19
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Don't know what tires and wheels this guy is running, but even when my 2013 JKU was stock, on it's best day, going down a hill, I might be able to get 23mpg.
Its a stock 2 door Sport which gets a little better mileage that an unlimited
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Old 08-21-2013, 10:48 AM   #20
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I routinely average 20mpg with 33" duratracs and 3.73s, revs relatively low on the highway with lots of power... It's the perfect combination IMO
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Old 08-21-2013, 11:40 AM   #21
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Quote:
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Its a stock 2 door Sport which gets a little better mileage that an unlimited
Maybe but my 2 door Sport never got above 21 MPG- stock. Note he said he cruises at 35 in 6th gear....That must be what, 800 RPMs? LOL. This exemplifies why gearing is subjective- I'd curse Chrysler every time I dropped under 1100 RPMs with my 3.21s. There is a (coco)nut for every squirrel.
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Old 08-21-2013, 11:50 AM   #22
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The 3.6 hates to be lugged.

I get a significant itch on the bottom of my left foot at 2000 RPM, and still manage 18.9 MPG on long highway trips though.

I'm good with that :-)
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Old 08-21-2013, 12:20 PM   #23
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Might as well toss in my 0.02.

I run big 35's on my daily driver (Cooper STT's, measured out to 34.7) and I have a 6 speed manual and 3.21 gears in my 2013 Jeep.

Any power loss was MINOR. I went from the factory 28 inch tires to these, and didn't notice a thing. I put 100 miles on this thing a day, in the city, on the freeway, etc etc. It still has more power than my TJ with 4.10's and 31's
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Old 08-21-2013, 12:43 PM   #24
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I've got 410s and the stock 32" BFGs. I averaged over 20 mpg in the first 20,000 miles. Remember, the engine does't even get to full torque until about 2100 RPM and that is just over 60 with 410s. There's more to mileage than simply RPM.

Get the lower gears and quit lugging. The Pentastar has to rev a bit.

I don't see how you guys with 3.21 can pull any grade at all in 6th.
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Old 08-21-2013, 01:15 PM   #25
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Agreed, with 3.73s and 33's it still lugs bad in 6th on just about any grade... Can't imagine what 3.21s would be like
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Old 08-22-2013, 10:19 AM   #26
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12 JK with 35s and computer calibrated with 3.21s in a auto.

My drives great around town and on the highway. No complaints off the line or anytime for that matter. I even hauled a M416 from time to time with no problems.

I have driven a a 12 JK with 37s and 3.73s and it basically drove the same as mine maybe a touch more drag up hills but very livable.


I have been considering swapping 4.10s and locking the rear but no real reason other than curiosity.
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Old 08-22-2013, 10:23 AM   #27
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I test drove both, and the jeep with the 3.73 gears felt so much more powerful. This is a fun vehicle for me, so I went with the fun gears. I ordered the 3.73 gears and haven't looked back.

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Old 08-22-2013, 11:19 AM   #28
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6 speed and 3.73 here. I know I couldn't live the the 3.21 gears with the current transmission ratios. 1st gear may be a bit too tall of a ratio getting off the line, though this is very subjective. The 3.73 is perfect on the highway cruising at 75MPH. I wouldn't want a taller ratio in 6th or that gear would be pointless (IMO).
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Old 08-22-2013, 11:53 AM   #29
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I've got 33's with 3.21 gears and I don't mind it so much where I live (mostly flat). The Jeep does lug pretty bad anywhere south of 1500RPM in any gear, but it did that with the stock 32's too.

6th is useless on any grade however. But again, it was also useless with the stock 32's.

All in all, I haven't really noticed that much of a power loss except for in first gear taking off from the line. I need to rev it a bit higher to compensate, but its a very minor difference.
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Old 08-22-2013, 03:02 PM   #30
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I am running 3.73 and 35's. Jeep runs awesome, getting 18.9 mpg and performace is great. I did use a programer but I am really happy with it....

Go 3.73 without a doubt.

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