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-   -   3.73 or 4.11 (http://www.wranglerforum.com/f274/3-73-or-4-11-a-124718.html)

DADavis03 11-27-2011 10:51 AM

3.73 or 4.11
 
I am having a hard time calculating what my RPMs would be with 3.73 or 4.11 gears. I currently have 3.21 gears, 0.84 final manual trans gear, 33" tires on 17" rims. Any insight or information will be greatly appreciated because all of the charts I have looked at have been for 1:1 final trans ratio. Of course I could be making this way harder than it should...........would not surprise me. Below is my best "guesstimate".


3.73 gears @ 2243rpm
4.11 gears @ 2472rpm

kjeeper10 11-27-2011 11:22 AM

Always go with the higher numerical lower GR.

Especially when deciding between 3.73-4.10.
There's not going to be much of a difference and since going with/have 33's 4.10's will only benefit.
$1500 is a lot to spend twice. You might even want to go lower depending on engine/tranny/use.

Just my .02

panthermark 11-27-2011 12:49 PM

Gear Ratio Calculator

You will have to input you gears manually.

kbwwolf 11-27-2011 01:16 PM

Quote:

Originally Posted by DADavis03 (Post 1775841)
I am having a hard time calculating what my RPMs would be with 3.73 or 4.11 gears. I currently have 3.21 gears, 0.84 final manual trans gear, 33" tires on 17" rims. Any insight or information will be greatly appreciated because all of the charts I have looked at have been for 1:1 final trans ratio. Of course I could be making this way harder than it should...........would not surprise me. Below is my best "guesstimate".


3.73 gears @ 2243rpm
4.11 gears @ 2472rpm

Plug these #'s into the gear ratio calculator that Panthermark gave you:

Plug-In values for gear calculator (for 2012 manual):
For #1 - your ratios are:
1) 4.46
2) 2.61
3) 1.72
4)1.25
5) 1.00
6) 0.797

For #2
High = 1
Low = 2.72

For #3
Ignore

For #4
I'm assuming 3.73....or 3.21....or put in what you want to play with.

For #5
Put in your tire size.


kbwwolf 11-27-2011 01:21 PM

You might also find this helpful. See post #42:

Gear Ratio & Tire Size Chart - Page 5

DADavis03 11-28-2011 06:41 PM

Wow
 
Quote:

Originally Posted by kbwwolf (Post 1776183)
Plug these #'s into the gear ratio calculator that Panthermark gave you:

Plug-In values for gear calculator (for 2012 manual):
For #1 - your ratios are:
1) 4.46
2) 2.61
3) 1.72
4)1.25
5) 1.00
6) 0.797

For #2
High = 1
Low = 2.72

For #3
Ignore

For #4
I'm assuming 3.73....or 3.21....or put in what you want to play with.

For #5
Put in your tire size.

Thank you for such a detailed response, it is appreciated and I used these specs.

kbwwolf 11-28-2011 06:43 PM

:thumb:

Believe I actually got them from Panthermark, originally. But we all share.

MTH 11-28-2011 06:46 PM

You want the 4.10s. Always.

There are some folks who have complicated explanations as to why they selected 3.73s, and I don't begrudge them their choice. They're an adamant group and their jeeps all of course run just fine (heck, I have a 2010 with 3.21 gears). But no explanation I've ever seen from them really made any sense.

Take a look at a dyno chart showing the hp curve of the 2012 Wrangler engine. HP continues to increase way, way up into the RPM band. Redline isn't until some ungodly high number you'll never hit with any kind of factory gearing. The difference in gas mileage from 3.73 to 4.10 is utterly miniscule, and in any event choosing Wrangler features based on mpg numbers is like trying to keep your cholesterol down by choosing KFC for dinner every night.

You want the 4.10s.

kbwwolf 11-28-2011 06:53 PM

Good point. I gave you a bunch of #'s to plug into the gear ratio calculator, at the expense of the original question.

4.10's would be my choice, as well.

DADavis03 11-28-2011 06:55 PM

Quote:

Originally Posted by kbwwolf (Post 1776195)
You might also find this helpful. See post #42:

Gear Ratio & Tire Size Chart - Page 5

I came up with my numbers and you are correct 4.11's are the way to go especially taking into account the increased rpm range of 2012. I have attached my comparison with my inputs, if you see anything that is incorrect with my numbers please let me know and thank you for your time and knowledge.

3.21 with 32.71" tires
54mph @ 1500rpm
81mph @ 2250rpm
90mph @ 2500rpm

3.73 with 32.71" tires
47mph @ 1500rpm
62mph @ 2000rpm
78mph @ 2500rpm

4.11 with 32.71" tires
42mph @ 1500rpm
56mph @ 2000rpm
70mph @ 2500rpm

4.11 with 34.36" tires
44mph @ 1500rpm
59mph @ 2000rpm
74mph @ 2500rpm

kbwwolf 11-28-2011 07:36 PM

Are you sticking with your 33's, or planning to go up to 35's?

bo9roadking 11-29-2011 08:15 AM

When I bought my 2012 with the auto, I had the choice between 3.73 and 4.10. I chose 4.10. Running the stock 32" tires with the 4.10 gears was not a problem. I didn't feel like I was over revving at hwy speeds and there was plenty of acceleration. With 33" tires, 4.10 would put you right in the middle of the peak torque curve that is in the 2200-2500 rpm range.

I'm running 35" tires now with the 4.10 gears and I still think the gears are good. At 70 mph, I'm running around 2250 rpms.

Here is a dyno chart of aFe's testing of their CAI and exhaust. It is the first chart that I've seen that shows the 2012 hp/tq at the wheels. You can see that the highest amount of torque is in the rpm range that you would be running on the hwy.

http://cdn.wranglerforum.com/attachm...0&d=1322316566

DADavis03 11-30-2011 06:01 PM

Quote:

Originally Posted by kbwwolf (Post 1780230)
Are you sticking with your 33's, or planning to go up to 35's?

I will be staying with my 33's because this is my DD/grocery getter and my 3 sons are all still under the age of 8 and not quite the climbers yet.


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