gear ratio for Rubicon - Page 3 - JeepForum.com

Reply
 
LinkBack Thread Tools
post #31 of 35 Old 09-14-2013, 09:24 AM
HOKIES2010
Registered User
2011 JK Wrangler 
 
Join Date: Jul 2010
Location: Pensacola
Posts: 1,902
I ran heavy 37s with 4.10s for acouple months down in flat FL. It was doable but not fun. I think 35s would doable as well but also not fun.

I run 5.13s now with the 37s. Pairs well with the manual and 3.8.

HOKIES2010 is offline  
Sponsored Links
Advertisement
 
post #32 of 35 Old 09-14-2013, 12:40 PM
HappyTrails
Registered Voter w/ID
 
HappyTrails's Avatar
2008 JK Wrangler 
 
Join Date: Nov 2008
Location: West Georgia
Posts: 2,899
Quote:
Originally Posted by HOKIES2010 View Post
I ran heavy 37s with 4.10s for acouple months down in flat FL. It was doable but not fun. I think 35s would doable as well but also not fun.

I run 5.13s now with the 37s. Pairs well with the manual and 3.8.
I remember running my 37's with 4.10's for a short while in the hills around NW Georgia. All I remember thinking was, "Thank God for the supercharger! This think would be absolutely unbearable." Then I put 5.38's in it and am back to being a happy camper.

2008 2-dr Rubicon, auto,
RK 2.5" Max Travel, Rancho 9000XL shocks, 37" Nittos, 5.38's, RR skids, Warn VR8000-S.
RIPP Gen 2 Stg 2 Supercharger.
Political Correctness offends me.
HappyTrails is offline  
post #33 of 35 Old 09-14-2013, 05:21 PM Thread Starter
jenniferjeep
Registered User
2010 JK Wrangler 
 
Join Date: Sep 2008
Location: Temecula
Posts: 310
So this got me thinking what does regearing to lower gears do to your gas milage? I would think that it is going to drop.
jenniferjeep is offline  
post #34 of 35 Old 09-14-2013, 06:14 PM
JIMBOX
Registered User
2008 JK Wrangler 
 
Join Date: Oct 2008
Location: NORCAL/NORNV
Posts: 7,212
If you regear to one of the better ratios (5.13/5.38) your gas mileage drops drastically---at first, because it's like you gotta engine transplant (almost), but

As soon as you get over the new toy, mileage gets better-

I was able to get high 18 mpg driving 60 mph and the avg mileage driving at 70 is 16.2 and towing 14.9-

However my JKUR weighs over 2-3/4 tons when ready for a trip-so the lighter and more economically driven can show great benefits in gas mileage--

This is only for 07 to 11 JK/JKUs--because you're putting the 3.8l v6 in its happy comfort zone-- 2200/2400 rpm--

Of course, everyones different and the tire size is instrumental in these figures-

JIMBO

Yellow Jeep No. 683
http://i294.photobucket.com/albums/m...10-snow027.jpg
--YA GOTTA HAVE CLASS--
JIMBOX is offline  
post #35 of 35 Old 09-14-2013, 06:59 PM
SLADE
Registered User
2004 TJ Wrangler 
 
Join Date: Jul 2010
Posts: 3,287
Quote:
Originally Posted by jenniferjeep View Post
So this got me thinking what does regearing to lower gears do to your gas milage? I would think that it is going to drop.


Not if you increase your tire size at the same time. Lower (numerically higher) gears can improve your fuel mileage when your running a tire that is too tall for your gear ratio. Larger tires make fewer revolution per mile so in turn it takes fewer revolution of the axle shaft to put the motor in it's RPM range for a given speed. The numerically higher gears also adds a mechanical advantage to help turn the taller and heavier tires.


Your average speed is also a factor on the fuel mileage for a given ratio. Most gear charts have are based on going around 70 MPH. If the average speed of your typical commute is only 45mph -60mph, you can run a numerically higher gear than the chart recommends and still maintain your fuel economy.

It has less to do with the number and more to do with matching the gear ratio, tire size, and speed to a given motors efficient RPM/power range.

2014 Wrangler JKU
2013 Wrangler JK
2004 Wrangler TJ on LEAFS
2001 Dodge Ram 2500
SLADE is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome