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Modified JK Tech Tech related bulletin board forum regarding subjects such as suspension, tires & wheels, steering, bumpers, skid plates, drive train, cages, on-board air and other useful modifications that will help improve the performance and protection of your Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) on the trail.

PLEASE DO NOT START SHOW & TELL TYPE THREADS IN THIS FORUM

Help Needed........ GEARS.....

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Old Jul 5, 2014 | 10:40 AM
  #11  
nthinuf's Avatar
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From: Austin <--> Colorado Springs
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Originally Posted by H8MUD
Cannot find the Drivetrain Section. Do you have to be a registered user?
Stuck to the top of this modified area, not up on top of the forum. If the links 'still' haven't been fixed, just scroll down.

(open modified area, look at the first couple of threads at the top. It will be the one that says something like "sticky: MODIFIED TECH FAQS")

Last edited by nthinuf; Jul 5, 2014 at 10:46 AM.
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Old Jul 5, 2014 | 12:07 PM
  #12  
barnettd's Avatar
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Joined: May 2008
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From: Fort Myers, Florida
Default gearing

Originally Posted by Reber76
Trying to decide if I should switch out the gears on my 09 JK, drive about 60 miles a day to work. It is not sluggish with all the mods that I have done so far, but the mpg just keeps tanking, getting close to single digits on the highway. Also have a lot of gear searching. Any help would be greatly appreciated.
I have an 08 unlimited 6 speed with 32" Goodrich rugged terrain tires. I replaced the original 3.21s with 4.10 gearing and it really woke up. My recent Florida trip I averaged about 16.5 to 17 highway around 70 mph. I have not resumed my normal commute of 40 miles round trip but I expect it to be about the same.
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Old Jul 5, 2014 | 12:37 PM
  #13  
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From: Austin <--> Colorado Springs
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Originally Posted by barnettd
I have an 08 unlimited 6 speed .
Automatic transmission, his gearing needs are different than yours. 4.10's would be a complete waste of money.
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Old Jul 5, 2014 | 05:08 PM
  #14  
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From: Toronto, Ontario
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You need 5.13s with the 3.8 auto. I run them and they are perfect. I do a lot of hwy driving as well.

While crossing Colorado I wish I went with 5.38s but I doubt it would of helped too much with the altitude.
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Old Jul 5, 2014 | 07:27 PM
  #15  
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From: Auburn, WA
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Originally Posted by Joe_B
You need 5.13s with the 3.8 auto. I run them and they are perfect. I do a lot of hwy driving as well. While crossing Colorado I wish I went with 5.38s but I doubt it would of helped too much with the altitude.
X2 I just upgraded to 5.13's in my 08 Rubicon and it is the way to go. I am running 35's and get about 14mpg on average.
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