Gearing Question For Automatic
04-09-2008, 08:15 AM
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JK Newbie
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Gearing Question For Automatic
I have an Unlimited X (automatic) and plan on running 35's. It's a daily driver and will see moderate trail use. I will also be taking several 10 hour roadtrips per year. Any good ideas about what will work better 4.88's or 5.13's??
Any help or insight will be greatly appreciated.
2008 Black X Unlimited
Future Plans: 2.5 Teraflex, 35x12.5x17 BFG M/T's, 4.88 or 5.13 Gears and lots of underbody armor!!
Any help or insight will be greatly appreciated.
2008 Black X Unlimited
Future Plans: 2.5 Teraflex, 35x12.5x17 BFG M/T's, 4.88 or 5.13 Gears and lots of underbody armor!!
04-09-2008, 08:24 AM
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JK Junkie
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04-09-2008, 08:30 AM
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True. However, an automatic X with 4.1 axle ratio's are better than you may think. it would still need better gears for the 35s.
For my automatic 2007 X:
Crawl ratio = 1st gear X t-case X diff X 2
Crawl Ratio = 2.84 x 2.72 x 4.1 x 2
Crawl ratio = 63.34:1
Manual:
Crawl = 4.34 x 2.72 X 3.21
Crawl = 37.89 (or 48.4 with optional 4.1)
For my automatic 2007 X:
Crawl ratio = 1st gear X t-case X diff X 2
Crawl Ratio = 2.84 x 2.72 x 4.1 x 2
Crawl ratio = 63.34:1
Manual:
Crawl = 4.34 x 2.72 X 3.21
Crawl = 37.89 (or 48.4 with optional 4.1)
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04-09-2008, 08:32 PM
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JK Super Freak
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They're fine on a long-distance high speed trip (ask anyone how fast WoL drives, and I can follow him
). Power-wise, well, it feels like a lifted jeep! 
Seriously, a little slow off the starting line, but I've got heavy tires. Once you get rolling you're fine.
04-09-2008, 09:15 PM
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x3 on the 5.13's with 35's and an auto...
Lets put it this way, without the 5.13's, you will not even be able to hold 75mph on the highway with 35's! 
Before I changed the gears while on 35's, I couldnt hold speed at all without down shifting out of OD.
Even still with my 5.13's on the highway going into a head wind up a decent hill, my Jeep still slows down a mph or two, but it doesnt need to down shift.
So Im glad I went with 5.13's and not 4.88's
BTW....I get about 16.5 mpg on long trips going 70mph....I also found out she'll do 100mph easy before I backed off
Along with the gears.... the CAI, muffler and Hypertech tuner make a real nice improvement too, my Jeep actually feels fast now
Before I changed the gears while on 35's, I couldnt hold speed at all without down shifting out of OD.
Even still with my 5.13's on the highway going into a head wind up a decent hill, my Jeep still slows down a mph or two, but it doesnt need to down shift.
So Im glad I went with 5.13's and not 4.88's
BTW....I get about 16.5 mpg on long trips going 70mph....I also found out she'll do 100mph easy before I backed off
Along with the gears.... the CAI, muffler and Hypertech tuner make a real nice improvement too, my Jeep actually feels fast now
Last edited by Eracer76; 04-09-2008 at 09:19 PM.
04-09-2008, 09:44 PM
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definately 5.13's with the auto and 35's and go for the hypertech too, I cant believe the difference with the hypertech on the highway with premium settings/fuel.....even before the hypertech cruising at 75-85 was no problem on highway