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Hi guys. This is my first post. I currently have a 84 CJ7 as you can see my pic on my profile. I have always considered CJs the only real jeep. But I am not knocking Jks cause I am about to buy one. I am buying a 2010 Unlimited Sahara with the towing package and 3.73 gears. I already have plans for a 2.5" lift and 35's. My question is will I need lower gears to run the 35s. I would like to keep the performance as close to stock as possible. If I need to change anybody know what gears I should go to. I don't want to go too low, say 5.13's. I don't even know what is available right now. Any info or suggestions appreciated!
 

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Welcome to jkowners.

Depending on tire size....4:88's, 5:13's, and 5:38's are generally the choice. I think that if you are getting an automatic, that 5:13's will suit you best. In a manual, you might be okay with 4:88's.

Drive it for a while and see how it feels for you after you get the 35's. I stayed with stock 4:10's for over a year after I went to 35's....but I have a manual too, so it was easier to get away with the low gearing. I ended up with 4:88's which is fine for my manual/ 35's.
 

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Now, FWIK, 3.73 are not gona help you move those 35", with 4.10 some guys here have no troubles but to me they seem slow as hell, or not even close to factory. This is a discussion that can go forever and i can write about it but theres a chart that i attached and it seems to be the one that looks right. If you are going to ride on 35"s for ever...... 5.13, will make you happy and better than stock performance. 5.38 is the jackpot in case later on you decide to grow up and stick some 37"s on it.

I'm pretty sure somebody else will chime up with more knowledge and better understanding on this subject. BTW if you don't have any lockers might as well trow some in there while your diffs are open. Oh and do some research around, theres a lot of literature about this subject, Getting aRED STAR will help a lot more when doing the search portion. Welcome to JKO:thefinger:
 

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Thanks

Thanks for the chart. That helps a bunch. I never thought I would 5.13's. I am thinking about holding off buying a JK until the 2011 model comes out. Its is supposed to have a new Pentastar V6 with 280hp and around 260 ftlbs.
 

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I have 5:13s and when i had 35s i found that it was a little too much gear for the road. When i went to 37s, it got way better.

corey d
 

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I'm running 3.73 gears and auto with 35's. It's doable but I will eventually regear. If you drive a lot of highway miles you'll be irritated more quickly as you'll have a difficult time sticking in OD at ~70mph. Half the time I just turn it off. Kills the mileage. This is after tweaking the shift points, which you'll really need to do if you're going to run stock gears.
 

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I actually have 4.10's in my 07 stock. From every chart I have seen staying that way would be acceptible but much more sluggish than it is now. My plan is to go to a 5.13 or 4.88 FIRST then upgrade the tires.
 

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If I read the chart correctly, an auto with 35" and 5.38s will run the almost same RPMs as a stock manual with stock 32" and 4.10s at 70 mph.

I'm leaning towards the 5.38s.
 

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5.13's will perform closer to stock, but I have not heard anyone regret going to 5.38's. There is some concern about the quality of available 5.38's right now.

The 3.6 Penstar is rumored to be in the 2012 model, so you may be waiting a little longer.
 

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According to that chart, my stock setup is in the yellow.

I have an '07 X unlimited with the Sahara tires (P255/75R17), 32". I'm pretty sure I have the 3.73 gears (though I haven't officially checked). It doesn't exactly feel sluggish, but I haven't experienced other gearing.

I also plan on increasing my tire size to possibly 35" which would pretty much guarantee me needing to increase my gears to at least 4.56 but ideally 5.13, according to the chart of course. The chart almost makes it seem like it would be impossible to run 35s with stock gearing... unless you plan on going nowhere.
 

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I'm running 3.21 and 33s with a 6spd. I was originally afraid to go with 35s for the fear of hating my jeep. And until I superchipped it, I think I was right in my decision. Now it has a lot more jam in it, and I wish I'd grabbed the 35s from the start. As it is, 35s 4.56 & lockers are in the plans.
 

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Just to give you an idea but I'm running 38.5inch Maddogs with the stock 4.10 gears and it's livable. I don't want to stay like this forever but it'll do for now. :beer::)
 

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I ran 35's on 3.73's for a long time with a manual trans. 6th gear was a rare occasion, 4th up hill but it was bearable.

I recently switched to 4.10's and it was a major difference. 6th is frequented now, even up hill.
 

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i have 35's and 3.73's, its ok to drive i use 6th gear unless i have to go up a hill. I plan on getting 4.88's ASAP!

By the chart i stand corrected someone must have put 4.10's in before i bought it.
Still need more gear, not enough A$$!
 

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They say there is no such thing as a stupid questions so.....

Can you put 5:38's in a Dana 30? Any issues?
 

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My current set up is a 07 Sahara, 4 dr, 35's, 4.88 gears. Around town it works great. But a few weeks ago I took my first road trip up to Moab. And I found the 4.88's were a pain. It was a buddy and myself, maybe 100-150lbs in gear, and it was a nightmare trying to stay at 70mph. For the most part I kept the OD off. Hills were a struggle. The engine seems to rev too high at times. Really feels as if it can't find its power ban "sweet spot". I am very close to pulling the trigger on 5.13's. My concern is the front 30. Has anyone out there run 5.13's with a front 30 for more then say 10k or more miles? Any issues?
 

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Now, FWIK, 3.73 are not gona help you move those 35", with 4.10 some guys here have no troubles but to me they seem slow as hell, or not even close to factory. This is a discussion that can go forever and i can write about it but theres a chart that i attached and it seems to be the one that looks right. If you are going to ride on 35"s for ever...... 5.13, will make you happy and better than stock performance. 5.38 is the jackpot in case later on you decide to grow up and stick some 37"s on it.

I'm pretty sure somebody else will chime up with more knowledge and better understanding on this subject. BTW if you don't have any lockers might as well trow some in there while your diffs are open. Oh and do some research around, theres a lot of literature about this subject, Getting aRED STAR will help a lot more when doing the search portion. Welcome to JKO:thefinger:
Man, that is one of the sexiest charts I have seen. I mean, it isn't a pivot table or anything, but it is one sexy damn chart! :bounce:

Thanks!

RC
 

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They say there is no such thing as a stupid questions so.....

Can you put 5:38's in a Dana 30? Any issues?
I don't think 5.38s are made made for the JK Dana 30. The main issue would be the size of the pinion.
 
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