Regear... 5:13. Search around a bit on the forum and you'll find what you need... Just a bit of reading.

 

Likely 3:21s that's what my sport has . It's got plenty of power with my 33s and six speed stick . 37s would be a lot for mine . But if I had 4:10s and a stick I think it would be ok ? That's why I asked if u had a stick and what gears .37s and 3:21s would suck though .

 

Depending on tire brands true. Big difference no. Not 100 percent as i dont have 37s but i doubt the extra inch would change my opinion at all. On my heavy 35s after dropping the stock tires it wasnt extremely noticable imo.

 

I am getting my 37" mud grapplers on Monday . I have a 2010 rubicon 4 door. I currently have 35" and have no problem with 4:10. If I was to regear what would everyone suggest?

 

I've had 33's and 37's on stock 4.10s with the 3.8L... You DEFINITELY will want to regear. I have 35's with the new 3.6L and 4.10s and will likely regear to 4:56 or 4:88.

 

5:13... I've had that setup and it felt like it returned close to stock for the 3.8... Which is still a turd.

 

Actually, if you have an 07-11 automatic and 3.73 gears and 37s, you could delay a regear.

The reason why is that if you simply turn off your overdrive and run the highway in 3rd gear, you will turn the about the same engine rpm as you would with 5.38s in 4th (overdrive) gear.

5.38s with an 07-11 automatic and 37s run about the same highway rpm as a stock 6 speed Rubicon on stock gears and tires. This is actually more fuel efficient at highway speeds than 5.13s if you live in a mountainous, hilly, or windy area because with 5.38s, the transmission downshifts less frequently than with 5.13s.

The problem with 5.38s for a JK with a front Dana 30 is that they are less durable if you offroad aggressively. If you rarely go offroad, 5.38s in a Dana 30 are fine.

 

Id do Yukon brand. In my experience they set easier and have guides and markings to help. As for ratio i did 5.13 to save some strength.

 

X2. Well put.

 

Unless you never tow, live at sea level, with no mountains, or routinely drive over 80 mph, if you have a 6 speed, you want 5.13s, or if you have an automatic, you want 5.38s.

If you are really hard on your jeep offroad, you might consider 5.13s instead of 5.38s for added strength.

However, with an automatic, you are less likely to have problems running hard with 5.38s due to the slippage/give of the transmission--unlike the sharper loads possible with the 6 speed.