Hi,
I am just starting my jk build up. I have a 4 door Rubicon with a 6 spd manual. Just purchased a 4 inch suspension lift and want to add 37s without re-gearing. Has anyone driven a set up like this? I owned an auto 4 door Rubicon on 35 and it was still driveable with the stock gearing, but I keep hearing that once you go with 37s that you have to swap gears no matter what. I am currently just using my JK as a daily driver and do not get a chance to go off-road much. Your advice is thanked in advance.

 

Not a big deal at all. Im running 37's with 4:10 on an auto! (auto worse than manual). I could run like this for another year if I wanted to. Ive even been four wheeling and the rubicons 4:1 transfer case just does it for you. I will get 5.38's later eventually. I have them purchased, just have not installed them yet.

 

Take a look at the gear chart in the FAQ. 37s in 6th with a manual will be sluggish, but could get by on the highway flats and can somewhat cope. Without using 6th gear you would be OK, but you really need to make a plan about getting gears and off road performance will be much better once you get them.

Here's another chart to give you an idea about interim performance without new gears that should help set your level of expectation.

 

Thanks for the advice. You all were extremely helpful.

 

Unless you really feel like spending the money, there is no need to re-gear at all. I've got 37's / 6 spd and its great around town and plenty of torque in 4 low to tackle anything.

I don't do much uphill on the highway. That would be the only reason I could see re-gearing. Otherwise, around town, flat highways, and off roading the stock gears are fine.