Regear question for my new to me 2016 JKU Rubi. 35’s currently on 3.73’s. Changing to 37’s (and researching True 37’s). This is exclusively my trail vehicle and it only sees highway speeds on the way to the trail. I’ve got a 2.5” RE lift and the wells have already been shaved.

I’m leaning towards 5.13’s due to my purpose. Thoughts?


Day one of ownership… Mud pit at prairie city… Never again in my life. sediment in the auto tranny = valve body overhaul 🙄 with lots of other frustrating after effects.

 

My wifes JKUR has 4.88 with 37's and it works well. It came with 4.10 when delivered. With the 4.1 low range it is a pretty good combination. 5.13 & 37's would be the same as the factory Hard Rock that had 4.10 with the stock tires.

 

Having researched the build sheet I can say with confidence that mine is the Hard Rock version. One of my biggest concerns is the minor overheating it does when crawling at slow speeds. And I do believe I’m missing out on power/torque with my current gear ratio.

 

the minor overheating will not go away with gear ratio change... sorry to say .... if you find the answer for that let us know

 

I would look at a smaller lighter 37 on the factory axles for a off road rig. KO2 or simular size. 5.13 gearing.

 

You don’t think I should go with a true 37 due to axle strength? Also, the front axle now seems to be making a grinding sound when in 4wd going in a straight line. Makes a crunch sound when turning in 4wd. No issues whatsoever in 2wd though. Thoughts on that cause? I’ve already drained and refilled all the fluids in the car with the exception of the brake lines.

I feel like that one mud pit is going to hurt me for a while.

 

Yes, you will be walking the razors edge with 37's on the stock axles. You will be find on 37's until you are not. Grinding could be ring and pinion, bearings, u-joints, or the driveshaft.

 

Any pointers on how to diagnose those particular issues? And what if I get my Dana 44’s gussetted? Thank you for the help!

 

if you are running the factory drive shaft check up at the tracnsfer case connection, jack up the front wheels and spin the shaft. It should turn smooth and no noise. Pull the diff cover and check the gears, look for metal shavings in the oil or a metallic look. you can see the front axle u-joints behind the hub. Gussets and trusses do little good on the factory axles. If you are in Reno, bring it by my shop and I can do an inspection for you.

 

A rubicon will take 37s all day long without any added hardware.

To answer the question...5.13s. I went 4.88s on my JKUR when it was on 37s and immediately regretted my decision. Went to 5.13s.