Anyone running 37s with 5.13s or 4.88s on a 2012 and up Unlimited with the Auto?
I am getting ready to order up some gears and cant make up my mind...4.88s or 5.13s.
I have a 2012 Rubi Unlimited with the auto and 37 MTRs....

I've always run lower gears on all my other Jeeps because I drive my Jeep like I stole it.
I'm just a bit worried about long road trips running 80MPH....

Thanks

 

There's a great write up on project jk about regearing your 2012+ JK. They went with 5.13s and are loving it.

http:// project-jk.com/jeep-jk-tech/...ep-jk-wrangler

 

I've got a '12 auto running 4.88s with 37" KM2s and love the way it drives. If it were more of a dedicated trail rig, I'd probably have gone 5.13s, but mine is a daily driver.


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I'm going 4.56s in my 2012 JKUR on 37s. I run 80 - 85 MPH often (we have 85 MPH speed limits here) and 4.88s are going to put me over 3000 RPM at that speed. It drives pretty well with 3.73s but crawling sucks.

I'd vote for 4.56s.

Marcus

 

So what are your RPM's gonna be at 85 MPH with 4:56 gears?

 

I would expect 2900ish but it might be a little higher. 70 is supposed to be 2400 on 37s.

Marcus

 

I can't imagine running 5.13 with the new engine and 37. I'm running 37 on 4.10 and think its a great mix of mpg and power. 5.13 to me seems like overkill unless you live in the mountains. I like the fact that at 75 I'm running around 2200 rpm.

 

5.13s are the most suitable for people who want more power and better performance off road, and who don't drive much over 75 mph.

4.10s are suitable for 33s and are a stock option for 32s for people who want more performance.

2200 rpm at 75 isn't enough for heavy rigs, towing, or driving through mountains and hills.

 

The 4.10 are too much for stock Rubi IMO. I thought they were perfect on 35s. My rig is about as heavy as they get and 2200 rpm is great for me. I know you are a fan of over gearing and that is fine. If I lived in the mountains or this was a trail rig I would agree with you. I live at the beach and it's my dd. 5.13 are definately out of the question for me and 4.88 are borderline. 4.56 is probably ideal for me but that's a lot of coin for a small change.

 

Right. Flatlanders at sea level who don't tow can give up off-road performance to save regearing costs.

The difference between 2200 and 2500 rpm at highway speeds won't make a material difference in fuel economy or engine durability. I don't drive my jeeps over 75 mph too often. So, I would still spend the $1000-$1300 to regear. If I cared about fuel economy, I'd be more concerned about tire rolling and wind resistance than a few hundred engine rpm.

I am one who prefers performance. True, that is my bias.

With '12+ automatic transmissions, lower gears are not as critical as with '07-'11 automatics.