JKLarson

Hey guys, just picked up a new 2012 rubi...love it!

Planning out my build and I think I am going with a 4" TeraFlex (not sure if LA or SA yet...) and 37's...

Stock Dana 44's front and back with 4.10 gears...should I go with 5.13 or 5.38 gears?? The 3.6 engine is awesome so far...I live in Colorado and it will be a DD and a trail beast. Will 5.38 be too much?

I have an auto tranny...

Thanks in advance...

mattgt5

I have a 12 rubi with 4.10 auto and 35s. I would not change gears. Plenty of power and get around 18 mpg on my daily commute. I am going to 37 soon and have no plans to regear

JKLarson

What kind of elevations do you go through? Living in Denver and heading up to the trails in the mountains is a hike...5,000 feet to 11,000+ feet...I am worried about those long runs uphill with 4.10's

arjeeper

I think with the pentastar we have to set some of the past gearing suggestions aside. I also wonder if either of the options you're suggesting are too much. What about 4.56s?

JKLarson

You make a great point, this is a totally different engine with a lot more power...I based my gear calculations on "old school" rule of thumb. I looked at some online calculators and it says jumping from a 32" (stock) to a 37" tire a 4.88 would bring it back close to stock...

Any Colorado guys out there have the pentastar and did some gear changes?

ranjr

Unless you want to climb the hills in OD, 5.13s & 5.38s are too much for 37s. I too have 35s and 4.10s and still find myself with the ECO light on all the time. I'd look at 4.56 or 4.88s.

TeraFlex

Running 37's with 5:38's in mine. Makes it nice on climbing up hills, lots of bottom end. However not the best for mpg's, I'd consider 4:88's -5:13's. However there is no way I would ever change mine down.

ornjeep

I'm in Colorado with 37s an went with 4.88. It feels pretty much the same as stock. Cruises E470 at 80-85 and gets up the mountains well. I don't have any complaints with the setup. I'd agree that the pre2012 recommendations don't apply to the 12s.

JKLarson

Thanks dude, I appreciate it. How big is your lift and what kind?

ornjeep

4 1/2 AEV. So far I'm loving it.