WY-JK10

Much thanks. Will be looking forward to seeing the numbers tomorrow. My 2010 is 2080 at 70 mph & think about 300 hundred more would have been a lot better. New 5 speed with the OD being lower geared should create significant higher rpm with the same 410 gearing. Thinking the sweet spot should be around 2400 at 70 mph, so the reason for the request of both the 373 & 410. The 2400 at 70 perhaps is not the sweet spot, so if not why?

Canito is1

After 8,800 miles on my '12 Rubi Unlimited with 4.10's and a 6 speed, I have averaged 18.3mpg, living at 8,000 ft.

The gearing is a bit short in town, and on the highway the best "cruising" speed seems to be about 55 to be in the ideal place for fuel economy. That being said, at 80mph, I am just above 3k rpm which is not ideal. If I go to 35's way down the road, that will be a different story. Stock, 6 speed with 4.10's, there is more than enough power everywhere. With the gear ratios being so short, and I had to do it over, I probably would have picked up an auto, but I am very happy with my selection.

Hope this helps!

EK's JK

On the way to work this morning I was going 70mph on a flat highway turning 2400rpm's. I think it is the sweet spot. When I accelerated at 2400rpm's the jeep was very responsive. Like driving a stick of butter!!

lensstj

I am on my second 2012. On the first one it was a $50 option I thought it was the same on my current one. I have heard now that it is a free option. I am happy with the 4.10's in a currently stock 4 door and plan to keep them when I go to 35's.

aristobrat

As a auto 2010 guy that had to regear from 4.10 to 5.13s to get performance back after going to 35s, I'm pretty jealous it sounds like you're going to be fine running 35s with the stock 4.10s in your auto 2012! That's ~$1200 saved for you!

WY-JK10

Thanks again. Finally found the gear-rpm charts in the Modified Tech FAQ. It was hiding in plain sight. Feel kinda dumb for it taking me so long. Anyway am surprised the 2400 you reported does not match the chart. With the 3.8 in my 2010 I get exactly what the chart says I should with 410 gears & auto trans with stock Rubi tires, 2080 rpm at 70 mph. The chart for the 3.6 says 2533 with same set up, so hope your number is the more accurate. Would be good to hear from others on this. From the chart layout it appears a true 2400 would be the sweet spot for my use just as I had thought before viewing it. 2400 to 2600 is all close enough to make the 410 the preferred gear ratio for me. It works well for my altitude use now & if I get the urge to go bigger tires in the future will still be great. Love my 2010 Rubi & I'm retired & on a slim budget, but I think this change is well worth the money. Hope to keep the 2012 the rest of my life & think this motor & trans combo is much more likely to hold up the 20 or so years I hope to have left than my 2010.

j0ew1120

NOt to thread jack but, the 2010 JKU Rubicons come with 3.73 then?

bbolander

what is standard on the 2012 rubi has been confusing, but i think its the 4:10s. early on looked at some online stickers and with max tow package with 3.73s there was a $50 extra to get 4:10s. mine didn't have the max tow and came with 4:10s, no extra, nothing extra listed in the options regarding gears. since i did't see an extra i assumed i had 3:73s until i looked on the standard side of the window sticker that says 4:10s. with the lower geared auto i would have liked the 3:73s for the better mpg, but i'm happy with the 4:10s, awesome crawler.

WY-JK10

Yes confusing. My dealer says the 373 is standard & the 410 comes with the max tow. Showed that too when I built my own on the jeep website. Think the reasoning is now with lower auto transmission gearing & added hp the stock jeep Rubicon for average use is better suited with 373. with stock tires the new 373 turns 200 more rpm at 70 mph than the 07-11 with 410.

Wrangle_on

One of the options that sealed the deal on our '07 Sahara auto was 4.10 gears - and it doesn't have the tow pkg. It's my wife's DD around town and so averages 15-16 mpg. Does better on longer trips but we still have the advantage of 4.10's off road. (Running stock BFG Rubi takeoffs now)