I have a 2012 JK with the Pentastar motor. I have a 3" lift and 35"s with an automatic. It still has the stock 321 gears, I'm wanting to do a gear change but not sure what to go with. This is primarily a daily driver, most people are telling me 488's but that seems a little steep with my combo. It still seems as though it gets around pretty good right now as it sits. Any suggestions?? THANKS

 

If it helps...I ordered mine with 4.10s and just put 35s on. I used the AEV procal to change speedo and shift points. I hold 75 mph at 2500 rpm and don't really notice any loss of power on acceleration. There is a gear chart for the 2012s in one of the stickies.

 

Just regeared my JK 2010 (though) to 5.13 and flashed the performance 93+ tune, loving it !!!!! drives soooooo much better

 

Here's the gear chart from the FAQ. I would probably opt for the 4.56s as it would just pain me too much to get 4.10s that I could have got from the factory with ordering a Rubicon.

 

[QUOTE=JPop;2855175]Here's the gear chart from the FAQ. I would probably opt for the 4.56s as it would just pain me too much to get 4.10s that I could have got from the factory with ordering a Rubicon.

[QUOTE]

Im having this debate right now, I have only had my JKU about a week, and because the dealer made me a deal I just couldn't pass up on my Jeep because it was on the lot, downside it has 3.21's. So im going back and forth between re-gearing to 4.10's or 4.56's. I live in FL and will only be wheeling about once a month, and here in FL we mostly have sandy trails and occasional mud. UGH...

 

Awesome to hear, that's why I ordered mine with 4:10s, and sounds like I made the right call on that one. Not to de-rail the thread, as it may be relevant to the OP, but did you notice any gain in mpg on the highway due to the lower rpms? Do you do any off-roading, and if so, assuming you have a Rubi TC, how's the crawling w/ the larger tires and 4:10s? JK or JKU?

 

4.10 would be perfect for you, 4.88 is flat out to much gear!
2500 RPM @ 75 MPH is nice.
I have 4.56 with 35's 2750 RPM @ 70 MPH which is a bit tight, I may drop down to a 4.10 ...wish they would come up with a 4.30!!
Keep in mind your tires most likely measure closer to 34in...
That gear chart is for reference, with all do respect it's close but not perfect.
For a daily driver there is no need to spin the new motor beyond 2500 RPM's @ 75 mph.
I find it a bit odd that Jeep even offers a 4.10 in the Rubicon, but it is nice of them to do so.
All this pertains to the 2012 only!

 

250 rpm is probably pretty meaningless in terms of relative stress on the motor.

 

I have a 12 with 35's rubi with
4.10 and auto
For most peeps doing a mainly
Daily driver jeep it will be great

I'm going to change to 4.56 because of the altitude and terrain plus I plan on pulling a boat during summer

4.56 puts it very close to the factory ratio with 4.10's and 32" tires


Sent from my iPhone

 

I have a 2012 With 35's and factory 4.10's
Also, a 2012 with 37's and 4.88's
Both drive great so far in the city and on the highway.
4.88's Might not be too steep, but I think that 4.56 would be a better option.