mr_alex2

I chimed in another thread, but maybe I can help here too.

Lots of people give input without knowing what the application is.

Also, lots of people ask for advice with very little details.

We all need to understand the factors and make better decisions. I'm only saying this since I myself researched this for a long time. It comes down to preference.

Factors:
- Engine / Tranny combo
- Plans for Jeep? Looks, rock climbing, mud, etc...
- Geography - where do you mainly drive? Flat, hills, etc.
- Driving style. Do you find yourself to be the first one taking off from a red light, do you coast at speed limit. Are you bouncing off the rev limiter?
- Not all rims and tires are equal. The weight of both fluctuate greatly. It's possible to get a 35" and 17" combo that is same weight as stock. Do some research.

Me? 2012 JKU AUTO, bought new. 3.21 - rolling with 17", 35's for over 20k miles. No problems. I dont off road, lots of highway. I live in FLAT south florida.

Hope that helps! Any questions. Shoot'em my way.

lewvsal

My experience: bought a 2016 2 dr 6 speed with 3:21 gears. Lifted it 2.5 inches and put on 35inch general grabbers (actually measure 34") on 16 alloy wheels. Run no top, no spare, no armor so it's fairly light relative to others.

3:21 gears was bearable but not ideal. Really slowed down on hills. (I'm in socal, at/around sea level). Mainly got into 4th and maybe 5th on fway, never 6th.

I recently regeard to 4:56 and I must say it feels like it's too much gear. I easily hit 3k rpm in 6th. My MPG went down about 1-1.5 mpg as well which surprised me.

I get that higher RPMs could equate to worse gas mileage; I always thought it had more to do with how much throttle you give it.
I'm considering a tune

shabbernigdo

i dont know how you guys stand 3.21 gears. If you have a 6 speed but can only really use 4 or 5 of those speeds on normal highways thats seems pretty clear they its not geared properly.
2012 rubi with the 4.10's going to 4.56's here in the next few months.

DJORDJ

I am happy peeps are still chiming in on this one. As I have a question or three about axles and gears/ transmissions.
so 1st Q's; Axle
What can the Dana 30 on unlimited Sport actually support? What makes the Dana 44 so sought after? Is it because of the 4.10? And lockers? Why can't the 30 support a 4.10 third member? Or can it? What makes them so un-popular?

2nd Q's; Gears
So Rubi's have Dana 44 axle and 4.10 gear option with lockers. Will the rubi third member with 4.10's fit the 30' pumpkin? Or is that the problem with the 30 making them in popular.

3rd Q'S; Transmission
Manual and off-roading: I hear manual is more difficult to off road with. Has anyone experience a slipping clutch while off-reading? If so what clutch did you have installed?
Auto and off-roading: how well does the trans cooler work and how well does the Auto trans actually withstand heat caused by (a): crawling (b): big tires.

Last Q's; Lifts vs Warranty
will installing a lift void the manufacturer's warranty? On a brand new JK?


I know know it's a lot but I am trying to get the most info before making a decision on buying a jeep.

thank you again

shabbernigdo

1. From what i understand the on the 44 the center housing is larger can hold a larger R&P.
2. From what i understand no they are not interchangable.
3. manual is more work while offroading if not geared low enough it requires you to work the clutch more and can shorten the life span of your clutch.
Autos are generally easier but agian if not geared properly they tend to have over heating issues many like to add aftermarket AT coolers to help fight this.
4. When modding you will void the warranty on any parts you mod obviously and any parts that fail and can be linked to any mods you made will probably be voided as well.
IE add bigger heavy wheels and tires and the balljoints shit the bed they can fight you on the warranty claiming your mods caused the failure on the other hand if you change the exhaust and your control arm fails obviously they cant claim your mod had any thing to do with that and will honor the warranty ( normally )
Some dealerships are cool and will work with you even on / with modded parts while some are ass holes and will see mods and try to screw you.

DJORDJ

Ahh makes sense. I guess whenever I do buy my Jeep I'll have to keep it stock until the warranty is up, unless I don't give a care about it.

Thank you for the information

shabbernigdo

I tried that. I did not make it. I made it about a year before i had to started changin things. There are just too many options out there : )

Jahamm88

Yeah I tried that as well, thankfully my dealer has been good and generally speaking as long as you don't go crazy with your build they should still honor the warranty. Obviously anything you change won't be covered but power train should remain intact

MarcF

I recently purchased 2012 sport with auto and 3:21 gears, added 2.5 lift and 33" tires. Dont like it at all, I have to drive about an 1 1/2 hrs to get to mountains and at 70 mph constantly shifting 3rd, 4th, 5th. In the mountains find myself having to manual shift the automatic. Anybody have advice on which gears to go with, not a daily driver but still a lot of time on the road.

rob_engineer

did you reprogram the computer for the larger tires. That will help your shifting a bit, though new gears are the long term solution.