Differential Issues
 

Hey Y'all....I've been out of the country for a few months, so I spent most of my per diem on my 2014 JKU Altitude:

Smitty Built Rock Crawler Front & Rear Bumper
Smitty Built Rock Gaurds
Rough Country 3.25 Suspinsion Lift w/Shocks
Rough Country Dual Steering Stabilizer
Radar Renegade R7 MT 35x12.50x20...Still searching for wheels

I'll be back in the States in couple of weeks, so Im trying to have this stuff ordered and ready upon my return. With all that, Im still a little confused on the gears. Watching Youtube, I realize now I have to upgrade from 3.73 to 4.10 with the 35s I purchased. My question is - Which gearbox do I upgrade...or do I upgrade both? :dontknow2:

You regear both the front and rear differentials. They have to be matched for you to use 4 wheel drive.

Awesome...thanks for the quick response!

Bullpucky.

You do NOT have to replace your gears. I was on 3.21 for 2 years with my 35s. Going from 3.73 to 4.10 would be practically useless. You'll spend $1200 on gears and labor for next to nothing. If you insist in putting in new gears, you'd be better served by going to 4.56 and adding lockers (either limited slip or a selectable). The labor to regear is substantial and would be repeated if you added lockers later.

My advice to you is to just drive with your current gears. You may find you like it just fine. Don't believe all the BS hype that you have to regear. You don't. When you start crawling rocks, or want some extra boost when accelerating, then go buy your gears.

....and that's where the confusion starts. I've heard both opinions from Jeep owners out here in Germany(Hilly terrain, but mainly interstate travel), but New Orleans is flat. So I guess I'll have to feel it out once I have everything installed.

Be sure to get a tuner (ProCal or FlashPack) to set the tire size correctly for the computer with whatever gears you run... this will ensure proper shift points and keep your fuel mileage from going crazy.

Yes. Do this. You will not break your Jeep. I promise.

And absolutely do what Scooby suggested and get an AEV ProCal to re-calibrate your speedo for the tire size. This is especially important for an auto trans as it does affect shift points.

Before you go and purchase gears my recommendation is to ask yourself is 35's the biggest tire you are eventually going to go with? I say that because when I went to 35's my jeep had 3.73 and the performance dropped. A buddy has a 2013 Rubicon and when he went to 35's with 4.10's he lost some pep. Google gear charts to see what gears will work best for your situation. For me I like playing on the rocks and will jump to 37's next set and I knew this when I had my Jeep regeared and went with 5.13's. I ran 5.13's in a D30 with an Aussie locker for a week in Moab and had only catastrophic failure which was both stock front axle shafts. I chose to keep the stock axle shafts so that they were my weakest link. I have since upgraded to an Ultimate 44.

BLUF chose your gears so you only have to pay for labor once.

R/
Will

In my honest opinion, I'd save the money for the time being. I ran 3.73's on my 14 Altitude for over a year. I upgraded to 4.56's in November because I went 37's and like LA, Florida is flat! I honestly had ZERO issue running 3.73's on my 35's and would have saved my money but at the time, I wanted to lock the front and rear so figured I'd do everything at once. Hell, we even had some folks go to Ocala to Hard Rock on 35's and 3.21's and didn't have too much of an issue...Just on really STEEP climbs.

After re-reading ShutterBugs comment, I concur! :P

I'm on 35's with the 3.73 and auto trans on a three inch lift. I've posted that my driving around the Seattle region is satisfactory, although I won't be winning any races, but then again, this is not a hot rod. Yes a little acceleration loss. However, on my first real road trip to Moab and back a couple weeks ago where the speed limits are 70-80 MPH and lots of mountains and hills in between, it really sucked! I maintained at or below 70 MPH the entire trip and drafted off every tractor-trailer I could get behind. 5th gear was almost never used, except on downhill slopes, or while drafting, and gas mileage was about 13 mpg. I usually get 16-17 mpg around town and the slower freeway speeds we have here.
While I still don't mind how it handles around town, if I ever go back to Moab, I will find a way to trailer it. The gearing for me on the trail was a non-issue.