Howlerbro

Hi All,

I have decided to change the gears in my 2013 Wrangler and have some questions about it. I have the stock 3.21 gears now and want to switch them out for either 4.56 or 4.88. I do run 35" tires and have aftermarket bumpers, winch etc. I am leaning towards the 4.88 because of the added weight and added weight of the tires. I do use the Jeep on the highway quite often as well as off the beaten path. At this time I do not feel like I need to have lockers but am open to a selectable locker for the front first. Is there an open carrier that I can use instead of using a locker for the front? I have been told both by 2 different people. What about the rear? Any insight or help I can get on this is much appreciated.

Howlerbro

resharp001

If you don't add a locker up front, you will indeed need a new carrier as the currently one for your 3.21 gears will not be compatible with the new gears. That is neither a big deal nor a big expense to replace; however, if you have any inkling that you might add a locker later, now is probably just the time to do it as it would require the whole regear process again in the future. That said, if you don't need it and would never use it, a selectable locker would be adding ~$1k to the job for no real benefit.

Depending on what your 35's are actually measuring, 4.88 might be a tad aggressive when cruising at highway speeds. 4.56 is a bit more of the sweet spot. I have 5.13s in my 3.6L '13 with 37" Trail Grapplers. My highway travels are right at 3k RPMs or more for 75-80mph. Mine isn't a full time daily driver so I deal with it for the offroad benefits, but I'd prefer to be around 2700 RPM at those speeds tbh. When you look at the gear charts, factor in ACTUAL tire measurement, and then factor in that you're probably not cruising right at the 70mph the charts are referencing on the highway.

nthinuf

An open carrier for the d30 shouldn't be more than $80-90. If you do want to add traction, a Detroit Truetrac is a good option instead of buying that new carrier. You can find them for around $400. (you could probably get front and rear truetracs for less than a single selectable...)

The rear open carrier will be fine with the new gears, if you decide to leave it.

ATown17

Great info. Thank you.

shabbernigdo

i have a 2012 with the 6 speed and changed over to 4.56 They work well on the road and the rpm's are right in the usable area when in 6th and cruising on the highways. at 70 / 75 im a little over 2600 and at 65 im just a tad under 2500. Just enough to be in the powerband but not so much as to be high on the revs. Running XRC bumpers front and rear and Rockmonsters on 35's so my set up isint really light but it still works well.

BoraBora

4.88 will be way too aggressive for you. I'm rolling on 35" MTR's that now measure out to 33.75" and I'm right at 2600 RPM going 70 down the highway in 6th gear. I still feel like I can comfortably run 37s once these wear down without losing any real power.

Also, I'd do a rear locker over a front if you're only planning on locking 1 of the axles...you'll reap more benefits out of it.