I have a 2010 JKU with a stick, 3.8L, 3.21 gears running 33's. I'm looking to move up to 35's next year but definitely will need to regear to do it. I'm going to regear first (hopefully this Fall) then get the tires in the Spring. After looking through the gear/tire size charts on the forum it looks like either 4.1's or 4.56 is the best suited for me. I drive a lot of highway miles (currently have 65K miles on the jeep) and wheel it 6 or 7 times a year at Rausch Creek (nothing crazy, I stick to the blues). Since we'll be opening up the differential it would be a great time to put a locker in. This thread https://www.jk-forum.com/forums/modi...-170103/page2/ makes me think a TrueTrac is one of my best options for my limited needs. But I keep finding confusing advice as to whether it should go in the front or rear. I do drive through snow and ice several times a year here in the Philly area.

With all this in mind, I think what I need is something like this:

4.56 gears with overhaul kit (given my mileage). Something like this Northridge 4X4 JK Non Rubicon 30/44 Gear Package and Master Overhaul Kits. Although the extra $110 for the 4.56's hurts a bit.

TrueTrack locker Eaton Detroit Truetrac (DETROIT_TRUETRAC)

It looks like I need a carrier for the D30 up front, but if I put the TrueTrac up front I don't think I'll need the carrier?

After reading through a bunch of the "how to do gears" threads I've determined that this is beyond my capabilities, so I'm looking for a good shop in the Philly area (northern suburbs would be ideal) to do it for me. Any recommendations would be appreciated.

Thanks all!

 

I forgot to ask, any advice on which gears brands to stick with (or avoid) would be good.

 

The truetrac is a great traction device for those that don't actually need full lockers. A rig with a pair of truetracs will be able to go most of the places locked rigs go. Front or rear is a debated topic. I would go rear if only doing one, but there really isn't a correct answer for all situations. Flip a coin. But, you are correct that it will take the place of the carrier, so in your case it would be used instead of buying a new open carrier for the d30.

Search on these numbers for it.
Front d30 - 912A585
Rear d44 - 913A589

The front you can find $390-ish. The rear for $460-ish. So --> why not save a bit more and buy both?

Unless something has changed, most of the 'JK' gears are still coming out of Asia. Compare price and warranty, not the name on the box.

 

This is good info. Thanks

 

Make sure you are looking at the correct gear ratio chart. With the 3.8, manual trans, and 35s, you want 4.88 gears. I had this same combo with the Trutracs and it was perfect.

 

I have Yukon 4.88's with Yukon Zip Lockers front & rear. I run 35' Nitto Trail Grapplers. D30 front axel with carrier, Nitro axle sleeves on my 2011 2door and I do great. Fuel mileage sucks, but a SC is eminent. Sent from the swamp while taggin' a gator!

 

No off-roads for me and running 35's. I swapped gears about 3 months ago and went with 5.13's. When I pulled the rear diff cover I found the spider gears were all chewed up so I popped a Truetrac. I'm very happy with my choices and have no regrets, also my city MPG has been bumped up a little and highway MPG yielded even better gains. I can't wait to see how the Truetrac handles on the snow and ice.

 

I've been using the bottom table of this chart https://www.jk-forum.com/forums/uplo...atio-chart.jpg

My concern with the 4.88 gears is that on the highway doing 70 it shows 2756 rpm. For a long drive (4 hours) that seems a bit high for me (especially since I'll be more around 75 mph). How would you rate your highway experience with the 4.88s?

 

Thanks for the info!

 

The charts are built off of 'actual measured' tire height, not mfg spec. So depending on the specific tire and the weight of your rig, using 34" (2837 rpm), or less, might be more accurate than the 35" (2756 rpm) in your example.


You are concerned with high freeway rpm's, so the plan is to re-gear six months before getting taller tires?

3.8 manual, 4.56's, 33's that measure 32" = 2817 rpm @ 70. (Looks quite a bit like 4.88's with the 35's, doesn't it?)

I have an auto, so zero experience with gearing for a 6-spd. Just trying to make your head explode from second-guessing everything...