Mancinis34

I went with 4.56 open in the front and TrueTrac in the rear. Its all you will need as you can still do almost any trail, you just want to be smart. I am not sure I would go with 4.88's on a 2012 and newer unless you are planning on going bigger which then you would want the PR44 or PR60. I just know if you are on the highway a lot 4.88 will be getting up there around 70mph let alone higher which I hardly recommend. Best of luck in whatever you decide.

decoy5657

I'm planning 4.10 and will probably keep the front open. I think I'm going to stick to 285/75/17 - I spent too much time going 80 to run anything higher than that! There's always a winch.

WineCountryWheeler

Yup, D30 is a stronger axle than most give it credit for. C's, truss and/or sleeves, HD BJs, call it a day and enjoy wheeling!

jtphoto JK

Just a heavy diff cover on it to reduce the housing flex and gear deflection and you are golden.

hornetman

This is an excellent thread. I have 3.8 manual and recently upgraded my gearing to 4.88 and added an Eaton selectable in the rear. I left the front open and after reading this thread I'm glad I saved some cash. I have stock ball joints (70K on my 08) and think BJ will be my next item to upgrade as well as have my C's reenforced. I hear the recommendation on dynatrac BJ but $500 is pretty pricy...what is an alternative recommendation for a less expensive BJ? I have heard Pro's and cons on the synergy, how about theTeraflex?

Sorry if hijacked op, I'm quite pleased though with my regear and now have extra confidence. I have played in some rock gardens in the past with my old 3.73 and was able to get through some hairy obstacles can't wait to try out the new gears but before I do I want to beef up my steering and D30.

resharp001

Honestly, if you got 80k miles out of your factory ball joints, spending money on Rare Parts or Dynatracs are most likely a waste of money for you. If you used your jeep to the point that you need those, there is NOOOO way you would have gotten 80k miles out of the factories. Synergy's or Teraflex are probably a good option for you. More expensive than factory replacements, but 1000x better. Personally, I'd opt for the Teraflex between those two. I have Dynatracs myself....but I know everyone has a different use and different build. The extra $300+ for those ball joints is probably best spent elsewhere for you specifically. I think it's mainly important to have proper geometry in your suspension. If you have proper geometry, you're most likely good with either of those.

hornetman

Thanks resharp01, I have tried to take it easy off road and bought my jeep used with 34K and I don't believe previous owner ever took it off the road. That being said I was steering towards the TeraFlex because of some of the negative comments on the synergy and never considered the dynatrac due to the $$$ price. Has anyone else had any problems with the TeraFlex BJ to sway my decision?

Wrangeler X

First of all you can put 4:10 gears on a carrier that has 3:21 gears. You will have to change the carrier. And I would like a 30 for diffs, if your going to upgrade but don't want or can't afford aftermarket axles, IMO go to rubi take offs already geared to 456,488 or 5:13 depending on your final target tire size and Motor trans

Northridge 4x4

Bear9494

I put in the TeraFlex. After 3 months I pulled them out and replaced them with Synergy. For whatever reason the TF just never felt tight. After 6 months now no issues.

jtphoto JK

My stock BJ lasted over 100,000klm .. replaced them with Synergy and they didn't last a year before both lowers were shot. Maybe 30,000klm. Replaced all 4 with stock and I am now a 259,000klm and no probs.