jpone

My 2012 JKU Sport came OEM with 3.21s. I am considering re-gearing because I tow a trailer and it would be nice to improve the performance. Probably just going to go to 3.73s, or maybe 4.11? Just want to improve performance and not impact the usual ride if possible.

I have an LSD in the rear.

Any advice if I can retain the factory LSD without any major changes? Someone mentioned the potential of having to "change the case" which will add expense I assume.

What will I need in terms of the swap? Brand suggestions?

I am sure these are dumb questions for those many experts out there, but some advice would be great.

hypeiv

Most shops won't recommend going from 3.21 to 3.73... its such a small step it won't be worth the cost of the install, I would say go to 4.10 or maybe even 4.88 if you ever plan on running 35's. 4.56's would probably be the best bet but I know that ring and pinion can be hard to find for the JK dana 30

You are going to need a new carrier for the rear if you go higher than 3.73 so its unlikely you will be able to keep the LSD if you go higher than that (I could be wrong I have heard someone makes a ring and pinions to fit the 3.73 down carrier).

In my area you are looking at $1500 for parts and labor and I would value the OEM LSD at $200 tops... so for me its worth just losing the LSD to go to a numerically higher than 3.73...

BTW I have 3.73 LSD and I am thinking about 4.56 or 4.88 and plan to either run open in the rear or get a locker if I ever change my gear ratio.

hypeiv

Just googled it... you might be able to run "thick cut" gears for the dana44 4.10 or higher and keep the trac-lok

jpone

This is helpful. Thanks. I would prefer the 4.10 and to keep the LSD, but it sounds like it might be a "no go". The mechanic is researching now. Will I need a new carrier for the front with 4.10s?

Seems like the least resistant path to keep the LSD, would be to go to 3.73, but that would only make a small difference?

jpone

What's the deal with Thick Cut gears?

hypeiv

for dana 30 there is a carrier for 3.21 and lower, and another for 3.73 and higher... so your dana 30 has the carrier for the 3.21 and lower

for the dana 44 the two carrier sizes are 3.73 and lower, and another for 4.10 and higher... so your dana 44 has the carrier for 3.73 and lower

your rear LSD is sized for the 3.73 carrier so when you get higher gears you will need to buy a new carrier and thus lose your LSD.

However they do make what I found out via google is called "Thick cut" gears which are higher gears that fit on the lower carrier so you can run a 4.56 thick cut gear for the dana44 on the 3.73 and down carrier. What I don't know is if said thick cut gear will fit over the stock LSD but its most likely your best bet to get this to work.

For your front you will also need a thick cut gear or a new carrier, but the new carrier is only like $60 so its not really that big of a deal... the problem is replacing the rear carrier you lose the LSD so hopefully a thick cut gear works with the trac-lok.

If I were you I would call a few shops and ask if they know if the d44 trac-lok works with a tick cut 4.10 or 4.56 ring

edit: but like I said in the first post... I have the same LSD and its really not the most amazing thing in the world. I wouldn't spend too much money trying to keep it, if it costs you a few hundred extra just to keep the LSD, you would be better off getting a locker or just running it open to save the money. Most reviews on the trac-lok say the clutches wear out before too long and it basically turns into an open diff anyway.

16 Unlimited Ways

I was told 4.10 - 4.88 or higher for sure...I also have 3.21 set up...O-K when in tun
my 32" set up for winter but summer 35" needs a little help...

boson

To carry on the same thread, I'd like to bump my 3.73s up to 4.10. Can I purchase 4.10's from a Rubicon owner to install on a Sport? I believe it would work for the rear since both models have the Dana 44, but I don't know if I can place the OEM 4.10 ring and pinion in the Dana 30. Is it just a matter of acquiring a new carrier or does the whole differetial need to be updated to a Dana 44?

Thanks,
Jason

Ryan0260

You would need a complete D44 in the front. The D30 has a much smaller ring and pinion gear.