Gear Work

Hi, long time reader, first time poster. Anyways, I am getting ready to do a re-gear on my 08 JK. It's an X model, so D30 front and D44 in the rear. My stock gearing is 3.21 (I was a jeep virgin in 08, didn't know any better.) I want to upgrade to 4.88 and put an eaton e locker in the rear. I know there are a lot of different opinions about putting a single locker in the front vs. the rear. I chose the rear mainly because it is a 30 spline and when I upgrade my front to D44 I don't want to have to replace a 27 spline locker as well. I do a lot of off roading now, but no rocks (my gears suck of course.) I'm going to do all of this myself and have budgeted about $1500 for the project. I guess I'm looking for opinions on what I'm about to do. Is there a better way to spend the money? Any special considerations? My current build is a 4" lift (got 5 ¼ out of it), run 35s, all 8 control arms (short), adjustable front track bar, drag link flip kit, and some odds n' ends I can't think of at the moment. Thanks!!

Welcome :standing wave: sounds like you got a plan.

viperfoxfa said:

Hi, long time reader, first time poster. Anyways, I am getting ready to do a re-gear on my 08 JK. It's an X model, so D30 front and D44 in the rear. My stock gearing is 3.21 (I was a jeep virgin in 08, didn't know any better.) I want to upgrade to 4.88 and put an eaton e locker in the rear. I know there are a lot of different opinions about putting a single locker in the front vs. the rear. I chose the rear mainly because it is a 30 spline and when I upgrade my front to D44 I don't want to have to replace a 27 spline locker as well. I do a lot of off roading now, but no rocks (my gears suck of course.) I'm going to do all of this myself and have budgeted about $1500 for the project. I guess I'm looking for opinions on what I'm about to do. Is there a better way to spend the money? Any special considerations? My current build is a 4" lift (got 5 ¼ out of it), run 35s, all 8 control arms (short), adjustable front track bar, drag link flip kit, and some odds n' ends I can't think of at the moment. Thanks!!

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Considering you have 3.21's your going to need a new carrier as well. If you had 3.73 gears you would have saved yourself a little money.

Your doing it right (IMO) by locking the rear and not the front. Locking the front in a d30 allows you the chance to break a r&p sooner.

Do you know how to properly install gears? I have never done it but heard it's a lot of work to make sure the backlash and stuff is right. If I were you I would look for a shop to do it just to make sure it's right.

4" lift and 35's? That's a lot of lift for that tire. I run 2.5" of lift and 35's with flat fenders with room to spare. I would suggest lowering it to maybe 3". This will save you money on control arms since you will only need front lowers and rear uppers to get your caster and pinion right. Also it was allow you to budget I'm new driveshafts.

cozdude said:

Considering you have 3.21's your going to need a new carrier as well. If you had 3.73 gears you would have saved yourself a little money.

Your doing it right (IMO) by locking the rear and not the front. Locking the front in a d30 allows you the chance to break a r&p sooner.

Do you know how to properly install gears? I have never done it but heard it's a lot of work to make sure the backlash and stuff is right. If I were you I would look for a shop to do it just to make sure it's right.

4" lift and 35's? That's a lot of lift for that tire. I run 2.5" of lift and 35's with flat fenders with room to spare. I would suggest lowering it to maybe 3". This will save you money on control arms since you will only need front lowers and rear uppers to get your caster and pinion right. Also it was allow you to budget I'm new driveshafts.

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I'm glad you mentioned the carrier. I knew I had to change it but I hadn't thought of it when I put my parts list together. Thanks.

As far as installing gears...I have done a couple, but never on a jeep. BUT, I've watched like 50 you tube video's I'm willing to give it a try. I have all the tools except a backlash tool. I'm going to either rent one or buy it before I start. I think I can do it.

As for the lift, I'll just get bigger tires...I already have all the control arms. I know I'lll need new drive shafts eventually, but It isn't an issue right now. Thanks for the input.

viperfoxfa said:

I'm glad you mentioned the carrier. I knew I had to change it but I hadn't thought of it when I put my parts list together. Thanks.

As far as installing gears...I have done a couple, but never on a jeep. BUT, I've watched like 50 you tube video's I'm willing to give it a try. I have all the tools except a backlash tool. I'm going to either rent one or buy it before I start. I think I can do it.

As for the lift, I'll just get bigger tires...I already have all the control arms. I know I'lll need new drive shafts eventually, but It isn't an issue right now. Thanks for the input.

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4.88's will work great with the 35's but if you plan on stepping up to 37's I'd be putting in 5.13's. which I think causes more issues with the D30 but I'm not 100% on that, I'm sure one of the others will chime in on this.

HILLZ said:

4.88's will work great with the 35's but if you plan on stepping up to 37's I'd be putting in 5.13's. which I think causes more issues with the D30 but I'm not 100% on that, I'm sure one of the others will chime in on this.

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I would agree on both as it's what I have. Since I want 37's at some point I planned ahead and did 5.13's. It makes the R&P really small in the d30 but IMO it's worth it for when I get a pr44 and 37's. I will not have to regear my d44.

If you're going to be changing the carrier in the front, why not drop a trutrack in there as well? it's a bit more money, but it'll help a lot and won't stress the D30 too much.

Krynn said:

If you're going to be changing the carrier in the front, why not drop a trutrack in there as well? it's a bit more money, but it'll help a lot and won't stress the D30 too much.

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Sorry for the late response, I've been "in the field." I have thought about trutrack, and even an ausie locker for the d30. I've heard they can make some noise in turns, which I don't care about, but also make Turing while on the gas difficult. I don't want to loose the drivability as it is my DD. Thoughts?

viperfoxfa said:

Sorry for the late response, I've been "in the field." I have thought about trutrack, and even an ausie locker for the d30. I've heard they can make some noise in turns, which I don't care about, but also make Turing while on the gas difficult. I don't want to loose the drivability as it is my DD. Thoughts?

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Either one will be fine in 2wd, so your on road handling will not be impacted at all.

The Aussie Locker is a lunchbox style autolocker, so it will ratchet in turns (even in 2wd). Also, it doesn't replace your existing carrier - it fits inside it instead. You'll want to remember that it's your inside tire that's getting all the power (unless it starts slipping), so you might have a slightly wider turning radius.

The Detroit Truetrac is a helical gear style limited slip differential, and is nearly invisible until it starts working. And even then there's no sudden grabbing or jerking, you just have traction. Because of how the helical gears work in transferring the power, you'll almost never notice it affecting your turning radius (unless you like to do doughnuts under full power).

If you ever have to go into 4-high due to icy conditions, there's no question: avoid autolockers. Instead, either stay open, install a selectable locker, or go for a limited slip (aka Truetrac). Autolockers can cause your vehicle to jerk a bit when they engage, which is the last thing you want on ice.