Gears & Lockers

J

JEEP93

New member
Hey Everyone,

I am getting close to purchasing some gears and locker for my 09 2 door. I currently run 315/70/r17 duratracs and will possibly run 37's in the future. So I am trying to decide which ratio will suit both tire sizes the best. It is an auto, so from what I've heard I may need to go higher. In addition, while the gears are getting done I figured it'd be the best time for lockers. What are recommendations for this that won't totally break the bank. Obviously ARB is best for DD, but I am wondering what other selectable ones are out there.

Would it be advisable to run ARB rear and then like a lunch box up front? Since I'm 2WD on highway I assume it wouldn't alter driving.

Thanks in advance for all opinions and advice.
 
Lunchboxes get a lot of hate for no reason. It'll click and pop a lot, but such is life with a lunchbox. It'll be fine in the front. It would be fine in the rear too, since the engagement is only when under throttle.
 
Five-N9ne said:
Lunchboxes get a lot of hate for no reason. It'll click and pop a lot, but such is life with a lunchbox. It'll be fine in the front. It would be fine in the rear too, since the engagement is only when under throttle.
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How exactly does that work with the throttle? Wouldn't that technically always engage in that case?
 
You can better determine the gear ratio that will suit your needs based on transfer case.

With an automatic transmission and 37" tires you can go with either a 5.13 or 4.88 gears. 5.13 is best suited for a 2.72:1 low range transfer case, while you can get away with a 4.88 with a 4:1 low range transfer case.

The advantage of the 5.13 is definitely the off road performance. Your jeep will climb like a billy goat. The disadvantage is higher RPMs on the highway.

The advantage of the 4.88 is definitely highway performance. The disadvantage is off road performance with a 2.72:1 low range transfer case it will be doggish.
With a 4:1 low range transfer case you'd be ok.

Some people don't mind the higher RPMs at highway speeds because they'd prefer the performance off road. Since you'relooking at lockers, I guessing you don't have a Rubicon, so you probably have a 2.72:1 low range transfer case.
I'd go with 5.13 gears.

There's no right or wrong answer, just what is right for you.

And as far as lockers, I prefer a selectable locker up front.
 
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FallonJeeper said:
You can better determine the gear ratio that will suit your needs based on transfer case.

With an automatic transmission and 37" tires you can go with either a 5.13 or 4.88 gears. 5.13 is best suited for a 2.72:1 low range transfer case, while you can get away with a 4.88 with a 4:1 low range transfer case.

The advantage of the 5.13 is definitely the off road performance. Your jeep will climb like a billy goat. The disadvantage is higher RPMs on the highway.

The advantage of the 4.88 is definitely highway performance. The disadvantage is off road performance with a 2.72:1 low range transfer case it will be doggish.
With a 4:1 low range transfer case you'd be ok.

Some people don't mind the higher RPMs at highway speeds because they'd prefer the performance off road. Since you'relooking at lockers, I guessing you don't have a Rubicon, so you probably have a 2.72:1 low range transfer case.
I'd go with 5.13 gears.

There's no right or wrong answer, just what is right for you.

And as far as lockers, I prefer a selectable locker up front.
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Thanks a lot, this clears up what I was wondering. Very informative.
 
JEEP93 said:
How exactly does that work with the throttle? Wouldn't that technically always engage in that case?
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When there's no power going to the pinion, the locker can ratchet and the diff can do its thing- differentiate revolution velocity between each axle. Example: going around a corner, most of the time you let off the throttle, turn, then power out. when you let off the throttle, a lunchbox will disengage and allow differential rotation. When you step on it again, it will lock up. They take getting used to, and yes your tire wear will increase to a point. They're not going to spontaneously vaporize into mist like you'd be led to believe by some people. I have (and have had) an Aussie (or two, in the 9er's case) in both my current ZJs and my past ZJs/XJs/MJ. You can't beat them for bang/buck comparison. That's a thousand extra dollars for things like gears, skids, tires... plus you don't have to screw around with air lines or mounting a compressor or running a cable or wires or any of the other selectable headaches. You can install an Aussie-style lunchbox in an hour, two hours tops, with basic hand tools, jack/jackstands, and a new diff cover gasket and fluid.
 
Yeah, there are those that swear by the 5.13, and also those that will tell you to never go above a 35" on a D30.

I always forget that non - Rubicons come with a D30. 4.88 would definitely be more survivable.

Somebody needs to do a flow chart sorted by tire size, transfer case low gear ratio, engine size axle type and recommended gear ratio.

That's a big decision. Only you can make.

Good luck!
 
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For what it's worth I just did the dynatrac trail leader package with 4.88s and for the rear pinion I was amazed at how much smaller the pinion was over the original 3.21. I chose 4.88 over the 5.13 to try and avoid the much smaller pinion and mine are both D44s I can't imagine how small the 5.13 pinion would be in a D30. But if your light on the skinny pedal I'm sure it will be fine.

Sent from my SAMSUNG-SM-G890A using WAYALIFE mobile app
 
I have a TJ with a 4.0 and a stock transfer case. It’s equipped with a dynatrac pro rock 60 with arb locker and 4:88:1 gears on 35’s. Can’t go wrong with arb. Although you do need to purchase an air compressor and run a line it is definitely worth the few extra hundred bucks!


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FallonJeeper said:
Yeah, there are those that swear by the 5.13, and also those that will tell you to never go above a 35" on a D30.

I always forget that non - Rubicons come with a D30. 4.88 would definitely be more survivable.

Somebody needs to do a flow chart sorted by tire size, transfer case low gear ratio, engine size axle type and recommended gear ratio.

That's a big decision. Only you can make.

Good luck!
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Any idea how often these actually blow out?
 
wrpaul said:
I have a TJ with a 4.0 and a stock transfer case. It’s equipped with a dynatrac pro rock 60 with arb locker and 4:88:1 gears on 35’s. Can’t go wrong with arb. Although you do need to purchase an air compressor and run a line it is definitely worth the few extra hundred bucks!


Sent from my iPhone using WAYALIFE mobile app
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Thanks for the locker response. Newb locker question, but how much benefit would I get with only lockers in the rear? Is it worth doing the front too?
 
JEEP93 said:
Any idea how often these actually blow out?
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Depends on how you use your Jeep. If you are thinking about a locker in the front, I would definitely stay away from 5.13. Even leaving the diff open, 5.13 is a really small pinion.

Any chance you'd be considering a front axle swap in the future? If so, may be better to wait until then.
 
We're regearing soon so I just happened to have a 4.88 set.

Here's a D30 pinion. 4.88 compared to 3.73.

IMG_20180120_161610_139.jpg

And a D44 pinion. 4.88 compared to 3.73.

IMG_20180120_161521_587.jpg

As you can see, the D44 is a lot more forgiving as the pinion gets smaller.
 
WJCO said:
Depends on how you use your Jeep. If you are thinking about a locker in the front, I would definitely stay away from 5.13. Even leaving the diff open, 5.13 is a really small pinion.

Any chance you'd be considering a front axle swap in the future? If so, may be better to wait until then.
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Not really trying to do a swap or lockers up front. I wheel once a month or so, but is mostly a DD. I would honestly like whatever gives the best on road benefit.
 
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