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Discussion Starter #1
Is anyone aware of any 4.27 or 4.30 gear sets for the "next gen" Dana30/Dana44?

I've looked around a little bit and haven't come across anything. Just curious if someone had any info on those ratios availability, or lack thereof?
 

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Nobody makes those ratios for the JK axles.

The D30 never had them available as far as I know. You can find 4.27's for the old generation D44 but they're rarely in stock. The Ford 9" uses a 4.30 if you can find it. Some of the bigger axles may also have something in that range.
 

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Discussion Starter #4
Thanks. I figured since they weren't readily listed, that they probably weren't available. Sometimes there are obscure sources though. Oh well.
 

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Is anyone aware of any 4.27 or 4.30 gear sets for the "next gen" Dana30/Dana44?

I've looked around a little bit and haven't come across anything. Just curious if someone had any info on those ratios availability, or lack thereof?
If you are using a gear calculator and it is coming up 4.27 or 4.30, go to the next lower gear which would be a 4.56. You'll want a little lower gearing than what is needed just because of diameter to make up for the bigger tires being heavier.
 

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Discussion Starter #6
If you are using a gear calculator and it is coming up 4.27 or 4.30, go to the next lower gear which would be a 4.56. You'll want a little lower gearing than what is needed just because of diameter to make up for the bigger tires being heavier.
That was exactly my thinking. I was planning on 4.10's but thought a 4.27/4.30 gear set would help offset the extra weight some. Sure would be a nice option for our axles, if one of those were available.

It's my daily driver for now but I think I'm just going to say "F-it" and do 4.56's. I'll just deal with the slightly higher highway rpm's, for the benefit of the grunt I'll gain for climbing long and steep sand hills at the dunes.
 

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Discussion Starter #10
He's right. There's about a 6% difference between the two. You wouldn't notice much difference.
Right taken tire size into account too. But there is a larger difference between 4.10 and 4.56, which is why I asked about the 4.27/4.30 option. Either way, they are apparently not available so discussion is moot.
 

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Discussion Starter #12
Certainly, but that really is the point. 6% is not worth the hassle of a gear change whereas 10-12% would make a worthwhile difference.

I hear ya. Take into account the more powerful 3.6 and the fact that it's a daily driver and you'd better understand my (now abandoned) search for those ratios.

Besides, anything is "worthwhile" when re-gearing from 3.21's.
 

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I hear ya. Take into account the more powerful 3.6 and the fact that it's a daily driver and you'd better understand my (now abandoned) search for those ratios. Besides, anything is "worthwhile" when re-gearing from 3.21's.
I fully understand .. The power difference is negligible under 4000rpm. What makes the difference is the transmissions. Now back to the gear change. Going from 3.21 to anything even 3.73 is an upgrade. From 3.21 to 4.56 would be an excellent improvement for 35" tires for a DD.

I DD my rig 5 days a week 70 miles a day on 37" tires with 5.38 gears (the equivalent gear for your 3.6 would be 4.88). My average highway mileage is 16-17 mpg. The motor runs 2100rpm in Overdrive at 60mph.
 

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Discussion Starter #14
Ordered 4.56's and an overhaul kit from 4WS.
Hopefully it's not too much with a tire that actually measures 34.5" with the weight of the JKU on them. I kept leaning towards a bit more performance anyway.
 

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Ordered 4.56's and an overhaul kit from 4WS. Hopefully it's not too much with a tire that actually measures 34.5" with the weight of the JKU on them. I kept leaning towards a bit more performance anyway.
You will be more then happy with the change.
 

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Discussion Starter #16
I'm sure I will. Playing with a gear calculator is showing around ~27-2800rpm at 75. It should get up and skoot pretty good!
 
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