which stock axle for a swap?

[Dmorton]

I have the much-maligned 3.07's in my 2006 4.0 6 speed. There is a guy relatively local to me that parts out TJ's and he seems to always have plenty of axle sets for sale. He recently listed a Dana 44/Dana 30 with a 3.73 and a Dana 35/Dana 30 with a 4.10. I am not looking to off road my jeep at all, and the price difference for the Dana 44 or Dana 35 is only a few hundred bucks. My reasons for wanting to change axles are : 1) better fuel mileage, 2) because it seems like a fun project 3) Better overall drivability

Given the choice, which would you prefer, The Dana 44 with 3.73 or Dana 35 with 4.10?

 

[imahnu]

For such a small change in price I think the 30/44 combo would be better because it gives the ability to off-road in the future should the want arise without having to do as many modifications.

For fuel mileage the higher gear the better the fuel mileage will be so the 3.73 would return better mpg than the 4.10 would. I don't think the 4.10s would be a big enough difference over the 3.73s to be worth getting a Dana 35.

Plus if you do decide to move to bigger tires you'll likely want to re gear anyways.

Hope that helps!

 

[Jerry Bransford]

I have the much-maligned 3.07's in my 2006 4.0 6 speed. There is a guy relatively local to me that parts out TJ's and he seems to always have plenty of axle sets for sale. He recently listed a Dana 44/Dana 30 with a 3.73 and a Dana 35/Dana 30 with a 4.10. I am not looking to off road my jeep at all, and the price difference for the Dana 44 or Dana 35 is only a few hundred bucks. My reasons for wanting to change axles are : 1) better fuel mileage, 2) because it seems like a fun project 3) Better overall drivability

Given the choice, which would you prefer, The Dana 44 with 3.73 or Dana 35 with 4.10?

I'd definitely go for the Dana 44/Dana 30 combination, assuming you're still running factory size tires or close to that.

 

[Jerry Bransford]

For fuel mileage the higher gear the better the fuel mileage will be so the 3.73 would return better mpg than the 4.10 would.

Sometimes but not always. With my 35" tire size and 42RLE transmission, my engine was lugging slightly with a 4.88 axle ratio. It never got above 11-something highway mpg. To fix the lugging I regeared to 5.38 to raise the engine rpms which really helped the Jeep drive better. What was surprising was my mpg went up to 14.6 on the highway after converting from 4.88 to 5.38. That's a 25% boost in mpg by regearing from 4.88 to 5.38.

 

[Dmorton]

I'd definitely go for the Dana 44/Dana 30 combination, assuming you're still running factory size tires or close to that.

I should've mentioned in the original post, running 32's on 17 inch rims.

 

[Jerry Bransford]

I should've mentioned in the original post, running 32's on 17 inch rims.

4.10 would be a better ratio than 3.73 for that size tire.

Depending on your $$$ situation I'd go for the Dana 30/Dana 44 combination and then regear the axles to 4.10 later. But if $$$ is too tight for that I'd go for the Dana 35 with 4.10 ratio since you don't plan to offroad.

The Dana 44 is a much better and stronger axle than the Dana 35 but the Dana 35 is fine for your 32" size of tires and would hold up fine to easier forms of offroading.

 

[imahnu]

Sometimes but not always. With my 35" tire size and 42RLE transmission, my engine was lugging slightly with a 4.88 axle ratio. It never got above 11-something highway mpg. To fix the lugging I regeared to 5.38 to raise the engine rpms which really helped the Jeep drive better. What was surprising was my mpg went up to 14.6 on the highway after converting from 4.88 to 5.38. That's a 25% boost in mpg by regearing from 4.88 to 5.38.

Jerry,

Correct. I have the same situation happen on my truck that's constantly loaded down pretty heavy and runs (slightly) bigger than 35" tires. It gets better fuel mileage with 3.92s vs the 3.21s my old truck had. I should've made the statement clear that its based on the stock tire size.

 

[Dmorton]

Is the Dana 44 a direct bolt up going from the Dana 35?

 

[Jerry Bransford]

Is the Dana 44 a direct bolt up going from the Dana 35?

Yes, that's an easy bolt-in job. I did the same conversion in 1999 or so. You can also keep your existing brakes attached to your brake lines while doing the conversion and than bolt them back into place on the new axles.

 

[suicideking]

Not sure how much you're paying for both axles? If you already have a Dana 44/Dana 30, might be better to re-gear.

As Jerry mentioned, Dana 44 is stronger, but the Dana 35 combo has slightly lower gears. Though not by much.

 

[Dmorton]

Not sure how much you're paying for both axles? If you already have a Dana 44/Dana 30, might be better to re-gear.

As Jerry mentioned, Dana 44 is stronger, but the Dana 35 combo has slightly lower gears. Though not by much.

Dana 35 in the rear right now with 3.07's. From what I understand, the carrier will not support 3.73 or lower gears.

 

[pagrey]

Don't expect returns on the mileage, maybe more smiles. Carriers are cheap if you re-gear, it wont add much to the total cost. Most good gear shops can find used carriers and even new ones aren't too expensive. I wouldn't let that determine your choice of gears.

 

[NashvilleTJ]

... It gets better fuel mileage with 3.92s vs the 3.21s my old truck had. ...

All I know is that when I went to 392 in my rig, my mileage went to shit....

 

[pagrey]

Could be worse, you could have gone with 427