dana 30 with 37" tires ?

[dbach]

i have a 2013 jku automatic tera flex dana 30 housing 4:56 gears and 35:tires . 35s are starting to wear out i would like to replace them with 37s .i think axle will hold up well , just afraid of losing power , power with 35s is fine . what do you think ? another gear change would be too expensive now

 

[Greg]

I think it would be OK far as gearing.... not ideal, but it would work decently. Where you will see the JKU needing deeper gears is over 70 MPH, IMO. Around town, on the highway it'll probably be fine. In the mountains at freeway speeds I think you'll be dropping down into 4th and 3rd gear at times, working the engine harder than it does now.

The Pentastar and the 5 speed auto both make great use of power and are a great combo for JK's... ideally you'd be running 4.88's for 37's but 4.56's aren't so far off that it's not an option.

I'd be curious about the u-joints and ball joints holding up to 37's on the trail! I'm sure they'll be OK with careful driving, but still curious.

 

[kmboren]

A dana 30 with 3 7s with any type of serious wheeling will see breakage. Better start caring parts to change it out.

 

[Hickey]

I agree with Greg. Rock on.

 

[Jay5.9L]

When I changed axles I also when from 4:56 and 35s to 4:88 and 37 which is mechanically almost identical. I gained a lot more weight per corner which took a little pep out of my Jeep (CJ with. 4.0l). Since your not changing gears I bet you will feel a similar effect

 

[Bart]

I hate to be harsh, but if you do any wheeling at all that's just an axle looking for a place to break down. It can be done, but.......

 

[rholbrook]

I go to Moab with a guy that is running the exact setup as you want to run (Dana 30, 4:56 with 37s) and he has had zero issues in the 5 or so I have wheeled with him. He isn't out there hammering it bouncing up things either. He is very confident in his jeep and his driving ability off road. He does just fine, the hills are where he struggles to keep up if we drive the jeeps to Moab up over SF Canyon but other than that he is fine.

 

[RockChucker]

I think it would be OK far as gearing.... not ideal, but it would work decently. Where you will see the JKU needing deeper gears is over 70 MPH, IMO. Around town, on the highway it'll probably be fine. In the mountains at freeway speeds I think you'll be dropping down into 4th and 3rd gear at times, working the engine harder than it does now.

The Pentastar and the 5 speed auto both make great use of power and are a great combo for JK's... ideally you'd be running 4.88's for 37's but 4.56's aren't so far off that it's not an option.

I'd be curious about the u-joints and ball joints holding up to 37's on the trail! I'm sure they'll be OK with careful driving, but still curious.

He has the exact same ball joints and u joints that you do in your D44. In 2013, Jeep moved to the larger 1350 sized u joint both the 30 and 44. Should be fine. I drove a 2012 2 door around on 38x14.50s on beadlocks with 3.73 gears. It would pull all the hills between SL and Moab no sweat. It dropped down to 3rd at times, but really wasn't a concern. Seems like the pentastar loves to sing.

 

[Herzog]

I hate to be harsh, but if you do any wheeling at all that's just an axle looking for a place to break down. It can be done, but.......

I enjoyed the challenge of beefing up lighter components and playing the weight to power ratio game with everything, but even with D44s that had all the chromoly parts running 38" tires, I ALWAYS worried. The peace of mind that comes with having the right axles is so much worth it.

But yep! It can be done.

 

[dbach]

thanks everyone for your advise ! i'am thinking i will be just fine also , if it don't work i'll just go back to 35s .probably wont happen untill the first of the year i'll let you now how it turns out

 

[Cody]

As someone who used to break stock d44 parts with 37's and watch grand cherokee people break d30 parts without too much trouble, I think it's a bad idea.

I mean, as has been said, if you're locked up and aren't out on Pritchett trying to be proud, then I'm sure you can keep it together. But, at that point what are you achieving with 37's? I would contend that any trail that you need to size up from your 35's to get through is probably not a trail to be testing the mettle of stock d30 parts on 37's, you know?

 

[Shawn]

The general rule has always been D30 limit is 35" tire. Is the JK D30 stronger than a non-JK D30? I like hearing about the 1350's in the D30 JK's, that is cool, but is the shaft up to the par?

 

[mesha]

Run the 37s. If you break, then buy a 60

 

[Bart]

Good luck. Like a few that have posted I ran 37s with a 30 and a couple of 44s. I'm very light on the skinny pedal and made due. I just got tired of breaking in bad spots and taking the time and expense of replacing parts. YMMV.