3.73 gear ratio and 35's on 2013 JKU Auto

[adamsnewone]

I just got mine done. It's a 2013 2 door with 35 mt/r kevlars. I had 3.73, also have a 80 mile commute everyday. The hills are what kills it. On long trips I could get up to 17.5-18. Normally about 15 though. I just regeared to 4.56. Seems to be a lot peppier. I'll have to wait and see how the mileage will do. But the power is definitely there.

 

[suicideking]

If I had an idea how much a used Dana 44 front would be that may be factored into my upgrade...but going 5K for a Prorock 44 just isn't going to work...I would be the swallow being crushed by my coconut wielding wife!

Donny

I hear ya there. I went that route and found a near new Rubi D44 with around 1000 miles for $1500. Put on some C gussets and a diff cover and you're good. Sure, I'd like a PR 44 (or 60) too someday. Unless my D44 starts to so signs of problems, it's just hard to justify spending that much.

 

[matt1171]

I hear ya there. I went that route and found a near new Rubi D44 with around 1000 miles for $1500. Put on some C gussets and a diff cover and you're good. Sure, I'd like a PR 44 (or 60) too someday. Unless my D44 starts to so signs of problems, it's just hard to justify spending that much.

Not to say you wasted $1500 but the only difference in a factory D44 and D30 is the size of the ring and pinion. Everything else from the Diff out is identical. Most ppl think the rubi 44s are stronger but they aren't - except for the ring and pinion because they are larger. Not sure that is worth the price of the upgrade.

 

[KJ_CJtoJK]

If you do the math on the gearing (ignoring increased weight) the final drive ratio of 35" tires with 3.73 gears will be the same as stock 32" tires and 3.50 gears (rpm/mph the same in 5th gear at 60MPH). This is a better ratio than many stock jeeps come from the factory with 32" tires and 3.21 gears (Sport S & Sahara).

I have a 2012 2 dr with manual and it is really not that bad at all - I would do it again. I get a consistent 17 mpg on my 12 mile in town commute to work. I honestly could not feel the difference at all driving the manual around town (if anything, I like the first gear ratio better now).

 

[suicideking]

Not to say you wasted $1500 but the only difference in a factory D44 and D30 is the size of the ring and pinion. Everything else from the Diff out is identical. Most ppl think the rubi 44s are stronger but they aren't - except for the ring and pinion because they are larger. Not sure that is worth the price of the upgrade.

Just depends on your priorities. If you want 35's, the D44 is sufficient. If you're planning to do 37's, probably want to start with a PR44 or 60.

At the time I did the axle swap, I was on 33's wanting to get 35's. Doing the axle swap, I also got a locker and an axle strong enough for 35's. Many say it's not much different than a D30, but the larger diff will handle 5.13 gears which are low enough for 37's (my next step). I don't know many that have broken their D44. Those that did, we're consciously taking risks that the axle couldn't handle, and knew it would eventually happen.

If I do break it, hopefully enough pieces will survive so I can get the PR44 housing and transfer everything. I still may eventually just buy the housing and transfer everything. Then I can sell the housing and get back some of my original investment.

Plus, for most, $5K is just not a realistic price. It's much easier to stomach spending $1500.

 

[Simmons]

I'm running 35 with the 373s till I get my new gears in. And yea the mpg sucks hilly road witch is most Im about 12-13.5 granny mode 14 max and that's on strait roads

 

[ghost13]

i run 35 with 321 and a 6 spd.... i went and bought a second set of tires for the commutinf a/t for street and my m/t for off roading....im getting 18.43 mpg on the highway...which aint to bad...... but gears going in next weekend......:rock:

 

[Donny]

Just depends on your priorities. If you want 35's, the D44 is sufficient. If you're planning to do 37's, probably want to start with a PR44 or 60.

At the time I did the axle swap, I was on 33's wanting to get 35's. Doing the axle swap, I also got a locker and an axle strong enough for 35's. Many say it's not much different than a D30, but the larger diff will handle 5.13 gears which are low enough for 37's (my next step). I don't know many that have broken their D44. Those that did, we're consciously taking risks that the axle couldn't handle, and knew it would eventually happen.

If I do break it, hopefully enough pieces will survive so I can get the PR44 housing and transfer everything. I still may eventually just buy the housing and transfer everything. Then I can sell the housing and get back some of my original investment.

Plus, for most, $5K is just not a realistic price. It's much easier to stomach spending $1500.

I guess if I can buy 3 D44s for the price of one PR44 I'll go D44. I haven't seen anyone personally break a D44. Now in some of the wayalife vids it happens but I also assume many of those type situations I will never find myself in. My wallet cannot withstand that type of carnage more than once a year! Too many other toys and things I enjoy doing.

Donny

 

[terrabit]

So my SLR is 14.75 x 2= 29.5. So does this mean that my 255/75r17 are 29.5 in diameter instead of 32.1? Thanks

Only if the top of your tire is as weighted as the bottom. In other words no, you dusche, the radius of your tire is shorter ONLY WHERE IT CONTACTS THE GROUND!!!

Sorry, I couldn't resist.

 

[Cajun JK]

Only if the top of your tire is as weighted as the bottom. In other words no, you dusche, the radius of your tire is shorter ONLY WHERE IT CONTACTS THE GROUND!!!

Sorry, I couldn't resist.

I understand that part. If I follow the directions from Discount tire on page 1 they say with vehicle fully loaded and tires aired up measure the SLR and it gives you a more accurate diameter of the tire. I'm trying to understand how that is so being the tire is flat on the bottom you will lose some height.