Talk about lucky, my coworker's father rebuilds vintage vehicles (trucks, cars, jeeps, go-carts, etc) for fun and sometimes sells them if he doesn't fall in love with his builds. Anyway, he is very confident that he can help me regear my JK and is willing to do it free of charge. I was trying to save my money for a new mountain bike, but I have just about had it with the sluggishness of my JK and this is quite the opportunity: to regear free of labor charges. So I'm of course doing some mental shopping at the moment and reading up on regearing on JK-forum. Unfortunately, I can't decide on what gearing to go with according to my setup and needs. So for you well-experienced Jeepers on this matter, a little .2 cents would be great...

SETUP:
2 door JK
Automatic
D30 front and D44 rear (I have no intentions or money to swap my front axle)
3.73 gearing as of now
33x12.50 tires (eventually going to do 295/75R16 which is like 33.5x11.5)
3" coil lift that netted an actual 4" of lift

JK USAGE:
DD
Forest service roads (limited to almost no rock crawling)

ENVIRONMENT:
I live in Scottsdale, Arizona. The roads are fairly nice and flat around town, but the JK struggles to catch speed on the highway on-ramps. I also do a lot of camping and rock climbing up north (Sedona/Flagstaff/Page), so that few-thousand feet increase in elevation change causes the JK to eat gas and I'm forced to hit 3,300 to sometimes 4,000+ RPM's in order to make it up a hill, sometimes idling at anywhere from 50mph to 65mph unless I want to be almost red-lining. The speed limit up this elevation change is 70mph to 75mph. I would love to be able to maintain a constant speed of 75mph without having to overwork the engine and without guzzling my gas tank.

I don't do any hauling with a trailer behind the JK or put anything on the roof. All of my outdoor gear fits in the trunk space of the JK when I pull the rear seat out.

QUESTION:

1) Is any gear manufacturer better than the other? Or as long as the install and break-in period are done properly, any manufacturer will do?

2) Should I definitely look into an overhaul kit and not just the ring and pinion?

3) Yes, my JK is 4wd. I've read that taking off and leaving off the front driveshaft can positively effect gas mileage. Is this true? Regardless, I ask because I am really trying to preserve my money and so I am thinking of doing this regear in steps... I would only regear the rear of the JK as of now, and leave my front driveshaft off until finally regearing the front mainly so I don't dumbly throw my JK into 4wd with two different gears. Think this is good idea? Remember, at the moment my JK is like 95% my daily driver and 5% access road explorer. I don't plan to rock crawl anytime soon.

4) I was considering 4.56 gears. According to my usage, current set up, and environment, what gearing do you think is wisest in order to keep my RPM's from overreving up inclines, maintain a nice idle speed on highway driving, get me up those hills, and if possible, help out with the gas guzzling? I know that's asking for a lot, but any thoughts you can give me are much appreciated.

Thanks, and let me know if you need me to be more specific on something or have any questions to help give you better insight so you can help me out.

 

I think that's an awesome deal that you have someone who can help you do this. I had a similar experience... my father is a retired mechanic and he offered to help me do my gears. Not to say anything negative about my father, but we (him and I) made some mistakes... luckily we caught them before driving the Jeep, so the R&P and everything else was still perfectly good. However... I had to pay to take my Jeep to a professional shop and pay them the labor to finish the job right.

Not saying your friend isn't 100% capable of doing this right... but I've seen (and experienced) too much heart ache about DIY gear installs... have a backup plan (and money).



Which is better, Ford or Chevy?

No, seriously, you are going to hear a LOT of differing arguments with little backing info.

I went with Yukon, because it's what David @ Northridge sells, and I REALLY trust his judgement


Yes... get a full overhaul kit... don't risk it without it. Might as well do it right, and do it once.


I wouldn't do it in steps... seems like a PITA. Not to mention, I'd also have the nagging fear that somehow I'd be about to F somethin' up... even though if you disconnect your drive shaft you should be good


You will have a hard time getting 4.56s.... plus, with an Auto and 33s you should really be looking at 4.88s.

 

What problems did you and your dad run into that I should possibly look out for?

 

Here is a write-up... follow it to the 'T'
https://www.jk-forum.com/forums/show...?82262-Gearing

The problem we ran into was my dad got ahead of himself, and pressed the pinion bearing directly onto the pinion without any shims... again, not bashing him, I should have been paying close attention too.

Either way, he press the bearing on, right up against the pinion gear and then says, "Ok, what does the instructions say is the next step..." I reply that it's to do some measurements (or something like that) and press the bearing off and add more shims if necessary....

At this point we realize we're in over our heads, as we are not prepared to remove the bearing from the pinion as there was not shims and therefore no room to wedge our bearing removal tool

Also... not to scare you... but you should at least read these threads and see if there is anything you can learn from their costly mistakes:

https://www.jk-forum.com/forums/show...er-the-install

https://www.jk-forum.com/forums/show...uld-cause-this

 

with an auto and if you never plan on 35's go to the 4.88's. i was torn on what ratio to go with and went with 4.88 and i am very pleased. i have alot of extra weight(look at profile)

 

You have been here long enough to have seen just about a bazillion gearing threads, right? And all of them were saying basically the same things. The guys that do not have JK's or have not regeared their JK, will tell you 4.10 or 4.56 at most. But all of the guys that actually have Auto JKs and have regeared their auto JK's will tell you at least 4.88. (and many of use will tell you to go ahead and do 5.13s !!)

So -
4.56 will work
4.88 would be better
But, you have an auto. There is no reason not to go ahead and drop 5.13's in. There isn't a huge rpm difference, but the 5.13's will keep you in overdrive longer, which, contrary to popular belief, will save gas.

Yes, you can regear just the rear. Yes, you will want to pull that front driveshaft. And No, don't expect any huge mpg gains.
I ran an empty front housing for several months (not just a pulled driveshaft, but a completely empty housing as well), and noticed no increase in town. - I did not do any freeway during that time, so you may notice a little something there?

You will need either an Install Kit, or an Overhaul kit for each axle. The install kit is used for very low mileage axles, and you have to hope that your current bearings are not damaged, and that your coworkers father does not F them up when he removes/replaces/removes/replaces/removes/replaces/etc them.

With the exception of US Gears JK D44 4.88's, all JK gears are still produced overseas. There hasn't been anything saying that the gears from one of the Asian factories are any better or worse then the next. Compare price and warranty and get whatever you want.

 

Thank you so much for the replies. I will definitely read through those provided threads. Is there a big performance and/or proper install difference between an overhaul kit and an install kit?