I have a 92’ XJ with a D30 front/D35 rear and an AX-15 5-speed. Stock gearing tags show 3.07. Currently running 31s with some extra weight from heavy bumpers in the front and rear. Not sure what lift the previous owner put on but it looks somewhere around a 2.5”-3”

I’m looking to upgrade to some 33” BF mud-terrains and with my current setup she’s struggling a bit so I wanted to know the best way to go about regearing.

Doing some math, (33” x 3.07) / 28.3” (converting from metric size) = 3.58

I’ve read posts where people say 3.55 is the best gear for the manual transmission but I wanted to know if there’s any pro’s/cons’s to running a 3.73? No plans to lift it any higher or go bigger than 33”s for now, as she’s my daily driver. However, I’m looking to get somewhat good gas mileage on long distance trips and also be “quick” off the line since I have to do a fair bit of city driving to get into work and need to keep up .with traffic

I imagine for 3.73s I will need new carriers in the front and rear but in the interest of saving some $ I was wondering if it would be more effective to swap in a C8.25 that had the gear ratio or carriers I needed already and then just match the D30 in the front?

If you are going to 33s the best gear ratio for the standard tranny is 4.10 if you are running a little heavy. jBut that means a carrier change front and rear

Thanks. I’m looking to get a Yukon gear set for it and I’m okay with putting in new carriers, there’s just a lot of different opinions out there so just trying to figure out the best ratio that’s not too aggressive on the street or highway but also capable on the trail. Also any suggestions on carriers would be great

Carriers are carriers. Not much difference that I can tell. Yukon is good and so is Dana

If your spending money to regear, why not get a beefy rear axle? regear cost is high in parts and labor, might as well spend it on a stronger axle. my buddy has the high pinion 8 1/4 inch Chrysler rear end, I got a 9 inch Ford rear we both have D30 fronts however he has 31 tires, me I have 33 tires. Both of us have automatics with 4.11 ring and pinion ( I wish I had 4.56, but at least my xfer case is super high ratio low at 4.11 so that helps)
Get a high pinion as that allow improved drive shaft angle for lifted jeep. You are getting big tires, so get a bigger axle, most importantly for the rear

It will be more expensive if you build your D35 rear, then next year say " Ah shucks, I want a beefer rear end" and then have to go thru the regear on a different rear end$$$$$$$. If you think you might go to 35 tires later, well do it now and gear for them. Pick up a cheap bigger rear end used, ratio and internal condition dont matter so much as you will redo it anyway.

The most wasteful expensive part of jeeping is not going big enough, high enough, etc.. the first time, then having to repeat all that work later when after you determine you NEED more upgrade. That is exact.y why my ratio is wrong, prior owner geared for 31tires, then several years later went to 33 tires, but since he had recently regeared, it couldnt afford to do it again for the 33 tires. Why have I not regeared for the 33 tires? Well I might eventually go to 35 tires, I thus dont want to regear twice!

Also time to consider a locker perhaps? Do that now, at regear time, not later so as not to do the job twice.

Also have diff drilled and tapped for a drain plug, use a magnetic plug. Make fluid changes easy, so that you actually do them frequently. frequent fuid change is Important if you wheel hard, or travel thru water up to axles, etc...

4.56 dont even think about it just do it.

Don't spend any money on your Dana 35, swap an 8.25 in and for gears get 4.56.

To stick to topic to gearing alone, you will likely not feel any difference between 3.55 and 3.73. It's a lot of money and time for no discernable difference....I'd recommend not doing it. I ran 33s on a AX-15 with 4.56; it was wonderful. Strong and still hits highway speeds no problem. If I were to do it again, I would not go any lower than 4.56....especially in any place with hills.

Thanks for all the feedback. My tires were getting low on tread and I was trying to move up in size and get a lot done on the Jeep in a short period of time before winter hits. That’s why I was initially looking at just regearing. However, I can definitely see why it’s worth taking the time to set it up right. I’m definitely looking to upgrade my rear axle before I regear. It’s not terrible right now so I can just throw on a set of 31s to get by in the meantime. I know there’s a lot of threads on what axle to choose but any suggestions on what direction to go towards? I was looking at a C8.25 or Ford 8.8 depending on price/availability. From what everyone’s mentioned so far I would most likely go with a 4.56 ratio

A Chrysler 8.25 is a direct bolt in, a Ford 8.8 you will have to cut the old brackets off and weld spring perches and shock mounts on for it to work.

What gearwhine said.
3.55 3.73 are virtually the same on paper and were the rubber meets the rd.

I agree to get a 8.25 will have 3.55 gears if you can get the pair cheap it may be a Budget swsp then save for 4.56 and lockers.

I went with 4.88 on mine I run 35s

Well, just to add to the dilemma if you can find them, you can save a ton of money by finding an 8.25 and D30 from a 4 cyl XJ. 4.10s already set up and with some help you could change it all out yourself in one day. If you go with any 8.25, be sure to grab the U bolts for the rear springs. The 8.25 has a thicker housing

I didnt know the 4cyl had a 8.25.

I think the late 00 and 01 did. I could be wrong, but that is what I think I remember. And even if they didn't. Using the front 4.10 D30 already set up would be a significant saving on time and money and then regear the 8.25