so,
im contemplating upgrading my 3.21's that came with my X and called my local "mod friendly" jeep dealership (Jeff Daniels Jeep in Lansdale PA) and asked for a quote.

i also have a cousin who is a mechanic and asked for his input on re-gearing. his advice to me... dont waste my money on the gears, spend it on trying to get more horsepower from this sadly underpowered engine, ie... chip, programmer, turbo, intake and /or exhaust system.



anyone else have some input? aside from "i should have gotten the taller gears when i bought it" (which is also what my cousin said)

 

3.21's? ugh.

I would personally regear if it was mine. I have 4.10's and with my 33's they are borderline, 4.56's or 4.88's would be more appropriate to stock conditions before the tire change on mine if you do the math.

I think you will get the most noticeable improvements in the power department with regearing over the minimal amount of horsepower you'll pick up with chips/programmers/exhaust. Not that those are bad investments, i am beginning some of them myself, but IMO gearing will help you more.

You will also adversely effect your mileage, if you care about that.

 

i forgot to add that my tires are equivalent to 33's

in talking to the guy at the shop, he recommended 4.56's.... said the 4.88's would be rough even with my 6th gear. i am considering 35's as my next tire and he still says 4.56's.

the best part of the re-gearing idea is my gf is looking for a big ticket x-mas gift for me, sssssoooooooooooo

as for the mileage, my mpg's are in the crapper now, how much worse can it get?

 

i am going to 35's at some point, I am at a toss between 4.88's & 5.13's myself, both come highly recommended to me. 4.88's slightly better milage, 5.13's slightly better power. 50~50 to me, cant make up my mind.

When i said 4.56's i had a couple people just tell me i would be sooooooooooorry i didnt go bigger for the price.

 

I am also curious about this question. I also have the 3.21's, with Rubi wheels and tires. Curious to know the cost. I think it is between $600 and $800 or so. Anyone else able to chime in on costs, and do you think that someone only marginally mechanically inclined can do it themself?

While I'm not positive, I think the re-gearing is a much better option than adding horsepower. Isn't the main problem the torque in 1st and 2nd gear?

Thnaks for posting the question. I've been wanting to do the same, but so far it seems like too much money to bother with unless/until I find more time to make more than a handful of off-road trips each year.

 

ill post the prices from the quote when i get it.

my biggest prob is mostly the 1st and 2nd gears... i also feel it when off roading, especially on uphill climbs.

as for doing it yourself, the general consensus is unless you have a real shop to do the work in, dont.

 

Thanks. Figured the work was probably way over my head, but thanks for the clarification. And I think you answered your own question by confirming that the main problem is in the lowest gears and when off-road. Re-gearing seems like a far better choice than adding horsepower.

As an aside, if you have the latest 4WD Hardware catalog, there is a chart on page 136 that is helpful in picking the most appropriate gears, FYI.

 

I'd go with the gears!


I also had a hard time deciding on a gear ratio.
The descision should be based on these things at a minimum:

Automatic or manual? ---autos will have lower RPM's at given speeds, and too high of gearing may not allow the overdrive to stay engaged at highway speed. Your manual is more forgiving.

What size tires WILL you have? ---if you will get 35's and stay there, 4.88s may be a better choice. If 37's are even a possibility, 5.13's may be the winner.

The Unlimited's extra weight should also be a thought, but you can only compensate "so much" for a weak engine.

Another consideration may be where you drive.
I drive often above 7,000 feet on highway through the mountains.
(and it sucks)
But I can go up the steepest pass at 60mph

With auto's, the Unlimited JK will downshift to second, regardless of gearing on steep passes.

If I had 5.13's I would be doing more like 55mph at the same high rpm.

My 4.88's and 35" tires with auto tranny do pretty good considering the stock engine performance with air intake.


The bottom line?
Everyone (including myself) has an opinion, and this topic is mainly subjected to personal preference.

 

Go with the gears!!! I have 5.13 with 35s and love it. I am really glad I didnt go 4.88. I would say if you do alot of higher speed fwy driving 5.13 may not be for you. It seems if I keep the speed under 70 im getting about 15 mpg. I would find a good off-road shop in your area. I would think the dealership is going to rape you for a gear change..

 

stick or auto?