CreepyJeeper

I have been comparing X models to Rubicon models and was wondering what the difference in the 3.21 and 4.1 axle ratios are and where I will really tell the difference assuming that the X model has the upgraded wheels and 32" tire package. Will I be able to tell while daily driving or is it mainly an off-road upgrade? Will the acceleration be the same, will the Rubicon seem to have more power, etc.

overmanjh

.89!!! On a serious note, yes you will get better performance both on road and off with the 4.10 gear ratio. Especially if you are going to be in the mountains or towing.

HappyCurmudgeon

Yes, you will notice it pretty much everywhere, especially with the larger tires on the X.

I drove a brand new X with the Sahara tires on it (32's) and 3:21's, it was very "doggy" feeling in comparrison to my Sahara with 4:10's. I was not impressed at all with the power. I had to play with turning the OD on/off rather often to get any "umph" out of the thing.

a Jeep with 4:10's will run a higher RPM at a given speed, than an identical jeep with 3:21's. This is basically the same effect as driving in a slightly lower gear than you need in a standard transmission vehicle. It keeps the rev's up, giving you the "feel" of more power when you stomp on the skinny pedal. The compromise is fuel mileage. the 3:21's will get a smidge better mpg as the engine will be running at a slower RPM to maintain the same speed, than the 4:10's.

Given the choice if it was me, I'd go for the one with the better gear ratio(4:10's). I dont care that its a Rubi, that holds no sway with me. I am purely speaking my opinion on the gearing. It will consume ever so slightly just a smidge more gas, but to me that is WAY more than worth it in terms of power.

RedneckJeep

That's actually a better answer than you might imagine. .89 is the mathematical difference. Think of it this way....most overdrive ratios are .69. I believe that's what the JK's is. So, you can easily tell the difference in a .69 variance when the Jeep shifts from third to fourth...BEFORE converter lockup. Though the OD ratio isn't quite as steep as .89, it gives a good base of comparison. A .89 varaition in gear ratio is a huge difference.

db09JKU

Need to change your name to Educated Redneck

Ge99ne

It's already been said here, but HUGE DIFFERENCE. When I bought my 2007 there was a bone stock x with 3.21's and an s package x with an auto trany & all the electric doodads. I drove them back to back and the auto felt more peppy than the six speed.

If I was an engineer at jeep there woulb be no 3.21 option. And certainly not with the auto tranny. The rpms are just too low for the power curve of our enginge. It would be fine withthe old straight 6, but you gotta wind up that 3.8 to get some power out of it. It's like they ignore the whole aerodynamics of a brick side of the equation when determining final gear ratios. I imaginge a 15 mph gust of wind would cause a downshift at highway speeds.

Get the 4.10's if you can. If you are regearing anyway I suppose it doesn't matter.

F200

If an X is more in line with the budget then find one with the tow package. That gives you 3.73's, which aren't bad. CM

drschem

OK. axle ratio 101. For a 3.21, the wheel (axle) turns one time for every 3.21 turns of the drive shaft. For a 4.10, it's 4.1 turns of the drive shaft for every turn of the wheel. This is about the same as driving one gear down on the shifter. So, if you want the extra power and don't mind the extra engine noise and worse fuel economy, put your shifter in "2" and drive. The advantage of the 4.10 is in starting off or when going extremely slow. This gives the engine the mechanical advantage it needs to turn the wheels.

Chainsawjames

4.10's all the way. The 3.8 pairs well with the 4.10. I have no problems in the mountains or pulling out in traffic. I said "pulling out", hehehehe.

rlabbott

I got lucky and got an 07 Unlimited Sahara with the 4:10 tow package. Now you can get the 4:10 only on the Rubi. (07 was the only year for 4:10 option on Sahara.)

I also have a 6 speed. I cannot imagine driving this thing with less than the 4:10. Coming from the previous TJ, the JK simply needs to wind out more to have any power.

If I had to get a new Wrangler now, I would have to go Rubi to get the factory 4:10. There is no way I could stand any less power.

For other reasons, the Rubi will have better resale if/when you get rid of it.

The only other option in my opinion is: If you plan on a big lift and big wheels, you'll have to regear anyway... to 4.88 or 5.13 in the extreme. Thats changes everything... but you might still want the Dana 44 differentials. The Rubi has D44s both ends. My 07 Sahara is D44 rear and D35 front.

Happy shopping!