rj'sjeep

Or maybe dodging one I have an 08 rubicon auto I am about to put new tires on it an am looking at 315 70 17 maybe the toyo at -2 maybe nit terra grappler g-2 maybe bfg KO2 in their 34 x10.5
I have a lift ome hd so room is not an issue.
Iknow there are tons of threads about gearing and such but right now that's out of the budget.

So how bad do all of you with the 3.8 auto rubicon ( 4:10 gears) really hate driving ?
and is there any one who lives around encinitas, or carlsbad CA that would let me drive their ride to see what I think ? I know its a lot to ask but >>>>>


Was going to sell this one and get a new 15 with a stick before I put tires on it but That doesn't look like it is gonna happen

nthinuf

Good call, definitely try and find someone. Since this forum moves so fast, toss a post down in the Staging Area for your region.

If you find that the gearing sucks or keeps dropping in and out of overdrive, you can always press the OD/Off button. Plug the numbers into the gearing chart (in the faq's, just scroll down to them) and see what you come up with. Search a few threads to see if you can find some guestimates on the actual measured height of whatever tire you want and plug the number in with your current gears. Once you find that rpm, divide it by .69 to get the OD/Off rpms.

Using 4.10's and 34" measured, you get 1958 @ 70, and 2837 @ 70 with OD Off. Flat roads at sea level, you may be ok in OD. The od/off is a bit high, but this engine doesn't seem to have any problems with it. (actually not far off from when I ran short 35's with 5.38's)

Joe_B

I ran 33's with 4.10's (3.8 & auto) and it was alright. I moved up to 35's and lasted 2 months before going to 5.13's. Swapping out the gears was the best thing I could have done.

You can try it without swapping gears but I think you'll end up wanting a lower ratio. I wish I went 5.38s at times since I have 37s on order.

Good luck!

Blacksahara2011

I have an '11 Sahara with 3.73 and 34" trail grapplers. Before install, I heard so many people talk about how bad it was going to be without regearing. It wasn't in the budget at the time so I stuck with what I have and I was pretty surprised. It def does not drive like stock, but it is not as bad as people make it out to be. All depends how you drive. It's a slug going uphill but if you live in a flat region, it shouldnt be that bad for the time being. Good luck

Christian13

Hi. I didn't want to start a new thread so I found one that is kind of relevant.
I have a 2011 unlimited auto with 35s.
I am about to change gears and am not sure whether to go with 5.13 or 5.38
I will upgrade to 37s when my 35s are done. I have looked at the gearing charts and think that the 5.38 would be the best option but hope it is not to short as there seems to be so many people who are on those tire sizes with 4.10 4.88 and claim they have no issue.

nthinuf

You have a non-rubicon, with a d30 front? 5.38's are no longer made for that axle, so unless you move to a new front d44, 5.13's are the highest (numeric) ratio. (Though i suppose it's possible that you might find a set of d30 5.38's gathering dust on a shelf somewhere?)

For all of the comments you are seeing - remember that there will be different wants/needs depending on which engine they have, which transmission, what elevation they live at, how and where they drive, etc, etc, etc. And many people with the newer 3.6 engines are happy with lower numeric gearing than those with 3.8 auto's. For me, at altitude with a 3.8 4door, 5.13's were ok with 35's. But I then went on to 5.38's when I swapped out the d30 for a d44.

Christian13

Where I live and wheel is full of hills and highway driving is minimal. Sorry I didn't mention I am upgrading to terra 60s so ratios are not an issue. Sounds like 5.38 is still the best option. Thanks for your help.

Christian13

Or should I go even higher?