AMPDinCOLORADO

So I have looked at the charts, I have an automatic 2014 Jku sport, but I haven't made the choice. I live in Colorado, currently have 35's and 3.73 gearing, I know I want/need to change my gearing, I don't want to go to low like 4.88 as I don't see myself getting 37inch tires. As far as drivability, highway and trails, what kind of improvements can I expect from the 4.10 vs the 4.56 gearing? Maybe I'm just looking for a nudge in either direction.. halp? Anybody?

kejtar

I have auto 2012 with 32's and 4.11's are just right. With 35s I would definitely go with 4.88's. 4.56's would make life bearable but you'd be surprised how much better your life will be with 4.88's!

I run 4.88's on my XJ - I know 4.0, manual - apples / oranges BUT the principle idea is the same - your drivetrain is working way too hard with 3.73's and seeing how much it costs to regear, you might as well do it right the first time around.

Btw, if you had Rubicon - for the trails 4:1 would help alleviate the 4.56's but without it you'd almost want to go 5.13's BUT that would make the highway driving a bit more "interesting". 4.88's would give you a good balance of things.

akguy09

3.73 to 4.10 will only give you about a 200 RPM change, doesnt seem like enough to be worth the expense, where as 4.56 would be about 500 RPM change

http://www.ringpinionservice.com/calculators.html

This calculator will let you put in all factors, tire, speed, R&P, trans ratio. Should help you make a good decision

resharp001

The difference between 3.73 and 4.10 will be like a fart in the wind, and the cost would not be worthwhile. You'd have to go 4.56 to see a nice difference and be where you probalby want to be. 4.88s with 35s is getting a bit too aggressive.

kejtar

How do you figure that 4.88's are too aggressive? There are really two parts to this equation. One is tire diameter and another one is vehicle weight. Looking at the chart itself yeah - you might be fine with 4.56's..... Life experience - 4.56's will make you wish for more... 4.88's you will be happy with.

Yes, folks will post up saying that any gear ratio is fine... hell... I have seen folks make a case for 3.23's and 35's..... it sounded good till you really thought about it....

What you might want to do is find someone in your area that will let you take their rig for a spin

resharp001

Well, I have 37" Nittos, a 3.6L, and 5.13 gears. That's about as comparable as you're gonna get with 4.88s on 35s with the 3.6L. I can tell you that most people on here aren't gonna like pushing 3k RPMs at 75mph. It gets old....fast. If you have a heavier foot it's even worse. 80mph is maybe 3150 RPMs for me and the gas gauge drops fast. I don't mind it for the off road benefits of the gearing, but MOST people are not looking for that.

I'll presume you have 35s and 4.88s yourself and you're happy with that set up?

edit - nm, i see you have 4.10 and 32s. So you're basing your opinion on having 4.88s in your XJ?

karls10jk

This is actually the best advice you can take. Drive another jeep equipped similarly to yours to see how you like the feel.

kejtar

Well... 80MPH.... there is a middle ground there someplace but you touch on a topic that really raises a big question - how do you want to use the rig? If cruising at 80 is expected to be a regular thing, then yes - you would keep the gears shallower. If you go on rocks and tougher trails a bit and or expect to tow a trailer than you go deeper. Again I stand by my recommendation to not even think about 4.10s and lean towards 4.88s rather then 4.56s.

resharp001

I'm not trying to be jerky or anything. Just saying....unless you stick to the city, that low gearing is a killer on the interstate. I had 3.73, 4.10, and now 5.13 on the same jeep, and just base my opinion on personal experience. If I didn't see the off road benefit of my gearing, it would drive me crazy. I do a lot of wheelin', and I typically have a couple 10-14hr trips a year with several 2-5 hr trips to parks. I'd say I have a pretty decent mix of city/highway driving in general. Gearing doesn't bother me at all in the city, but highway driving I'd definitely prefer to be few hundred RPMs lower at cruising speed.

I will agree that gearing is not something you want to repeat, so do your homework and get it right the first time.

kejtar

On the XJ I went from 4.11s to 4.88s while on 31s because I knew 33s and later 35s were in my future. I drove it like that 70mph to Rubicon and back... Not really an issue... Btw that wad my daily driver across LA county 60 miles each way....

I do understand where you're coming from but 4.88s with 35s are not an issue. I have driven JK for a few miles that was geared that way and it didnt bother me. 5.13 though would be on the painful side.