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4.88 gears

25K views 108 replies 33 participants last post by  XTJake 
#1 ·
Hey guys I'm wanting to step up to different gears in my JKU. Currently have 3.21's. Dana 30/44. I do about 100miles a day highway to and from work. I'm wanting to go bigger gears so I can finally go 35's in the future. Looking at a bunch of options and seems lots of people like 4.88 gears. Can anyone help with if this is a good or bad route to go? Any other gears that may work better??? Keep in mind it's my daily and I do drive a lot. I don't mind averaging 15/16 mpgs but don't wanna re-gear and go down to 10mpg or anything crazy like that. Any advice or help is much appreciated.


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#2 ·
Hey AJLO12,

Sounds like you're thinking ahead which great!

If you're thinking about stepping up to 35's in the future and drive 100 miles a day on the highway then I think 4.88's may be a little too steep of a re-gear. If you're looking to save your MPG, but still re-gain your acceleration after switching to larger tires than I would recommend either 4.56 gears or 4.10's. The best way to base your decision would be to checkout this chart posted below. I'm not sure if you have a manual or automatic trans, so both are posted below.

If you have any questions just let me know!

-Jake

 
#94 · (Edited)
Is the tire size on the left side of the chart the "quoted" or "listed" size that the mfg. provides or is it the actual tire size after installed on the Jeep? As we all know, there can be a big difference between the two.
 
#3 ·
With your driving, I wouldnt go beyond 4.56. It's also plenty for 35's down the line (and even select 37's - KO2's). Lots of people on this forum are fans of shorter gears (higher number: 4.88, 5.13 etc..) but their uses maybe different.

Jake (above) is right on with his advice
 
#4 ·
The shop I'm working with is currently ordering parts for my regear. I decided on 4.56 just for the highway reason that you're talking about. We take one or two trips a year from New York to Michigan and every other weekend in the summer we take a trip to camp about 120 miles. I don't want to be running 3000 RPM's on a 12 Hour trip.
 
#8 ·
I agree. 4.10's are a much better choice for your type of driving.
 
#9 ·
I just went 3.21 to 4.56 in my 2015 JKU. I daily drive 68 miles round trip (55-65 mph mostly/ no highways). W/ the exception of the extreme cold weather my mileage has not dropped significantly compare to the same temp range last winter. I'll find out for sure once the weather warms up.
what I have noticed is much less down shifting to keep it up to speed w/ the winter winds etc.
I think a lot of guys w/ automatics feel they have not lost too much power if they are light footed from a dead stop and don't really pay attention to what gear the trans has shifted to. The auto downshifted a lot to keep me up to speed when it was windy or I hit some inclines because I had to give it more gas to keep it up to speed.
Just my thoughts.
 
#12 ·
Why don't you go drive a JKUR with 4.10s? See how it feels- and remember you will be more sluggish with 35s. Gears are very much based on opinion. I am sure Brando's numbers are correct but keep in mind that the average person will see a drop in MPG. There is a reason Jeep put 3.21s in there. You and he would be one of the few people where MPG comes into play for a valid reason- with that mileage 4.10s do make more sense. Otherwise 4.56s all day long.
Install is not easy. For the pros unless you have a well-stocked garage and a decent amount of expertise.
Why are you re-gearing BEFORE The tires? Because this is what's going to happen- you'll be ecstatic to get away from 3.21s on your current tires. You'll be like a kid in a candy store. Then you'll put on 35" tires- and its going to feel sluggish because you were used to the stockers on 4.10s. Cart before the horse a little? Why not get the tires and plan to re-gear right after?
 
#13 ·
Dang never thought of it this way. Figured if I regear before tires it would be better than the other way around. But yes I see your point. I'll have to go check out a new JKUR soon! Thanks for the advice!!


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#14 ·
Is there a chart for the 3.8L? I'm building towards the future, about 3 years from now when we move to Arizona and will be doing more off-roading in that enviroment. I rarely drive above 65 so I was planning to go from 4.10 to 4.88 with 35" but you all have me second guessing things.
 
#20 ·
i drive 130 miles a day with 35's, and went with 4.56's, no regrets, and i do offorad on the weekends, so the combination is perfect for my driving/usage, + i have no intentions of going higher than 35's.
 
#21 ·
Perfect! Good to know! Thank for man! Glad to see there's more people out there that drive insane miles daily like me. Everyone around me keep giving me crazy looks for driving my JKU so much as a daily.


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#23 ·
I have 2012 JKU with 35s aftermarket bumpers, winch, and skid plate among other things. It is my DD, but I work from home so light driving. Several hour long road trips are fairly common to get to good wheeling places. I am currently have 3.73s and considering 4.88s over the 4.56s due to the extra weight of accessories. I don't want a massive drop in MPG, but want better off-road ability. Recommendations?
 
#25 ·
I'd do 4.56. Next time youre driving down the highway keep her steady at 2450rpm, then jump to 2650 rpm and see how enjoyable that will be long distance. At 65mph I'm at 2450 with my 35s, 4.56 gears. My jeep is s heavy pig as well. I'm extremely happy I didn't go 4.88. It would have been too much for my needs. I know everyone says it's only 200 rpm difference, but the difference between 2450 and 2650 is VERY noticeable. Mind you I'm being generous with 65 mph so chances are you'll be doing over 70 which makes it even more noticeable. Again if that doesn't matter to you, then by all means go 4.88. I'm just a regular guy that dailys his jeep and occasionally takes it offroading. I have zero interest in crawling and do not plan on 37+ tires. So for me, 4.56s made the most sense. It all boils down to what's important to you.
 
#28 ·
The 3.6 pent engine basically has power almost at any rpm and the 4.10 gears are still as snappy with 37" as they were with 32" tires.if I find the 3.6 power chart...I will post it,I forgot where I seen it but it is true and my rubi rpm finally doesn't race at 70mph!
 
#33 ·
watchThis....I have driven my stock 4.10 2016 jkur 6 speed for over a yr and it stunk,my 3.23 2012 jku 6 speed was much more of a pleasure to drive.these 37" tires actually made my rubi finally a pleasure to drive again(no more racing rpm's at 70mph although my rpm's are still higher than my 2012 was).i am truly happy!
Test drive a properly geared Jeep for 37s. You will see the difference. It is astronomical. 4.10s are wayyyy far from "snappy" with 37s. Again, 2700-2800 cruising is not "racing rpms" by any stretch of the imagination.
 
#29 ·
watchThis....I have driven my stock 4.10 2016 jkur 6 speed for over a yr and it stunk,my 3.23 2012 jku 6 speed was much more of a pleasure to drive.these 37" tires actually made my rubi finally a pleasure to drive again(no more racing rpm's at 70mph although my rpm's are still higher than my 2012 was).i am truly happy!
 
#36 ·
I've been running 35s and 4.10s on my 2015 JKUR for a couple of years now. Snappy is not a word I'd choose to describe the performance. It does pretty good but I'm longing for more gear. I'm really leaning towards 4.88s over the 4.56. My Jeep is heavy with all of the armor and bumpers and winch, ARB fridge, four people, etc. My engine is noisier at the higher RPMs as well. But it's also having to use more gas to maintain those RPMs. Let off the gas a bit when you're at those higher RPMs. It quiets right down before it shifts back down. I like to drive about 80 mph everywhere too. I have zero plans of ever going to 37s. I just bought my second set of 35s today. Could have paid an extra $150 or so and had 37s. No thanks.
 
#37 ·
Mommymallcrawler...I test drove my stock 6 speed jkur (4.10 gears)for over a yr and it was soo annoying TO ME,I hated the sound of the engine racing but then again this is my daily driver and I live in NYC and not Colorado(I also do a lot of 70-80mph ny-nj hwy driving)?
 
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