4.56 Gears?

8293 Views 9 Replies 7 Participants Last post by StepsRide, Jun 20, 2010

cab76

Discussion Starter · Feb 6, 2008 (Edited)

Is anyone currently running the 4.56 gears? I think Superior offers them, but I can't seem to find any info on google and I'm not even sure if they're available yet. If you have them what tires/trans are your running and what do you think?

I currently have a Rubi Unlimited Auto. I will be moving up to 33-34" tires for sure, but there is a slight possibility that I will go with 35s (now or in the future). I'm happy with the 4.10s and 32s and I don't want to regear to gain more driveability (although a little more would be nice), but I want to make sure my rpms at speed are at least no worse than the 4.10s w/32s. I'm kinda leaning towards 4.88s just in case I end up going with 35s, but fuel economy is a big consideration for me and I'm worried that the rpms would be too high with 33s. What do you think I should do - 4.56s or 4.88s?? Any other considerations that I'm missing?

Thanks in advance for any info/opinions.

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CO Hummer

· #2 · Feb 7, 2008

It seems like most people are liking 4.88s with 35s. That's what I plan to get at some point.

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PhilD

· #3 · Feb 7, 2008

I believe Superior will be offering 4.56's shortly.

To maintain the same RPM with 33's the ratio would be 4.22, and I personally wouldn't worry about it and would stick to the 4.10's unless you want some more RPM or better crawl ratio.

For 34's it would be 4.36, which is closer to 4.56 than 4.10, so would make more sense to go with 4.56's.

For 35's it would be 4.48.

Generally you want add a few more RPM to help compensate for the bigger tires, rolling resistance, etc. But looks like 4.56's would work out fine should you decide to go with 35's later.

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· #4 · Feb 7, 2008

I'm running 4.88's with 35's and am happy with the setup. If I had to choose to go either higher or lower, I would go for slightly lower gearing (higher numerically) but think the current ratios are just about right.

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cab76

Discussion Starter · #5 · Feb 8, 2008

Thanks for the info. Looks like 4.56s will be perfect for me.

Still curious about the 4.88s and 33s, though - anyone running that setup? How are the rpms?

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Steve-UK

· #6 · Feb 8, 2008

Hi I have not had time to play with the JK gearing, but I have with TJ gearing.

I have run both 4.10's and 4.56's with 33" tires the 4.10's worked okay, but the 4.56's let the engine rev more freely, and I seemed to get better fuel economy as well. This is with a manual

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cab76

Discussion Starter · #7 · Jun 18, 2010

Sorry to revive a really old thread. I ended up going w/34s and stock 4.10 gears which works OK, but as my 34s wear down I have recently been thinking of upgrading to 35s and 4.56 or 4.88 gears (or I may stick w/34s when I replace the tires). I've heard a lot of good things about 4.88s w/35s but I still haven't heard of anyone running 4.56s on a JK.

Anyone running 4.56? What tires/transmission? Are you happy with them?

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planman

· #8 · Jun 19, 2010

cab76 said:
Sorry to revive a really old thread. I ended up going w/34s and stock 4.10 gears which works OK, but as my 34s wear down I have recently been thinking of upgrading to 35s and 4.56 or 4.88 gears (or I may stick w/34s when I replace the tires). I've heard a lot of good things about 4.88s w/35s but I still haven't heard of anyone running 4.56s on a JK.

Anyone running 4.56? What tires/transmission? Are you happy with them?

With an automatic 4 dr Rubi & 35s, you want 5.38 gears. They will put you at about 2500 rpm at 70 mph--which is about the same as a stock 6 speed Rubi on stock Rubi tires.

With 5.38s & 35s with your automatic, you will get better in town & highway gas mileage than you are getting now. Your engine & tranny won't have to work so hard & your frequency of tranny downshifting will go way down.

4.56s would be a complete waste of money for you.

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bubba2u

· #9 · Jun 20, 2010

Ive been running 4.88's on my 6 speed with 35/12.5/15 km2's ( 34.25") for about 6 months. i love it off road, plenty of power. only issue i have is i like to run 80 MPH on the highway and it will run about 3100 rpm so my gas mileage drops to about 10mpg. :beer:

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StepsRide

· #10 · Jun 20, 2010 (Edited)

Hey I am having the same dilemma. I have a 6sp 2 door. The bottom line is how are you going to use your rig. Very important questions, Do you have a daily driver 5 days a week and running interstates, OR does it come out on the weekend only for your drives around town and to the trails. Very Different uses. For me with 35's I am PROBABLY going with the 4.56 because I run up and down I95 in FLORIDA. VERY FLAT. Very flat is another thing you have to take into account. If I was driving up I81 in Virginia everyday I would be running a 4.88. So you need to take all the variable and play give and take. Take a look at the link below and you will see if you are running up and down the interstate 5 days a week over FLAT terrain 4.56 will be your best blend of performance. If you do not log many hours on the highway you will want the 4.88. If it is a weekend only truck go with the 5.38. In my opinion.

Great link to help you OVER THINK this!
http://www.grimmjeeper.com/gears.html
:bawling:

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