An age old question...

Yes yes I'm sorry to bring it up again, but I've been hearing mixed thoughts about what gears to run in my JK. I have a 2 Door JK Sport S with the 3.21s, and there's no way in hell that's livable with the 35s I'm planning on.

I have a '97 TJ that's been regeared to 4.10 in the front and 4.11 in the rear. It has the straight six and 33s, and it performs flawlessly in my opinion - provides sufficient power and decent mpg, so I know what I'm doing.

I'm more concerned over power loss for sure, but as my JK is my daily driver it wouldn't hurt to stay above 15 mpg, given my smaller tank.

So anyway, I've looked at three options: 4.10s, 4.56s, and 4.88s. Not leaning one way or the other, but I've heard that 4.56 is the sweet spot for Auto JKs with 35s. I've also heard that 4.10s (Basically a Rubicon) runs at a lower RPM (2300 to 2600 at highway speeds) while 4.56s run closer to 3000. (With 35s in both these cases) I commute about 20 miles each day I work, where my time behind the wheel is unfortunately. It's pretty flat down here in SD, but I go and plan on going on lots of wheeling trips all over the west. Again, mpg is not a major concern but I'd go with 4.10s if you think it has a decent power output. I cant imagine it's too bad having 35s on a stock Rubicon, so I want to know what you guys think.

I also plan on 37s in the future, but with an axle swap up front to a PR44 or something related and will swap gears again then, since it'll most likely have 5.13s, but that's at least a couple years away, until I move to a more Jeep friendly and trail filled community out of the locked down California.

I've always leaned towards 4.56 and just wanted to know what you guys think - Thanks in advance!
 

Seahawkfan

Hooked
Yes yes I'm sorry to bring it up again, but I've been hearing mixed thoughts about what gears to run in my JK. I have a 2 Door JK Sport S with the 3.21s, and there's no way in hell that's livable with the 35s I'm planning on.

I have a '97 TJ that's been regeared to 4.10 in the front and 4.11 in the rear. It has the straight six and 33s, and it performs flawlessly in my opinion - provides sufficient power and decent mpg, so I know what I'm doing.

I'm more concerned over power loss for sure, but as my JK is my daily driver it wouldn't hurt to stay above 15 mpg, given my smaller tank.

So anyway, I've looked at three options: 4.10s, 4.56s, and 4.88s. Not leaning one way or the other, but I've heard that 4.56 is the sweet spot for Auto JKs with 35s. I've also heard that 4.10s (Basically a Rubicon) runs at a lower RPM (2300 to 2600 at highway speeds) while 4.56s run closer to 3000. (With 35s in both these cases) I commute about 20 miles each day I work, where my time behind the wheel is unfortunately. It's pretty flat down here in SD, but I go and plan on going on lots of wheeling trips all over the west. Again, mpg is not a major concern but I'd go with 4.10s if you think it has a decent power output. I cant imagine it's too bad having 35s on a stock Rubicon, so I want to know what you guys think.

I also plan on 37s in the future, but with an axle swap up front to a PR44 or something related and will swap gears again then, since it'll most likely have 5.13s, but that's at least a couple years away, until I move to a more Jeep friendly and trail filled community out of the locked down California.

I've always leaned towards 4.56 and just wanted to know what you guys think - Thanks in advance!

Time to bust out the chart again..:D
Snap37.png
 
Time to bust out the chart again..:D
View attachment 358013
Ah yes I love the chart [emoji108]

The chart almost single handedly convinces me to make an executive decision. I actually have never saved it to my phone for some reason so thanks for posting it up so I could haha

I love how 4.10 and 4.56 are both in the green, and I can just pick the one biased to power...

Starting to regret spending time creating this thread now [emoji848][emoji23]
 

jdofmemi

Active Member
Go 4.88 so the Jeep is fun to drive, and performs in a way you will like.

That is basically the equivalent to 5.13 with 37s.

My new axles came with 4.88, and my mileage is worse than it was with the 5.13s, plus the performance is down as well.

With 5.13 gears I was getting 16+ mpg, even with the added Tom, plus it was more fun to drive.

Just my opinion, your mileage may vary.
 

AZ Explorer

Caught the Bug
Agree with the 4:88's. Had the 5:13's with 37's and it was perfect. So, yeah 4:88 is the closest RPM range.
Plus you could run 37's on those for a bit until you can do the 5:13 gears.
 

jab1719

Member
I vote 4.88s. Not worth the jump to 4.10s in my opinion. That’s leaves 4.56 or 4.88s. I went 4.88s cause I wanted the most performance I could get out of the regear. My understanding is 4.56s and 35s is pretty close to 4.10s and 32s from the factory in a rubicon so I wanted to have it geared a little more and went 4.88s.


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jesse3638

Hooked
When thinking I was going to stay on 35's my plan was to go 4:88's to gain a little extra power. As mentioned 4:56's would have put me close to stock. Since making the jump to 37's I went 5:13's and couldn't be happier. Sure it runs a bit in the high end of things on the freeway but it so nice having the added power offroad. Granted I have a manual, I'm running about 2900ish at 75 mph. Cruising between 65 and 70 I can get near 15 mpg. Not too much different than 4:10's and 35's.

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zimm

Caught the Bug
I had 4.10's from the factory. I still went 4.88 on 35's they're perfect. Then went 37's and they were still good. Now I'm back on 35's and still happy after 40k miles. The 3.6 loves RPM's, don't bog it down.

The difference between 5.13 and 4.88 is less than 200rpm- not worth worrying about.
 

Bear_JT

Hooked
I’m running 4.88’s with 35’s and it did give me back my power around town and on flat roads. Driving on road/highway at 80 mph with bigger hills I do loose power which causes a downshift and major spike in RPM’s with a slow down. Off road I have no issues but on road is where I wish my results were different.


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TrailHunter

Hooked
I’m running 4.10’s with 35’s... Which in general isn’t that bad... Only time I wish I had more gear is on grades when loaded down... I drive 65-70 on LA fwys then once I hit the smoother open roads I tend to drive 75-80. It takes me 1.5- 2 hrs to reach a decent trail so highway rpms are a factor... 4.56 would probably be perfect but there is still a chance I might go 37’s ...in which I’d want 4.88’s. So I’m staying with 4.10’s till I get a PR44.. then bumping to 4.88’s even if I still run 35’s.
 
I’m running 4.10’s with 35’s... Which in general isn’t that bad... Only time I wish I had more gear is on grades when loaded down... I drive 65-70 on LA fwys then once I hit the smoother open roads I tend to drive 75-80. It takes me 1.5- 2 hrs to reach a decent trail so highway rpms are a factor... 4.56 would probably be perfect but there is still a chance I might go 37’s ...in which I’d want 4.88’s. So I’m staying with 4.10’s till I get a PR44.. then bumping to 4.88’s even if I still run 35’s.
Cool thanks for your input. I think I'm going 4.56 since I know 37s are decently far into the future for me, and will go 5.13s with a PR44 up front once I get there
 

TrailHunter

Hooked
Cool thanks for your input. I think I'm going 4.56 since I know 37s are decently far into the future for me, and will go 5.13s with a PR44 up front once I get there

A lot of input here saying 4.88's are good with 35's.... Another consideration might be how you load your Jeep and what add ons you have... A Winch, cage, skids, bumpers all add weight... Roof top tents, fridges, kitchens and all that BS if you are into that.... may be another reason to go to 4.88's. Just a thought.
 
A lot of input here saying 4.88's are good with 35's.... Another consideration might be how you load your Jeep and what add ons you have... A Winch, cage, skids, bumpers all add weight... Roof top tents, fridges, kitchens and all that BS if you are into that.... may be another reason to go to 4.88's. Just a thought.
Yes my good man, I am not so much of an overlander yet and am only adding bumpers, winch, and a tire carrier. I really dont think I can go wrong with either setup, but I will think on 4.88s more than I have before.
 

desertrunner

Active Member
Yes my good man, I am not so much of an overlander yet and am only adding bumpers, winch, and a tire carrier. I really dont think I can go wrong with either setup, but I will think on 4.88s more than I have before.
What's the hesitation on 4.88s instead of 4.56? The difference in highway RPM will only be about 200 and as mentioned the 3.6 loves RPM. I think you'd be disappointed knowing you would have a little more take off torque and passing power with the 4.88s.

I have a 2dr with 4.88s and 37s and I regret not doing 5.13. not a huge difference in highway driving but everyday in town I just wish I had that little more umpf. I do have the 6speed so maybe the auto is a little different.

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You know I'm not necessarily sure. Like I said I dont think I can go wrong with either but my Jeep is sadly daily driven on road, in town and on the freeway, miles and miles more than off road. There's no two lane highways here in SD really that are used regularly by me and I've never needed an extra umph when passing, even in my TJ. Dont get me wrong I love my Jeep as a daily. I really want a setup that's biased towards performance, but still get decent mpg. So 4.56 sounds like it's more in the middle of those two or I'm just retarded. Up until today I've been pretty set on 4.56s, but the just little extra power over close to stock, and with 35s is very intriguing. I'm not too heavy on the skinny pedal either, so I can probably make the best of it. Any mpg numbers on 4.88s or any setup just for reference from you guys?
 

-AINOKEA-

Hooked
You know I'm not necessarily sure. Like I said I dont think I can go wrong with either but my Jeep is sadly daily driven on road, in town and on the freeway, miles and miles more than off road. There's no two lane highways here in SD really that are used regularly by me and I've never needed an extra umph when passing, even in my TJ. Dont get me wrong I love my Jeep as a daily. I really want a setup that's biased towards performance, but still get decent mpg. So 4.56 sounds like it's more in the middle of those two or I'm just retarded. Up until today I've been pretty set on 4.56s, but the just little extra power over close to stock, and with 35s is very intriguing. I'm not too heavy on the skinny pedal either, so I can probably make the best of it. Any mpg numbers on 4.88s or any setup just for reference from you guys?

I get anywhere from 14-17 on mine with 4.88s, 35” toyos, and 6-speed manual. I’m fairly heavy on the skinny pedal though. Might be able to squeeze out another mile or 2.


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Bear_JT

Hooked
I’m right around the same MPG’s with 14-18. As others have said before the 3.6 loves it’s RPMs and when you put the winch, bumpers, armor... you’re going to want any extra kick you can get. All who have done it and been where you’re at pretty much agree 4.88’s are the way to go.


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I’m right around the same MPG’s with 14-18. As others have said before the 3.6 loves it’s RPMs and when you put the winch, bumpers, armor... you’re going to want any extra kick you can get. All who have done it and been where you’re at pretty much agree 4.88’s are the way to go.


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Came back to this thread to let ya'll know I've made the decision to go to 4.88s. Thanks all again for the input. I can't wait!
 
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