Rubicon - 5.13 or 5.38's for Re-Gear?

[JKDream]

Shifting down constantly to 3rd gear at 79mph is terrible...running 500rpm or more constantly is not big deal.

Chris

It's going to be a bigger issue when you overheat on mountain grades revving the shit out of your motor like I did. You can take my opinion for what it's worth, I've actually had the tire size/gear set so I can confidently say it was shit. You sound like you have your mind made up anyway, so this post is pretty irrelevant.

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[ravencr]

I'm not following you. Are you saying it's better for it to shift down to 3rd and 4th gear and rev the crap out of it every time it comes to a hill, or it's worse to have it constantly be running at a higher RPM? I'm not following...my mind isn't made up.

Chris

 

[JKDream]

I'm not following you. Are you saying it's better for it to shift down to 3rd and 4th gear and rev the crap out of it every time it comes to a hill, or it's worse to have it constantly be running at a higher RPM? I'm not following...my mind isn't made up.

Chris

No, I'm saying you should consider 4:88's if this is your daily driver.
I'm not saying what you currently have is better by any means, but it doesn't make sense to go to one extreme to avoid another.
Your original thought was "I'm constantly shifting, let's go with the most gear possible"

I'm leaning towards 5.38's

That doesn't make any sense though, now you're revving too high in the gear you're supposed to be in as you would be with 5:13's.
If 37's are a month or two out, then sure, it might be tolerable, any longer and I (personally) would reconsider your decision.
Just an FYI, I still have to downshift with 5:13's and 37s on big hills otherwise it bogs out.

 

[wjtstudios]

84?!? What wheels and tires are you running? My 37 BFGs can handle up to 75 mph, from there on I’ll start getting vibrations that I’m not comfortable with.




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[zimm]

Maybe he didn't calibrate the speedo. I wouldn't take my jeep over 80. Even crossing Texas with an 80mph speed limit, she's so much happier at 73.....

 

[BaddestCross]

I run 80-85mph often even with my 37s and 5.13s... until I realize it. Gas milage goes to shit over 70.

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407

 

[wjtstudios]

There is that issue too.


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[Tanktitan]

I am firmly in the 4.88 camp with 37’s. Even at that I don’t want to run over 65. I can’t imagine wanting to run long distance at higher RPM’s, just so it does not downshift - to what - higher RPM’s? I have driven it across country 5 times and tried my best to stay off interstates and on as many back roads/dirt roads/trails as possible, just because I have a Jeep.

To those that want to run a JK over 80, it’s your Jeep, do as you please but you might consider trading up to a JL. That one is designed for it. My JK is not.


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[jesse3638]

I run 80-85mph often even with my 37s and 5.13s... until I realize it. Gas milage goes to shit over 70.

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407

I always chuckle when I see a jeep, stock or modified, fly past me doing 80+mph. I usually cruise between 70-75

 

[BaddestCross]

I always chuckle when I see a jeep, stock or modified, fly past me doing 80+mph. I usually cruise between 70-75

Yeah... I've got a heavy foot and, honestly, my Jeep runs so smooth (knock on wood) I just don't notice sometimes. I try to set the cruise control at 70-75 so it takes me out of the equation.

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407

 

[QuicksilverJK]

When people say they wouldn't drive fast in a jeep I laugh. I tend to drive fast in whatever I am driving. I have zero concerns doing 90+ with my 37s 5.13s and a 3.8. I catch myself in that range on a regular basis.


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[QuicksilverJK]

That being said my old TJ wanted to run me off the road if I hit 65 . I guess it's all in how well you're front end is dialed in.


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[BaddestCross]

When people say they wouldn't drive fast in a jeep I laugh. I tend to drive fast in whatever I am driving. I have zero concerns doing 90+ with my 37s 5.13s and a 3.8. I catch myself in that range on a regular basis.


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Same.

That being said my old TJ wanted to run me off the road if I hit 65 . I guess it's all in how well you're front end is dialed in.


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This for sure. I laugh when I hear others talk about how poorly lifted Jeeps handle... I just think to myself "you're doin' it wrong" as I fly by 'em.

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407

 

[Gbint]

All of my M38’s and M38A1’s came with 5.13’s. Going that route when warranty expires in 8 months. I’ll be looking for advice from you folks concerning tire size then.


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[fiend]

Same.

This for sure. I laugh when I hear others talk about how poorly lifted Jeeps handle... I just think to myself "you're doin' it wrong" as I fly by 'em. [emoji41]

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407

If you have a cheap ass lift, the Jeep will handle poorly. If you address caster, roll center, and bump steer, as most of the better (and more expensive) kits do, it will handle fine.

 

[BaddestCross]

If you have a cheap ass lift, the Jeep will handle poorly. If you address caster, roll center, and bump steer, as most of the better (and more expensive) kits do, it will handle fine.

Yep... What gets me though is the people that accept shitty handling and don't listen to the folks that tell them how to fix it.

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Build Thread - Adventures of Fiona - https://wayalife.com/showthread.php?t=47407

 

[Kenthejeepguy]

‘11 jkru 3.8 engine, manny tranny. Went to 5.13’s and lovin it! Currently running 35’s, will go to 37’s next time.

 

[jjlong]

When I went to Evo to get a re-gear I asked for 5:13's. They talked me into 5:38 because I have the 3.8 auto. I'm glad they did! At 70 with 37's it sits very nicely in the powerband.

 

[fiend]

When I went to Evo to get a re-gear I asked for 5:13's. They talked me into 5:38 because I have the 3.8 auto. I'm glad they did! At 70 with 37's it sits very nicely in the powerband.]

5.38s are the best ratio for that setup, except that the pinion gear is tiny and vulnerable to breakage, assuming you’re on 44s. If you’re just cruising on pavement, it’ll probably hold up ok.