O/D off equivalent to Re-gear
Thread Starter
JK Enthusiast
Joined: Sep 2016
Posts: 256
Likes: 0
From: California
This may be a stupid question but...
First off I know re gearing obviously does not give you anymore power
Would running 35's (33.5 measured) with 4.10's feel the same as let's say 4.10's and 31's at 2500 rpms. And then running 5.13's at the same rpm with the same tire size scenarios.
Would it hold 2500 rpms better with the 5.13's? That's the real question
Is there any sort of mechanical advantage allowing the motor to work easier at that rpm with the 5.13's opposed to the 4.10's?
Am I making sense or smoking paint chips? Haha
Let's just say somehow they are both in 4th gear
First off I know re gearing obviously does not give you anymore power
Would running 35's (33.5 measured) with 4.10's feel the same as let's say 4.10's and 31's at 2500 rpms. And then running 5.13's at the same rpm with the same tire size scenarios.
Would it hold 2500 rpms better with the 5.13's? That's the real question
Is there any sort of mechanical advantage allowing the motor to work easier at that rpm with the 5.13's opposed to the 4.10's?
Am I making sense or smoking paint chips? Haha
Let's just say somehow they are both in 4th gear
JK Jedi Master
Joined: Jan 2008
Posts: 11,463
Likes: 165
From: Austin <--> Colorado Springs
And then running 5.13's at the same rpm with the same tire size
On the other hand, if the speed is the same, the rpm will be different. And if the rpm is different, the HP and Torque (power) will also be different. And if ...
I was bored, so played around with the calculator linked earlier in the thread. Using 2500 rpm with 33.5" tires :
4.10 (OD/Off) = appx 61 mph
5.13 (OD/On) = appx 71 mph
Would it hold 2500 rpms better with the 5.13's?
Last edited by nthinuf; Jun 6, 2017 at 12:07 AM.
JK Freak
Joined: May 2011
Posts: 868
Likes: 8
From: Cairo, GA
Without a doubt, going to lower gears is much better. But in the meantime, turning overdrive off is much better than the constant downshifting. I know that with 35's, and 3.73's our JKU will downshift if I even look at a hill! LOL 
JK Freak
Joined: Mar 2011
Posts: 791
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From: Vancouver, BC
For those that have re-geared and for those that have not.
3.8/Auto/35's or 37's/ 4.10s. Or with 5.13s etc.
What are your opinions on this? Realistically with overdrive off your turning 2900~ or so rpms. And with a re gear it's 2500~ or so. Both in the power band.
So no matter what the transmission is still going to downshift when going up a hill right?
Besides losing 4th gear all the time with o/d off what else am I missing? Do the 5.13's actually help stay in 4th on hills? Generate more torque per say?
3.8/Auto/35's or 37's/ 4.10s. Or with 5.13s etc.
What are your opinions on this? Realistically with overdrive off your turning 2900~ or so rpms. And with a re gear it's 2500~ or so. Both in the power band.
So no matter what the transmission is still going to downshift when going up a hill right?
Besides losing 4th gear all the time with o/d off what else am I missing? Do the 5.13's actually help stay in 4th on hills? Generate more torque per say?
With that being said, you can always regear, if money is not an issue. Might lose some mileage though.
Thread Starter
JK Enthusiast
Joined: Sep 2016
Posts: 256
Likes: 0
From: California
If you're on 35's and 3.73 gears, OD off, 42RLE, you are turning same RPM as OD on with 5.13 gears. So if you're looking to regear just for highway performance, then don't, and simply use the OD button to do the same. With that being said, you can always regear, if money is not an issue. Might lose some mileage though.
Adding 5.13's I would still not keep my speed and probably make it worse. (On the highway up hills)
That's why I'm happy with OD off. Holds most hills and everywhere else fine. At 65 the rpm is around 2700ish. Not bad