Why should I regear?

[CarbonSteel]

That does change the math a little. Especially with the 2.72:1 transfer case.

I maybe would go to 4.56 with a 392 and 37s if I regeared. No need for really short gears like you need with the 3.6. 4.10's may work for the 392 but again, not enough to swap for 3.73s.

Yeah...I am thinking about the disposable torque sitting with a 392. I doubt that I would re-gear it unless I went larger than 37s. I cannot see a 392 struggling with being under geared, not that 3.73 is that under geared with that engine.

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[ParadigmDawg]

Yeah...I am thinking about the disposable torque sitting with a 392. I doubt that I would re-gear it unless I went larger than 37s. I cannot see a 392 struggling with being under geared, not that 3.73 is that under geared with that engine.

Yep, I totally planned on regearing but after my trip, I just don't think I need too. I also got my best MPG to date but that's likely because my wife followed me in her Jeep and I promised to just go 5 mph over the speed limit and it's the first time in history that I never floored.

 

[grimmjeeper]

Yeah...I am thinking about the disposable torque sitting with a 392. I doubt that I would re-gear it unless I went larger than 37s. I cannot see a 392 struggling with being under geared, not that 3.73 is that under geared with that engine.

I bet the only reason the 392 didn't get 3.45 axle gears was for the same reason the diesel didn't.

The tallest gear in the front M210 is 3.73.

 

[CarbonSteel]

I bet the only reason the 392 didn't get 3.45 axle gears was for the same reason the diesel didn't.

The tallest gear in the front M210 is 3.73.

Indeed--FCA is looking for CAFE credits, especially on a 392...

 

[tomk62]

@oldcjguy @gm920 thank you I can now see me current gear.

So today I was able to easily get into 7th going 50 mph down a country road, and into 8th gear at 70 mph on the highway. Is this to be expected?

 

[grimmjeeper]

@oldcjguy @gm920 thank you I can now see me current gear.

So today I was able to easily get into 7th going 50 mph down a country road, and into 8th gear at 70 mph on the highway. Is this to be expected?

That sounds about right. What RPMs are you running at those speed?

 

[Terry R]

All,
Follow up question about regearing. I got at least one comment about getting Rubicon take off axles. My question is would I have to swap out both axles, or could I only swap out the rear?

 

[Zandcwhite]

All,
Follow up question about regearing. I got at least one comment about getting Rubicon take off axles. My question is would I have to swap out both axles, or could I only swap out the rear?

You'd need both for the gearing to match, plus the track width and lockers. It's not really an upgrade to do one and not the other as you'd still need to regear an axle at that point.

 

[Terry R]

Thanks, not being mechanically inclined I wasn’t sure if it would work or not. Just looking online the cost of Rubi take offs are around $1500-1800 per axle. That’s $3000+ before additional parts and installation cost. Probably a $5000 project. Doesn’t seem worth it for me right now. Maybe down the road after wheeling it more.

 

[tomk62]

That sounds about right. What RPMs are you running at those speed?

Did some more experiments on the highway and I can routinely get to 70 MPH in 8th at 1800 rpm.

 

[nickberkeley]

Did some more experiments on the highway and I can routinely get to 70 MPH in 8th at 1800 rpm.

@tomk62, just curious, have you regeared, and do you have a 2.0 or 3.6? I have a '20 2.0T Sahara and in stock setup, 70mph was just under 1800RPMs, but now that I have 315/70R17, 70mph is a little under 1600RPM. These are in 8th gear and I still have 3.45 gears. It still drives well, and I can cruise some in 8th gear on flat terrains, but as most have said, 8th gear is few and far between...

 

[tomk62]

@tomk62, just curious, have you regeared, and do you have a 2.0 or 3.6? I have a '20 2.0T Sahara and in stock setup, 70mph was just under 1800RPMs, but now that I have 315/70R17, 70mph is a little under 1600RPM. These are in 8th gear and I still have 3.45 gears. It still drives well, and I can cruise some in 8th gear on flat terrains, but as most have said, 8th gear is few and far between...

This is with the 2.0T, auto trans, and stock gears.

What I'm trying to understand is "how often and when should we be getting into 8th gear"?

 

[mtbjeep]

I would mention that if you have a MT and routinely drive on the highway with cruise control, re-gear or you'll go nuts shifting at every incline and re-engaging the cruise.

 

[Mac2457]

4.88 with 35s on the 3.6 woke my jeep up. I regret nothing about every dollar spent on regearing.

I know this is an old post but do you have a manual transmission or auto? I'm considering regearing my rubicon 3.6 with 6mt but I don't know if it's worth going to 4.56 and if 4.88 would be to much. I drive highway alot but I'm constantly down shifting from 6th to 4th on hills and I see alot of them. Thanks

 

[grimmjeeper]

I know this is an old post but do you have a manual transmission or auto? I'm considering regearing my rubicon 3.6 with 6mt but I don't know if it's worth going to 4.56 and if 4.88 would be to much. I drive highway alot but I'm constantly down shifting from 6th to 4th on hills and I see alot of them. Thanks

What size tires are you running?

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