Compression-Ignition

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Yeah we'll have to agree to disagree.

Unless the transmissions are designed differently I don't see how you can say
Completely different ballgame. You must throw every bit of conventional wisdom regarding axle ratios out the window.
What I'm getting from you is that all these manufacturers have got shit for brains and they should be doing it your way. Correct me if that is not what you're trying to convey.

I wish we could order things exactly as we the customer specify. I would even within reason pay a hefty premium to make it so. But I totally understand that the manufacturers make compromises to get the most people closest to the product they would like to purchase.

I understand my response is a little disjointed. You just caught me off guard with this "taller gears always!" warcry you got going on. Lol. I'm sitting here trying to come up with a good analogy to explain why I think putting more stress on the axle gears isn't necessarily the best idea, but nothing is coming to me.





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Jteakus

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Deeper gears for taller tires. A lot of us instantly lift our jeeps and bump tire sizes up. With a 4.10 the need to regear and void factory warranty would be eliminated. 4.10 and a 37" tire would be just about right. To each their own though.
 

BuffaloBill

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I would prefer 4.10 with 35” tires, if given the choice.
 

GearWhore

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My 2021 build sheet shows 3.73 gears, like the 2020s. Hopefully I will be in possession in the next week or so and can confirm by the differential tag.

I would prefer the 4.10 as I already have 37s mounted and ready to install. I feel that would certainly keep me from having to regear. With the 3.73, I will probably hold off on the regear, but it will be a future expense (already planned 4.56) that I will accommodate for in my build process/timeline. As @BuffaloBill says, I think the 4.10 with 35" would be just right long-term.

FCA does have to account for a lot of factors in determining which vehicle will get which gearing, including vehicle-specific mileage and fleet mileage, "average" consumer, reliability/serviceability, drivability, and more. The torque and feeling of the 3.0 (2nd gen) in my WK2 is what convinced me to sell that for a JL with the similar, though more off-road focused drivetrain. I also loved that I could go 500-600 miles or more comfortably per tank, even off-road.

The biggest issue I have had is the highway driving out west is 70-80 mph (or more) and anything above 70-75 I noticed a considerable mileage hit (and/because of higher rpm required).

EPA does use some higher-speed testing in the current test, though the average speed is still under 50. https://fueleconomy.gov/feg/fe_test_schedules.shtml
 
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I doubt they care if we want to put taller tires on. I'm guessing that if they changed it, it's because they now have the hybrid JL for 2021, so they don't need the diesel with higher gears (and higher mpg's) to bring up their CAFE numbers. All Rubicons getting 4.10's is much easier from a manufacturing perspective. An additional benefit they would get with those lower gears is increased RPM's, and therefore higher temps through the EGR system to hopefully reduce intake soot.
 

Jteakus

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“I doubt they care if we want to put taller tires on.”

Isn’t that the truth? Way back when I got my ‘83 CJ7 it came from the factory with a set of 2.73 gears. Lovely.
 

Sydwaiz

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Well here is something interesting. I have a 2021 on order and my build sheet shows. 3.73.
My window sticker just went live today and does NOT show the gear ratio unlike the sticker for the 2020 I ordered (canceled, long story)
What is interesting is the fuel mileage has changed. From 22-29 now to 21-26.
 
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Well here is something interesting. I have a 2021 on order and my build sheet shows. 3.73.
My window sticker just went live today and does NOT show the gear ratio unlike the sticker for the 2020 I ordered (canceled, long story)
What is interesting is the fuel mileage has changed. From 22-29 now to 21-26.
Quick hijack here, but where do/did go to see your window sticker? And yes not surprising that the MPG's went down with what I am sure is the lower gears....
 

Sydwaiz

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Quick hijack here, but where do/did go to see your window sticker? And yes not surprising that the MPG's went down with what I am sure is the lower gears....
You can sign up here in this thread and enter your vin number once you get from your sales rep after they place the order. Usually takes a few days to get your vin after ordering.
https://www.jlwranglerforums.com/fo...sticker-and-build-sheet-order-tracking.12503/

Also here to get your sticker directly. Just replace the last question mark with the vin.
https://www.jeep.com/hostd/windowsticker/getWindowStickerPdf.do?vin=?

And here for the build sheet. Same thing with the question mark.
https://www.jeep.com/webselfservice/BuildSheetServlet?vin=?
 
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You can sign up here in this thread and enter your vin number once you get from your sales rep after they place the order. Usually takes a few days to get your vin after ordering.
https://www.jlwranglerforums.com/fo...sticker-and-build-sheet-order-tracking.12503/

Also here to get your sticker directly. Just replace the last question mark with the vin.
https://www.jeep.com/hostd/windowsticker/getWindowStickerPdf.do?vin=?

And here for the build sheet. Same thing with the question mark.
https://www.jeep.com/webselfservice/BuildSheetServlet?vin=?
Thanks!
 

JLURD

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I’ll add some fuel to this fire as I’ve got actual wheeling experience in a 3.0 on 3.73s. We’ve covered 10,600 miles and probably more miles off pavement than anyone running a 3.0...all on 37s and almost all with a 2.75” lift. At no point have I felt even the slightest need for a 4.10. Hell on most trails where I’d have my ‘18 JLUR 3.6 (33” KO2s) in 4L, the 3.0 is holding its own in 4H still. I’m sure certain use cases might drive some interest in 4.10 and above, but good luck finding it this side of running 38-42” tires. I still hold 8th in the low to mid 60s and get ridiculously good (23-24mpg) fuel economy for a brick rolling 117 lbs per corner and over 5000lbs gross weight.
 
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I’ll add some fuel to this fire as I’ve got actual wheeling experience in a 3.0 on 3.73s. We’ve covered 10,600 miles and probably more miles off pavement than anyone running a 3.0...all on 37s and almost all with a 2.75” lift. At no point have I felt even the slightest need for a 4.10. Hell on most trails where I’d have my ‘18 JLUR 3.6 (33” KO2s) in 4L, the 3.0 is holding its own in 4H still. I’m sure certain use cases might drive some interest in 4.10 and above, but good luck finding it this side of running 38-42” tires. I still hold 8th in the low to mid 60s and get ridiculously good (23-24mpg) fuel economy for a brick rolling 117 lbs per corner and over 5000lbs gross weight.
That's all Ive heard as well. Honestly, I would've preferred to keep the 3.73's and decide for myself. I think its probably the simplicity of manufacturing that drove the decision, but also maybe the added EGR benefit.
 

WXman

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Yeah we'll have to agree to disagree.

Unless the transmissions are designed differently I don't see how you can say

What I'm getting from you is that all these manufacturers have got shit for brains and they should be doing it your way. Correct me if that is not what you're trying to convey.

I wish we could order things exactly as we the customer specify. I would even within reason pay a hefty premium to make it so. But I totally understand that the manufacturers make compromises to get the most people closest to the product they would like to purchase.

I understand my response is a little disjointed. You just caught me off guard with this "taller gears always!" warcry you got going on. Lol. I'm sitting here trying to come up with a good analogy to explain why I think putting more stress on the axle gears isn't necessarily the best idea, but nothing is coming to me.
More specifically: All these manufacturers never had shit for brains in the past because they did 3.55 or numerically lower with diesel engines ALWAYS. It's only recently that they've started growing shit for brains by drastically over-gearing the diesel, especially in light of the fact that we now have 8-speed transmissions which makes deep axle gearing even more asinine.

For the last 30 years, "don't fear the gear!" has been the war cry on Jeep forums. But that's because we've been saddled with gas engines making mid-200s lb/ft of torque mated to shitty 4 and 5 speed transmissions. Today we've got double the torque and nearly double the gearing in the trans. So now we do not need 4.10 axle gears anymore. It's pointless and does nothing but cause the trans. to shift constantly and suck down fuel.

Now, if you're running 38 or 40" tires, that changes things up as well. But for the guys on stock tires or even 35s....4.10s are NOT what you want with the diesel. That's just how it is. If I had the money I'd prove it. I'd take a Jeep EcoDiesel, swap 3.21s in, and show how well it tows, how much more quiet it becomes, how the MPG increases significantly, and how smooth it drives on the road and on the trail.
 

Killdozer

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So it the gear change for rubicon only or all models. I have a sport on order so should know soon enough
 

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