Can you say Gears?

[Ramsgear]

So, looking to buy a 2018 Unlimited Rubi with 6sp. Just looking through the posts for used Rubi's most are auto which I could probably be persuaded to buy. The reason for the Post; Most I see have 37's but when I dive deeper into the additional bits that people add, most if not all the time I am seeing no gear swap. What do you with 37's think about acceleration on the road? Is there a noticeable difference between the auto and manual when accelerating too? I guess I'm thinking if I find a Rubi and want to go with 37's it is more of a "must do" then "might do" when it comes to gearing.

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[Ratbert]

All that really matters is how it feels to you when you drive it. Definitely test drive a similarly-equipped auto and manual to feel the differences yourself.

 

[JT1]

With the 6spd and 37s, you won't use 6th, and 5th will only be at turnpike speeds. You will spend most of your drive in 4th. Also, starting off in 1st on a steep hill is sketchy too..

 

[OrneryBear]

As someone with a manual rubicon, I'll tell you that I personally wouldn't run 37s without regearing to 4.88 gears. Hell even with the stock 33s I still wish I'd listened to a lot of people here and gone with the 4.88s from the factory. first gear would be crazy short but it would tow and accelerate a lot better.

 

[6.2Blazer]

One thing to keep in mind....
A Sport S comes with 245/75R17 tires (31.5" on paper) and 3.45 gears. Running the numbers in a gear calculator that is 1,602 RPM @ 65 mph.
Compare that to a Rubicon with 4.10 gears and 37" tires. Running the numbers in a gear calculator that is 1,621 RPM @ 65 mph.
According to those numbers running a Rubicon on 37's is basically the same as a stock Sport model with stock tires. Before people freak out, I understand that the 37's are heavier and have more rolling resistance. That means that the Sport S should feel better, but point being a Rubicon on 37's shouldn't be that bad compared to a base model....at least it means that changing gears should not be an absolute requirement.
Do I recommend changing gears with 37's.......absolutely! Do I think you will have any issues cruising to the mall with stock 4.10's and 37's.....no. In regards to if you actually go off-road, just put in low range. Especially a Rubicon with 4:1 transfer case gears which is plenty of gearing for most off-roading and easily compensates for 37's.
And yes, I have a lot of experience with bigger tires on vehicles. Currently have a newer truck that came with 33's and now runs 37's (also use it to tow), and have a dedicated off-road rig that I have ran 33's, 35's, 38's, and 40's on it with the same gearing.

 

[autotragic]

One thing to keep in mind....
A Sport S comes with 245/75R17 tires (31.5" on paper) and 3.45 gears. Running the numbers in a gear calculator that is 1,602 RPM @ 65 mph.
Compare that to a Rubicon with 4.10 gears and 37" tires. Running the numbers in a gear calculator that is 1,621 RPM @ 65 mph.
According to those numbers running a Rubicon on 37's is basically the same as a stock Sport model with stock tires. Before people freak out, I understand that the 37's are heavier and have more rolling resistance. That means that the Sport S should feel better, but point being a Rubicon on 37's shouldn't be that bad compared to a base model....at least it means that changing gears should not be an absolute requirement.
Do I recommend changing gears with 37's.......absolutely! Do I think you will have any issues cruising to the mall with stock 4.10's and 37's.....no. In regards to if you actually go off-road, just put in low range. Especially a Rubicon with 4:1 transfer case gears which is plenty of gearing for most off-roading and easily compensates for 37's.
And yes, I have a lot of experience with bigger tires on vehicles. Currently have a newer truck that came with 33's and now runs 37's (also use it to tow), and have a dedicated off-road rig that I have ran 33's, 35's, 38's, and 40's on it with the same gearing.

Man I've tried to do the math and show people the same thing you're doing and they still come out of the woodwork and tell you how wrong you are and how you're just a big dummy and they know everything and you don't know nothing. Good luck using facts and logic.

But that's just my opinion. Personally I think a Rubicon on 37s would be fine. I'm going to be on 35s here soon. I'm waiting on the dealership to get done doing some warranty work and then I'll have mine set up with all the new parts here soon.

 

[jeep1]

It will entirely depend where you live and what you do with your jeep. Out in the PNW, my wife's JLUR 6spd on 37s couldn't maintain highway speed in the mountains and was just plain miserable to drive most of the time. We regeared to 5.13s and have been extremely happy with it.

 

[Alligatorgun]

As someone with a manual rubicon, I'll tell you that I personally wouldn't run 37s without regearing to 4.88 gears. Hell even with the stock 33s I still wish I'd listened to a lot of people here and gone with the 4.88s from the factory. first gear would be crazy short but it would tow and accelerate a lot better.

I am picking up my manual Rubi tomorrow with 4.88s from the factory.
I thought it would be too deep for 33s!
I was lucky enough to find one to test drive, and it’s not! It’s an absolute hoot to drive. I do enjoy shifting, and you will…more. 1st gear is ok, like you said a little short, but man does it pull in 2nd and third! If I (when) fit 35s it’ll still be fine.
I’d never want a manual with 4.10s and anything more than 33s. Would it work?
Yeah, kinda…but no thanks.

 

[lowmpg]

All that really matters is how it feels to you when you drive it. Definitely test drive a similarly-equipped auto and manual to feel the differences yourself.

THANK you for this. There will be no shortage of the scientific opinions on gears when all that really matters is what the owner feels like doing.

 

[OrneryBear]

I am picking up my manual Rubi tomorrow with 4.88s from the factory.
I thought it would be too deep for 33s!
I was lucky enough to find one to test drive, and it’s not! It’s an absolute hoot to drive. I do enjoy shifting, and you will…more. 1st gear is ok, like you said a little short, but man does it pull in 2nd and third! If I (when) fit 35s it’ll still be fine.
I’d never want a manual with 4.10s and anything more than 33s. Would it work?
Yeah, kinda…but no thanks.

don't say that, you're making me jealous

On my way to the dealer to place the order I had already gone through my whole spreadsheet and had every single detail figured out, except the gears, and didn't decide before getting there. As my sales guy was walking me through the order, we got to gearing and I made a knee jerk reaction to opt out. It was less than 1k option. I regretted it, and was going to call the next morning to modify the order, but Jeep accepted the order right away the next morning so I couldn't modify it.

 

[Alligatorgun]

don't say that, you're making me jealous

On my way to the dealer to place the order I had already gone through my whole spreadsheet and had every single detail figured out, except the gears, and didn't decide before getting there. As my sales guy was walking me through the order, we got to gearing and I made a knee jerk reaction to opt out. It was less than 1k option. I regretted it, and was going to call the next morning to modify the order, but Jeep accepted the order right away the next morning so I couldn't modify it.

I was on the fence, my brother said idk man sound like deep gears. I was super fortunate there was a 6spd with 4.88s on a lot 23 miles away. I immediately knew it was a must have.

 

[grimmjeeper]

Man I've tried to do the math and show people the same thing you're doing and they still come out of the woodwork and tell you how wrong you are and how you're just a big dummy and they know everything and you don't know nothing. Good luck using facts and logic.

But that's just my opinion. Personally I think a Rubicon on 37s would be fine. I'm going to be on 35s here soon. I'm waiting on the dealership to get done doing some warranty work and then I'll have mine set up with all the new parts here soon.

Sure, the math works out. Math is math and it always works out the same. Even if you use the actual rolling diameter of the tires instead of advertised O.D. from the specs, the numbers are close.

Where the problem comes in is the opinion on whether the stock 3.45s are "good" with stock size sport tires.

Some people think they're fine. A lot of people, especially people who do serious rock crawling, don't think 3.45s are anywhere near enough for stock tires.

It depends on where you live and what you do with your Jeep.

To the OP, tell us what you're going to do with your Jeep (and where) and we can give you useful advice that matches your intended use.

 

[OrneryBear]

I was on the fence, my brother said idk man sound like deep gears. I was super fortunate there was a 6spd with 4.88s on a lot 23 miles away. I immediately knew it was a must have.

Man wish I was that lucky to get one of those test drives. I tried to drive every combo I was interested in but obviously that was a rare one. I really wanted the diesel but my wife really wanted the 6spd, so twist my arm, hard decision there. We traded in a 3dr vw golf diesel 6spd which was amazing but didn't fit our life anymore. If jeep had paired the 6spd with the diesel that would have been perfect for me.

 

[6.2Blazer]

Good comments above. While I stated in a post how 3.45's and stock are the same on paper as 4.10's and 37's, it is all in perspective. How good do you think 3.45 gears really are?
I also think a lot of people don't have a good perspective of the difference between gears. They also tend to way over exaggerate the difference. If you taped over the tach so you couldn't see the RPM at a certain speed, the average person would not be able to guess if the Jeep had 3.45 or 4.10 gears. If you drove two Jeeps back to back that were identical except for the gears some people would notice the difference....but many wouldn't. Not saying that the lower gears are not "better", and if I was ordering a new Rubicon today I would likely opt for 4.88's. Just the average person wouldn't notice the difference. I will guarantee you that the majority of Jeeps you see on the road with bigger tires still have the stock gearing. Why? Because the average person is not going to spend thousands of dollars on gears that nobody at the mall can see. A lift, big tires, winch, lights....sure, because it makes it look tough. Can't count how many people I have talked with that have Jeeps on big tires and very few have done gears....and most don't even know what you are talking about.

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