Re-gear?

[OldBob]

Ok, I know this question has been asked in different forms previously but let me ask once more.

I have a JLU sport with 3.45 gears and std tires from the factory. I want to put a set of Rubicon pull-offs on it so say 33”. I do not plan to ever go larger on the tires. I want to maintain the current acceleration and highway behavior and keep reasonable mpg. My use is 9 on road and the other 10% is beach sand and dirt roads. The labor for a gear change in my case is free.

3.6l v6 and auto trans

question: So change to 3.73 or 4.10?

will I need any spacers or suspension change in height to avoid rubbing or better shocks to control the heavier tires?
thank you very much in advance.

P.s. I may tow a boat or overland camping trailer. In my 2007 JKU I have run TrueTrac front and rear with 4.10 and 33s and will likely do that on this one as well. Of course that is a different engine and transmission.

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[Dyolfknip74]

Try driving it first. I think you won't need a regear with those tires.

 

[TheBirdie72]

You are going to get numerous different opinions on this one since gear changes are one the most debated topics on here. But I can tell you that I got the 3.45 gears, 2.0T, and 33" falkens and my 2-door is still plenty quick. So based on my use case, you should be just fine. If you get Rubi take-offs, you shouldn't need to do anything else.

 

[CarbonSteel]

Which engine and transmission? That will make a big difference.

 

[jhackathorne]

Try driving it first. I think you won't need a regear with those tires.

Agreed. And if you do decide to do it, go to 4.10. You would likely not even notice a difference in the 3.73 from 3.45.

 

[kah.mun.rah]

I do not plan to ever go larger on the tires.

Raise your hand if you have ever said that....

 

[Remorseless]

Try driving it first. I think you won't need a regear with those tires.

100% seconded, try driving it first. If you don't like it, 3.73 will be a moderate upgrade, 4.10 will be a bigger upgrade.

 

[aldo98229]

My guess is the 3.45 gears will do fine on 33s.

Like others have said: drive it first.

TIP - enable the automatic transmission gear display on your EVIC. This will help you evaluate how your transmission is behaving with that setup. If you don’t see 8th gear popping up much, that’s a sign that you should consider regearing.



Good luck.

 

[OldBob]

Raise your hand if you have ever said that....

I have been on 33’s in my JKU for over 10 yrs. They fit my mission.

 

[LOBBS]

If 33s are as big as you plan on going you've already got your answer. Just match the 4.10s that's the same factory setup on the Rubicon. It is mathematically impossible not to lose performance, driveability and mileage going to a heavier, taller tire. You can offset that in two ways. More power or more gear or some combination of both.

 

[6.2Blazer]

I put Rubicon take-offs on a Sport recently and it's really hard to tell any difference in the performance. I'm sure 4.10 would be "better" but the stock 3.45 stills seems "good".......just a lot of time and money involved to change gears. As said above I would not recommend going to 3.73 as from personal experience that little bit of a change from 3.45 is simply not worth it. I've installed lifts and bigger tires on multiple vehicles over the last 30 years, and have also rebuilt and regeared axles.
Rubicon take-offs should fit on a stock Sport model just fine. On the one referenced above I did install Rubicon take-off springs and shocks for a little bit of lift, but I'm sure wasn't really needed to run the tires.

 

[kah.mun.rah]

I have been on 33’s in my JKU for over 10 yrs. They fit my mission.

Cool. You will notice a huge difference with 33s on a JL compared to 33s on a JK (especially if you have the auto transmission) so I would suggest trying the 33s on your JL before investing in the re-gear. The wheels on your JK will also fit your JL if you want to swap them for a test run.

 

[JayCeeX2]

I have JLU with 3:45 gears with 33 inch tires.

Toyo Open Country A/T III 285/70R17
Dirty Life 17x9 -12 offset

Had slight rubbing issue at full turn on those euro splash guards that come on the Sport model, easy fix.

Jeep still has plenty of pep, I didn't really notice much difference. Sometimes will hunt for 8th gear on the highway if start going up incline or have strong head wind. Im in S FL so everything is really flat.

I don't plan on going any larger either.

 

[entropy]

Try it first. I run 33s on the stock 3.45 gears, it is perfectly fine. I wouldn't re-gear to 4.10. not worth the money. 4.56 maybe so you can end up upgrading tire size down the road. 33s on 4.56s should be pretty nice too.

Eventually I am going to 4.56s and true 34s. Nice sport setup imo. front lunchbox locker, selectable rear locker, small lift. "Rubi Lite"

 

[entropy]

If 33s are as big as you plan on going you've already got your answer. Just match the 4.10s that's the same factory setup on the Rubicon. It is mathematically impossible not to lose performance, driveability and mileage going to a heavier, taller tire. You can offset that in two ways. More power or more gear or some combination of both.

With the auto transmission going from 31.5s to 32.7 tires you wont see a difference in mileage from 3.45s and 4.10s. And minimal performance decrease. The difference is there "mathematically" but the smaller the tire, the more negligible that difference is.

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