Performance impact of 35s with Rubicon 4.10 gears

AVGeek99

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I have a 3.6L 6spd Rubicon on order and am having the dealer put on 35s. I'm wondering how much of a performance impact I will notice.

I currently have a lifted 2012 6spd JKU Sahara with 35s. When I first got it a few years ago it still had the original 3.21 gears. It got around ok but was a bit of dog, think Basset Hound as opposed to Greyhound, when it came to performance. 6th gear was useless; I very quickly learned to not go higher than 5th. I took it out west and I had to drop it all the way down to 3rd to keep up with semis going up the mountain passes.

A couple years ago I had the 3.21s replaced with 4.56s; the difference was night and day. I instantly had a useable 6th gear. This past May I went out to Reno and Yosemite. On most interstate mountain passes I could hold 70mph in 6th gear.

Obviously 4.10 is much lower than 3.21, but the JL 6spd is also geared a little higher than the JK was. In the back of my mind I'm a little worried about what performance will be like with my Rubicon in 6th gear. Is 6th gear still fully useable on a stock 4.10 Rubicon running 35 inch tires?
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turbosix

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There are gear ratio calculators all over the internet that would answer this question for you.
 
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AVGeek99

AVGeek99

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I'm fully aware of the gear ratio calculators. I know that with the stock 33s at 70mph the engine will be turning 2105rpm. With 35s it will be turning 1985rpm.

What isn't obvious to me from the calculators is what kind of useable power will it have in 6th gear from 55mph to 85mph. I don't need it to accelerate, but I'm wondering how well it will hold speed when going up a hill or into a strong headwind.
 

turbosix

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I'm fully aware of the gear ratio calculators. I know that with the stock 33s at 70mph the engine will be turning 2105rpm. With 35s it will be turning 1985rpm.

What isn't obvious to me from the calculators is what kind of useable power will it have in 6th gear from 55mph to 85mph. I don't need it to accelerate, but I'm wondering how well it will hold speed when going up a hill or into a strong headwind.
There are also dyno charts available that will help much more than asking people "how it feels".
 

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No expert here, but my JLUR 6sp only uses 6th for flat pavement at 70+ on 33s. The 3.6 has no ass below 2500 rpms, so if u see a hill or need to accelerate you will be dropping down alot...... if you find youself needing to go fast, you will be dropping to 4th at 60+ and running up to 5500+.

For the trolls....yes I get that all transmissions have to drop gears when passing, my point is that 5th and 6th are cruising gears only (even on 4.10s).

There are reports from people running 35s using the 4.10s and they don't seem to mind it much. I personally won't be doing it cause I dont have the type of trails were 35s are needed. Now that may change if i go forced air induction, but that is a ways off in the future.

If you want some real evidence, I would be happy to shoot some dash cam video flooring it in 6th gear on flat ground and climbing a slight grade. That way you can see exactly what the acceleration capabilities it has on stock wheels.

IMHO, unless your doing serious wheeling, stay with the 33s. I wouldn't sacrifice the driving experience just to butch up my stance (#secure), but wear what you dig.
 
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I'm fully aware of the gear ratio calculators. I know that with the stock 33s at 70mph the engine will be turning 2105rpm. With 35s it will be turning 1985rpm.

What isn't obvious to me from the calculators is what kind of useable power will it have in 6th gear from 55mph to 85mph. I don't need it to accelerate, but I'm wondering how well it will hold speed when going up a hill or into a strong headwind.
I can't give you input from a 6 speed point of view, but I can from an 8 speed one. With 35's, 4.10 gears, and the 3.6L, it would not hold 8th except on VERY flat ground WITHOUT a head wind.

Any hills or head winds and it would be in 6th and stay there. Even more annoying was the constant up and down shifting that happened to the point of being a real PITA.

I re-geared to 4.88 and got the Jeep I should have had from the factory.
 

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I have a thread I am too lazy to look up, where I thrashed this question to death in the context of my own build. I basically concluded that if I already had 4.10 gears, I would probably do nothing.

Since having that discussion, I threw the 35s on my Jeep, and it still has the stock 3.45 gears for the time being. I am most definitely looking forward to the day I drive away on my new 4.56 gears, but it's not THAT bad on the 3.45s. It's not good, but it's not THAT bad.

I definitely still feel like if I already had 4.10 gears, I would just skip the complication and expense of regearing. I could almost certainly live with 4.10 gears. I could just about live with 3.45 gears if I really had to, but luckily I don't.
 

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You want 6th to be efficient, not powerful. Who cares if you have to occasionally downshift climbing mountains or passing, isn’t that part of the fun of rowing your own gears.
 

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I have 4.56 gears and 35s with a 6 speed. I started with the 3.45s (I have a sport), but I think the 4.56s are the lowest I personally would go. Next time I’ll go 4.88.
Regearing was the best mod I did hands down. It transformed my JLUS. It is a blast to drive.
I may get a 6 speed Gladiator next, and I’ll regear that to 4.88 and add 35s.
 

lowmpg

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35's on my Rubicon created almost zero difference in performance.
 

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Since OP asked for subjective opinion, my $0.02 is that 4.10 is doable, but not optimal. I would have re-geared to 4.56 or 4.88. It's up to you to decide if the cost / effort is worth sticking to a slightly sub-optimal set up.
 

somedude922

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Technically you wont notice ANY difference. You wont have anything to compare it to since you will be driving it from the dealer with 35s already on. Just sayin😁
 

Devil6Dog

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There are also dyno charts available that will help much more than asking people "how it feels".
There are gear ratio calculators all over the internet that would answer this question for you.
This is the problem with this world. I still prefer to talk to real live people first to gain knowledge then if not there I'll take the easy route. I always thought part of driving a Jeep was to not take the easy route....But to each their own
 

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Depends on weight of tire and if you’re using stock wheels or heavy aftermarket ones , but you lose performance no matter what. If it’s a 35” KO2 (AT) it’ll be (significantly) less noticeable than say a 35” Nitto (hybrid or MT).
 

turbosix

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This is the problem with this world. I still prefer to talk to real live people first to gain knowledge then if not there I'll take the easy route. I always thought part of driving a Jeep was to not take the easy route....But to each their own
The problem is he's asking for anecdotal evidence. With vague questions like "hills" or "wind".

How steep are these hills? How windy is this wind? How many people are in the car? Is it loaded up with gear?

What is fast? What is slow?

Blah blah blah...

We already know it's going to be slower. He does too. These questions are too vague to be helpful.

Shoots 🤙🤙
 
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