Question on gears with 35"'s on always keeping/getting to use 8th gear in any situation on or offroad

[Donta1979]

I have about 62k miles or so to go when I will make a choice upgrade to 37"'s and go to 5.13 gearing to make sure I have 8th gear at all times. Or stay with my 35"'s and gear for them so I have 8th gear back at all times. Am Curious what gears should I go with so I have 8th gear in any driving situation on or off road with 35"'s? I already know what I will have to plan for with 37"'s but at 35"'s to always have 8th gear again I am at a loss because I do know some gears with some tire sizes you can lose a gear like say 8th right now constantly. My Jeep is my daily driver in the city to the highway, and wheeler so it's something I have to keep in mind.

Oh this is on my JLU Sport 2.0T 8 Speed automatic transmission. Only asking this because I have seen people saying multiple gear ratios. Like 37"'s with 5.13 gears and 8th not dropping at all I am wondering if there is a gear ratio that does the same thing with 35"'s and 8th gear. I have seen people say 4.10 to 4.88 and 4.56 with lots of back and forth's on the subject.

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[conFUcius]

I have about 62k miles or so to go when I will make a choice upgrade to 37"'s and go to 5.13 gearing to make sure I have 8th gear at all times. Or stay with my 35"'s and gear for them so I have 8th gear back at all times. Am Curious what gears should I go with so I have 8th gear in any driving situation on or off road with 35"'s? I already know what I will have to plan for with 37"'s but at 35"'s to always have 8th gear again I am at a loss because I do know some gears with some tire sizes you can lose a gear like say 8th right now constantly. My Jeep is my daily driver in the city to the highway, and wheeler so it's something I have to keep in mind.

Oh this is on my JLU Sport 2.0T 8 Speed automatic transmission. Only asking this because I have seen people saying multiple gear ratios. Like 37"'s with 5.13 gears and 8th not dropping at all I am wondering if there is a gear ratio that does the same thing with 35"'s and 8th gear. I have seen people say 4.10 to 4.88 and 4.56 with lots of back and forth's on the subject.

When I had a 2014 JKU 6-speed, I re-geared to 4.56 for 35s but ended up at 37s; it was a pig to get started with bumpers, winch, rock sliders, and rock armor (I had a supercharger too) on the 37s and I regretted not doing 4.88s.

The takeaway from my experience? Focus on what tire size you want to end up with as I would not want to pay to re-gear twice. Sounds like you’ve settled on 37s so if you really want to re-gear before then, go to the ratio to 37s and just drive slower on the 35s. Since you have a Sport, there are other components you need to consider upgrading too for 37s with a re-gear.

 

[Headbarcode]

First step, is reprogramming the current tire size. The 8-speed is a learning transmission and needs accurate information fed to it, so it can properly and efficiently place its shift points. I see 8th gear all the time, and I'm on 38's and stock 4.10 gearing. No plans for regearing.

 

[Redbaron73]

First step, is reprogramming the current tire size. The 8-speed is a learning transmission and needs accurate information fed to it, so it can properly and efficiently place its shift points. I see 8th gear all the time, and I'm on 38's and stock 4.10 gearing. No plans for regearing.

Is the programming from a tazer adequate to tell the transmission a different tire size is being used?

 

[Headbarcode]

Is the programming from a tazer adequate to tell the transmission a different tire size is being used?

Yes, it most certainly is. I have the Tazer mini on mine. The Lite version is less money, for those not interested in all the other features. There are other options that are more cost efficient, but I have no experience with them.

 

[Redbaron73]

MY*JLUR has 37s, 3.6L, 8Spd, and stock gearing. I do occasionally hit 8th, but frequently see less than 8th when head winds or other driving conditions exist.

I will eventually regear.

 

[jeepoch]

Rob,

I concur with Stephen. Only invest in the gearing that makes sense for the tires you are planning to end up with.

I too have a 2 door Sport S but with the 3.6L Auto. I lifted it and installed 35's without regearing. I wanted to first experience exactly how this 8 speed transmission was going to do on this setup with the stock 3.45 gears. My expectations were low and I was fully expecting the need to regear to at least 4.56.

I did also invest in the Tazer Mini in order to set the proper tire size. As a side note, I should have purchased the much cheaper Tazer Lite, I use none of the other Mini's 'live' features. Reprogramming the tire size was essentially just to get the speedometer accurately recalibrated.

However, with the proper tire size programmed, this 8 speed Auto is basically magic. It 'adapted' to the 35's remarkably well. It's shift points are smooth and for the most part totally unnoticeable. It downshifts like a dream and certainly exceeds my initial expectations.

Unfortunately, and as you allude to, 8th gear while not completely gone on the freeway, is certainly not in my current vocabulary. I do see it occasionally but not very often.

On the bright side however, I've now become very fond of this behavior. Really. I can always very easily manually select 8th gear whenever I'm at highway speed. And it performs flawlessly for it's purpose; I now have an overdrive gear on steroids.

My mileage climbs a good 3 to 4 mpg when I select 8th. Granted the conditions need to be right, pretty flat grade with very little to no passing situations. Still, it now presents a whole other dimension that would be lost with any taller gearing. Yes 8th would again be more automatically selected, but the highest obtainable aspect ratio would certainly then mean lower gas mileage. For any long range trip, I'd rather get 400 miles per tank than only sub 350.

So my opinion has now shifted (pun intended). I do now much prefer my current setup of 35's with the 3.45 gears. This transmission has adapted quite nicely to the different power-band at take-off and it's shifting seems natural and intended (almost designed-in and factory calibrated).

I have no further plans to regear at all. I do concede however that this setup would probably not work well (or at all) with 37's. There just wouldn't be enough margin to make much of anything behave remaining on the 3.45s with that size tire. I have no direct experience, but based on what I do know, the trend would most likely be in the wrong direction. 37's would certainly cry for taller gears.

Still, that's your issue. I have no desire to go beyond 35's. My Sport off-roads better than stock Rubi's (simply based on experience in helping pull some of these Rubicon's through some obstacles that I had no trouble with). And yet it's still my daily driver.

It's fun, peppy (enough), extremely capable as much as possible (without lockers), and gets amazingly good on-road mileage (just shy of 24mpg city).

I'm loving this setup immensely.

Good luck in being as happy with your JL as I am with mine
Jay

 

[WranglerMan]

I also like several here chose not to regear and do occasionally see 8th but not often, I run 35” KO2’s with a 2.5” lift and ROAM stubby front bumper with a winch and usually get 19-20 on the highway but if I set the cruise and roll I can boost that by a few

 

[JLAFAKASI]

I also like several here chose not to regear and do occasionally see 8th but not often, I run 35” KO2’s with a 2.5” lift and ROAM stubby front bumper with a winch and usually get 19-20 on the highway but if I set the cruise and roll I can boost that by a few

are you still running on no regear and 35s? I love the rig

 

[JLAFAKASI]

are you still running on no regear and 35s? I love the rig

Do sport and Sahara share the same gears?

 

[blnewt]

Do sport and Sahara share the same gears?

yes, 3:45s

 

[WranglerMan]

are you still running on no regear and 35s? I love the rig

Yes Sir and they are wearing well, I can’t go above 35’s without a regear

 

[JLAFAKASI]

Yes Sir and they are wearing well, I can’t go above 35’s without a regear

Are you running the 2.0 turbo or 3.6L 8 speed?

 

[WranglerMan]

Are you running the 2.0 turbo or 3.6L 8 speed?

3.6L... I get 20-21 HWY on a good day but see 19-20 most of the time and city driving is avg 16-17

@TTEChris of Tank Customs advised if I wanted to run bigger than 35’s I would have to dig deeper to regear and possibly look at larger breaks if I recall correctly and I just did not want to spend that kinda $$ as I just wanted to run slightly larger tires than the stock 31” ones that came on it and then I added the steel bumper and winch and that caused it to drop alittle more

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