JLU Sahara Shiftpoint Question

[FFM069]

Hi everyone,
I just recently changed tires on my JLU Sahara and went from 265/70R18 Falken Wildpeaks to 275/70R18 Duratracs. I also installed Spidertrax wheelspacers at the same time.

I noticed that on my first drive on the highway it would not shift into 8th gear at all and mostly stay in 6th gear (it would occasionally hit 7th gear). Fuel consumption also went down by like 2-3 mpg. I am a little surprised given that both tires are more or less a 33inch tire so I would have never guessed that big of a difference.

My question is will the transmission eventually adapt and shift into 8th gear again (because it's a learning transmission)? I did not recalibrate for the new tire size as the old one was almost the same (although I also did not recalibrate the tire size when I went from the stock tires to the Wildpeaks).

Should I simply wait and drive a bit more and see if the transmission adjusts? Or is it recommended to recalibrate the Jeep for 33 inch tires? Again, I am surprised because with the 265/70R18 Wildpeaks I would hit 8th gear on the highway all the time and now I am in 6th with only marginally larger tires...

Any help, thoughts or general advice is as always much appreciated fellow Jeepers!

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[aldo98229]

Basically, you went from a 32.6-inch tire to a 33.2-inch tire. In other words, you increased tire size by 0.6-inch, or 0.3-inch by the time they are mounted. That is not enough to matter.

If your transmission continues to refuse to shift into 8th gear, I suspect something else is amiss.

 

[aldo98229]

PS - the wider tires and the spacers will increase drag; still I highly doubt it will be enough to affect your transmission shifting.

 

[Dyolfknip74]

Basically, you went from a 32.6-inch tire to a 33.2-inch tire. In other words, you increased tire size by 0.6-inch, or 0.3-inch by the time they are mounted. That is not enough to matter.

If your transmission continues to refuse to shift into 8th gear, I suspect something else is amiss.

On top of Aldo's great message, it should be noted that the tranny will "learn" to some extent as well. I'd say give it a few hundred kms to let it settle and see what's up then.

 

[FFM069]

Basically, you went from a 32.6-inch tire to a 33.2-inch tire. In other words, you increased tire size by 0.6-inch, or 0.3-inch by the time they are mounted. That is not enough to matter.

If your transmission continues to refuse to shift into 8th gear, I suspect something else is amiss.

That's exactly what I was thinking as well. How can such a little increase change so much regarding my shift points. I'll try and drive like 500 miles or so and see if it adjusts

 

[Dyolfknip74]

That's exactly what I was thinking as well. How can such a little increase change so much regarding my shift points. I'll try and drive like 500 miles or so and see if it adjusts

For sure. There is no way that small of a difference would do much, if anything. Unless someone is calibrating the Willys as well. They're about that much different from a sport or a Sahara I think....same gearing as well.

 

[tuffytuffy]

I'm going from stock 32" to 35. For that much I need a recalibration. You don't,

 

[Terminex]

make sure you recalibrate the tire diameter using taser or jscan. I had the exact same issue as you in my '19, and once I updated my tire size it got better in terms of mileage & transmission.

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