Does Rubicon even use 8th gear??

[roaniecowpony]

My 18 JLUR on stock 33s hits 8th in the ZF pretty quick on level ground or downhill. But the least bit of acceleration and it downshifts. If I'm going downhill and want to downshift one gear for engine braking, I just stab the accelerator pedal and let off quickly and it drops a gear and stays there as long as I keep my foot off the accelerator.

I'd say your trans is probably fine. These ZF transmissions are the best automatics I have driven. I really can't get over how good they are and note it every time I drive it 2 years into owning it. It's probably the highest quality part on these things. Quit looking at what gear it's in and just drive it and enjoy.

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[MrMischief]

At 110 km/h (68 m/h) it is almost always in 7th gear. Is this normal?

I don't see your location listed, providing that may help shed some light on it. I find that it won't use 8th if the transmission not warmed up, which can take quite a long time in extreme cold. I also suspect that the 3.6L is going to use 8th less often if you're at a higher elevation. Also the 2 door is around 110 - 140 kg lighter than 4 door, not a lot but it may be making a difference. I also notice a huge difference if the top/doors are off.

My 2 door 3.6L at 1,600 m of elevation when warmed up and doors/roof in place the transmission will roll into 8th at speeds over 100 km/h pretty regularly.

 

[BuffaloBill]

I have the 3.0 L diesel. If I am above 56 mph at constant speed and if the grade is <6%, I am in 8th, at 1,850 rpm.

What gears did you put in your diesel? With the stock 3.73 and a 35” tire, the rpm would be about 1500.

 

[Jeepsk8]

Mine used to. Added a lift and 37's on beadlocks and 8th only happens on downhills...7th only if it's flat and no headwind and I'm under 65mph.

 

[calemasters]

What gears did you put in your diesel? With the stock 3.73 and a 35” tire, the rpm would be about 1500.

My JLURD powertrain is stock. My tire diameter is 32.8". Under normal highway driving conditions at ~65 mph, in 8th gear, I am usually around 1,800 rpm. The ZF-sourced 8HP75 TorqueFlite 8-speed, does a good job keeping the diesel at 1,800 - 2,200 rpm, which seems to be the sweet spot. The Jeep powertrain engineers picked the right final drive ratio (3.73:1) for this vehicle. It's the best powertrain I have had in my Wranglers.

 

[Quadjeeper]

My '20 Rubicon with stock tires is in 8th by 45 mph on flat ground with easy throttle.

 

[Cuyose]

Maybe try same speed, same road and use cruise control if you arent already. If you are not and are like everyone else on the highway not using it, you are wavering 5 mph +- constantly. The transmission is probably staying in a lower gear as it has seen the need for it during the acceleration up again.

Also a 10 mph headwind can have a hue effect at those speeds and get the trans to downshift to maintain as well.

 

[Thunderjet]

I’ve added 315/70/17 to stock rims and I still see 8th gear routinely.

How do you like that tire size ?

 

[DavidArmen]

Fully stock 2021 JLUR
I see 8th pretty much all the time.
I’ve driven like a granny since I got the jeep at 8miles on the odo so i’m pretty sure my ZF8 has trained itself to keep high gears and low RPMs whenever possible.
Anytime I’m above 45, be it street or highway, I see 8th gear routinely on flat ground.
Also, it pretty much always uses 8th on the freeways unless there is a noticeable incline.

 

[exlax66]

If you have a heavy foot.....like to accelerate quickly........you are training the "adaptive" transmission to shift at higher RPM's than if you drive like a Granny. You may have trained it to think it should not shift until the RPM's are a little higher.

Any idea how long it takes to train the transmission?

 

[Headbarcode]

I have had it in 8th gear in 4 Low. I am pretty sure at interstate speeds it is in 8th gear? This system reminds of those old farm trucks that had 4 speed but had a high low trigger. This thing in a sense has 16 gears or speeds. I have been impressed with it.

I'm guessing that you don't have your dash set up to display the current gear next to the D at the bottom of the guage cluster? Using the left steering wheel control buttons, I believe it's in the configure dash section. Factory default has it turned off.

 

[beaups]

Any idea how long it takes to train the transmission?

The transmission does not get trained at all, it simply adapts to its wear levels and how you are driving it “in the moment”. The rest of it is urban legend.

 

[Quadjeeper]

The transmission does not get trained at all, it simply adapts to its wear levels and how you are driving it “in the moment”. The rest of it is urban legend.

I beg to differ. Ever since Chrysler introduced the 604 4 speed overdrive back in 1989 the TCM adapted its shift algorithms to the drivers habits. Back then we had many complaints from rental car companies stating the transmissions were not shifting correctly. That was caused by so many different drivers operating them. Since then, the adaptive memory learning period is much shorter, thereby it is not a noticeable issue anymore. Most if not all modern TCM's do the same thing. Chrysler tech for 26 years, then still in the industry the last 15+ years.

 

[dchemphill1]

I'm guessing that you don't have your dash set up to display the current gear next to the D at the bottom of the guage cluster? Using the left steering wheel control buttons, I believe it's in the configure dash section. Factory default has it turned off.

Thanks for the tip. I will check on that.

 

[_olllllllo_]

On the 6 speed manual, I rarely get past 4th gear. 6th is unusable.

I use 6th gear all the time when I am cruising at 65 mph on the highway here in Arizona with my manual. I am still on the stock 33" tires and also have a JLUR, but I never get into 8th either!

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