2020 Jeep JLU 6 Speed MT Issues

DanW

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My 2019 6spd 3.6 gets great fuel mileage in 5th at up to 70mph. If I go to 6th, it is really for 75mph and over or you are out of the power band and the 3.6 doesn't have the torque to move the heavy vehicle. The auto is much, much better on the highway. The computer does it all for the driver. Lots of shifting and slipping in the auto to maintain 70 on various roads. I love my manual, but hate it on the highway as the gearing is too tall for 6th gear. But, I get 24+ in 5th at 70. I have an Altitude with 32" tires. The good thing, is that the 6th gear will last a long time:) They had to have gears to make the jeep go comfortably at 85mph, so 6th it is.
It isn't that. He should pull 5th easily and pull 6th even up mild inclines. What he described is not normal.

Mine pulls mild inclines in 6th just fine with 35s. It should at least do that we'll.

OP I still would not rule out a slipping clutch. Get @JeepCares involved. Make the dealer do the clutch test with you watching, or do it yourself. If I lived near you we'd do it together.

What tires are you running?
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DanW

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Looks like at least 35s. If running 3.45 axle ratio, then that could be it. If so, I'd regear with 4.56 or even 4.88. I think 4.56 would be the sweet spot for 35s.

Mine has 4.10 and does fine.
 
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StevenTexasJLU
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Did you say you have a 3.6? Have you had any ESS issues? If yes, there have been a few posts on JL forum and several on JT about rocker arm issues in certain 3.6 engines with those issues but it should throw a code if it is that.

The 6 speed in the JL now has been roundly panned for only being a 4 speed with two overdrive gears.
Yes I have the 3.6 penstar, I did see those posts and they had me thinking it could be a possibility but I have yet to have a light come on for anything. 5th and 6th do seem to be useless in my JL right now and even 4th some times struggles idk it's like I put the pedal to the medal some times and the throttle struggles to open, the Jeep goes from 60 to 45 slowly over about 10-15 seconds then it finally does start to get accelerating again.
 
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It isn't that. He should pull 5th easily and pull 6th even up mild inclines. What he described is not normal.

Mine pulls mild inclines in 6th just fine with 35s. It should at least do that we'll.

OP I still would not rule out a slipping clutch. Get @JeepCares involved. Make the dealer do the clutch test with you watching, or do it yourself. If I lived near you we'd do it together.

What tires are you running?
Agreed I don't think it normal either. I'm running 33" nittos, some steel sliders, a winch on a steel front bumber on a 2" lift along with the same 33" nitto spare on a soft top JL. Could it be the added weight on 3.45 gearing? Idk I just can't see it being normal even with the added weight of everything. I plan to do gearing in late December early January.
 

DanW

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Agreed I don't think it normal either. I'm running 33" nittos, some steel sliders, a winch on a steel front bumber on a 2" lift along with the same 33" nitto spare on a soft top JL. Could it be the added weight on 3.45 gearing? Idk I just can't see it being normal even with the added weight of everything. I plan to do gearing in late December early January.
Not sure. It still doesn´t sound right. I wish I lived near you and we could drive each other´s Jeeps to get a feel for what may be going on. I think 33´s with 3.45´s wouldn´t be too different from 4.10s with 35s. But I´m not sure.

5th gear is what is making me think there is a problem, and probably not gearing. It should pull 5th gear just fine.
 

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My 2019 6spd 3.6 gets great fuel mileage in 5th at up to 70mph. If I go to 6th, it is really for 75mph and over or you are out of the power band and the 3.6 doesn't have the torque to move the heavy vehicle. The auto is much, much better on the highway. The computer does it all for the driver. Lots of shifting and slipping in the auto to maintain 70 on various roads. I love my manual, but hate it on the highway as the gearing is too tall for 6th gear. But, I get 24+ in 5th at 70. I have an Altitude with 32" tires. The good thing, is that the 6th gear will last a long time:) They had to have gears to make the jeep go comfortably at 85mph, so 6th it is.
Hi there, we certainly see how this may warrant for concern. Please send our team a private message with your VIN so that we may look into this for you.

Kathryn
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I don't think you have an issue. I have a Sport with manual and 33s and this is pretty much just how it drives on the highway. I can cruise in 5th , but will need to downshift to maintain on any rise or to accelerate. 6th is for downhill over 70. If you don't like it then I would look at re-gearing.
 
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Not sure. It still doesn´t sound right. I wish I lived near you and we could drive each other´s Jeeps to get a feel for what may be going on. I think 33´s with 3.45´s wouldn´t be too different from 4.10s with 35s. But I´m not sure.

5th gear is what is making me think there is a problem, and probably not gearing. It should pull 5th gear just fine.
Agreed bro, hopefully will find a solution here eventually
I don't think you have an issue. I have a Sport with manual and 33s and this is pretty much just how it drives on the highway. I can cruise in 5th , but will need to downshift to maintain on any rise or to accelerate. 6th is for downhill over 70. If you don't like it then I would look at re-gearing.
How's your MPGs? Some times I will be cruising at 70 in 5th and be getting 20-24mpgs then out of nowhere on the same flat road it will drop to 14mpgs and sometimes even as low as 12 or 10. Then eventually it work back up to 20 idk that doesn't seem like normal to me even with a sport on 3.45 gearing.
 

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How's your MPGs? Some times I will be cruising at 70 in 5th and be getting 20-24mpgs then out of nowhere on the same flat road it will drop to 14mpgs and sometimes even as low as 12 or 10. Then eventually it work back up to 20 idk that doesn't seem like normal to me even with a sport on 3.45 gearing.
I get around 20mpg highway. One of the reasons I shift a lot on the highway is to stay in the power band.

I did use cruise control last week. I kept it in 4th and saw a lot of fluctuation in the real-time MPG as it tried to compensate. But I was driving in the mountains so not flat.
 
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I get around 20mpg highway. One of the reasons I shift a lot on the highway is to stay in the power band.

I did use cruise control last week. I kept it in 4th and saw a lot of fluctuation in the real-time MPG as it tried to compensate. But I was driving in the mountains so not flat.
Yea I never use the Cruise Control either, to much traffic here in Houston when I'm on the road. Idk I guess it could be gearing I plan to get it regeared by January 2021 if nothing else we will know by then if that's the cause for my situation.
 

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@rustyshakelford lives nearby if you need a shop to help with your issues. If nothing else, he has experience and some good advice.
 

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Yea I never use the Cruise Control either, to much traffic here in Houston when I'm on the road. Idk I guess it could be gearing I plan to get it regeared by January 2021 if nothing else we will know by then if that's the cause for my situation.
Our air is thick and heavy with humidity. Add in a small head wind and it takes a lot of horsepower to move a JL at highway speed.

Unfortunately the 3.6 doesn't build any real horsepower until about 3000+ rpm. 5th and 6th are simply too steep to be useful in Texas
 
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