First real tow with the manual.....not good

[bleda2002]

I tow 3500 lbs with the payload max'd on 39s and 5.13s auto trans and have plenty of power. I can cruise in 6th at 70 mph and still accelerate if needed. I believe the guy mentioning that the tune is pulling power is correct and in lower gears you aren't getting all it's got as compared to the auto.

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[ShadowsPapa]

Before everyone jumps on the fact its lifted with 37's, it is running 5.13 gears, which puts it at an advantage over the factory with 3.73's and small tires.

No, it doesn't. It's still got the same horsepower. Tires take more power, and gearing doesn't give you more power. Easier to take off with, but it's not an advantage.
Gears give you low end grunt and the ability to take off fast, but at speed, those gears do nothing as horsepower is what moves the vehicle's weight at a given speed over a given distance in a given time.
HP is moving weight over a distance over a measured time. Your gears can't change that.

There's a reason these are restricted to 4,000/4500 pounds towing (depending on the JT) with a manual.
I agree the tune may be restricting the torque to protect the clutch in this case but we can't discount the negative impact of the extra weight and lift, either.
It measured the torque output and restricts - if the truck was lighter, easier to move with less rolling resistance, it would require less to move so the tune likely wouldn't cut it back severely.

 

[bd100]

(Kind of wondering, why the side-by-side if you already have a JT on 37s?)

Anyhow, people above mentioned the tune. I noticed my JT 6-speed suddenly improve its low-end torque around the 500 mile mark. Then it improved even more around 15,000 miles. Now it's very much like my old V8 pickup in behavior. I haven't towed the same mountain passes I did last year yet, but maybe it won't be stuck at 45MPH in the Colorado passes any more. (And I intend to carry less junk next time.)

We also have a WK2 Grand with the same motor but an automatic transmission. It routinely chooses overdrive at low RPM. It wasn't until recently that I could do the same in the manual trans JT, once it hit 15,000 miles.

So maybe your truck will be happier once you hit 15,000 miles.?

 

[BearFootSam]

You don't need to pull anything to understand how underpowered the 3.6 is, especially with bigger tires and the weight of other mods we add to these vehicles.

I had 2 passengers heading out of Grand Coulee a couple weeks ago with A/C running, maybe 2-3% uphill grade for a several mile stretch. Pedal to the floor in 4th gear just barely held 50mph.

I would easily swallow less power if it was an efficient engine. ...but it's not that either. Lol

After towing 2500lbs on an open top trailer with 500lbs in the bed and two adults + small boy onboard cross country I don't think the PentaStar is that underpowered. The 8 speed has a great ratio spread and excellent programming that make the most of the power. I crossed quite a few ranges and never had an issue holding speed on grades. At worst it would drop to third gear and run 3600-4000rpm but would still pull an accelerate if I asked.

The JT has terrible aerodynamics and is a heavy pig cresting 5k lbs. I never expected it to be quick and it's not, but it isn't lacking power. When I had a MT forester the darn thing could barely hold speed through the West Virigina hills when loaded up despite winding it up. At 12k' the subaru was almost unbearably underpowered.

 

[Zachattack50]

The sxs is because I'd rather beat that through fire roads than the jeep. I agree some on the rolling resistance. I need to plug my scanner in and verify im actually getting 100% throttle at WOT. I really suspect I'm not, just based off how the truck reacts.

As far as the wind goes, I still call BS that a stock height truck would be better than it lifted with this much trailor frontage. the amount of trailor above the tent is 24 sq ft, the rest is already behind the truck. If you lower the truck you effectively increase the wind resistance. Keep in mind this rig with the tent and full gear will roll 70mph in 6th with no issues, if I down shift for the same long grade its only to 5th.

At one point on a downhill I gave it the sauce and we clipped 90mph, smooth straight, no bucking from the wind. I have pulled plenty to know wind resistance feel compared to just plain over loaded feel.

Rolling resistance, ehh, I usually run 28psi to get a good contact patch, for pulling I aired up to the tires rated 50psi, again negligible. Gearing only moves your power band, it does not add HP, hence why I pulled mainly in 4th gear to hold 3500rpm, 67 was 3900. I saw zero benefit if I ran 3rd at 65mph to get the r's to 4500. Thats whats leading me to believe she is just plain tapped out. Again, not impressed, and I wouldn't bet 5$ that a max tow would do any better. But it is a mini truck after all.

Still to be clear, we love the truck, just not for pulling
Might have a mopar brake controller for sale soon too, haha

 

[Zachattack50]

(Kind of wondering, why the side-by-side if you already have a JT on 37s?)

Anyhow, people above mentioned the tune. I noticed my JT 6-speed suddenly improve its low-end torque around the 500 mile mark. Then it improved even more around 15,000 miles. Now it's very much like my old V8 pickup in behavior. I haven't towed the same mountain passes I did last year yet, but maybe it won't be stuck at 45MPH in the Colorado passes any more. (And I intend to carry less junk next time.)

We also have a WK2 Grand with the same motor but an automatic transmission. It routinely chooses overdrive at low RPM. It wasn't until recently that I could do the same in the manual trans JT, once it hit 15,000 miles.

So maybe your truck will be happier once you hit 15,000 miles.?

We have 24k on the truck, its been re geard since around 5k miles.

 

[AustinL911]

I pulled mainly in 4th gear to hold 3500rpm, 67 was 3900. I saw zero benefit if I ran 3rd at 65mph to get the r's to 4500.

Your math seems off. Did you adjust your settings for the new gears? In 4th, you should be pulling waaaaay less RPMs than what you stated at those speeds. For reference, he's the calculation for my exact setup with 35s/5.13s (34.6" true). So yours should be pulling less RPMs than mine.

Are you actually running 80 and think you're only running 65?

 

[Zachattack50]

Your math seems off. Did you adjust your settings for the new gears? In 4th, you should be pulling waaaaay less RPMs than what you stated at those speeds. For reference, he's the calculation for my exact setup with 35s/5.13s (34.6" true). So yours should be pulling less RPMs than mine.

Are you actually running 80 and think you're only running 65?

Yes the tire size in correct in the jeep. set with the taser, speed was verified with the gps vs the speedometer. the only time I saw 80 mph was downhill lol. The speed linit here is 75 in most places, so at 65 your get passed like your standing still. in 6th with no load the truck sits right around 2500 rpm at 62 for reference.

 

[Zachattack50]

Your math seems off. Did you adjust your settings for the new gears? In 4th, you should be pulling waaaaay less RPMs than what you stated at those speeds. For reference, he's the calculation for my exact setup with 35s/5.13s (34.6" true). So yours should be pulling less RPMs than mine.

Are you actually running 80 and think you're only running 65?

Your correct, I meant 3100rpm, not 3900. 4rth at 60 is 3100ish, I did run 3rd way deep several times to no avail. Power is flat from 3200 to 5500 rpm

 

[AustinL911]

Yes the tire size in correct in the jeep. set with the taser, speed was verified with the gps vs the speedometer. the only time I saw 80 mph was downhill lol. The speed linit here is 75 in most places, so at 65 your get passed like your standing still. in 6th with no load the truck sits right around 2500 rpm at 62 for reference.

Clutch slipping? Using a true 36" diameter tire as a safe calculation, these are the speeds you should be running with the D478 tranny, 1:1 transfer case ratio, and 2500rpms. Pending this calculator is correct (which I assume it is since its what everyone uses), your speed vs rpm seems off. 37s and 5.13s, right?

 

[Zachattack50]

Clutch slipping? Using a true 36" diameter tire as a safe calculation, these are the speeds you should be running with the D478 tranny, 1:1 transfer case ratio, and 2500rpms. Pending this calculator is correct (which I assume it is since its what everyone uses), your speed vs rpm seems off. 37s and 5.13s, right?

I will verify tonight with pictures and post them tomorrow. The actual height of the "37's" if I remeber correctly is 36.2' when I measured. yes 5.13's If the clutch were slipping, it would have gave up the ghost on a 8hr trip. I never once smelled anything. I assume the calculator your posting is 1.1 in 4th, right ?

 

[Zachattack50]

My point remains, I could not down shift enough to maintain speed on a grade. regardless of rpm.

 

[Joe Dillard]

I picked up a 20' 6 lug 10K# GVWR tandem axle dovetail equipment trailer not long ago. I drove a couple hours in my low milage '21 JT Mojave on 37's & MT to pick it up. Regretfully, I still have stock 4.10 gearing.

The MT JT did NOT like towing this empty 2800# beast.

On the other hand - my 3500 4x4 6.7L CTD Ram with a 4K# camper tows the same trailer & JT with no sweat.

 

[AustinL911]

I will verify tonight with pictures and post them tomorrow. The actual height of the "37's" if I remeber correctly is 36.2' when I measured. yes 5.13's If the clutch were slipping, it would have gave up the ghost on a 8hr trip. I never once smelled anything. I assume the calculator your posting is 1.1 in 4th, right ?

Oh, I believe you. I'm just genuinely curious why.

Stock on the left, your setup (theoretically) on the right:

Hopefully you can read the small print from my phone's screenshots.

 

[@californiajeeping]

Its a shame because the diesel makes drastically more torque and hp at a reasonable rpm but then overheats its oil on any hill :\

Now youll get a 3.6l with less payload due to 600lbs of battery for 40ft lbs of torque next year. They really miss the mark on utility with these vehicles.

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