First impression towing

Jrscrib · May 25, 2020

Well just traded my 2018 for a 2020 both High Country Duramax. We camp with a 16,000 pound fifth wheel so tow often in the summer. The 2020 has the factory hitch with a curt 25k. First off had to move the hitch to the highest setting and it still touched the bed rail pulling in my driveway the old truck was close but didn’t touch. The truck pulls very smoothly and feels good in the road transmission shifts a lot smoother than the 2018 but when pulling hills in Vermont is noticeable less power. With the 2018 I could set Cruze control at 72 and it would maintain speed today I was not able to at all was down to 68 for a bit on a hill I could go 75 if I didn’t pay attention. Does not have the pulling power. Then after pulling hill I had to go down a 7% grade one mile long and stop at the bottom and found the exhaust brake way less effective.

I am over all impressed with the truck and the way it rides handles and pulls with confidence but they have missed the mark when programming the transmission for towing. This is my fourth duramax and I work on these as my day job and feel they really have cut power while towing not sure if it is engine power or just they way it is delivered with the transmission but feels about the same as my 15 duramax maybe little less.

Still a great truck

dalek77 · May 25, 2020

Well just traded my 2018 for a 2020 both High Country Duramax. We camp with a 16,000 pound fifth wheel so tow often in the summer. The 2020 has the factory hitch with a curt 25k. First off had to move the hitch to the highest setting and it still touched the bed rail pulling in my driveway the old truck was close but didn’t touch. The truck pulls very smoothly and feels good in the road transmission shifts a lot smoother than the 2018 but when pulling hills in Vermont is noticeable less power. With the 2018 I could set Cruze control at 72 and it would maintain speed today I was not able to at all was down to 68 for a bit on a hill I could go 75 if I didn’t pay attention. Does not have the pulling power. Then after pulling hill I had to go down a 7% grade one mile long and stop at the bottom and found the exhaust brake way less effective.

I am over all impressed with the truck and the way it rides handles and pulls with confidence but they have missed the mark when programming the transmission for towing. This is my fourth duramax and I work on these as my day job and feel they really have cut power while towing not sure if it is engine power or just they way it is delivered with the transmission but feels about the same as my 15 duramax maybe little less.

Still a great truck

I don't decelerate on hills towing 17k, but there is a delay on cruise control before it starts accelerating. Might need to break yours in some more? I agree with exhaust braking, could be better. Love the truck though and I hit my tonneau cover rails often, but they come in 2.75" on each side. My hitch weight varies between 2600 and 3100. Truck will sit quite a bit with that much weight and still unsure if I want bags. Wheel seems a little loose with that weight on as well, but unsure if it's my imagination.

Still love the truck as well. Gas mileage is around 10 towing that much too.

Dk

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KCJackson1 · May 26, 2020

5 hours ago, Jrscrib said:

Well just traded my 2018 for a 2020 both High Country Duramax. We camp with a 16,000 pound fifth wheel so tow often in the summer. The 2020 has the factory hitch with a curt 25k. First off had to move the hitch to the highest setting and it still touched the bed rail pulling in my driveway the old truck was close but didn’t touch. The truck pulls very smoothly and feels good in the road transmission shifts a lot smoother than the 2018 but when pulling hills in Vermont is noticeable less power. With the 2018 I could set Cruze control at 72 and it would maintain speed today I was not able to at all was down to 68 for a bit on a hill I could go 75 if I didn’t pay attention. Does not have the pulling power. Then after pulling hill I had to go down a 7% grade one mile long and stop at the bottom and found the exhaust brake way less effective.

I am over all impressed with the truck and the way it rides handles and pulls with confidence but they have missed the mark when programming the transmission for towing. This is my fourth duramax and I work on these as my day job and feel they really have cut power while towing not sure if it is engine power or just they way it is delivered with the transmission but feels about the same as my 15 duramax maybe little less.

Still a great truck

The axle ratio is likely making the difference. 2018s had a 3.73 with the Duramax, while 2020s have a 3.42. The 3.42 is intended to improve fuel economy in the higher transmission gears, while the extra lower tranny gears help with a heavy launch. If you were used to pulling a grade in 4th gear of the 6-speed Allison (1.00:1) with the 3.73s, you may need to drop from 7th (1.00) in the new 10 speed to 6th (1.26) to get better torque multiplication (3.42 x 1.26) = 4.31 > (3.73 x 1.00). That will give you more grunt when you need it. In 3rd gear of your 2018, you were at 3.73 x 1.406 = 5.24, so 6th gear in the new truck splits the difference between 3rd and 4th of your old truck.

Shawn T · May 26, 2020

19 hours ago, Jrscrib said:

Well just traded my 2018 for a 2020 both High Country Duramax. We camp with a 16,000 pound fifth wheel so tow often in the summer. The 2020 has the factory hitch with a curt 25k. First off had to move the hitch to the highest setting and it still touched the bed rail pulling in my driveway the old truck was close but didn’t touch. The truck pulls very smoothly and feels good in the road transmission shifts a lot smoother than the 2018 but when pulling hills in Vermont is noticeable less power. With the 2018 I could set Cruze control at 72 and it would maintain speed today I was not able to at all was down to 68 for a bit on a hill I could go 75 if I didn’t pay attention. Does not have the pulling power. Then after pulling hill I had to go down a 7% grade one mile long and stop at the bottom and found the exhaust brake way less effective.

I am over all impressed with the truck and the way it rides handles and pulls with confidence but they have missed the mark when programming the transmission for towing. This is my fourth duramax and I work on these as my day job and feel they really have cut power while towing not sure if it is engine power or just they way it is delivered with the transmission but feels about the same as my 15 duramax maybe little less.

Still a great truck

I went from a '15 LML 6-speed 3.73 to this my '20. I agree with the post above, the 2 highest gears are not made to pull above 10k IMHO. The improved fuel mileage is very noticeable unloaded due to the higher gearing. I only pull ~14K (double-tow) but, it's over Colorado mountain passes, i.e. Monarch Pass, which does not get any steeper up and down. My first legitimate pull was this weekend, my comparison as follows 15' to '20

No noticeable difference in climbing, flat land, acceleration, etc. I would guess 20K + would be the true test

Downhill the 10 speed, using manual shines for compression hold-back, mainly because in manual mode you have more gears to choose from, the exhaust brake is barely noticeable like the '15

My 5th Duramax, and I love them, no other machine like them!

I have the Curt 25K puck system hitch, as well. Totally too low on the highest setting, almost laughably too low! I imagine it will take a DOT, engineering approval but they need an extension system, at least 3 more bolt holes up. Not happy at all with it. Pro Grade app/system is buggy at best, the commercials make it look perfect. My cameras have been on back order for 5 months but I created a profile for my 5th wheel and it constantly turns my brake gain to 0 when I turn the truck off, and I run the TPMS system all of the way through. When I hit the "Done" button the readings disappear, went through it 8 times and gave up.

Edited May 26, 2020 by Shawn T

ssowie · May 27, 2020

I have a 2020 3500 srw and tow my 5th wheel with a goose neck conversion. I had a 2017 3500 srw with same set up and hit the sides a couple of times. The new trucks are supposed to have a 1” lower side and I have not hit the sides yet(knock on wood).

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