Question: Towing with GM 8 speed

[DocBrown]

I've had nothing but 4 speed automatics until now. I always towed in 3rd. What gear should I be using for the 8 speed? I'm assuming 7 but...

[Quantum]

Originally Posted by DocBrown

I've had nothing but 4 speed automatics until now. I always towed in 3rd. What gear should I be using for the 8 speed? I'm assuming 7 but...

I guess it depends on a few factors.

On my 10 speed F150, I tow in in 7th, that's the direct drive 1:1. 8-10 are overdrive gears. I can tow in 8th, but every overpass it downshifts, but in 7th it doesn't shift unless I encounter a hill.

[CAG]

If you have tow/haul us it. If not check you manual for towing instructions. I would think not in overdrive and let the computer in the vehicle do it's job. You signature does not say if the truck is a Duramax. If it is, always in tow/haul as that keeps the turbo brake active and doing the proper work down hills.

[DocBrown]

Originally Posted by CAG

If you have tow/haul us it. If not check you manual for towing instructions. I would think not in overdrive and let the computer in the vehicle do it's job. You signature does not say if the truck is a Duramax. If it is, always in tow/haul as that keeps the turbo brake active and doing the proper work down hills.

5.3 gas. I always use tow/haul. That doesn't lock out OD though. The manual says to tow in D unless it shifts a lot. Well, that's stupid.

[Shokyle1]

Looks like 6th is one to one

[DocBrown]

Originally Posted by Shokyle1

Looks like 6th is one to one

That's a good find. Very helpful. Somewhere I thought I read it was 6th.

Thanks!

[Scott]

My '14 has a 6 speed transmission. I'm not sure when they added the 8 speed option. I always use tow/haul mode as well on my truck and have the gear shift in D, just like the manual says. How can you tell what gear you are towing in if you are just in D?

[Jay2504]

Easy to do Scott. Just put the truck in M1 at a light and up shift it manually until you get to 60 MPH or what ever speed you tow at. Look at the tachometer in 4th, 5th and 6th gear giving enough time in each gear for the truck to “ stabilize” and lock up the torque converter. Then later when towing in D you will know what gear you are in by reading the tachometer. On my 2014, it goes between 4th and 5th gear. Jay

[Quantum]

I use T/H mode on my truck, but if I don't lock out 8-10, it still likes to jump up into 8th gear. For my Ecoboost (turbo), the mileage slightly suffers in 8th as the truck is creating a lot of boost. If I drop it to 7th (1:1), the boost drops off, the instantaneous MPG goes up by about 1MPG.

I'm guessing you'll have to feel it out and see how the truck runs with your trailer. With T/H engaged, try 7th, if it shifts too frequently drop it to 6th. I'm sure it won't take you long to find out what makes the truck happy.

[DocBrown]

Originally Posted by Scott

My '14 has a 6 speed transmission. I'm not sure when they added the 8 speed option. I always use tow/haul mode as well on my truck and have the gear shift in D, just like the manual says. How can you tell what gear you are towing in if you are just in D?

They added the 8 speed in 2015 to certain models.

My 2016 has the ability to set what ever gear I want to max out on. So if I put it in M (there is no M1) there is a +/- button next to the Tow/Haul button. In M set the desired gear, for example 6, and the transmission will only shift 1-6, not 7 or 8. I haven't played with it yet, I'm waiting until it's warmer out. I'm hoping I can do a test tow before our first trip in mid-May.

[Scott]

Originally Posted by Jay2504

Easy to do Scott. Just put the truck in M1 at a light and up shift it manually until you get to 60 MPH or what ever speed you tow at. Look at the tachometer in 4th, 5th and 6th gear giving enough time in each gear for the truck to “ stabilize” and lock up the torque converter. Then later when towing in D you will know what gear you are in by reading the tachometer. On my 2014, it goes between 4th and 5th gear. Jay

Thanks Jay, I'll give that a try in the Spring!

[Scott]

Originally Posted by DocBrown

They added the 8 speed in 2015 to certain models.

My 2016 has the ability to set what ever gear I want to max out on. So if I put it in M (there is no M1) there is a +/- button next to the Tow/Haul button. In M set the desired gear, for example 6, and the transmission will only shift 1-6, not 7 or 8. I haven't played with it yet, I'm waiting until it's warmer out. I'm hoping I can do a test tow before our first trip in mid-May.

Hmm, I have those +/- buttons on mine as well. I wonder if I can do that too?

[DocBrown]

Originally Posted by Scott

Hmm, I have those +/- buttons on mine as well. I wonder if I can do that too?

It's on pages 292 & 293 in my truck's manual. Look for "Range Selection".

[Cavie]

Originally Posted by scott

hmm, i have those +/- buttons on mine as well. I wonder if i can do that too?

yep.

[Cavie]

I have a 2016 six-speed. Was told by an Auto tech teacher to use Tow Haul and lock it in 5th.

[alwalk63]

Originally Posted by DocBrown

I've had nothing but 4 speed automatics until now. I always towed in 3rd. What gear should I be using for the 8 speed? I'm assuming 7 but...

You are perfectly fine to leave in drive and activate tow haul mode.

[Cavie]

Originally Posted by Scott

My '14 has a 6 speed transmission. I'm not sure when they added the 8 speed option. I always use tow/haul mode as well on my truck and have the gear shift in D, just like the manual says. How can you tell what gear you are towing in if you are just in D?

My '16 showes on the dash.

[kblast523]

Originally Posted by DocBrown

I've had nothing but 4 speed automatics until now. I always towed in 3rd. What gear should I be using for the 8 speed? I'm assuming 7 but...

My 2015 EB 2.7 with a 6 speed towed in 4th sometimes, 5th most of the time.

Always used tow mode but it didn't change much, occasionally got a kick downshifting to 4th when slowing, know tsb issue.

My 2019 HEMI equipped Ram 1500 8 speed ran mostly in 6th but would drop to 5th often and seldom made 7th. Tow mode increased engine revs by 1000 rpm across the board. Busy shifts if towing and not in tow mode.

2018 Nissan Titan 5.7 7 speed is different. Towing with cruise control on in tow mode results in 4th gear, sometimes 3rd. Take it off cruise, it runs in 5th and 6th. with WAY LOWER engine rpm. Take it out of or forget to put it in tow mode, it feels like you just dropped anchor at port. Tow mode keeps the revs up almost 2000 rpm above normal shifting, and that is what gets you going with 7000 lbs dragging behind you.

[TN2010Jayco35RLTS]

If you have a "Tow Haul" mode just put it in that, you should be fine..

[newhampshirecampers]

I have a 6 speed GMC 3/4 ton with tow package. Is possible to tow a 155th 000 lb wheel?