23 GMC Sierra 10 speed trans

[Sean Rankin]

Transmission Observation:

 

I just traded in my 2017 GMC Sierra 6.2 with 8sp trans for a new 23 GMC Sierra 6.2 with 10sp trans.  I loved my old truck.  It had 90k miles, ran great and never gave me any issues.  One of the things I liked most about it was the motor and performance.  It sounded great (muffler delete), and felt quick for a truck.  The transmission always shifted very solid and always surprised me how crisp the shifts were. 

  My new truck, a 2023 Sierra AT4 6.2 with 10sp has a 6in lift and 35 in tires.  I love the way it runs and looks.  I don't like the transmission.  It seems sloppy.  You can barely feel the shifts, there is no predictability, and it almost feels like the torque converter is constantly locking and unlocking.  I'm not sure if it has anything to do with the lift and tires, but it's a bummer.  I even tried putting it in sport.  The 2017 transmission almost felt like a sports car....the trans on my new truck feels lost and slushy.  Anyone else experience this?

Edited January 25, 2024 by Sean Rankin

[gemarsh]

How did the tranny feel before adding the 35's?

 

I would have a hard time believing a lift would have anything to do with the sloopynees you feel.

[Bikerjon]

On 1/24/2024 at 6:14 PM, Sean Rankin said:

Transmission Observation:

 

I just traded in my 2017 GMC Sierra 6.2 with 8sp trans for a new 23 GMC Sierra 6.2 with 10sp trans.  I loved my old truck.  It had 90k miles, ran great and never gave me any issues.  One of the things I liked most about it was the motor and performance.  It sounded great (muffler delete), and felt quick for a truck.  The transmission always shifted very solid and always surprised me how crisp the shifts were. 

  My new truck, a 2023 Sierra AT4 6.2 with 10sp has a 6in lift and 35 in tires.  I love the way it runs and looks.  I don't like the transmission.  It seems sloppy.  You can barely feel the shifts, there is no predictability, and it almost feels like the torque converter is constantly locking and unlocking.  I'm not sure if it has anything to do with the lift and tires, but it's a bummer.  I even tried putting it in sport.  The 2017 transmission almost felt like a sports car....the trans on my new truck feels lost and slushy.  Anyone else experience this?

The transmission in my Trail Boss operates very smoothly. I can barely detect the gear changes. I sort of agree with you. I would prefer a more solid gear change. You used the word crisp and I definitely would not describe the shifts as crisp in my 23 w/ 10 speed. I only have 2800 miles on mine so far. Not to scare you but you should search the 2019-2023 Silverado & Sierra Troubleshooting forum for valve body replacement. There are 2 guys on there that need valve body replacement on their early model year 2023 ten speeds.

[kmeleon]

You have to be the first person ever to like the 8 spd over the 10 spd. Your Comment about not feeling the 10 spd shift.... That's a good thing. The 10spd is light years better than the 8. 

[Sean Rankin]

8 minutes ago, kmeleon said:

You have to be the first person ever to like the 8 spd over the 10 spd. Your Comment about not feeling the 10 spd shift.... That's a good thing. The 10spd is light years better than the 8. 

Hey man, you can make love to the 10sp if you want.  I am making an observation.  If I was driving a luxury car, I'd be ok with the lazy, sloppy shifts, but it's a truck.  In my opinion a truck should shift like it has a pair.

Edited January 26, 2024 by Sean Rankin

[garagerog]

14 minutes ago, Sean Rankin said:

  In my opinion a truck should shift like it has a pair.

You can use tow/haul for that.

[kmeleon]

35 minutes ago, garagerog said:

You can use tow/haul for that.

 

53 minutes ago, Sean Rankin said:

Hey man, you can make love to the 10sp if you want.  I am making an observation.  If I was driving a luxury car, I'd be ok with the lazy, sloppy shifts, but it's a truck.  In my opinion a truck should shift like it has a pair.

You're in the minority here, the 10spd is anything but sloppy. Maybe there's something wrong with your's but the majority around here rave about it. Trucks shifting like they have shift kits are a thing of the past. Most people would prefer to not even feel the shift. 

 

My camaro with the manual 6 speed is for banging gears. 

[Sean Rankin]

That's what I'm looking to find out.  Is my truck operating normally, or should I have it checked out.  Sounds like maybe I should have it checked out if most people are happy with it.

Edited January 26, 2024 by Sean Rankin

[Jay P]

Unless you have the truck corrected for the 35" tires that is part of your problem. The transmission shift points were all set up using a stock size tire and a stock height truck. The tire will also mess up the ABS/Traction control/Stabilitrak. If you take it to the dealer they likely won't touch it due to the lift and bigger tires and will probably void your factory drivetrain warranty (unless the dealer sold it with the lift/tires).

FWIW the 10 speed in my past 19 Sierra 6.2l, 21 Silverado 3.0l and current Tahoe 3.0l all shift fine. I do understand the feeling of the trans shifting since I put shift kits in most of my pre electronic transmissions.

 

Jay

Edited January 26, 2024 by Jay P

[ExYukon]

I have a 2023 with the 6.2 and Max Trailering.  I would describe the shifts as "smooth". Smoother than my 2001 Toyota minivan or my 6.2L 2010 Yukon.

 

[Trotorx2]

I've had 2 2500HD's with the Allison 6 speed, one built and one with just tuning. I thought they shifted good but this 10 speed is so much better. I really like the way it smoothly goes through the gears. 

[typhoon186]

 

Smooth is the word.  Almost like a variable speed.  Very little change in rpm between gears.  I say that is all a plus.  great transmission.  Probably the best every by GM.   

However I would like to tune to make it feel a little more peppy and firmer for my taste.

[Sean Rankin]

1 minute ago, typhoon186 said:

 

Smooth is the word.  Almost like a variable speed.  Very little change in rpm between gears.  I say that is all a plus.  great transmission.  Probably the best every by GM.   

However I would like to tune to make it feel a little more peppy and firmer for my taste.

I feel the same.  I've been researching to see what can be done as far as tuning goes.  So far it looks like gm has the trans computer locked so that you can't tune it yet.   That info is just from a brief internet search, so if someone knows more please elaborate.

[Bikerjon]

1 hour ago, Sean Rankin said:

I feel the same.  I've been researching to see what can be done as far as tuning goes.  So far it looks like gm has the trans computer locked so that you can't tune it yet.   That info is just from a brief internet search, so if someone knows more please elaborate.

Following. I would like to know about tuning the trans also.

[Edwin Grundy]

We have a  2024 2500 Sierra that we bought off of the lot.  It is a basic work truck with the 6.6L  gas engine. It has 8000 miles and is currently in the shop needing a valve body for the transmission. It has been in the shop 3 weeks and the part is on backorder.  GM is unable to give information on when the part will be available.  At first it was between 7/31 to 8/13.  The dealer now says 8/14 to 8/26.  The customer service people are nice but have no authority and will not let you speak to upper management. I use the vehicle to tow and the dealer does not have a 2500 loaner.  GMC will not authorize the cost to rent an equivalent vehicle.  They would only state that their policy would reimburse me less than 50% of the cost and I could send them the bill for further consideration.   We have averaged 11.5 - 12 mpg in the city. Highway was 13.5 - 15 mpg.  Towing is another story. On a recent trip to pick up a pontoon boat in Florida we averaged 5.7 mpg at 65 miles per hour.  It tows reasonably well for a gas engine.  The boat and trailer combined weight was around 7800 lbs.  If you are considering using the truck for towing be aware that we have had problems with the trailer brake controller.  Under normal driving conditions, the truck will randomly display "Trailer wiring fault".  During this time that will last from 3 to 60 seconds the trailer has no brakes.  Recently with an 11,000 gross weight trailer and load, we were pushed through a red light with the antilock brakes chattering so bad that I thought that the truck was going to shake apart. GM has stated that they do not have a problem with the controller but if you search the internet you will find many articles regarding this. A dealership checked the controller and said that it was OK. I forwarded a few posts from the internet to my service advisor. A few days later when I called to check on the transmission part, he stated that they checked the controller and found a fault and that they were going to replace it.