Transmission question

[15 Z71]

I have a 2024 silverado 1500 with the 8 speed. When I drive in normal mode I'm getting a bad vibration at low speeds.  If I'm going 25-30 mph when it shifts into a higher gear it feels like I'm going over rumble strips. On got 23000 miles on it. Does not seem to do it if I'm on gas or even in sport mode. Any advice before I go to dealer? 

[Bikerjon]

8 hours ago, 15 Z71 said:

I have a 2024 silverado 1500 with the 8 speed. When I drive in normal mode I'm getting a bad vibration at low speeds.  If I'm going 25-30 mph when it shifts into a higher gear it feels like I'm going over rumble strips. On got 23000 miles on it. Does not seem to do it if I'm on gas or even in sport mode. Any advice before I go to dealer? 

8 speed? Is this a 4 cylinder?

[15 Z71]

17 minutes ago, Bikerjon said:

8 speed? Is this a 4 cylinder?

Yes 2.7. 

[MTY55]

Get the same thing with my23 Denali 5.3 10 spd. Drive mine in in sport mode, gets the rpms up when it shifts Does your 2.7 I don't notice it. Drive in L9 shifts smooth as silk. Does your 2.7 have DFM?  Mine does and I was thinking its the culprit.

[silveradosid]

2020 2.7 8 speed , same thing same speed, worse if you are on a uphill. 95k miles and its still the same

[15 Z71]

So I guess my question is,is the Dealership going to do anything or just" says that's normal ". I'm stopping by there to see what they say. 

[DK91105]

I had the same exact issue with my 19' 8 speed at 58k miles, I took it in for warranty. They flushed the trans and replaced the fluid with a different kind per some tech bulletin. This eliminated the issue and its been fine since.

[15 Z71]

18 minutes ago, DK91105 said:

I had the same exact issue with my 19' 8 speed at 58k miles, I took it in for warranty. They flushed the trans and replaced the fluid with a different kind per some tech bulletin. This eliminated the issue and its been fine since.

Ok. Maybe that's what they will do. Thanks for the heads up. Maybe I'll bring that up.

[Jay P]

7 hours ago, 15 Z71 said:

Ok. Maybe that's what they will do. Thanks for the heads up. Maybe I'll bring that up.

I wouldn't get your hopes up. Your transmission should already have the updated fluid. The original fluid for the 8 speed was hygroscopic (absorbs water) which is what caused the problem. They replaced it with a Mobil synthetic fluid which didn't absorb water (don't remember the year it was changed but it was around 2020). Other manufactures like VW/Audi have had the same issue with moisture so GM is not alone with this issue.

https://gmauthority.com/blog/2019/08/tsb-seems-to-fix-8-speed-automatic-gm-transmission-problems/

[15 Z71]

I stopped by dealership today. I have an appointment Thursday to have there transmission guy go for a ride with me. Now hopefully it does it when he is with me. 

Edited April 14, 2025 by 15 Z71

[redwngr]

On 4/14/2025 at 9:51 AM, DK91105 said:

I had the same exact issue with my 19' 8 speed at 58k miles, I took it in for warranty. They flushed the trans and replaced the fluid with a different kind per some tech bulletin. This eliminated the issue and its been fine since.

 

On 4/14/2025 at 10:11 AM, 15 Z71 said:

Ok. Maybe that's what they will do. Thanks for the heads up. Maybe I'll bring that up.

 

8 speed had a change in recommended fluid a few years ago. 

 

Each of 6, 8 and 10 speed currently have different recommended fluids

[15 Z71]

37 minutes ago, redwngr said:

 

 

8 speed had a change in recommended fluid a few years ago. 

 

Each of 6, 8 and 10 speed currently have different recommended fluids

But being a 2024 it should have the newest fluid correct?

[redwngr]

13 minutes ago, 15 Z71 said:

But being a 2024 it should have the newest fluid correct?

Yes,

 

Comment was to possibly explain why the '19 mentioned had a different fluid installed.

[15 Z71]

Well update...got my truck back today from dealer.  They reprogrammed the transmission control module so far it's seems alot better.  They told me drive it 500 miles so it can relearn it's self. Also they have to do this before changing any parts per service bulletin.  I guess see how it goes.