'21 Silverado 8speed Cold Shift issues

[rgholmes08]

I just picked up a brand new 2021 Silverado on Friday with the 5.3L and 8 speed transmission. When I test drove the truck there didn't seem to be any issues with up shifting or down shifting of the truck. It ran smooth and looking back I am guessing it's because they had the truck already pulled up/warmed up waiting for me to arrive to the dealership. Fast forward to the next day when I went to take the vehicle to the store and pulling out of my driveway when I started accelerating the truck hesitated to shift into 2nd, then just slammed into 2nd and I was able to continue on my way. The shift into 3rd had a bit of hesitation but nothing like 1st to 2nd. Then once that first initial issue happened, the remainder of the drive that day had no issues. Then again today, the same scenario happened.

 

Now obviously this truck is still under warranty with 75 miles on it but I am not sure how to approach the issue with the dealership. It's going to be tough to recreate the issue as the truck will be warm from me driving it there. I guess my hope is that someone else here maybe has suffered from this same issue and has a resolve to it or a path they took to get it resolved at the dealership.

 

Thanks,

Ryan

Edited March 29, 2021 by rgholmes08

[Adamace1]

It seems the 8 speeds have some weird things they do. I'm sure you have read the complaints over the years. Mine has a hard downshift into first gear. Happens all day, then the next 10 days it shifts great. Then it will come back and have a hard downshift all day again. Sometimes the trans will do a learn, maybe yours will start shifting better.

[Jac365]

Clutch packs/torque converter filling with fluid causes this. Vehicle sitting overnight allows fluid to drain/settle. Letting truck warm up a bit prior to driving usually alleviates the issue. Colder climates=longer warm up. Known quirk and normal (according to GM)

[175vTrailbossLT]

Lots of similar experiences. I stopped thinking about it. Had truck almost 2 years now (2019). Sometimes - same as you out of driveway or initial acceleration from parked spot..SLAMS into second with a big Ass jerk. Happens every couple months and worse if I go from R to D. I just shift slowly now.m and it’s not as bad. I don’t care if it breaks it’s covered under warranty. But I have not read of any catastrophic transmissions anyway. Just a messed up issue. If it starts to really bother me I’ll sell it after 3 years and get the 10 speed. It’s BS..everything is so expensive these days and quality sucks. Across the board with everything.


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[dgstarr63]

Mine does the same thing, accept that it is worse after warmup. 2021 8 speed.

[Diamond817]

Let it break in. I have a 21/RST/5.3/8spd. It was quirky the first 200-300mls. It's silky smooth now. If I didn't read about 8spd problems on the internet, I wouldn't  know there were any problems with the 8spd.

[c.schill]

My 19 with the 5.3l and 8 speed does this occasionally. 2 different dealers said GM is aware and it's "expected behavior" of the transmission when operating cold. As stated above, it's less likely to happen if I let the truck run for a few minutes before pulling out and putting it in drive. I read at some point in another thread here that it has to do with the clutch packs or valves needing time to fill with fluid, or something along those lines. 

[Bigfoot98]

How long are you letting the truck warm up? It needs a few minutes to warm up if it's been sitting and it was cold outside. The warmer the better.

 

I find it doesn't do it once the temp hits 55 degrees for the trans. If it's been sitting overnight in the snow I just give it a 5-10 minute warm up so I'm comfortable and drive and deal with the 1 harsh shift and go about my day. Otherwise by the time I leave the house and let it run for 2 or 3 minutes in the morning it's fine.

[Dunn]

My 19 RST had a tiny bit of this but my 21 GMC has been flawless so far....not too cold here either

 

[BigdaddyoCan]

On 3/28/2021 at 9:27 PM, rgholmes08 said:

I just picked up a brand new 2021 Silverado on Friday with the 5.3L and 8 speed transmission. When I test drove the truck there didn't seem to be any issues with up shifting or down shifting of the truck. It ran smooth and looking back I am guessing it's because they had the truck already pulled up/warmed up waiting for me to arrive to the dealership. Fast forward to the next day when I went to take the vehicle to the store and pulling out of my driveway when I started accelerating the truck hesitated to shift into 2nd, then just slammed into 2nd and I was able to continue on my way. The shift into 3rd had a bit of hesitation but nothing like 1st to 2nd. Then once that first initial issue happened, the remainder of the drive that day had no issues. Then again today, the same scenario happened.

 

Now obviously this truck is still under warranty with 75 miles on it but I am not sure how to approach the issue with the dealership. It's going to be tough to recreate the issue as the truck will be warm from me driving it there. I guess my hope is that someone else here maybe has suffered from this same issue and has a resolve to it or a path they took to get it resolved at the dealership.

 

Thanks,

Ryan

I had the same experience last week with my new '21 LT as well. Low speed as I started down the street and even once it was warmed up at store parking lot low speed felt the bump/thump again. 

[dgstarr63]

I have a 2021 Silverado 8 speed . My dealer has witnessed the transmission problem, but does not know what's wrong and is not getting any help from GM. I told the service manager that if they can't repair the transmission , why not replace it? He said GM won't do it.  Apparently GM wont acknowledge that the 2021 trucks have an issue with the 8L90. I hope that Chevrolet and GM read this, because they are about to loose one of their best customers.  I am almost 74 years old and have driven GM vehicles exclusively my whole life.  I am a member of VCCA and have been a Chevrolet judge for almost 30 years. The 2021 is a great truck with the exception of the 8L90 transmission. My next truck will be a Ram!

[MPops]

I recently purchased a used 2021 LT Silverado. Jerks into gear after backing out of garage. Mine doesn’t jerk if I shift to drive after backing out just enough to clear garage door while keeping foot on brake, wait 5 seconds, then continue with reverse until I hit the streetand then back to drive. Guessing it allows those clutch packs to fill that others have mentioned