Transmission hard shift

[Phantom 4D]

Have a 2019 Sierra SLT X31, yeah, that's a mouthful. Anyway, when coming to a stop, I've noticed the transmission wants to "jerk" in 1st gear creating a bit of a thump, if you will. I've tried several ways of braking. Light, medium and heavy pedal. It still wants to jerk to a stop. At one time, back last year, every stop caused very hard down shifting. Of course the dealer found nothing. 

Has anyone else had this or a similar issue? If so, what was the outcome?

[driver1965]

The 2019 / 2020 Silverado had issues with the transmission fluid being used. In colder climates the fluid would allow "water" to get into the gears. Many transmissions were replaced and dealerships were directed to replace the transmission fluid. One can look online for the correct transmission fluid. Yes, GMC screwed up with the wrong type of fluid.

 Not knowing where you live, and if you do not trust your dealership, I would flush/replace the fluid. 45K is the recommended fluid change. I have used BG products but after every 30K I flush/replace the fluid. Enjoy your day.

[ejdziurka]

Sounds like typical 8 Speed behavior.   My solution was to trade it in on a 10 speed.

[dgstarr63]

My 2021 8 speed did this intermittently. They just replaced the valve body under warranty. So far it shifts OK, time will tell if it is a permanent fix.

[11bravoZ71]

I had the EXACT same issue develop with my 19 LT Z71 around 20k miles I now have almost 50k miles and it never did it again. After I took it in and described what you said… they checked and said it was a “software anamoly” and updated the transmission I called it the the 2-1 transmission jerk only happened when coming to a stop.  After they fixed it I drained and filled my tranny with the new Mobil 1 blue label ATF and mew filter from the dealer. For good measure. Because of possibility that that is was filled with the old specd ATF fluid since mine was one of the first 19’s produced. This 8 speed has been great since then. 

[Phantom 4D]

Thanks for the input. Taking it to the dealer for the fourth free oil change. Going to give them a heads up before I go. Tell the service writer I want a tech to ride with me. If they refuse, the owners office is just down the hall. 

[Black02Silverado]

Just curious as to when you purchased your truck and how many miles on it.  I would push the issue and at least have them change out the fluid.

[Adamace1]

I have same issue. Hard downshift into first. Dealer couldn't it to do it on test drive. It only does it one day out of 12 days. They said GM will not do fluid change because 21 have new fluid. Plus they say it has newest software installed. If it gets worse I'll bring it back. The 8 speed has complaints for over 5 years, so I knew what I was getting into.

[Acpantera]

I only have about 2,000 miles on my 2.7 w/8spd. I had a few late down shifts to 1st, making for a not so smooth slow stop. Hopefully this tranny has learned my habbits, hasn't done it in the last 1,000 mikes or so.

[SpeedRacerHD]

I have 2017 sierra 1500 with about 30k on the clock. This thing shifts like its got 300k not 30k. Hard in and out of first. Bang thru the gears. Only shifts good if i hammer on it! So im comin in hot everywhere i go lol......why?

 

[denny noname]

On 9/18/2021 at 8:14 AM, SpeedRacerHD said:

I have 2017 sierra 1500 with about 30k on the clock. This thing shifts like its got 300k not 30k. Hard in and out of first. Bang thru the gears. Only shifts good if i hammer on it! So im comin in hot everywhere i go lol......why?

 

LOL That's what I'm doing now . Coming in hot.

[pokismoki]

 

 

if these aren't tuneable, then I would reflash the factory TCU software or updated GM software  into the transmission, or have GM tech do a relearn proceedure.  the clutch to clutch hand offs for gear swaps are getting hung up, and need to be dialed in 

Edited June 21, 2022 by pokismoki

[pokismoki]

could try driving in "Tow Haul", this has a whole other shift parameter map function VS  "Drive" gear change mapping

 

 

 

[Stevo 06]

On 9/12/2021 at 4:28 PM, Phantom 4D said:

Have a 2019 Sierra SLT X31, yeah, that's a mouthful. Anyway, when coming to a stop, I've noticed the transmission wants to "jerk" in 1st gear creating a bit of a thump, if you will. I've tried several ways of braking. Light, medium and heavy pedal. It still wants to jerk to a stop. At one time, back last year, every stop caused very hard down shifting. Of course the dealer found nothing. 

Has anyone else had this or a similar issue? If so, what was the outcome?

I have a 2017 Silverado with 67k miles on it and my transmission is the doing the same hard down shift into 1st when stopping.  It happened six months ago the first time first thing in the morning.  After I got to Lowe's and finished shopping and returned to my truck, it was fine (although the check engine light was still on).  I cleared the fault and it didn't happen again for six months.  This time it happened again first thing in the morning and normalized after my first stop when I returned to the vehicle.  The cruise control wouldn't set while the fault was going on but worked when the system normalized (after first stop of the day).  I have an appointment with the Chevy dealer but I have to leave it there for a few days.  This is baffling to me and I hope it doesn't cost a fortune.     

[Stevo 06]

I have a 2017 Silverado with 67k miles on it and my transmission is the doing the same hard down shift into 1st when stopping.  It happened six months ago the first time first thing in the morning.  After I got to Lowe's and finished shopping and returned to my truck, it was fine (although the check engine light was still on).  I cleared the fault and it didn't happen again for six months.  This time it happened again first thing in the morning and normalized after my first stop when I returned to the vehicle.  The cruise control wouldn't set while the fault was going on but worked when the system normalized (after first stop of the day).  I have an appointment with the Chevy dealer but I have to leave it there for a few days.  This is baffling to me and I hope it doesn't cost a fortune.