2019 trail boss 8spd problem

madconcept · February 19, 2020

Noticed mine has the same issue. 2019 Sierra Elevation 5.3 8 speed.

Overall the transmission is 1000 times better than the 4 speed that was in my 2007 Silverado during regular driving, city or highway.

The older truck I use to be able to go from reverse to drive without any issues, even be able to go into drive while still slowly rolling back. I’m not talking full speed rolling back but almost at the point where the truck was stopped but still ever so slightly rolling and it would never slam.

The new truck there is definitely a delay transitioning from reverse to drive and if you are rolling backwards at all and you touch the gas pedal during the shift it will slam.

Just need to really pay attention to what the transmission is doing, make sure the truck is completely stopped before making the shift.

My truck is an early build, think Dec 2018 probably still with the old style fluid I’m going to ask to have replaced during the next service.

Anyone know the best way to get the dealer to do fluid flush under warranty? I’m just going to complain about shifting issues and shuttering etc.

Edited February 19, 2020 by madconcept

Rick Franklin · February 19, 2020

My 19 Sierra is a 7/1/19 build and it does it only the first shift of the day in subfreezing weather. Any other time it performs flawlessly.

Does anyone have issues with the brake pad life indicator, mine shows 48% life after 3200 miles!

BIGDOGx · February 19, 2020

On 2/17/2020 at 1:10 PM, Vicarod said:

I'll tell you, I have no gripe with this transmission. I like how it shifts and it is smooth. I find it better than the 6spd I had previous.

Hopefully the 10spd is even better...when I upgrade to a new interior

Not going to argue that owning a 6 speed which has been without question the worst shifting, acting slop box i have ever had the displeasure of owning. Would rather have the 4l60e back to be honest, sure it's archaic and had its fair share of problems too, but driving it never made me want to kick puppys down the street like this 6 speed can do from time to time!

AD80 · February 20, 2020

I also have the slam/ clunk, but only in reverse. Doesn’t matter if I let it run for 10 seconds or 10 minutes before shifting, it will still do it. Mine is not really a jerk or lunge, it’s more like a metal clunk, like the gears are slamming into place. Once I drive it a few miles and let the trans warm up, It’s not as bad. It will still do it, just not as hard. Never does It going to drive, only reverse. Shifts fine while driving also. Build date 6/19. 1700 mi so far. Feels almost like the trans or transfer mount may be loose, as I can feel it shake as it clunks, but if that was the case, it seems like it would do it in drive also. I crawled under and looked a while back but didn’t see anything. I now back into my garage when I get home while the trans is warm so I can just pull out in drive in the morning to avoid this. And when I park somewhere I try to find a spot where I can pull straight out without using reverse if possible. Sucks I have to do this on a new truck.
Took it to the dealer, but after driving there, the trans was nice and warm so they just felt the medium clunk and not the hard one I feel in the mornings. So of course they said it’s normal. Sorry for the long post.

Edited February 20, 2020 by AD80

madconcept · February 21, 2020

I also notice I get a little clunk when slowing to a stop from time to time.

It’s like the transmission shifts itself into 1st gear before I slow to a stop which I know for a fact if I did it manually I would get the same clunk.

Driving manual transmission vehicles I would never downshift to 1st ever.

Same with an auto I tend to never manually shift to 1st gear while the vehicle is in motion, wondering why the truck itself would do that resulting in a clunk.