I AM HAVING PROBLEMS WITH THE 6L50 SIX SPEED AUTOMATIC TRANSMISSION IN MY 2017 CHEVROLET COLORADO DIESEL.

Thanks for the reply.. theres a bit more to this situation.. I was on I95 here in South FL..
Of course everyone is in a huge hurry for no good reason and not paying attention to anything.
There was a pile up directly in front of me.. fortunately my cat like reflexes kicked in, once I saw all the tire smoke from brakes being slammed on, I glaced in my rearview to see a kenworth 10 feet behind me with his brakes locked.

I had to take a high speed, 80 mph off road excursion through the grass median to avoid being crushed like a beer can.

I was literally going 80 down the median as vehicles were piling up 30 feet to my right.

Just as I was entering the median, a triple axle flat bed had one of the steel fenders ripped off by another vehicle and it went airborne.. of course it landed slap in front of me.

It hit the skid plate, gouged and dented it.. then got wadded up under the truck and spit out the back to go on its merry way. It left a large spiral scar down the driveshaft as well.

I passed the multi vehicle **** show in the median and ripped it back onto the highway, another look in the rearview and saw the cranage behind me. By that time I was half a mile down the road.

I got off the next exit and pulled into a station, crawled onder the truck and inspected.. the previous damage mentioned was all I saw .

I put it on the lift yesterday and did a close visual inspection and noted no other obvious damage.

It started this directly after that.

I scanned the entire system .. no codes.

I do have to give major credit to that DSSV suspension.. it performed perfectly and allowed me to keep control of the truck.

The " warranty" is out.. not to mention the dealerships here have some of the most unknowledgeable " techs" I have ever seen. Even with a TSB in hand, they still can't get it done.

It will be a comp claim on my insurance at this point..
I cant help but think that the shock of the off road adventure broke a hard part inside there somewhere.
Tires were off the ground multiple times..

But I didn't get killed.

Theres the complete picture.. this is not a TC shudder.. I don't believe anyway, it seems like something broke from the treatment.. just have to have it torn down I guess.

5,6 were the gears I was in during all this, so it makes sense the issue would show there.

Well you described I-95 in South Florida (Palm beach, Broward and Dade counties) as what is a daily SOP day. Glad you escaped a disaster and death.
I would try a full flush with filter change. Run it for a few hundred miles. Go from there. Could be a number of things. Some have added a shudder additive to the ATF. It may solve other related issues. Some have swapped over to the Mobil 1 ATF fluid used in the 8 speed transmission with positive results. All things to consider before pulling the transmission for a overhaul.
Basically it's a process of elimination or troubleshooting steps. Who knows maybe a transmission tune will solve your problem.

If you flush try O'Reilly auto parts 5 gallon Dexron VI. Free delivery to your home. Best price I've found. I did a flush on my 2019. 90% improvement immediately and after driving for several hundred miles it's 99% better.
A flush can help with some problems.
Keep us posted.

OK.. so I am currently waiting for an opening at the local driveline shop, we are going to drop the pan and do a very thorough visual inspection.. for any particles of metal that may be there. Fluid change with better fluid and new filter to start. if there is metal.. it will be replaced. Insurance tried sending me to a "body shop" those clowns just read a script and know not a damn thing about anything.. I don't need a "body shop" and told them I would persue the repairs myself, with the proper type of operation.

At this time there is no CEL illuminated, I also scanned the TCM and codes, there is NO code set, not even a temporary "oh I fixed myself" code... nothing, nada.. everything reads perfect.

So during my online searching I stumbled on to this..
This is the exact issue I am having here.. same range of speed, same sound same everything.. Are these relabled Ford transmissions????

Because this is EXACTLY what is going on.

So anyone have any thoughts?

2020 ZR2 Bison LWN (Baby Duramax) Lots of talk and information about torque converters on these trucks; looks as though the Dex6 trans fluid Chev puts in them from factory isn't great long term. Either needs routine flushes or a swap to Mobil 1 Blue, which I've done... But the truck is now at dealer for a simple delay/slip between 1st-2nd under power. It will also get clunky here and there during downshifts, shifting to reverse, and it only does any of this when trans temp is above 180 degrees (which is fairly normal operating temp). Being told my converter is actually fine, and that the internal clutches are simply worn and failing. I don't see much info on this happening with anyone in the forums, but it seems likely most would mistakenly assume its the same issue being reported about the converters. I hate to say it, as I love this truck and think Chevy makes an altogether good line of light and heavy duty trucks... But the 6L & 8L-series transmissions might be Honda-in-the-Nineties junk.

BobbyBison said:

2020 ZR2 Bison LWN (Baby Duramax) Lots of talk and information about torque converters on these trucks; looks as though the Dex6 trans fluid Chev puts in them from factory isn't great long term. Either needs routine flushes or a swap to Mobil 1 Blue, which I've done... But the truck is now at dealer for a simple delay/slip between 1st-2nd under power. It will also get clunky here and there during downshifts, shifting to reverse, and it only does any of this when trans temp is above 180 degrees (which is fairly normal operating temp). Being told my converter is actually fine, and that the internal clutches are simply worn and failing. I don't see much info on this happening with anyone in the forums, but it seems likely most would mistakenly assume its the same issue being reported about the converters. I hate to say it, as I love this truck and think Chevy makes an altogether good line of light and heavy duty trucks... But the 6L & 8L-series transmissions might be Honda-in-the-Nineties junk.

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Some have installed a tune to remap the transmission shift points with success. Feedback has been positive. I just ordered a tune from Green Diesel Engineering. It was highly recommended by a member on this forum. As of this posting the tune is being shipped. Can't wait to install it and feel the difference. I also flushed my transmission twice. Last Thursday was the second flush. My shudder has improved 90% after the first flush around 12,000 miles. It got better over time. I decided a second flush might be a good idea with 16,000 miles. My shudder is still lightly noticeable at speeds above 75 mph but nothing like it was before the first flush. My mileage is low but I want to jump on this early. After the tune gets installed I'll see how it feels. The next step is to switch from Dexron-VI to Mobil One LV ATF HP.
If anyone is interested amazon has a case for $46.49 free shipping. Best price I've found.
And the last step would be a Torque Converter replacement. Definitely not looking forward to that.