Transmission shifts awful

[Kspinazzola]

On 4/12/2021 at 9:00 AM, It's Tim said:

Is this a salvage vehicle?

Not salvage. Original owner was for commercial use, and racked up lots of miles fast, but it’s a fully loaded every option (for an LT) crew cab truck, so I doubt it was worked super hard, might have been a foreman’s truck or something. Best part, origionallt from FL. Spotless underneath 

[Kspinazzola]

On 4/12/2021 at 7:17 AM, JacobC1983 said:

I felt the same thing in my 2015 and 2016 6 speeds with the 5.3.  I was happy to get rid of them.  

That’s what everyone who has one says. I drive a tow truck for a living and I’ve towed tons of these with blown trannys. 

[Kspinazzola]

On 4/12/2021 at 1:58 PM, dgstarr63 said:

I had a 2015, 1500, 5,3, 6 speed. 3.42 axle, 4x4 until it was totaled in an accident last fall with 54,000 miles.  This transmission was the best transmission that I have ever had in any vehicle. Now I have a 2021 with the  8 speed and wish it had the 6 speed.

Idk man I had to put in a reman at 150K. I drive a tow truck for a living and have towed lots with blown trannys. When they are nice and brand new they are awesome but I’ve driven a ton of higher mile 14-15s that hard shift like mine 

Edited April 21, 2021 by Kspinazzola

[Kspinazzola]

On 4/12/2021 at 8:18 PM, CamGTP said:

A P0420 or P0430 doesn't mean the cat is plugged, why do people always jump to that conclusion. Many vehicles could drive for 100k miles with that code and not have a single problem.

 

Get a tune for the truck and it'll completely change how it drives.

That’s what I was saying. And as much as a 5% change in O2 flow can set it off. I used to have a tune and it didn’t seem to help much. The slight increase in power was nice but tranny still sucked. Went back to stock 

[Kspinazzola]

On 4/17/2021 at 12:01 AM, swathdiver said:

Fix the cats and whatever killed them and then give the transmission a chance to run right.

 

The 6L80 is an awesome transmission.

I’m gonna get on that this week. Hoping a good cleaning will do it, seeing as it does have 160K it may be oil residue or something. No noise or rattle when you get under and hit it. As for whatever killed them is another question. Oil burning maybe? It doesn’t burn a ton but like I said 160K... 

[swathdiver]

4 hours ago, Kspinazzola said:

I’m gonna get on that this week. Hoping a good cleaning will do it, seeing as it does have 160K it may be oil residue or something. No noise or rattle when you get under and hit it. As for whatever killed them is another question. Oil burning maybe? It doesn’t burn a ton but like I said 160K... 

Mine is just past 160K as well and doesn't burn a drop.

[CKNSLS]

You can go to the dealer and ask for a flash so the transmission does a "quick relearn". But yes-it sounds pretty much normal.  While reliability generally hasn't been an issue-these things (6-speeds) are real slush boxes and are not that refined.

 

I'm going with ZF 8 speed and hemi  (RAM) next time around myself, verese the clunk-o-matic drive trains the Silverados have.

 

I'm done myself. The truck only has 35,000 miles on it. It's not a question IF I'M TRADING IN-ONLY WHEN. In all likelihood-probably 12 months or so-after supply meets demand.

Edited April 21, 2021 by CKNSLS

[pokismoki]

GM seems to be sabatoging thier products as usual,  they are famous for doing this, you can thank the Feds and thier EPA mandates on your short transmission lifespan.  definatly do a trans learn at the dealer, and the thermostat delete. but it needs tuning or else they damage themselves  in stock form by 85000 miles

 

the 6l80's are bad ass when tuned and built with good parts and gone thru. many guys pump 600-900 hp thru them.  if you stick with it you'll be happy when its dialed in. Call Prescion transmision  he's on youtube and shows the rebuild process. he's #1 trans shop.

 

 

[swathdiver]

It's no accident that we read of folks with K2s having more issues with their 6L80s than the previous generation.  Heat is the transmissions enemy and they beg to be tuned.

 

I had BlackBear tune my truck primarily to disable AFM and he tweaked the motor's calibrations mildly at my request but the very best part of the tune was what Justin did to the transmission.  I was completely happy with how the truck drove before the tune and amazed at how the transmission performed afterwards, like a different vehicle and for the better!

[Black02Silverado]

5 hours ago, swathdiver said:

It's no accident that we read of folks with K2s having more issues with their 6L80s than the previous generation.  Heat is the transmissions enemy and they beg to be tuned.

 

I had BlackBear tune my truck primarily to disable AFM and he tweaked the motor's calibrations mildly at my request but the very best part of the tune was what Justin did to the transmission.  I was completely happy with how the truck drove before the tune and amazed at how the transmission performed afterwards, like a different vehicle and for the better!

Yes,  Justin did a great job on our 2016 Suburban as well.  To me it was well worth the cost for the tune.

[superdave160]

I have a 2017 Silverado Crew Cab 4WD WT with the 5.3 and the 6 speed transmission.  I have an engine and transmission tune from BlackBear Performance.  The difference between before and after the tune is remarkable.  I believe that the biggest difference is in the transmission tune.  I believe that a lot of the shudders and jerks that people feel when driving these trucks are from the torque converter locking up.  The factory tune has the torque converter clutch lock up in all 6 gears, upshifting and downshifting.  The BlackBear transmission tune removed the torque converter lockup command for the first 3 gears.  The truck is now much smoother at lower speeds and when decelerating to a stop.  I also believe that the torque converter constantly locking and unlocking contributed to the premature failure of some transmissions.  Get a tune from someone who knows how these transmissions should work.  BlackBear Performance is an excellent source for aftermarket tuning, but I'm sure that there are others as well.

[Grumpy Bear]

On 4/20/2021 at 11:05 PM, Kspinazzola said:

That’s what everyone who has one says. I drive a tow truck for a living and I’ve towed tons of these with blown trannys. 

Ever hear of me? I'm Mr. Nobody. If nobody want's one I'm the guy that wanted it. My truck is now 7 years old, has 135K miles on it and has a 6L80E which I really REALLY like. Everyone is WRONG. Have to be. Because if he wasn't then I wouldn't be Mr. Nobody. I'd be Mr. Everyone. 

 

20 hours ago, swathdiver said:

It's no accident that we read of folks with K2s having more issues with their 6L80s than the previous generation.  Heat is the transmissions enemy and they beg to be tuned.

 

I had BlackBear tune my truck primarily to disable AFM and he tweaked the motor's calibrations mildly at my request but the very best part of the tune was what Justin did to the transmission.  I was completely happy with how the truck drove before the tune and amazed at how the transmission performed afterwards, like a different vehicle and for the better!

There's the trick....loose the thermostat and use a PAO/POE based fluid and change it like you care if it lives or not. 

Listen to the TSB's and rebuilders.

 

https://www.sonnax.com/tech_resources/845-6l80-6l90-transmission-tech-advisory-consider-an-updated-converter-in-your-next-rebuild