Over this tranmission

[Riotis54]

2016 suburban with 137k on it. Trans was rebuilt at 106k so it’s out of warranty miles and time wise. Started shifting oddly recently. Doesn’t feel like it’s slipping but the lower gears seem to have delayed shifts and other times tend to be harsh. The builder doesn’t want to stand by his work. Any suggestions? Does have an aftermarket tcm tune.

 

[Bigkevschopshop]

Did it get a fast relearn for the clutches?

You may want to bring to stealership, have them diagnose the trans. Could be as simple as a reflash needed to fix issue.

 

[NickTransmissions]

2016 suburban with 137k on it. Trans was rebuilt at 106k so it’s out of warranty miles and time wise. Started shifting oddly recently. Doesn’t feel like it’s slipping but the lower gears seem to have delayed shifts and other times tend to be harsh. The builder doesn’t want to stand by his work. Any suggestions? Does have an aftermarket tcm tune.

Try to find out what the builder did (parts replaced, procedures like valve body vacuum testing, pump resurfacing/machining etc.). Compare that to my parts and procedures lists in my 6L80 Info Thread (link is in my signature line) - let us know and we can go from there.

Odd shifting can be caused by a variety of things, both internal to the trans as well as external causes/sources.

One thing id try to find out for sure is whether or not the torque converter was replaced and whether it was replaced with an upgraded converter (thicker clutch, etc).

 

[Riotis54]

Did it get a fast relearn for the clutches?

You may want to bring to stealership, have them diagnose the trans. Could be as simple as a reflash needed to fix issue.

Ok I will contact them

 

[Riotis54]

Try to find out what the builder did (parts replaced, procedures like valve body vacuum testing, pump resurfacing/machining etc.). Compare that to my parts and procedures lists in my 6L80 Info Thread (link is in my signature line) - let us know and we can go from there.

Odd shifting can be caused by a variety of things, both internal to the trans as well as external causes/sources.

One thing id try to find out for sure is whether or not the torque converter was replaced and whether it was replaced with an upgraded converter (thicker clutch, etc).

Ok I will try to find it. The torque converter was definitely replaced.

 

[NickTransmissions]

Ok I will try to find it. The torque converter was definitely replaced.

When you say 'lower gears have delayed shifts' what gears are you referring to specifically? Are you flare-shifting from 2nd to 3rd? What about reverse - any issues w/reverse at all?

 

[Riotis54]

When you say 'lower gears have delayed shifts' what gears are you referring to specifically? Are you flare-shifting from 2nd to 3rd? What about reverse - any issues w/reverse at all?

Mostly 1st to 2nd and 2nd to 3rd is worse. I don’t know what you mean by flare shifting but it’s kind of like a hesitation then it grabs. There is no issues in reverse or even downshifting.

 

[NickTransmissions]

it’s kind of like a hesitation then it grabs.

That, in a nutshell, is flare shifting. There's a split-second but noticeable gap between the previous gear and the next gear where you're in neutral.

Sounds like the transmission (specifically, the 3-4 clutch pack) is worn and beginning to fail. If so, transmission will need to come out for rebuild.

But as mentioned above, I'd diagnose, fix/resolve the problems with the throttle position sensor first. If that's still not functioning correctly, you continue to have transmission shift irregularities with the rebuild unit.

Check out my 4L60E Information Thread for details on overhaul, parts selection, video instruction and resources - the link is in my signature line.

 

[Geotrash]

That, in a nutshell, is flare shifting. There's a split-second but noticeable gap between the previous gear and the next gear where you're in neutral.

Sounds like the transmission (specifically, the 3-4 clutch pack) is worn and beginning to fail. If so, transmission will need to come out for rebuild.

But as mentioned above, I'd diagnose, fix/resolve the problems with the throttle position sensor first. If that's still not functioning correctly, you continue to have transmission shift irregularities with the rebuild unit.

Check out my 4L60E Information Thread for details on overhaul, parts selection, video instruction and resources - the link is in my signature line.

He has a 6L80, I believe, so he'll want to view your excellent 6L80 information thread.

 

[NickTransmissions]

He has a 6L80, I believe, so he'll want to view your excellent 6L80 information thread.

You're right ! Lol, I'm constantly getting them mixed up when it comes to Forum discussions.

@Riotis54 - Substitute '3-4 clutch pack' with '3-5-R' clutch pack so it applies to your 6L80 transmission. The rest of my post can remain unchanged as it all still applies.