6L80 Shuddering - Questions

Question for everyone in here. Posting for a friends 2019 Silverado.

Yesterday he goes in for an oil change. Leaves and gets unusual shudders while accelerating on freeway. Takes it back in and they say its not the oil change and that there are misfires. Then they run it again and say no misfires, still do not understand this part.

We dropped the pan today, there was more sludge in his pan than on my Yukon but he has 40k more than I do. 138k miles. There was also a half dollar sized amount of sludge that was definitely metallic but oddly not over to the magnet yet just about an inch away in the middle of the lower section of the original pan.

Replaced the pan with the Dorman 625-582 with the drain plug. Put 6.5 quarts back in of new Dexron VI. Also installed the thermal bypass. I do not have the ability to scan currently. He drove home and it was pretty much the same some heavy shudders.

Looking at options. Should we continue to drain and fill the transmission fluid? Worried this is futile and that the torque converter has already shed something.

Would the transmission still work if the torque converter was tearing itself up?

Has anybody had any luck with products like Lubegard Instant Shudder Fix? (I know, I just have to ask.)

Looking for any and all advice. As always thank you for your time.

In all probability, the transmission is already toast. It needs to be removed and opened up to assess what is going on. In most cases, the torque converter grenades and sends shards of metal throughout the transmission, thus destroying it, as well. Sorry for the bad news, but that seems to be the situation.

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.

texasyukonfl said:

Looking at options. Should we continue to drain and fill the ATF? Worried this is futile and that the torque converter has already shed something.
Would the transmission still work if the torque converter was tearing itself up?
Has anybody had any luck with products like Lubegard Instant Shudder Fix? (I know, I just have to ask.)

Click to expand...

If the torque converter's clutch has already begun shedding, as it were, your only hope would be to tune the tcm to never lock the TCC again -
and even then it would hinge on how much TCC is running around loose inside the ATF.
IFF *you disabled the TCC completely AND *tried Instant Shudder Fix, it's probably still too late.
Odds are, it's time for a rebuild or replacement 6L80E.

When m son's 6L started going out it would feel like a cylinder missfire on easy cruise/light acceleration in higher gears. That was the TC clutch letting go and it sure did destroy the transmission. But on take off and under power in lower gears it was fine. The TC clutch is not doing anything at that point. Your shuddering at take off kind of points to the transmission I'm thinking.

Looking like my friend is going down the path of the rebuild. Does $4800 sound reasonable?

Anything I should have him ask/include in the rebuild that would "bulletproof" this transmission. What brand of torque converter should put in? I assume putting a GM one back in is stupid.

texasyukonfl said:

Looking like my friend is going down the path of the rebuild. Does $4800 sound reasonable?

Anything I should have him ask/include in the rebuild that would "bulletproof" this transmission. What brand of torque converter should put in? I assume putting a GM one back in is stupid.

Click to expand...

BILLET, Because the converter is the weak point. If the shop it goes to cannot or does not mention or show you hands on what they do to fix a 6l80 then find a shop that does
it needs extra welds on KNOWN to break parts.
you could even give them extra incentive and say you plan on installing a supercharger and you want it to be able to handle 500hp.
easily done. $4800 should be plenty, if they want more you better ask lots of questions there's no reason for it.

Thank you gentlemen. Shop recommended Billet and was very open book about what they were doing. Will be going down this route. Thank you all for the advice it was very helpful and I will be following up with how everything goes from here.

The Luk converter for the 6L80 has been out a while now. I have one in mine and it works perfectly, the Luk converter cost is less than a billet converter.
Luk claims a 1000 ft pound torque capable which should handle most rigs.
Luk has been an OEM supplier of torque converters for many years so they should know what they are doing?

Nothing against a billet converter since they were the first to offer an upgrade for our trucks and they seem to work. Luk was late to the party releasing their new converter for these just over a year ago.

I would not consider installing a standard or OEM GM converter knowing they usually fail before 150,000 miles and take out the tranny when they fail.

The add sheet for the Luk converter. https://www.repxpert.us/en-us/luk-torcon/luk-6l80-torcon

Edit: The quote of 1000 ft pounds torque capability by LUK is actually 1000 NM which converts to 783 Foot Pounds of Torque which is still a huge improvement of the OEM design. The 2008 GM 6.2L 400 HP engine only has 417 Ft Pounds of torque so these converters are rated for plenty, should help when worked hard or raced.

Start by cleaning the MAF sensor with electrical cleaner. I have fixxed many a 6l80e shutter with getting the maf cleaned up and reading proper air flow so it can the apply proper tranny line pressure. Maybe its screwed.. but worth a try.

West 1 said:

The Luk converter for the 6L80 has been out a while now. I have one in mine and it works perfectly, the Luk converter cost is less than a billet converter.
Luk claims a 1000 ft pound torque capable which should handle most rigs.
Luk has been an OEM supplier of torque converters for many years so they should know what they are doing?

Nothing against a billet converter since they were the first to offer an upgrade for our trucks and they seem to work. Luk was late to the party releasing their new converter for these just over a year ago.

I would not consider installing a standard or OEM GM converter knowing they usually fail before 150,000 miles and take out the tranny when they fail.

The add sheet for the Luk converter. https://www.repxpert.us/en-us/luk-torcon/luk-6l80-torcon

Edit: The quote of 1000 ft pounds torque capability by LUK is actually 1000 NM which converts to 783 Foot Pounds of Torque which is still a huge improvement of the OEM design. The 2008 GM 6.2L 400 HP engine only has 417 Ft Pounds of torque so these converters are rated for plenty, should help when worked hard or raced.

Click to expand...

Did you need a tune with the Luk converter?

Nope, my tranny and tune are bone stock. I did nothing other than install it with new fluid and filter. Has been very good so far.
The lock up seems to hold better than the OEM converter. The Stall speed seems just like the OEM converter. No complaints at all.