2015 Tahoe - 6L80E to 8L90E conversion

Performance modifications, tips & tricks

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Speeder
Posts: 10772
Joined: Fri Apr 30, 1999 9:12 pm
Location: 2015 Tahoe 2WD 5.3L 6L80E, 2008 Colorado work beater, 2003 Dodge Dakota pro-touring project

2015 Tahoe - 6L80E to 8L90E conversion

Post by Speeder »

Title says it all. My 2015 Tahoe with a 6L80E has started experiencing an occasional light throttle shudder. This could be the torque converter according to some forums, could be a poorly made driveshaft according to others, could be broken parts inside the transmission according to Sonnax. For now I plan to keep an eye on it, but if it gets worse I'll have to do something about it. Should it require a new transmission, I'd like to get an idea of what it would take to put the 8 speed in, since in 2015 GM put both in depending on options. Would this require a segment change and harness along with the trans, or would I be looking at more than this? If I have to to replace the transmission, might as well make the swap but I won't be doing it just to do it.

When it warms up I'll be pulling the driveshaft to get it balanced, if for no other reason than to eliminate it as a problem. I know GM has had a problem figuring out how to get the yoke welded squarely onto the shaft for years as my 96 Tahoe had to have the yoke installed correctly.

Hog
Posts: 5036
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

Any progress on this?

I just have the words " could be a major PITA" floating around in my head as I contemplate your tranny swap, I mean Automatic Transmission Retro-fit.

peace
Hog

Speeder
Posts: 10772
Joined: Fri Apr 30, 1999 9:12 pm
Location: 2015 Tahoe 2WD 5.3L 6L80E, 2008 Colorado work beater, 2003 Dodge Dakota pro-touring project

Post by Speeder »

Nah, not an active project. I'm just curious if anyone knows what it would take to do this. I'm not planning on doing anything with the Tahoe, but if the trans does wind up needing replacement (and that's not a given yet) I wouldn't mind making the swap if it's a plug and play thing and not something requiring heavy modification.

98Blackss
Posts: 861
Joined: Thu Dec 27, 2007 12:14 pm
Location: Native TEXAN living in Colorado; 1998 K1500 RCSB stepside Escalade and GMT800 AWD conversion

Post by 98Blackss »

I have three 15-19 Yukons in my work fleet and every one of them ate the torque converter.

Speeder
Posts: 10772
Joined: Fri Apr 30, 1999 9:12 pm
Location: 2015 Tahoe 2WD 5.3L 6L80E, 2008 Colorado work beater, 2003 Dodge Dakota pro-touring project

Post by Speeder »

98Blackss wrote:I have three 15-19 Yukons in my work fleet and every one of them ate the torque converter.
6 speeds or 8 speeds? I understand now (more research) is that the trans fluid was the problem. It was absorbing water. The new stuff they recommend is a Mobil 1 trans fluid that's something like 10-12 bucks a quart, and they recommend it to the point that they ordered all dealers to replace the fluid with the new stuff on all 8 speed vehicles on their lots, new or used. Sorry, I don't have the link to the story anymore but I think it was on GM Authority.

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