2016 Yukon XL Needs New Transmission - Not Happy

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lbenson

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You've got the 6 speed which has issues of its own... Can't say I know a ton about these transmissions besides others on the forum who have discussed "flipping the pill" to run it cooler and prevent it from overheating.

With that said, I know of two instances of a 2016 and 2017 Suburban with the same transmission destroying itself before 90k, both a while back without the fix for the overheating issue.
Ok, I joined just to seek education. I have a 2016 yukon xl slt 5.3L 4wd. Purchased 1.5 years ago with 100k miles and now has 140k miles on it. Turns out the trans was replaced before I bought it. I noticed odd fluttering with trans since day one but figured it’s just how the newer trannys do things. I’m used to old four speeds mostly. Recently a mechanic friend said I’ll need to replace it soon after he witnessed the flutter.

Seems to drive great just has the odd flutter.

What say this group? Will I be replacing it? Is my equipment even involved since mine isn’t a Denali? Are there things I can do to protect my gear? If I have to replace it, is there a bullet proof option so I don’t have to worry about it again?

All advice is welcomed and appreciated!
 

Plimbob

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FWIW - I have a 2017 with the 6 speed, I had to have it rebuilt at 89k. The TQ started causing issues with shearing and throwing off metal particles which in turn gets sent through the whole unit which caused various issues including a flutter or surging sensation.

The rebuild was done at a respected trans shop in my community, they used a Billet TQ, Sonnax valve body and the updated thermostat. It now has 92k and I can't say I am thrilled with it. It currently is back at the shop who built it because of hard downshifts at 35mph and 20 mph. This happens especially when hot.

They have had it a week and driven it around and tell me they are having trouble getting it to do it for them. I have this shop do work for me in the past and always satisfied with the work, however, I am skeptical at this point about things.

I have heard that if you use the ACDelco fluid it improves the smoothness of the shift cycles? I may go that route if needed to see if that helps.

BTW - the shop manager told me they do 3-4 2015-2017 GM 6 speeds a month?
 

John Buttino

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yes, a good purchase. Mine has served me well on my ‘15.

Trans fluid changes (pan and filter) should be done 45k without question on these, especially 8 and 10 speeds.

That warranty has taken care of:
Fuel pump
Many sensors
Battery cable
Seat lumbar
Fuel injector
My MRC struts
GPS antenna
And prob more items I’m forgetting

normally I don’t buy them, but with the ‘15 model year change I wanted to be safe.
How did you get the fuel pump and injectors covered ?
 

Doubeleive

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FWIW - I have a 2017 with the 6 speed, I had to have it rebuilt at 89k. The TQ started causing issues with shearing and throwing off metal particles which in turn gets sent through the whole unit which caused various issues including a flutter or surging sensation.

The rebuild was done at a respected trans shop in my community, they used a Billet TQ, Sonnax valve body and the updated thermostat. It now has 92k and I can't say I am thrilled with it. It currently is back at the shop who built it because of hard downshifts at 35mph and 20 mph. This happens especially when hot.

They have had it a week and driven it around and tell me they are having trouble getting it to do it for them. I have this shop do work for me in the past and always satisfied with the work, however, I am skeptical at this point about things.

I have heard that if you use the ACDelco fluid it improves the smoothness of the shift cycles? I may go that route if needed to see if that helps.

BTW - the shop manager told me they do 3-4 2015-2017 GM 6 speeds a month?
the hard shifts are likely the clutch plates they used, as long as there is no metal or burnt fluid you are fine, if you want "softer" shift's there going to have to pull it all apart and use a different clutch set.
also @BlackBearPerf can tune it for you and you will have all around better performance.
 
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Plimbob

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@ Wes, you are dead on regarding the clutch plates. When I went back to gt the vehicle and discussed that very point and the builder told me the shift kit is heavier duty and does tend to shift firmer/harder however you want to describe it. He said they checked the fluid for color and metals and nothing unexpected there. I checked the fluid as well and it's red, no brown tint.

They told me they used BG Trans Fluid in it because they feel it's one of the better fluids and doesn't shear easily. There is a 2 year/24,000 mile warranty on it. It's 5 months and 4,000 miles in. I guess we'll see.

I am thinking I will put another 1-2k on it and draw some fluid and send it into Blackstone for analysis just to be safe. Also, going to look into BB as you noted.

Anyway, thanks for your feedback on the clutch plates.
 

AJ_Victory_27

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Welp! I have a 16 Yukon SLt with the 6 speed. Just shit the bed yesterday at 107k miles, getting the tranny replaced at a cost of $5,250 + tax.
‘15 Yuke for me, 6-speed and trans fluid changed in April ‘22 about 132k and now in September at 138k trans is shot. Violent death rattle at 75MPH that my passengers noticed, then major slipping. $5.6k for new one with 3 year/100k mi warranty. What else should we do to preserve the motor? AFM delete?
 

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