2009-2014 6L80 better than 2015+?

[Chris2144]

I just bought a 2007 Yukon Denali 6.2 6l80 not to long ago. I bought it with the problem of the torque converter shuddering. Here is what I did.
Hook up to it and log while driving.
Saw that tcc line pressure would rise and fall normally with throttle input until the converter started slipping then it would jump around trying to control it.

Trans temp would hold pretty steady.
Trans fluid was a little dark but not terrible.
No harsh or erratic shifts.
I was pretty confident that the trans was healthy and the converter was just starting to let go.

Bought it got it home and immediately replaced the torque converter.

While doing this I dropped the pan and cleaned it out new filter.

Got trans back together and filled.
This was not a flush but a replacement of all fluid and clean pan. Now 6k miles later the trans is working great. Being that there is no service history and knowing that the stock converters are a common failure point I would say it would be a good idea to preemptively replace the torque converter and at that time change out fluid and filter.

This also is a great time to have the trans tuned.

 

[Prospect62]

Seems very logical Chris, I appreciate that and agree 100% with your course of action.

Problem is most days I don't have time to take a dump, let alone pre-emptively change out my torque converter so...we wait.

 

[mikez71]

Same boat, going to wait until failure!
Can't see myself pulling transmission just for the TC, which doesn't guarantee the trans won't crap out due to some other failure?
At 237k, and it runs great (as far as I can tell..) So I'm going to see how long it can last..

Haven't even done a filter replacement yet! I see myself wanting to do O2 sensors and exhaust manifolds at the same time..
But I have refreshed the fluid...

Another thought on 07-14 6l80 vs 15+ 6l80s, the TCC desired slip is different (and pca/line pressure and apply ramp)
So I wonder if one tune is more prone to wearing out the regulator valve or tcc....

'13 tcc desired slip in 4th

'17 tcc desired slip in 4th (More aggressive than '15-16 and '18-'20 which zero at 165lbft)

PCA vs line pressure graphs different and not interchangeable it would seem...
'13

'17

 

[j91z28d1]

Same boat, going to wait until failure!
Can't see myself pulling transmission just for the TC, which doesn't guarantee the trans won't crap out due to some other failure?
At 237k, and it runs great (as far as I can tell..) So I'm going to see how long it can last..

Haven't even done a filter replacement yet! I see myself wanting to do O2 sensors and exhaust manifolds at the same time..
But I have refreshed the fluid...

Another thought on 07-14 6l80 vs 15+ 6l80s, the TCC desired slip is different (and pca/line pressure and apply ramp)
So I wonder if one tune is more prone to wearing out the regulator valve or tcc....

'13 tcc desired slip in 4th
View attachment 479958

'17 tcc desired slip in 4th (More aggressive than '15-16 and '18-'20 which zero at 165lbft)
View attachment 479959

PCA vs line pressure graphs different and not interchangeable it would seem...
'13
View attachment 479960

'17
View attachment 479961

I don't know, I don't trust most places to rebuild trannys these days. I think if I had a known working good tranny, with the know tc failures and the leaky rear main/rear plate seals. I could justify dropping the tranny to do rear seals, oil pan and Tc before it goes out and I just gotta hope the rebuilder is good.

I'd probably do that valve body diagram kit. or whatever it was Don jet man did, and hope it lasted the life of the truck.

 

[Marky Dissod]

... wonder if one tune is more prone to wearing out the regulator valve or tcc ...

Feel free to stop wondering, figure out which tune wears things out sooner, use those values in your tune,
and let us all know what the deal is.
Very generally speaking, you might have to live with a slight increase in NVH to gain a considerable increase in longevity / durability.

 

[mikez71]

I have used the '17 and '18 TCC desired slip tables. No driveability issues either way.
Since the later ones go to 0 slip, I'm guessing later tunes may be modulating the pressure regulator a tiny bit more.
Whereas the earlier tunes will allow more TCC slippage when first you get on the throttle.
For whatever reason GM was more aggressive with TCC slip in '17 only, but then backed off again for '18-'20...

I haven't paid that much attention to the TCC in datalogs yet..(mainly focused on shift schedule and times)
Max TCC pressure I've seen about 65psi, pressure at cruise is a steady 18psi. (baseline whenever TCC applies)

I will say the later Torque Adders (shift duration) are worth using. (shifts quicker, but still stock feeling, not harsh)
Also the Inertia factor tables make the shifts feel more linear. (most noticeable on 1-2 shift)
I view these changes as the 2 best un-official 'updates' from GM.
Trial and error takes some time! Those 2 maps are virtually unchanged from '15-'20.. ('17+ Torque Adders refined a little, slightly smoother)
They drop right in and just plain work better IMHO.

 

[West 1]

I had a 2007 Escalade, started freezing on the 3-4 shift, would not unlock to drive again without a shut down and code clear. I talked to a tranny man I trust he told me the drum had cracked and I was losing fluid pressure, said it was very common on the 6L80. I had him do a full rebuild of that 6L80 using upgraded parts and a brand new GM drum with factory clutches and a rebuilt torque converter. Well he did all this but installed my original TECHM. The transmission shift control module inside the tranny pan. On install the Tranny worked great till I accelerated hard and it went into the same lockup it had before the rebuild. Turns out my shift issue was just a bad TECHM. Bought a new one from a company in Florida, they programmed it to my VIN and shipped it to me quickly. I am in California. New TECHM solved all shift issues. I did all the tranny removal and install work and installed the new TECHM. I sold that Escalade later even though it was in great shape and kept my 2003 GMC Yukon. Main reason, I did not like the color.

Now I have a 2008 GMC Denali, at 147,000 miles it needed a new rear main seal so I ordered the parts including a new LUK torque converter and installed that with the new RMS. On this truck the TECHM was replaced around 80,000 miles by GM so I am hoping this tranny with the newer TECHM and new LUK torque converter will be durable for a while. So far I really like the LUK torque converter. It drives like factory stock except when cruising at light loads where it stays locked up much longer than the factory torque converter did. Maybe that tells me the factory part was failing but not shuddering yet??? I will never know but the new LUK feels great. And the old oil in the tranny was pretty clean with no junk in the transmission pan so odds are I have a good transmission for now.

This job is not for those with no time or no experience. Pulling these transmissions is a lot of work and needs many good tools to be done safely. In the old days we could take a 66 Pontiac GTO and pull the muncie 4 speed in maybe 30 minutes, install a new clutch and pressure plate and be back on the road in 2 hours total. Not the case with one of these. The transfer case, exhaust, Starter, cross braces, sway bars, coolant lines and several electrical connections need to come out. The transmission bolts are not easy to get to at all. These bolts alone might take an hour and a half to get out and longer to put back in.

 

[rdezs]

The easiest way to get to those hard to reach bellhousing bolts.... Spend 15 minutes and pull the intake manifold. It puts all the upper bell housing bolts in reach. It also lets you lower the tail end of the transmission a little without the intake manifold hitting the firewall.

On the reinstallation, I can put the transmission up to the back of the engine while sitting on the transmission jack.... Go up above and get the bolts finger tight. Go underneath with a 24 inch extension and get everything torqued. Then back up on top for the nuts that secure the various ground wires, breather tubes, etc. In 10 minutes I have it bolted in and torqued. Then raise the tail shaft up, install rear mount and crossmember.

I can see it being a big PITA trying to do it any other way with a long extension and a swivel.

 

[Chris2144]

I lowered the engine and trans as much as I could and used about 3ft of extensions and a wobble socket the only real pain was getting the two bolts at the top out but it was manageable. But removing the intake definitely would have made it easier.

I could not agree more that the luk torque converter seems to be very solid and even behind the 6.2 it holds well.
I pulled a small load 1500 ish pounds with it and it did great. Real test will be with the boat in the hot summer temps.

Now that I tuned the trans it feels great and the new converter should last a long time being a dual disk. At only 400 bucks it’s kinda hard to beat it.

 

[West 1]

Rdezs, I have a top creeper which would make removing the intake and top bolts pretty easy. I had heard that was the way to go but did not do it. Next time for sure. Still not looking forward to a next time. All working well so far. Thanks for the tips.

 

[rdezs]

I think the biggest hassle is removing the exhaust y-pipe, specifically at the flange to the manifold. If you have one that's never been off in 10 years, even if it's been soaked with penetrating oil for 3 days, it's pretty common to have at least one stud from the manifold snap. (And that's in a vehicle not from the rust zone. I imagine it's more common if you're somewhere that you salt in the winter)