Project Carbon Next Gen 10 Speed Valve Body Kit - Finally Installed!

[viven44]

I hear you...There is never a good time unfortunately... but a good window where you can do mindless peaceful work is key... Working under pressure has often got me in trouble. A few weeks ago, some pending preventative work, all I was supposed to do was swap out the old distributor on my truck when I had exactly 30 mins before some family commitments so I was working with a sense of urgency...I pull the distributor and the cap retaining clip fell inside the block and wedged itself somewhere my magnetic pickup tools or borescope could not find... after an hour of struggle I decided to drop the pan and retrieve the clip..... turned a 20 min job into a 3 hour job.. Fun !!

 

[Kobot]

I watched that interview with The Car Guy and the Next Gen engineer the other day which led me to this thread after researching the issue. Just when I thought I was done spending money on this truck, I find out about this and I’m now considering the upgrade. It’s either dump money into this truck to keep it long term or dump money on a new one that will have issues later. I have a 19 with the 10L80 but it seems the Next Gen Project Carbon kit is still the same aside from the manual shift linkage. I’ve read every word in this thread so far and following for more info.

 

[jfoj]

@Kobot,

Yea, the deal is you drop $80k+ then you need to start spending.

Understand that I used to rebuild transmissions on a small scale for my vehicles and friends and some customers. 3, 4 and 6 speeds. Have not done any for a while. The bulletproof one were the older GM TH400 and Ford C6. The STUPID valve body separator plate that is too thin for the pressure it needs to seal and the fact they have the stupid thin paper gasket and screens, this is just a BAD IDEA. All the transmission work I did over the years had thick steel separator plates with no gaskets and no problems. So I know this is something that will solve at least the internal valve body fluid leaks. Along with the upgraded shift valves these just higher quality parts that should last longer without as many problems.

Based on what I learned over the years and reading about all the transmission problems I determined it was wise of me to invest close to $2k in the transmission valve body. My expectation is it is not IF but WHEN.

While I have a 2024 which was not under the transmission Recall, I have read about a lot of 2024 and 2025 that also have the same problems. They are no different than the 2021-2023, they just were not built when the Recall was released. I expect the 2024-2025 to be Recalled, but GM is trying to cover the turd in the catbox by updating the TCM software to put the transmission in Limp mode (45 MPH max) if the trans applies 4 clutches at one time.

Then the fun starts. How far are you away from home? How far to the nearest dealer? How many family members are in the truck with you? Were you going on or returning from an event with luggage and gear? Were you towing something? How long to wait for a reman valve body? How long before the reman valve body have the same problems? Did the valve body put wear and tear on the clutch packs or torque converter due to low pressure, so do you really need a full transmission? How long are you in a sub compact rental car? When does GM quit reimbursing your for a rental?

Just too many questions and I do not want to wait more that an afternoon to have this problem resolved. The problem for me is my schedule is crazy for the next 7-10 days. I hope to jump on the project SOON.

I look at things this way. Some people buy a brand new truck, spend thousands on mods, wheels, tires, tint, lift, exhaust. I just want a reliable vehicle, something that does not leave me stranded or I am without for months on end. Granted at some point the valve body delay should decrease, but why should I even have to just sit back and WAIT FOR IT??

Will update once I get to the job. Yukon has 8,000 miles at this point, I need to get it done soon as the problems are worse when the fluid gets hotter and thinner, I have lived that nightmare on VW 6 Speed Tiptronics many years ago!

 

[jfoj]

Just a quick update, I have had too many family members visit and other obligations that has delayed me tackling the project. Hopefully next week, but I have more travel coming up soon as well.

At this point I am only really using the 2024 Yukon for trips, so it has been sitting for the past 2-3 weeks.

Another interesting update:

 

[jfoj]

More details on 10 speed problems. I do not expect this is the end of 10 speed problems and bulletins. I fully expect the 2024-2025 to be recalled like the earlier model. The only caveat is if GM was able to roll out the transmission software update to "Monitor" for impending rear wheel lock up fluid leaks. If GM was able to roll out the software updates in the 2024-2025 before a recall and even perform some over the air update, they may be trying to hide these problems. The issue is the software does not solve the hardware problems, it just tried to make the problems "Safer" by putting the TCM/Transmission in a "Limp" mode that does not allow you to drive over 45 MPH.

I have some doubt the GM OEM checkballs are actually the more durable Torlon or imidized plastic. Every source I checked shows them as standard non hardened white nylon check balls. Just for kicks I have ordered the replacement checkballs part number that is listed in the bulletin it will be easy to tell if these check balls are standard white non hardened nylon and I will also see what I end up taking out of my valve body as well. I already purchased the upgraded Torlon checkballs and have them here with all my parts as I was pretty sure GM only used the standard white nylon non hardened checkballs for the OE transmission builds. I will also verify the size if there is some confusion over the checkball sizing as well. All my sources indicated the checkballs are 1/4" or 0.250", this will be verified during the valve body upgrade.

Even on the Sonnax description for these check balls it clearly indicates these imidized check balls are "These imidized plastic checkballs are not available through the original manufacturer." See the statement at the end of the description for the Sonnax checkballs in link below

Sonnax Torlon or Imidized Checkballs

Link for the GM checkball and separator plate update for the 2024 model 1500 pickup trucks with the L84 5.3l and the LZO 3.0l Duramax. Unclear why this bulletin only covers the 2024 Silverado and Sierra 1500 pickups. I believe these pickups have the 10L80 transmission but the same valve body is in the 10L80 and 10L90, the 10L1000 or "Allison" 10 speed pretty much has the same basic valve body with the exception of the cable controlled shifter vs the electronic shifting as in the 10L80/10L90's. I am also pretty sure the 10L1000 "Allison" transmission is typically in the 3/4 ton and heavier duty trucks and does not support the Auto Stop/Start and have the additional electrical fluid pump like the 10L80/10L90's.

So it is just very interesting what is going on with the 2024 1500 pickups that is different than the other vehicles.

GM Check Ball and Separator Plate Update

 

[jfoj]

I ordered the GM check ball part number that was listed in the latest GM Bulletin N242483540.

Turns out this checkball listed in the GM Bulletin is just the standard 0.25" or 1/4" Nylon check ball, not the more robust Torlon check balls that are offered on by the aftermarket suppliers.

I had already decided to early on to obtain the Torlon check balls for my valve body upgrade, so I am probably already ahead of this issue. Maybe on the gasoline engine transmissions, the lower operating temperatures the standard Nylon checkballs may be adequate, but on the Diesel engine transmissions it seems the transmission temps tend to be consistently 40+F higher or more, typically 200F+. Towing and other factors may cause the transmission temp to operate higher?

While 200F+ may not be a big problem for Nylon, it is unclear if the fluid temps in the valve body where the checkballs are located is actually higher or much higher the displayed transmission fluid temperature.

It is possibly that the Nylon checkballs soften and degrade over time in the 200F+ temps.

From a search AI info:

"Nylon does not typically become super soft at 200°F (93°C). It will still maintain a relatively rigid structure, but it can become more flexible and potentially deform or shrink if subjected to this temperature for extended periods. The Vicat softening point of nylon can range from 140°F (60°C) to 482°F (250°C). While 200°F is within this range, it's closer to the lower end, meaning the nylon might still be quite rigid."

 

[StephenPT]

I ordered the GM check ball part number that was listed in the latest GM Bulletin N242483540.

Turns out this checkball listed in the GM Bulletin is just the standard 0.25" or 1/4" Nylon check ball, not the more robust Torlon check balls that are offered on by the aftermarket suppliers.

I had already decided to early on to obtain the Torlon check balls for my valve body upgrade, so I am probably already ahead of this issue. Maybe on the gasoline engine transmissions, the lower operating temperatures the standard Nylon checkballs may be adequate, but on the Diesel engine transmissions it seems the transmission temps tend to be consistently 40+F higher or more, typically 200F+. Towing and other factors may cause the transmission temp to operate higher?

While 200F+ may not be a big problem for Nylon, it is unclear if the fluid temps in the valve body where the checkballs are located is actually higher or much higher the displayed transmission fluid temperature.

It is possibly that the Nylon checkballs soften and degrade over time in the 200F+ temps.

From a search AI info:

"Nylon does not typically become super soft at 200°F (93°C). It will still maintain a relatively rigid structure, but it can become more flexible and potentially deform or shrink if subjected to this temperature for extended periods. The Vicat softening point of nylon can range from 140°F (60°C) to 482°F (250°C). While 200°F is within this range, it's closer to the lower end, meaning the nylon might still be quite rigid."

View attachment 458868

View attachment 458869

Where are you getting 200F+ on the diesel transmission temp? Mine runs in the upper 160's to low 170's when cruising on the highway and low 180's when towing a 5K travel trailer...

 

[jfoj]

It may be engine, location or option dependent, but I have been finding a number of folks commenting on other forums and in other documents I have found that the Diesel trans temps on a lot of these trucks are running pretty consistently around the 200F+ mark.

At least my 2024 GMC Yukon Denali XL tends to runs pretty consistently in the 140-150F range, I have caught it around 160-165F a few times after driving on the highway for hours then hitting an accident or construction that caused stop and go traffic for about 20 minutes. Have not towed with the vehicle yet. My Yukon has the Max Tow package, unclear if this will impact the trans temps, but I believe the radiator is larger, probably 1 core thicker than the non Max Tow package.

The first 10 speed recall for rear wheel lock up was only for the Diesels as well. I can say from many years of experience even before the ULV transmission fluids that any leakage problems within transmissions was ALWAYS way worse at higher trans temperatures because the fluid would thin out. So any leak was worse at higher temperatures/pressures.

Even the latest "Checkball" and "Separator Plate" recall includes the Diesel and the 5.3l for some reason. It was only for the 1500 series pickups and not any with the 6.2l.

There was also a Gen 1 and Gen 2 10 speed that had differences are mainly in the valve bodies that could possibly be a contributing factor as well.

I suspect as the 2023-2025 models get more mileage, we will start hearing about a lot more of these valve body related shift quality and wheel lock ups. Unclear why GM decided they needed a thin paper gasket on the valve body separator plate. Not sure if it is just on 1 side or both, I will find out when I pull my valve body. My guess is because the steel separator plate is stamped, they need the gasket on at least the sharp side or exit side of the stamping for better sealing. This is one of the reasons the Next Gen separator plate is superior, it is 14 gauges steel that is laser cut vs stamped which will deform the plate and cause rounded and sharp edges with elevated material on the exit side of the stamping. The laser cut plates will not stretch, deform or have the beveled and sharp edges.

I think the valve body transmission fluid pressure is in the 200-300 PSI range and the separator plate seal is really critical.

Anyway, I have no interest in becoming a member of the "Valve body of the month club"!

 

[operator5362flink]

According to TSB 22-NA-182, the thermal bypass valve on 10L80 transmissions opens at 143°F except for LM2/LZ0 equipped vehicles which opens at 194°F.

 

[jfoj]

@operator5362flink

Thanks for posting this TSB, I may recall seeing this, but it is getting tough to keep up with all the bulletins and GM seems to be playing "Whack A Mole" with a lot of their problems lately with miss steps and constantly updating the rules and/or the window for impacted vehicles.

It appears from the TSB for the 6 cylinder Duramax engine equipped vehicles they have a frame mounted Thermal Bypass where the gas engine transmissions have an internal valve body Thermal Bypass.

The NextGen kit I have directs you to remove the Thermal Bypass brass thermostatic element and flip the thermal bypass valve around which will cause full time coolant flow to the transmission. I plan on doing this. The brass thermostatic element is likely a failure point and I assume GM tried to get the fluid temperature up quickly for "Fuel Economy" reasons but this will probably come at a reliability hit to the transmission.