My 18’ 8 speed has a cold chatter. Goes away when warmed up. You think it’s time to a torque converter change? It just hit 100k miles. Other than that shifts good.
my 18 with a 6.2 needed a new torque converter at 61k, still under warranty, first gear coming out of the driveway in the morning just went completely limp, and then slammed hard. Love these trucks but these 8 speeds need some babysitting, damn shame. dreading the next hiccup lol, probably gonna be a valve body.
I don't believe there to be any reason there's a large amount of air introduced to the system based on what we did, but I never thought about that, very good question.
The problem with the GM 8L90E transmission is not the Torque Converter or even the Fluid, believe it or NOT. For one, the transmission runs too hot for starters. The transmission thermostat bypass opens up about 194F degrees. Too damn HOT. The AFM System is what’s destroying these Torque Converters in my humble opinion respectfully. When the engine transitions back and forth from 8 to 4 & 4 to 8 cylinders, it significantly increases the TCC Desired Slip Rpm. I suspect GM engineers doing this to reduce vibration through the drivetrain for driver comfort at the expense of the Torque Converter it self. If the programming does not increase the TCC Desired Slip RPM during AFM, the customer would experience noticeable vibration every time the AFM engages. This act drastically wears out the Clutch lining inside the Torque Converter apply piston. The key to solving this issue if your transmission is not to far gone believe it or NOT is in the valve body and turning off AFM. The transmission valve body control the ENTIRE function of the transmission, to include the Torque Converter. There are 3 shift kits on the market that will absolutely eradicate this issue, if the transmission is still in good shape and not too far gone. These companies are SONNAX & TRANS GO I have personally myself installed and 😂combined 2 kits with a SONNAX TCC Kit and Shift Kit at 30,000 miles. I have 85,000 right now. Solved all my issues. Always remember that the Torque Converter Clutch Solenoid, TCC Pressure Regulator Valve and Pressure Regulator Spring is what controls the Torque Converter mechanically and electronically thru PCM to TCM commands thru CAN BUS…. communications.
I agree almost 100%. I know the dod tcc slip target rpm is double relative to when it's in v8, and I also agree with you on your theory why they do it. Unfortunately on this 2019, i'd have to take the ECU and TCM out and shipped to HP tuners for the unlocking service, which the used car lot did not want to do. Everything 15-18 (with an 8 speed) gets dod turned off at a minimum. I've experienced what a worn VB feels like/acts like and we've done the same thing, mixed a couple of those two brand's kits to alleviate some problems. I don't believe they all need the valve body repair kits, we've gotta away with converter and fluid with a lot of them.
I agree with you 1000% The only thing I would add. I think we can both agree that the Transmission Tuning in HP Tuners would help tremendously. Especially when you bump the shift pressures, TCC apply pressure and going into the TCC Desired Slip RPM tables and reduce the TCC Slip Values since DOD/AFM we would want turned off. Myself personally went with a Circle D Torque Converter and it’s been great. Love your work by the way. You are very talented my friend.
Also, consider as it pertains to the valve body, not only is it worn out, but the plastic check balls shrink from the transmission fluid heat causing massive cross leaks with the valve body. I went with SONNAX Anodized check balls as an upgraded when I did my valve body job.
@@HewigIsidore we used to target 0 in those tcc slip tables and up the regulator apply like 10%, and it seemed to be causing us issues. It would lock up TOO crisp and sometimes under load (lower rpm or going up a hill), it would chatter a little. Similar to what a bad windshield wiper across the windshield acts like. That was with putting a tube of the shutter fix in every transmission preemptively. So basically all we do is get rid of lockup in the earlier gears (1-3 normal and just 1-2 in tow haul) and delay the 5-6 shift (in a 6L80e) and 7-8 shift (if it's an 8L90), because factory it stuffs it into high gear way too soon in our opinion. 51mph seems happiest.
On my 8L90, we got rid of lock-up on 1st thru 5 gear and reduced TCC Desired Slip in those table from 10 rpm slip to half that (5 rpm slip) among other tricks here and there help. The Circle D Converter made the biggest difference along with going with an Amsoil Signature Series ATF and getting rid of the thermostatic bypass valve for the transmission. My Transmission temp are now around 155F to 165F at operating temp compared to 200F to 215F.
yes, yes yes
Sierra looks so nice compared to the other trucks.
Watching
My 18’ 8 speed has a cold chatter. Goes away when warmed up. You think it’s time to a torque converter change? It just hit 100k miles. Other than that shifts good.
Possibly.
my 18 with a 6.2 needed a new torque converter at 61k, still under warranty, first gear coming out of the driveway in the morning just went completely limp, and then slammed hard. Love these trucks but these 8 speeds need some babysitting, damn shame. dreading the next hiccup lol, probably gonna be a valve body.
@@nwrhaner yikes. Any codes?
@@cameron878 not a one lol
now is the manual shifting causing the TCM to adapt or is it getting air out of the system or both?
I don't believe there to be any reason there's a large amount of air introduced to the system based on what we did, but I never thought about that, very good question.
The problem with the GM 8L90E transmission is not the Torque Converter or even the Fluid, believe it or NOT. For one, the transmission runs too hot for starters. The transmission thermostat bypass opens up about 194F degrees. Too damn HOT. The AFM System is what’s destroying these Torque Converters in my humble opinion respectfully. When the engine transitions back and forth from 8 to 4 & 4 to 8 cylinders, it significantly increases the TCC Desired Slip Rpm. I suspect GM engineers doing this to reduce vibration through the drivetrain for driver comfort at the expense of the Torque Converter it self. If the programming does not increase the TCC Desired Slip RPM during AFM, the customer would experience noticeable vibration every time the AFM engages. This act drastically wears out the Clutch lining inside the Torque Converter apply piston.
The key to solving this issue if your transmission is not to far gone believe it or NOT is in the valve body and turning off AFM.
The transmission valve body control the ENTIRE function of the transmission, to include the Torque Converter. There are 3 shift kits on the market that will absolutely eradicate this issue, if the transmission is still in good shape and not too far gone.
These companies are SONNAX & TRANS GO
I have personally myself installed and 😂combined 2 kits with a SONNAX TCC Kit and Shift Kit at 30,000 miles. I have 85,000 right now. Solved all my issues. Always remember that the Torque Converter Clutch Solenoid, TCC Pressure Regulator Valve and Pressure Regulator Spring is what controls the Torque Converter mechanically and electronically thru PCM to TCM commands thru CAN BUS…. communications.
I agree almost 100%. I know the dod tcc slip target rpm is double relative to when it's in v8, and I also agree with you on your theory why they do it. Unfortunately on this 2019, i'd have to take the ECU and TCM out and shipped to HP tuners for the unlocking service, which the used car lot did not want to do. Everything 15-18 (with an 8 speed) gets dod turned off at a minimum. I've experienced what a worn VB feels like/acts like and we've done the same thing, mixed a couple of those two brand's kits to alleviate some problems. I don't believe they all need the valve body repair kits, we've gotta away with converter and fluid with a lot of them.
I agree with you 1000% The only thing I would add. I think we can both agree that the Transmission Tuning in HP Tuners would help tremendously. Especially when you bump the shift pressures, TCC apply pressure and going into the TCC Desired Slip RPM tables and reduce the TCC Slip Values since DOD/AFM we would want turned off. Myself personally went with a Circle D Torque Converter and it’s been great. Love your work by the way. You are very talented my friend.
Also, consider as it pertains to the valve body, not only is it worn out, but the plastic check balls shrink from the transmission fluid heat causing massive cross leaks with the valve body. I went with SONNAX Anodized check balls as an upgraded when I did my valve body job.
@@HewigIsidore we used to target 0 in those tcc slip tables and up the regulator apply like 10%, and it seemed to be causing us issues. It would lock up TOO crisp and sometimes under load (lower rpm or going up a hill), it would chatter a little. Similar to what a bad windshield wiper across the windshield acts like. That was with putting a tube of the shutter fix in every transmission preemptively. So basically all we do is get rid of lockup in the earlier gears (1-3 normal and just 1-2 in tow haul) and delay the 5-6 shift (in a 6L80e) and 7-8 shift (if it's an 8L90), because factory it stuffs it into high gear way too soon in our opinion. 51mph seems happiest.
On my 8L90, we got rid of lock-up on 1st thru 5 gear and reduced TCC Desired Slip in those table from 10 rpm slip to half that (5 rpm slip) among other tricks here and there help. The Circle D Converter made the biggest difference along with going with an Amsoil Signature Series ATF and getting rid of the thermostatic bypass valve for the transmission. My Transmission temp are now around 155F to 165F at operating temp compared to 200F to 215F.