2022 Silverado 2500HD with the dreaded 6 speed shudder

[Rogue Leader]

I'll try to make this as brief as possible.  Previously owned a 2008 Silverado 2500HD with the 6L80, sold it with 197k miles on it and 0 problems with the transmission.  Got myself a used 2022 2500HD Silverado Custom, 6L90, its got 99,840 on it.... so yeah almost done with that powertrain warranty.  Bought it in Mississippi and had it shipped up here to NY, because all used trucks here are rotten.  When I got it I felt this rumble at certain speeds which I thought was maybe a wheel bearing.  The coolant overflow was also leaky.  Brought it to my local dealer since its still under powertrain warranty, described the issue, said I thought it was the right side front wheel bearing.  So they say yeah its the wheel bearing and change it, also noticed a leak from the trans cooler so they fixed that and the coolant tank.  Only the trans cooler was under the powertrain, but the dealer I got the truck from covered the cost on the rest.  When I went to pick it up the service advisor says "oh the tech says you may feel a shudder from the transmission, but its fine".  The SA had also said it was pretty low on fluid and had been leaking for a while.  

 

I pick it up, and its doing the same thing as it was before... so yeah the wheel bearing probably wasn't the problem.   Once it warmed up, the shudder was maybe even worse.  Slightly better when cold I guess because of the properly filled fluid, but there.  I called the dealer shop and he suggested a 20qt flush and 500 miles of driving.  I pointed out that would take me out of warranty if I drive 500 miles and something is still wrong. He basically said "oh well sorry".  I'm none to happy about that.  Selling dealer (who is also Chevy) called them and they basically said the same thing to them.  I'm dropping it off tomorrow to get the issue on the record as the words "transmission shudder" are nowhere on the documentation from the prior repair, and the selling dealer is willing to cover the cost of the flush, if thats what the local dealer reccomends, but if that isn't the fix I feel like I may end up on the hook here for a converter or worse. 

 

Don't really know if this is going to go sideways for me just yet but wanted to see if anyone else had any experience with this problem and resolving it, especially at the end of the warranty.  Or having had to have something fixed after the warranty expired that the dealer had worked on under warranty.  Highly annoyed that I sold a perfectly working but kinda rusty old truck to buy a new truck for way more money with problems, but thats my luck.  At least the selling dealer is supportive.  

[Another JR]

Get the GMC ombudsman involved. I’m pretty sure an issue for which your complaint is properly documented within the warranty will get fixed under warranty even if the time or miles goes past the warranty during diagnosis and repair. 

[GMCustomerService]

This isn't the experience we hoped to hear. Your concerns are recognized, and we want to do our absolute best to find you a resolution regarding these transmission shudder concerns. For our support, please send us an email at [email protected] with your VIN, full contact information (full name, email address and phone number) and the name/location of your servicing dealership to assist best. Additionally, be sure to include "Rogue Leader/GM Trucks Forum" in the subject line of your email. We look forward to assisting you further. 

 

By sending us a message, you consent to the information you provide being monitored and recorded by GM or those acting on GM’s behalf, subject to the GM Privacy Statement: https://www.gm.com/privacy-statement. 

[Rogue Leader]

2 hours ago, GMCustomerService said:

This isn't the experience we hoped to hear. Your concerns are recognized, and we want to do our absolute best to find you a resolution regarding these transmission shudder concerns. For our support, please send us an email at [email protected] with your VIN, full contact information (full name, email address and phone number) and the name/location of your servicing dealership to assist best. Additionally, be sure to include "Rogue Leader/GM Trucks Forum" in the subject line of your email. We look forward to assisting you further. 

 

By sending us a message, you consent to the information you provide being monitored and recorded by GM or those acting on GM’s behalf, subject to the GM Privacy Statement: https://www.gm.com/privacy-statement. 

 Thank you!

[Rogue Leader]

To provide you all with a resolution, my truck was fully repaired under warranty.  All the clutches in the transmission were burnt, as well as a bunch of other damage, they replaced those, the pump, the torque converter, and other parts, flushed everything out, and I'm back in action.  Truck runs great and I have a 12 month/12k mile warranty on the work.  Thank you to @GMCustomerService for advocating on my behalf in this situation as well.  It took a while (5 weeks!) but it was done right.

[Jettech1]

@Pryme  this topic kind of surprises me.  I'm glad it all worked out for our member here but my question is, what ta hell burns out a 6L90?  Low fluid level perhaps?  Those trans are know to be darn near bullet proof.  My guess is this is a fluid level thing from a leak from the coolers.  What is your opinion on it?

[Pryme]

34 minutes ago, Jettech1 said:

@Pryme  this topic kind of surprises me.  I'm glad it all worked out for our member here but my question is, what ta hell burns out a 6L90?  Low fluid level perhaps?  Those trans are know to be darn near bullet proof.  My guess is this is a fluid level thing from a leak from the coolers.  What is your opinion on it?

Yeah that could absolutely be it coupled with an abused life. Most ppl with these trucks don’t really care about them like the type of ppl on this forum I.e. enthusiasts. they lead a tough life. 
 

Glad op got it replaced under warranty just in the nick of time. 
 

 

[carkhz316]

The same thing that wrecks the 6L80 generally: A poorly designed torque converter. The TCM control strategy has the TC clutch applying in low gears and to constantly slip so as to insulate the driver from transmission operation. The torque converter itself is very cheaply made and allows the TC clutch piston to deform and exacerbate the slippage causing the clutch to wear out and start churning out metal filings into the rest of the transmission. Valve body issues, such as the AFL valve can start to bind or chatter from dirty fluid, which contributes to the clutch wear issue, as well as the pressure regulator valve in the pump.

 

You can stave off valve wear/ sticking by adopting severe duty maintenance intervals on the trans fluid and filter, such as every 30-40k miles, which sounds extreme, but has been proven to help in the long term.

[Jettech1]

Just now, Pryme said:

Yeah that could absolutely be it coupled with an abused life. Most ppl with these trucks don’t really care about them like the type of ppl on this forum I.e. enthusiasts. they lead a tough life. 
 

Glad op got it replaced under warranty just in the nick of time. 
 

 

I agree to a point, but what is considered an abused life?  That trans should be able to live a happy life for 100's of thousands of miles if it is serviced at 50k (sever service) when it is being hardly used like towing heavy weight everyday day.  But I'm telling you, those older ones out there, being totally ignored, ran hard, put away wet, are still performing.  I still think this was a low fluid problem.  I still think the 6L90 will go down as one of the most reliable trans, as well as the 6.6l gasser.

[Jettech1]

12 minutes ago, carkhz316 said:

The same thing that wrecks the 6L80 generally: A poorly designed torque converter. The TCM control strategy has the TC clutch applying in low gears and to constantly slip so as to insulate the driver from transmission operation. The torque converter itself is very cheaply made and allows the TC clutch piston to deform and exacerbate the slippage causing the clutch to wear out and start churning out metal filings into the rest of the transmission. Valve body issues, such as the AFL valve can start to bind or chatter from dirty fluid, which contributes to the clutch wear issue, as well as the pressure regulator valve in the pump.

 

You can stave off valve wear/ sticking by adopting severe duty maintenance intervals on the trans fluid and filter, such as every 30-40k miles, which sounds extreme, but has been proven to help in the long term.

I agree to disagree.  You are bringing up the 6L80's.  Not the same beast at all.  Now the TCM control module is designed to slip, we will say for comfort reasons.  And that's ok.  What's not happening is the TC clutch piston deforming and sending fiings into the overall system.  It may be happening on the 6L80's but I have not heard of any of this concerning the 6L90's.  Educate me sir!

Edited March 24 by Jettech1

[carkhz316]

28 minutes ago, Jettech1 said:

I agree to disagree.  You are bringing up the 6L80's.  Not the same beast at all.  Now the TCM control module is designed to slip, we will say for comfort reasons.  And that's ok.  What's not happening is the TC clutch piston deforming and sending fiings into the overall system.  It may be happening on the 6L80's but I have not heard of any of this concerning the 6L90's.  Educate me sir!

I mention the 6L80 because they're nearly mechanically identical to the 6L90. They even use the exact same JMBX torque converter. 

 

The TCC clutch piston deforms under pressure and causes uneven wear over time. Once the friction lining is worn through on the clutch surface, it then begins grinding metal off the face and sending it with the fluid flow through the oil cooler and back into the transmission. Once the wear sets in, its a cascade affect. This manifests itself in the beginning stages failure as a "shudder" or sometimes torque converter clutch hunting at highway speeds; particularly with high load and low engine speed.

 

The 6L90 does have better shift and TC control strategies because it has to given its design purposes, including towing/ hauling and for performance in the applicable sports cars. Heat exacerbates the issues one sees. 6L90s in particular have lasted much longer historically, because (at least in the trucks) they never utilized a thermal bypass valve like the 6L80 did until the T1X trucks beginning in 2020.

 

For some more reading that goes over the 6L80/ 6L90 issues: https://www.sonnax.com/tech_resources/845-6l80-6l90-transmission-tech-advisory-consider-an-updated-converter-in-your-next-rebuild

Edited March 25 by carkhz316

[Jettech1]

42 minutes ago, carkhz316 said:

The 6L90 does have better shift and TC control strategies because it has to given its design purposes, including towing/ hauling and for performance in the applicable sports cars. Heat exacerbates the issues one sees. 6L90s in particular have lasted much longer historically, because (at least in the trucks) they never utilized a thermal bypass valve like the 6L80 did until the T1X trucks beginning in 2020.

Excellent comments, but yet the did have a thermally controlled valved.  Some here have bypassed them, I have not 

[Jettech1]

1 hour ago, carkhz316 said:

I mention the 6L80 because they're nearly mechanically identical to the 6L90. They even use the exact same JMBX torque converter. 

 

The TCC clutch piston deforms under pressure and causes uneven wear over time. Once the friction lining is worn through on the clutch surface, it then begins grinding metal off the face and sending it with the fluid flow through the oil cooler and back into the transmission. Once the wear sets in, its a cascade affect. This manifests itself in the beginning stages failure as a "shudder" or sometimes torque converter clutch hunting at highway speeds; particularly with high load and low engine speed.

 

The 6L90 does have better shift and TC control strategies because it has to given its design purposes, including towing/ hauling and for performance in the applicable sports cars. Heat exacerbates the issues one sees. 6L90s in particular have lasted much longer historically, because (at least in the trucks) they never utilized a thermal bypass valve like the 6L80 did until the T1X trucks beginning in 2020.

 

For some more reading that goes over the 6L80/ 6L90 issues: https://www.sonnax.com/tech_resources/845-6l80-6l90-transmission-tech-advisory-consider-an-updated-converter-in-your-next-rebuild

I want you to know that I really appreciate your knowledge and comments...This is how things get resolved.  By talking to each other and figuring out the bottom line as to what the actual problem is.  Thank you sir for your input.  I love it actually!!

[Jettech1]

1 hour ago, carkhz316 said:

I mention the 6L80 because they're nearly mechanically identical to the 6L90. They even use the exact same JMBX torque converter. 

Sorry man, but that's where I need to call BS.  I love conversation but there are huge differences mechanically between the 6L80 and 90.  And the TC is different as well.  Tell me I'm wrong.

[Jettech1]

Let me try to give everyone the most simplified aspect as to how an auto trans works.  Here I go...There are clutch packs, stators and rotors...these clutch packs need pressure to engage and clamp down to make forward motion.  So we add in switches that direct hydraulic pressure coming from the sun gears.  Their job is to provide pressure to the pressure switches of which provide and direct clamping force on the clutches.  It's really not that hard to understand if you can envision the whole process.  This can happen in milliseconds depending on how many gears that have to be changed depending on speed, pedal pressure, etc etc.... Automatic transmissions are a really truly amazing thing.  They really are. Here's the down side of any auto trans.  They rely on line pressure and clutches that are supposed to work in harmony.  The one thing they won't ever replace is the good old, standard trans that might have synchros in them to make gear shifts easier.  Totally different beast but they are amazing as well..  I love Automatics, I love the old, shift them yourself...but when something goes wrong, know your stuff...Keep in mind, these autos have electronic shift solenoids.  Keep in mind they can go wrong.  Keep in mind the TCM isn't perfect.  Nothing is!  So when things go wrong...well...here we go!!

Edited March 25 by Jettech1