Infamous 8 Speed Transmission Clunk - Dealer/GM Current Position on the Issue?

reardiff · March 20, 2019

Man I need to stop reading these posts. Everything is perfectly fine then once I get on here I swear the next time out my brain insists I have every clunk, bump, shudder and vibration - It's amazing how you can not notice anything and think you have the best truck ever, then all then after reading all the stories on here just know you have a lemon ;)

TXGREEK · March 20, 2019

Man I need to stop reading these posts. Everything is perfectly fine then once I get on here I swear the next time out my brain insists I have every clunk, bump, shudder and vibration - It's amazing how you can not notice anything and think you have the best truck ever, then all then after reading all the stories on here just know you have a lemon ;)

I’ve found myself contemplating the same. Every time I call my favorite off-road shop, the techs say “ oh no, what did you hear this time?” Lol. Think about it, if every time you get into a new vehicle then read some of these forums then you’ll start making excuses for every little sound you hear...WAIT....SHhhh! Did you hear that??? I think my truck is about to EXPLODE!!!!

Sent from above

SkiDooNick700 · March 21, 2019

The worst part is I use my dads '17 Ram 2500HD 6.4L when my truck is getting serviced. So much for that horrible reliability... does better than my truck lol!!

benelli · March 21, 2019

16 hours ago, reardiff said:

Man I need to stop reading these posts. Everything is perfectly fine then once I get on here I swear the next time out my brain insists I have every clunk, bump, shudder and vibration - It's amazing how you can not notice anything and think you have the best truck ever, then all then after reading all the stories on here just know you have a lemon ;)

Lol welcome to the club. All you guys forget about what the service advisors tell you. There all former mechanics that haven’t been under a hood I’m years. Dealerships bump them up to service advisors so they can upsale services most probably don’t need. Your transmission and hard shifting will never go away regardless of how many re-learns and trans flushes they do. It’s a bad designed transmission . They won’t put out a recall as it’s not a safety issue they will just keep stinging you along with let’s try this let’s try that. In the end they will tell you it’s normal operation. You really think the tech is talking to gm tech support about a fix for your transmission there trying to get confirmation if they can change out the entire transmission for a new one which is no better it will string along for awhile and do the same thing . It’s not that your trans is a defective one. There all defective (bad design) . So you would be getting the same crap installed and the dealer makes more money off of warranty. That’s all.

Edited March 21, 2019 by benelli

SkiDooNick700 · March 21, 2019

~~Just got a call from my Service guy, said that this Valve Body part is on back order, so I'll pick up the truck today and he'll call me when the part is in.~~

I asked him if they did the flush, they did not. I guess they determined the Flush would not resolve my issue.

~~So I guess no further updates from me until whenever this Valve Body part comes in.~~

UPDATE- looks like another guy has the same issue as me but he's on vacation for the next several days so I am getting the in stock Valve Body that was supposed to go to him.

Should be ready for pickup tomorrow.

Edited March 21, 2019 by SkiDooNick700

SkiDooNick700 · March 24, 2019

Hey all, wanted to give an update.

Picked truck up on Friday, have since driven it around 20 miles. Shifts noticeably better! Haven't had it slam into reverse or drive. Also I had delayed engagement before, however on the few cold starts I've done, it shifts pretty much almost right away into Reverse/Drive with no clunks/noise. As it shifts thru the gears, its pretty smooth now. The 3-4 and 4-5 shifts ( I think) sometimes have a slight firmness to them where to feel it switch. Otherwise, its been smooth. I'm much happier now. Will see how this week goes with driving it to work and back every day. Also, the shudder is gone and the tach doesn't flutter like it used to when in a higher gear between 1000 - 1500 rpm and holding a steady speed.

So here is what they did:

Replace Valve Body - mine had a damaged bore

Put in 8 quarts of the new trans fluid released by GM (they did not do a full flush)

"TEST DROVE VEHICLE, TRANS HAD HARSH 1-2 -2-4 SHIFT 3-1 DOWNSHIFT, INSPECT FLUID LOOKED OK. PERFORMED CIRCUIT TEST WITH GDS, SOLENOID PERFORMED WHEN COMMANDED, STILL HARD SHIFT. REMOVED VALVE BODY FOR INSPECTION FOUND VALVE BODY FAULTY BORE HAD DAMAGE. REPLACED VALVE BODY, PERFORMED CHARACTORIZATION ON VALVE BODY"

This is another reminder to myself that being patient and waiting til powertrain warranty expires in May 2020 is worth the wait. Between this trans issue and the lifter/pushrod work that had to be done, it's been completely painless to work with the dealership :-)

Euriel94 · March 26, 2019

Took in my 2015 Denali that had shuddering issues on steady speeds of 30-70mph to my gmc dealer they replaced the transmission fluid free of charge and feels brand new again ?

drumsbh · March 27, 2019

Took my 2016 GMC Sierra 5.3, 8speed in to have the TSB performed. Paid out of pocket since I'm past warranty.
No more shudder! Cost me $370.

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tyler.frost92 · April 2, 2019

On 3/12/2019 at 9:59 PM, JCKustoms said:

Had mine flushed this morning. It was covered under warranty even though I don’t have the “shudder”.

Have only driven 100 miles, but seems to shift a bit smoother... time will tell.

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How did you convince them to do it without having the shudder? I have the occasional harsh downshift and upshift and delayed engagement. Id like to see if the new fluid helps.

JCKustoms · April 2, 2019

How did you convince them to do it without having the shudder? I have the occasional harsh downshift and upshift and delayed engagement. Id like to see if the new fluid helps.

I made an appointment from the app. Wrote what issues I was having and suggested they perform the TSB for the “shudder”. I had to wait about 3 weeks because they didn’t have the correct tool to perform the flush, although they did have the fluid.

When I went in to drop it off, they didn’t even drive it. They just asked about the symptoms again and then I picked it up 2 hours later. All covered 100% (my truck had 8,400 miles at time of service).

By the way, the fluid didn’t help at all...

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benelli · April 11, 2019

On 4/2/2019 at 11:29 AM, JCKustoms said:

I made an appointment from the app. Wrote what issues I was having and suggested they perform the TSB for the “shudder”. I had to wait about 3 weeks because they didn’t have the correct tool to perform the flush, although they did have the fluid.

When I went in to drop it off, they didn’t even drive it. They just asked about the symptoms again and then I picked it up 2 hours later. All covered 100% (my truck had 8,400 miles at time of service).

By the way, the fluid didn’t help at all...

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If you don`t mind me asking what exactly did you write in the symptoms.

JCKustoms · April 13, 2019

If you don`t mind me asking what exactly did you write in the symptoms.

I wrote that the trans was experiencing some hard shifts from second to first and first to second. I also wrote that it was very clunky when pressing or depressing the accelerator pedal at speeds above 15mph. And that the trans was clunky when shifting out of park, between gears, and back into park.

I then mentioned if they would perform the fluid flush TSB. And they did. And it didn’t help at all.

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SkiDooNick700 · April 13, 2019

5 hours ago, JCKustoms said:

I wrote that the trans was experiencing some hard shifts from second to first and first to second. I also wrote that it was very clunky when pressing or depressing the accelerator pedal at speeds above 15mph. And that the trans was clunky when shifting out of park, between gears, and back into park.

I then mentioned if they would perform the fluid flush TSB. And they did. And it didn’t help at all.

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I wonder if your valve body is damaged like mine was.

jqcitizen · April 26, 2019

Having the same issues as the rest of you. Mine has been at the dealership for the last few days. Problems started around 7000 miles. Hard shift up, and downshifting, shuttering above 30 mph.

Dealer already performed the triple fluid flush. Worked for about 800 miles, then the problem started again. Nothing worse than doing 60 and feeling like someone has run into your rear end.

Looking like its time for a new valve body and possible torque converter. And the icing on the cake is the rear end vibration. Trying to see if it is the driveshaft or rear axle.