8 Speed hard 1-2 shift & Shudder TSB fix

Havasubum · September 15, 2019

I searched for a while I couldn't find this article anywhere on this site. It is dated August 13, 2019 and outlines a TSB fix for the troublesome shifting of the 8 speed transmission. My Denali is driving literally crazy with the hard up and down shift between 1 & 2. It also addresses shuddering, which I haven't experienced. I hope this works because I was about to get rid of it.

allgonoshow2 · September 15, 2019

The TSB is on here.

mnm99 · October 16, 2019

Supposed to fix the shutter only. Also people who have done the last of the 14 updates the problem still came back. GM has no fix.

https://www.classaction.org/gm-8-speed-transmission-defect-lawsuits

Jaychevy81 · October 16, 2019

GM has no fix there just throwing stuff against the wall hoping one sticks. I did the update 3 times the flush. Not taking anymore tome off of work. Shifts hard 1 to 2 bangs trying to find gears holds gears like a Manual trans. Learned to live with it.

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mnm99 · October 30, 2019

Well lets see...19, yes 19 TSB's on the 8 speed transmission. You decide if there is a problem. A class action suite and I own a truck that does all the symptoms in the suite. This last TSB fluid change isn't going to do anything. I just got my truck back a couple days ago (24000 MILES). They replaced the valve body and did a flush. Right now it drives ok. I am noticing when it's cold it bangs 5th gear every time until it warms up to like 100*. The problem will come back, it's a fact. Get this ...My dealer has said to me the last 4 times I brought it in they drove it and said they didn't hear anything. The 5th time a tranny guy drove with me and heard the downshift bang. I was told that it is normal for this tranny to downshift and hear a noise. Really! I was told not to bring it in again unless it gets worse. They changed the valve body on a Courtesy...A Courtesy..Huh. I can't wait to get rid of this truck. all and all I love it, but if they can't fix the tranny I'm done

simonsd0708 · October 30, 2019

I’ve been seeing and hearing good thinks about this particular fluid flush, I’m starting to finally get some shudder around 21000 miles so I may take it in, it’s not bothering me, but hey, free fluid flush...

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njk4o5 · November 1, 2019

the 6 speeds are just as bad. GM is sure putting out some terrible transmissions. they eat themselves alive due to poor tuning

mookdoc6 · November 1, 2019

On ‎10‎/‎30‎/‎2019 at 8:24 AM, mnm99 said:

Well lets see...19, yes 19 TSB's on the 8 speed transmission. You decide if there is a problem. A class action suite and I own a truck that does all the symptoms in the suite. This last TSB fluid change isn't going to do anything. I just got my truck back a couple days ago (24000 MILES). They replaced the valve body and did a flush. Right now it drives ok. I am noticing when it's cold it bangs 5th gear every time until it warms up to like 100*. The problem will come back, it's a fact. Get this ...My dealer has said to me the last 4 times I brought it in they drove it and said they didn't hear anything. The 5th time a tranny guy drove with me and heard the downshift bang. I was told that it is normal for this tranny to downshift and hear a noise. Really! I was told not to bring it in again unless it gets worse. They changed the valve body on a Courtesy...A Courtesy..Huh. I can't wait to get rid of this truck. all and all I love it, but if they can't fix the tranny I'm done

We recommend the 10speed F-150!

mnm99 · November 1, 2019

From what I'm reading the 10 speed has a class action also. I have been seriously looking at the 2019 or 2020 Raptor. It has the 10 speed also. We'll see...

wmgeorge64 · November 3, 2019

Honest to God, I have the 21014 six speed and its driving me up the wall. Today I get the shudders, first time I noticed ever. Crazy up/down shifting. I suppose I should go find anther Thread for the six speed.

Will a fluid flush fix it? I had it in to CarX for an oil change 64,000 miles and they recommended the transmission fluid flush as GM said its due??

Doublebase · November 8, 2019

On 11/3/2019 at 6:19 PM, wmgeorge64 said:

Honest to God, I have the 21014 six speed and its driving me up the wall. Today I get the shudders, first time I noticed ever. Crazy up/down shifting. I suppose I should go find anther Thread for the six speed.

Will a fluid flush fix it? I had it in to CarX for an oil change 64,000 miles and they recommended the transmission fluid flush as GM said its due??

Yeah I'm in the same boat...41,000 miles and it just started...shudder while going up hills on the highway. I'm going to do a fluid exchange and see if that helps. Honestly I can live with it, it's not that big of a deal...however I can't live with let's say, the transmission crapping out as soon as I get out of warranty. A friend of mine just had his torque converter replaced at 38,000 miles - I"m wondering if I'm headed in the same direction.

wmgeorge64 · November 8, 2019

7 minutes ago, Doublebase said:

Yeah I'm in the same boat...41,000 miles and it just started...shudder while going up hills on the highway. I'm going to do a fluid exchange and see if that helps. Honestly I can live with it, it's not that big of a deal...however I can't live with let's say, the transmission crapping out as soon as I get out of warranty. A friend of mine just had his torque converter replaced at 38,000 miles - I"m wondering if I'm headed in the same direction.

Well I got my AFM delete Range in the mail today and I am going to see if it works or not. Its the around town, slow traffic, shifts a lot what annoys me. And now of course the Shudders. I am out of warranty so thats scary.