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8 SPEED TRANSMISSION ISSUES


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Hi,

Still looking for some help with my 2020 Silverado my transmission has a 1-2 shift slip this only happens first shift of the day after that good for the rest of the day. I am not experiencing a harsh 1-2...this started around 2000klm.

 

 

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When you say still looking for help, do you mean you been to the dealer and it still is acting up and want more info from other owners?  How many miles are on it?

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Yes more info, I have 1800 miles on my truck the dealer is not being helpful a slipping transmission on a 60,000 truck is not normal if it did it on the test drive I would never have purchased it.

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On 5/18/2021 at 8:05 PM, Siebersh said:

Yes more info, I have 1800 miles on my truck the dealer is not being helpful a slipping transmission on a 60,000 truck is not normal if it did it on the test drive I would never have purchased it.

Is there another dealer you can take it to?  That would be the next step.

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I'm certain this has been talked about on here in different threads over the years.  My 2019 Silverado does the same thing.  It's not concern to me ask my dealer offers a lifetime drivetrain warranty (only stipulation is to bring it to them for every oil change and every scheduled service).

 

Either way, I believe the main resolution was to take it to the dealer and have them flush the entire trans with the "new" fluid that they are to be using.

 

If I were you, I'd video tape the truck doing this and show it to them if they don't believe you.

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Posted (edited)

I have a 2019 LT 5.3l and the 8 spd with mine had the TCC Shudder and the flush and refill with the Mobil 1 synthetic took care of it completely. 5000 miles since the service and very smooth at all speeds.

Hope this helps.

Edited by bigdoug42
Added since the service
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fyi......................

Quote

The lawsuit, filed in the U.S. District Court for the Eastern District of Michigan, alleges GM's eight-speed automatic transmissions may shift violently into gear. ... GM claims the problems with the transmission do not fall under the factory warranty, as it is a design defect and not a manufacturing defect.

 

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@elcamino, how many individuals do you know that have switched over to AMSOIL's ATL, ATF in their 8sp and don't have any issues?

 

I only know of one individual that has and all is good.

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Is the majority of 8 speed transmission reliable. I pick up my 2021 RST 5.3 Z71 Truck Wednesday June 2nd. Hope I didn't make a mistake. Getting rid of my 2006 Z71 with 168000 miles. It has hard shifts brake issues rear end issues. Transfer case has been replaced. Not a Ford or Dodge fan. Hoping to tow travel trailer 6000 lbs.

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All I can say is my 2020 z71 didn’t start to have issues until I had it a couple of weeks, the first problem was or I should say is a noise coming from the rear suspension ( dealer said this is common) I don’t agree, next was the rear head rest rattled ( dealer said known issue) no fix yet, and on occasion a strange thumping sound from the front end (dealer can’t replicate) no repair, drivers side rattle in the door post and lastly the transmission has an intermittent 1-2 slip first shift of the day says it common I said maybe the complainant is common but the transmission should NOT slip at all. All this for $60,000

i only have 3000 Klm on my truck.

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Maybe you just need to get used to the nuances of newer vehicles.  What you perceive as a problem maybe normal operation as designed.  People always look for something to complain about, drive it and stop nitpicking, you have a 3 yr bumper to bumper warranty.

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First of all I don't nitpick! I'm a certified class "A" MECHANIC for over 37 years and specialized in transmission rebuilding

if you think all these issues are normal then that's your opinion, I telling all the others that this is NOT normal for a new vehicle at any price. My truck has 1800 miles on it and a price tag of $60,000 the issues were not present when I test drove the truck and if they were I would never have bought it. This is not my first new GM vehicle but definite the first with all these issues. 

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3 hours ago, Siebersh said:

First of all I don't nitpick! I'm a certified class "A" MECHANIC for over 37 years and specialized in transmission rebuilding

if you think all these issues are normal then that's your opinion, I telling all the others that this is NOT normal for a new vehicle at any price. My truck has 1800 miles on it and a price tag of $60,000 the issues were not present when I test drove the truck and if they were I would never have bought it. This is not my first new GM vehicle but definite the first with all these issues. 

With all that transmission training, you should tear yours apart and report back any findings of fault. Sounds like it wouldn't be anything for you to do this and might help others to boot?

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I have owned GM vehicles exclusively since 1964. I have owned the following automatic transmissions: Aluminum Powerglide, Turbo 200, 350 and 400, 4L80E, 4L60E, 6L80E and 8L90E. The 8L90E is the worst of the bunch! My 2021 Silverado 8L90E has an   intermittent harsh downshift into 1st gear. So far the dealer has not been able to fix it, but has invited my to come back for the 3rd time to try to figure out how to fix it. Is this progress?

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