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8 Spd Harsh Shift Question

Matt G
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Matt G Enthusiast

Matt G

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Hi, all - new to the forum. Have owned my Sierra half ton for a few months now after years of Toyota trucks (very glad I made the switch)

 

Question regarding transmission that I couldn’t find an answer to on previous posts

 

My truck has the 8 spd transmission.  Every so often it will down shift upon acceleration pretty harshly

 

Has anyone heard of any damage to transmission due to this?   I don’t care that it does it if it won’t cause any harm to it but was curious if there have been any reported issues as a result of this

 

Thank you

Matt

Edited by Matt G
Grammar
Z45 Senior Enthusiast

Z45

Posted
Posted (edited)

GM claims the problems with the 8-sp transmission do not fall under the factory warranty, as it is a design defect and not a manufacturing defect.

Edited by elcamino
Robby James Enthusiast

Robby James

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Posted

Check for any kinked lines as I believe there is a Service bulletin for that.

Could be a contributing factor.

Matt G Enthusiast

Matt G

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Thank you both. Will do on the kinked lines, and I did read that about it being a ‘design flaw’ vs manufacturing.  They got creative on that one 

 

If lines aren’t kinked, suppose I will just drive it and worry about it if something happens

 

Matt

Matt G Enthusiast

Matt G

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5 hours ago, dgstarr63 said:

My 2021 does it also, so far dealer has not been able to fix i t and GM has no interest in doing anything about it. 

This is good to know. With that in mind, am not going to worry about it, as it seems there isn’t much that can be done  other than checking for kinks as was mentioned above

TNTSierra Senior Enthusiast

TNTSierra

Posted
Posted

I have been told by a buddy who owns a 2016 with the 8 speed, that “he” allows the truck to run for 2 to 3 minutes and it never jerks or chars him after that, but if he jumps in it, starts it up and drives that’s when it’s does it??  Idk both my older K2 trucks did it and it’s the main reason why I bought the 10 speed.  Always had doubt/worried about the transmission in the back of my head. 

Matt G Enthusiast

Matt G

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Suppose if it has been around since K2 body style and no known failures, it’s an annoyance but not a reason to worry (at least I hope).  Fingers crossed that it holds up.  Good call on going 10 spd with that in mind though 

 

Thanks everyone 

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