Who likes their 8 Speed?

m3n00b · October 6, 2016

What's "flair shift"? Just curious.

It's slow to shift from 1st to 2nd when cold. Usually only once per day. It allows the rpms to climb between the shift and causes a mild jerk when it finally gets into 2nd.

-tapa

Edited October 6, 2016 by m3n00b

Cjc · October 7, 2016

Now that I have 6000km.on it works like a champ.

jlilnc14 · October 11, 2016

It's slow to shift from 1st to 2nd when cold. Usually only once per day. It allows the rpms to climb between the shift and causes a mild jerk when it finally gets into 2nd.

-tapa

I've discovered that after the truck has been sitting a while, Shift into drive and let it coast for a few feet( it redistributes the oil in the trans) then slowly accelerate after. The jerk is either really mild or totally gone, depending on how long you coast. I usually just coast out of the garage and another 10 feet and usually there's no jerk. I plan on getting the TSB done to fix this when I go in for my first free service.

mookdoc6 · October 11, 2016

Is there is a TSB for this? I have exact same issue? I am in shop at moment to see what's up with the 1st to 2nd when cold?

jlilnc14 · October 11, 2016

Is there is a TSB for this? I have exact same issue? I am in shop at moment to see what's up with the 1st to 2nd when cold?

TSB #16-NA-014 : Delayed Engagement after sitting with the engine off. 2015-2015 models.

mookdoc6 · October 11, 2016

I thought it was for 6.2L 8speeds only?

jlilnc14 · October 12, 2016

I thought it was for 6.2L 8speeds only?

Here's an image of the TSB. Doesn't say its limited to 6.2l. Only which transmission and year is covered.

http://www.gm-trucks.com/forums/topic/187484-delayed-engagement-on-the-8l90e/

mookdoc6 · October 12, 2016

Thanks! I had what the dealer called a Fast Learn C4Clutch packs/Pads softening. And so far this baby is Spot On!

CptMcSaug · October 14, 2016

Been without mine for a week getting torque converter number 2 put it. Hope this fixes the shuddering...

mookdoc6 · October 14, 2016

Been without mine for a week getting torque converter number 2 put it. Hope this fixes the shuddering...

Hope so too bud! You might have been the lucky one to get both batches of shitty torque converters?

Croak · October 24, 2016

Had the delayed shift problem, but the dealer did a re-learn and the truck was great for a week or so. Started to feel a little lazy again after that. The re-learn didn't fix the occasional clunky downshift, especially with the shifter in M mode. Now it's started to fluctuate RPM at steady cruise around 40mph under light load - revs will climb a couple hundred RPM then drop again, keeps doing this. Truck has also developed a shudder through the whole drivetrain under a few circumstances, haven't figured out what triggers it yet. Guessing something is truly broke now. Will head to the dealer this week and hope they don't try to blame it on my dropped suspension.

powerhaulic · November 2, 2016

Been without mine for a week getting torque converter number 2 put it. Hope this fixes the shuddering...

How did you make out with new converter?

powerhaulic · November 2, 2016

Had the delayed shift problem, but the dealer did a re-learn and the truck was great for a week or so. Started to feel a little lazy again after that. The re-learn didn't fix the occasional clunky downshift, especially with the shifter in M mode. Now it's started to fluctuate RPM at steady cruise around 40mph under light load - revs will climb a couple hundred RPM then drop again, keeps doing this. Truck has also developed a shudder through the whole drivetrain under a few circumstances, haven't figured out what triggers it yet. Guessing something is truly broke now. Will head to the dealer this week and hope they don't try to blame it on my dropped suspension.

That is converter shudder

Occurs light throttle light load.

I'm thinking the additive package in the new spec Dexron HP is greatly at fault, combined with software....JMHO

CptMcSaug · November 2, 2016

How did you make out with new converter?

To be honest it actual feels alot better.

The truck is shifting better, smoother and quicker. No more shudder under light load. The RPMs don't fluctuate up and down cursing anymore. Truck feels quicker and is average 1 mpg more. Now the test will see if it last.

Edited November 2, 2016 by CptMcSaug

silver sled 16 · November 2, 2016

Hello all this is my first post here. I found and joined this site due to my ongoing issues with my 8 speed. It's been bad since the ride home from dealer. I had the converter replaced at 700 miles. That took care of the shuddering but I'm still left with awful shifts up and down. Only occurs when driving smoothly. Truck has 3700 miles on now and seams to be getting worse. Fuel milage is down too. Truck is 100%stock. Towing and leaning into it is awesome. Truck is a rocket ship. Dealers have been no help. "OPERATING AS DESIGNED" is what I get. No updates as of yet. Gm customer service sas bring it to dealer. Well after 10 new gm cars and trucks in past 15 years between me and my wife im little disappointed. Please help gm. I know it's in the programming. I myself am an nissan dealer mechanic. Nissan has similar issues that are usually repaired timely and simply with reprograms. Seams this issue spans years of production. What's going on,???

Edited November 2, 2016 by silver sled 16