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6 Speed Transmission Clunk Downshift

JacobC1983
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g2full Enthusiast

g2full

Posted
Posted
On 3/24/2018 at 7:48 PM, Hooper_c4 said:

It's a Chevy thing. They all do it

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Truth in this statement. The '04 I just got rid of did it for the entire 4 years I had it. Never caused issues.

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Grumpy Bear
Grumpy Bear

I'll be sure to tell my truck's 6L80E transmission about this. It has been picture perfect for nearly 60,000 miles. Evidently it doesn't know that it spoiling the others awful reputation.  

Mike GMC
Mike GMC

I believe the "mine is fine" posts are in response to the equally useless, "they all suck" posts.   That said, have you done a fluid change?  What does the fluid look like?  How is the fluid

Grumpy Bear
Grumpy Bear

Problems with threads like this. 10 guys who never met each other with 10 different situations assuming 10 different assumptions are creating the exact same issue. Make a guys head hurt....  

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rudyb Enthusiast

rudyb

Posted
Posted (edited)

My '16 has an aweful downshift while coasting down from 32mph->28mph. The seat belt has caught me a few times. It's pretty aggresive. If I'm braking it doesn't usually happen, just when I see a red light and let off the gas pedal. I also have some strange stuff while accelerating, but it's difficult to replicate. Sometimes it will accelerate through the gears like a dream. Other times the truck seems to be drunk and can't figure out what gear it's supposed to go to. 

Edited by rudyb
njk4o5 Enthusiast

njk4o5

Posted
Posted
15 hours ago, rudyb said:

My '16 has an aweful downshift while coasting down from 32mph->28mph. The seat belt has caught me a few times. It's pretty aggresive. If I'm braking it doesn't usually happen, just when I see a red light and let off the gas pedal. I also have some strange stuff while accelerating, but it's difficult to replicate. Sometimes it will accelerate through the gears like a dream. Other times the truck seems to be drunk and can't figure out what gear it's supposed to go to. 

classic k2xx transmission tuning

Sierra Dan Senior Enthusiast

Sierra Dan

Posted
Posted
16 hours ago, rudyb said:

My '16 has an aweful downshift while coasting down from 32mph->28mph. The seat belt has caught me a few times. It's pretty aggresive. If I'm braking it doesn't usually happen, just when I see a red light and let off the gas pedal. I also have some strange stuff while accelerating, but it's difficult to replicate. Sometimes it will accelerate through the gears like a dream. Other times the truck seems to be drunk and can't figure out what gear it's supposed to go to. 

Throw it in M5, and a run a few tanks of E85 through the system if you are E85 capable.

g2full Enthusiast

g2full

Posted
Posted (edited)
On 3/24/2018 at 7:48 PM, Hooper_c4 said:

It's a Chevy thing. They all do it

Sent from my SM-G930V using Tapatalk
 

My 04 did it for sure. lol. I'm so used to it I don't even notice anymore really. But I'd love for it to work as designed.

Edited by g2full
  • 1 month later...
Tigstoy97 New Member

Tigstoy97

Posted
Posted (edited)

My 17, k1500 is having same issue, started at 38K. Multiple trips to dealer (multiple re-flashes / updates), even opened a case with GM on it. Duplicated at the dealer, got ever excuse other than a possible fix in the works. just waiting for the 60K to expire, so my aftermarket extended warranty can deal with it. Got worse towing - had a up shift shudder from 30-45mph - with only a 4k load behind it, very disappointing.

 

Glad I did not trade in my 04 Suburban, 4 gears seems to be less problems than 6.

Edited by Tigstoy97
  • 3 weeks later...
6.2_GMC_DEN Enthusiast

6.2_GMC_DEN

Posted
Posted

It took hours any many revisions to fix the driveline clunk issue I experienced. It is a combination of upshift and downshift scheduling problems, torque converter lock up and unlock at the wrong times,  desired output torque factor issues, torque adder issues, stall torque management, tip-in torque management, limit torque management, torque reduction, and more. Basically the stock tune is commanding too much of everything at the wrong times.

 

Mine shifts like butter at part throttle and is nice and crisp at WOT. The way it should of been from the factory.

 

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wtfandy Enthusiast

wtfandy

Posted
Posted (edited)

I didn't have an issue with my 2017 1500, but got some of the symptoms mentioned in this thread. Set an appointment for Tuesday to drop off. Wondering if I can take this to work Monday.

 

2018 Sierra 1500 CCSB with 7.5k miles

 

http://imgur.com/gallery/DuennvB

Edited by wtfandy
  • 2 weeks later...
Lamekurt Enthusiast

Lamekurt

Posted
Posted
On 2019-01-11 at 9:53 PM, thekevin said:

My 2018 will clunk in the same spot pretty much every day. On the 4 lane to my house there is about a half mile down hill coast, then a mile long uphill and right at the top is my exit that is also uphill that comes to a stop sign. Pretty much every day when slowing for the stop sign it clunks really hard on the 2 - 1 shift. I have a Range AFM disabler.


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Ever find a fix for this? My 18 has the same thing too 

CSI-WALLEYE Enthusiast

CSI-WALLEYE

Posted
Posted

How common is this problem?  are the problematic transmissions defective or is this a design flaw?  If it is a design flaw why don't they all have problems?

Rusty Shackleford Enthusiast

Rusty Shackleford

Posted
Posted

Had this issue when I got my 2018 w/6spd. Talked to the trans guy at my dealer and he told me to run it in tow/haul every time I drove it for about two weeks, then revert back to normal. It largely solved the problem. I get a hard downshift about once a week now, much better than it being a daily occurrence. 

  • 5 weeks later...
Vonpaco New Member

Vonpaco

Posted
Posted

I am new to this site and found it while researching the harsh down shift issue. I purchased a new 2018 1500 with the 5.3 and 6 speed in july of 2018. Have had it into the dealer 6 times for the harsh down shift on rapid deceleration. The problem began after it hit around 2k miles and was ignored until about 17k miles. They performed the normal relearn repairs and sent me on my way. They finally agreed there was an an issue when i didn't go away and found the 3-5 reverse housing was leaking. They repaired ( only 1k miles on repaired trans) the trans and corrected the problem. Unfortunately, they created another issue I am now dealing with. The truck now slams out of overdrive when I push the throttle to pass another car. The dealer is of course saying it needs to "learn" the shift points again and want me to drive it another 1k miles.

I have my 7th service appointment on Wednesday. I attached my service invoice to show what they did. 20190513_210240.thumb.jpg.39d2ebb94f419167505debc459fd5907.jpg

  • 2 months later...
2014RedRado New Member

2014RedRado

Posted
Posted

My 2014 silverado does this when i'm in reverse and switch it in drive without stopping completely. Also happens when my truck try's downshift from 3rd to 2nd gear while i put torque on it. I haven't heard of a way to fix it. seems pretty common 

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
On 4/13/2019 at 7:29 AM, CSI-WALLEYE said:

How common is this problem?  are the problematic transmissions defective or is this a design flaw?  If it is a design flaw why don't they all have problems?

Problems with threads like this. 10 guys who never met each other with 10 different situations assuming 10 different assumptions are creating the exact same issue. Make a guys head hurt....

 

How would one begin to sort that actual defective units for those whose operators are aggravating a normal situation like the one below: 

 

25 minutes ago, 2014RedRado said:

My 2014 silverado does this when i'm in reverse and switch it in drive without stopping completely. Also happens when my truck try's downshift from 3rd to 2nd gear while i put torque on it. I haven't heard of a way to fix it. seems pretty common 

What? You mean you can't abuse a transmission and have it ACT NORMALLY?  :banghead:

 

:crackup:

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