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16-NA-175 8 Speed Shudder UPDATE


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  • 4 weeks later...

UPDATE.  PLAN OF ACTION AS OF 12/12/18:

 

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A new transmission fluid exchange procedure and new formula of Mobil 1 Synthetic LV ATF HP transmission fluid is being released to address torque converter shudder on 8L45 and 8L90 applications. The procedure and new transmission fluid is being rolled out regionally due to the limited availability of both the new transmission fluid and tool kit availability.  The dealer rollout was determined by paid warranty claims from TSB 16-NA-175.  It is anticipated that the new transmission fluid and tool kit will be available nationwide by late January or early February 2019.  Once the new transmission fluid and tool kit is available the detailed service procedure will be loaded into GM Service Information (SI) as a Technical Service Bulletin (TSB).  TSB's 16-NA-175 and 18-NA-177 will be eliminated from SI.  An additional Global Connect Message will be sent to announce these changes.

I tried to add this to my original post, but got nothing but the one more step CATCHPA screen and it wouldn't edit my post. 

Edited by newdude
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Only a fluid change? Whats the likelyhood of this actually being the real permanent fix? I am on my third tc and my truck is shuttering again. Starting to feel like a normal maintenance item, replace the torque converter and flush every third oil change. 

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  • 2 weeks later...
On ‎12‎/‎16‎/‎2018 at 1:41 PM, hotrdlx said:

Only a fluid change? Whats the likelyhood of this actually being the real permanent fix? I am on my third tc and my truck is shuttering again. Starting to feel like a normal maintenance item, replace the torque converter and flush every third oil change. 

 

GM's research:
 

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The current HP fluid has a greater tendency to be hygroscopic – or water absorbing. It also tends to hold that moisture even when the fluid heats up. As the moisture content in the fluid increases, the tendency to have TCC shudder increases.

 

 

 

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On 12/27/2018 at 7:55 AM, newdude said:

 

GM's research:
 

 

 

Not sure I'm buying GM's research 100%. Living In dry Arizona and towing a trailer I've seen the trans fluid heat up over waters boiling point. under these conditions i find it difficult to imagine how the dry atmosphere will not absorb water vapor boiled out of the tranny fluid. Yet my truck developed the shudder @25k and I am feeling it ever so slightly coming back occasionally just shy of 30k.

 

IMO the new fluid is all about friction modifiers. With a TCC designed to almost constantly slip ~10% you are really beating up on the fluid. And similar to a limited slip diff it can chatter without the correct additives to stop it. Even with the correct additives package is the slipping TCC just beating the snot out of the fluid? is it just breaking it down too quickly?

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  • 4 weeks later...

I've got another post on this site I've been tracking my issue.  I've had the fluid flush and then TCC + fluid flush.  Issue seems to have come back.

 

I'm scheduled to go in next week for this new fluid flush and reprogram.  It seems like they've gone full circle though.  The early PIP5337's indicated double fluid flush and then later on around PIP5337D/E they started saying it was TCC and now with PIP5337K it points to 16-NA-175.

 

I'm optimistically cautious about this.

 

Here's a link to my posting/findings in case it helps anyone.

 

 

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I just got an '18 Silverado High Country on 1/10. With a little over 100 miles on it the TCC shudder issue started mildly. I didn't really think much of it at first but it has gotten worse. It will be at the dealer today for them to look at with 427 miles on it. This is the 2nd time in a little over a week I have had my truck in to get something repaired. The first time was the tire pressure monitoring system needed service. That happened on the way home after signing papers. To say that I am having some buyers remorse is an understatement. 

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1 hour ago, GPHusker said:

I just got an '18 Silverado High Country on 1/10. With a little over 100 miles on it the TCC shudder issue started mildly. I didn't really think much of it at first but it has gotten worse. It will be at the dealer today for them to look at with 427 miles on it. This is the 2nd time in a little over a week I have had my truck in to get something repaired. The first time was the tire pressure monitoring system needed service. That happened on the way home after signing papers. To say that I am having some buyers remorse is an understatement. 

It is tough when you spend that kind of cash on a vehicle to have these problems right off the bat.  Give it a few hundred miles to break in though.  The tolerances are so strict on these 8L90E (assuming you have that versus the 10L80/90) that they are self learning and may learn the correct pressures over a few hundred miles.

 

Good news is the TPMS should be a quick fix.

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I hope there can be a permanent fix. This truck purchase was one of those things where we planned on getting one exactly like I wanted now and hold on to it for longer than I have vehicles in the past. I wont be able to get my truck looked at today after all due to weather. We had a bunch of freezing rain and so the dealer obviously doesn't feel comfortable testing in in those conditions. So the plan is tomorrow now. Hopefully this gets fixed and I can start enjoying the truck. This is supposed to be the fun times in a new vehicle and not running to the dealer weekly.

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I have had my truck at the dealership since Wednesday. They called me Wednesday afternoon and the transmission guy agreed that I had a TCC issue. The service manager said they had been talking to GM and they are getting some of the new fluid in on Friday that is supposed to be the fix. I am supposed to pick it up sometime today. I will ask them what fluid they put in and try to get more details but it sounded like this may be the new "fix" fluid. The service manager told me he had never seen one in with this few miles though, lucky me.

 

Edit: I forgot to add that the dealership gave me a 2019 Silverado LT Z71 to drive for the past few days. The 8 speed in that is silky smooth and feels nothing like the old 8 speed. Other than that the only things I like about it are the updated radio interface and the push button start. The rest of the truck seems cheap and the exterior and interior styling just does nothing for me. The interior styling looks great in pictures, but actually sitting in it something is just off. 

Edited by GPHusker
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I got my truck back on Friday.  The shudder is gone for now. They did the old service bulletin because they didn't  have the machine to perform the new one. Lets hope this fixes it, but I am sure it will come back. At least if it does the dealer should have the new machine by then.

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