My 2015 with 12,000 miles just started the shudder at cruising speeds, Is GM covering the fluid flush under the drive train Warranty? I am in Texas and it seems the humidity is what causes the moisture issue in the tranny. Am I going to have to fight the dealer on this repair?

 

Just had my 2015 done under warranty. Was even given a loaner vehicle

 

Thanks for the info I have an appointment for it to go in tomorrow hopefully the triple flush fixes it

 

Not sure they are doing the triple flush now that the latest fluid came out earlier this year. Just a drain and refill.

 

Is the latest TSB 18-NA-355 that removed the diagnostic test posted anywhere on the forum? I need a copy to have mine done. Thanks!!!!

 

I had the triple flush done last week on my 2017 w/ 32k miles, I probably won't get a chance to really evaluate if the fluid change has addressed the problem until next week when I take it to the mountains for a few days.

 

Shouldn't have to fight them on the Fluid change a service bulletin was released for this particular issue. I just took my car in and they said it wouldn't be a charge unfortunately the special tool they need to suck the fluid out is broken, so I have to wait for the replacement part to come in. I just hit 13k on my z51

 

We have a '14 with 6200 miles and were feeling something like a trans shudder with ours, is this an issue with all C7's or just certain years?

Thanks,

 

The shudder problem only happens with the 8 speed automatic. As your car is a 2014, it came with the 6 speed automatic so it doesn't apply to it. The 8 speed didn't come in the corvette until the 2015 model year.

John

 

I wanted to give a quick update on the results of the triple flush I had done on my car two weeks ago. I drove from Murfreesboro, TN out to Gatlinburg, TN and had a good chance to evaluate the transmission performance. The 100 RPM fluctuation in V4 mode was gone along with any shudder when the torque converter locked/unlocked. I am very happy with the results.

as background information, I had taken my car to the dealer for the transmission shudder in early February and was told to wait as the dealer had not received the tools and fluid to do the flush. When I took the car back in two weeks ago they did the triple flush with no hesitation.

 

Had mine done yesterday along with a new trans wiring harness. The difference is night and day in shifting and smoothness. Now I can drive the car the way it was intended to be used finally!

 

My 2017 GS developed the shudder about a week ago @ 17000mi. Dealer did the triple flush (TSB 18-NA-355) today. No shudder on the 40 mi drive home.

 

Had mine done as well at 39k a few weeks ago, all was covered under power train warranty. No more shudder...

-Rich

 

I am buying a used A8. Its still under powertrain warranty. Can I take it to the chevy dealer and have them do the flush?

 

Had mine done on a highly modded Z (over 800whp) and the dealer did it under warranty. Really smoothed the shifts out. No more shudder on the highway.

 

As an ASE certified shop owner, I'm with Yellow2007. I bought a new pan and am installing a GM style drain plug. Flushing it out and then drain & fills every once in a while. Lube Guard also makes an additive (small red tube) to help get rid of any TC glazing. I don't know any local GM dealers with a decent Tech that will work on my car the way I do. If anybody knows one in the Long Beach/LA area, please let me know...Good luck, guys!

 

So I thought I would share my experience with this issue. 2015 Z51 Stingray Coupe A8, 22,321 miles. I had a moderate shudder in V8/V4 AFM automatic mode anywhere between about 40-70 mph. Also had an engine speed variation of 100-120 rpm, with a 3-4 second frequency, when in automatic mode (AFM active) at anywhere between 40-70 mph. Given the experiences reported by others, I would say I had a moderate level of problem - more than "barely there" but not "horrendous". I had the current TSB 18-NA-355 (July 29, 2019 version 5) "triple flush" performed today (3-12-2020) with the "Blue Label" Mobil 1 ATF and the reset of the TCM. The work was performed under my original power train warranty which expires at the end of next month (although I also have a GM Certified Extended Warranty beyond that if needed). The dealer I used (more info below) was about one hour and fifteen minutes away - about 100 miles. The work was performed in exactly four hours, which included a 10-mile road test by the mechanic at the end to ensure that all was well. I was told, per the TSB, that it would/could likely take 200 miles or so for the improvements to materialize. I took the TSB with me just in case, but when I told my Service Advisor the nature of the issue, no questions were asked (I actually initiated the conversation last week on the phone when I made the appointment).

Following are the results, thus far, on the 104 mile trip back home on a combination of city and highway driving, in automatic mode:
1. The shudder is gone - at any speed
2. The engine rpm holds steady - maybe a nearly imperceptible occasional variation of 10-15 rpm, but mostly rock steady
3. Both the upshifts and downshifts are very different than before - smooth in transition and "quick" (as quick as an A8 is going to be) - no hesitation or jerking - exactly what anyone would expect of a quality automatic transmission
4. The shifts under acceleration/power are very solid and the timing of engine speed and shift sequence was very different than before - again, exactly what would be expected

I also drove some in manual mode, and even could tell a difference here in shift timing and "quality" - much more responsive and predictable.

As some others have experienced who have had this TSB work done, the improvements and "fix" appears to be immediate in my case and very effective. Going into this, I was actually a bit skeptical that this could happen, even though some others have reported it. I am, today, a bit amazed that a fluid flush/change and TCM reset could cause such dramatic improvements, not only in the "fix" of the problems but also the overall improvement in the A8 performance. We'll see if this lasts - hopefully with the "Blue Label" ATF, it will.

I want to commend and recommend the Chevy dealer I used - Jack Hanania Chevrolet in St. Augustine, FL. The Service Advisor is Stacey Bergbower, and the entire process from my original phone call with her last week to final delivery today could not have been better. If you are looking for a Chevy dealer in Central or Northeast Florida for this TSB or any other Corvette maintenance, I would highly recommend this dealer and Stacey. She has a special interest in Corvettes, they have two very good Corvette mechanics, and it shows.

Be glad to answer any more questions that anyone might have. I hope my experience is useful for others. My recommendation now, certainly, is that if you have this issue and are still under power train warranty, get the TSB work done.

 

Bingo.

 

Mine was triple flushed just a few weeks ago. Solved the issue.

 

Unfortunately your shutter will come back. I had the triple flush performed as a preventive maintenance to get the new fluid in there. I have a 2016 ZO6 I wasn't experiencing any shudder at the time of the flush. Fast forward seven eight months now I have shutter.