C7Flyboy15
New member
New (old) member here. I recently acquired a new girl friend that came with a 2015 Crystal Red Metallic Stingray Coupe. Car was bought new in 2014 by her deceased husband. Has sat in the garage for most of the last 4 years, and only driven occasionally. It has 8900 miles on it. I recently drove it for the first time. Noticed right away transmission shudder. 
The girl friend never noticed it, which is understandable, most people would not pick up on it.
Anyway, not a new problem. GM has had trouble with many 8 speed automatics. I had the same issue with a 2015 Yukon Denali. The TSB fix (temporary) is a triple fluid flush with Mobil 1 Synthetic.
So, took the car to a local GM dealer for service. They won't cover it under warranty.. Quoted $600 for service. Service manager calls to report they have an issue.. they can't do a fluid change without dropping the rear differential. ??? Adds another $400 to the cost for a total of $998.
In my opinion, the Service Manager and the Mechanic who told this story to the Service Manager are idiots. There is no need to "drop" the rear differential. Anyway, talked to another GM Dealer and they want $800 for a triple flush, plus he claims they will likely have to replace the Torque Converter that will add thousands to the cost.
At this point, if I had a lift I would do the job myself..
The entire debacle has me thinking however, this is a paddle shift car. When the transmission is in "M" (paddle shift mode) there is no shudder. Makes sense, since the torque converter is in lock mode. When in "D" the shudder is there, including nuisance shifting between 8 and 7th gear at highway speed. So, since the car will automatically downshift as engine RPMs decrease in "M" mode, they why can't the transmission be reprogrammed to lock the converter up in "D" also, and downshift as engine and vehicle speed require?
Maybe a good fix for this problem is not only a fluid change to fully synthetic, but a re-program of the transmission?
By the way, still looking for a good Corvette shop in the Maryland/Delaware area.
The girl friend never noticed it, which is understandable, most people would not pick up on it. Anyway, not a new problem. GM has had trouble with many 8 speed automatics. I had the same issue with a 2015 Yukon Denali. The TSB fix (temporary) is a triple fluid flush with Mobil 1 Synthetic.
So, took the car to a local GM dealer for service. They won't cover it under warranty..
Quoted $600 for service. Service manager calls to report they have an issue.. they can't do a fluid change without dropping the rear differential. ??? Adds another $400 to the cost for a total of $998. In my opinion, the Service Manager and the Mechanic who told this story to the Service Manager are idiots. There is no need to "drop" the rear differential. Anyway, talked to another GM Dealer and they want $800 for a triple flush, plus he claims they will likely have to replace the Torque Converter that will add thousands to the cost.
At this point, if I had a lift I would do the job myself..
The entire debacle has me thinking however, this is a paddle shift car. When the transmission is in "M" (paddle shift mode) there is no shudder. Makes sense, since the torque converter is in lock mode. When in "D" the shudder is there, including nuisance shifting between 8 and 7th gear at highway speed. So, since the car will automatically downshift as engine RPMs decrease in "M" mode, they why can't the transmission be reprogrammed to lock the converter up in "D" also, and downshift as engine and vehicle speed require?
Maybe a good fix for this problem is not only a fluid change to fully synthetic, but a re-program of the transmission?
By the way, still looking for a good Corvette shop in the Maryland/Delaware area.
I'm not so sure that they don't do some tweaks to the computer when they do the flush. Really surprised they don't do that as a service, but the car is 7 years old, but I thought powertrain warranty was 10 years... maybe that is just emissions system.
