remington9

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Mar 27, 2015
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2015 C7 Stingray
A few weeks ago I've noticed that my 2015 C7, with 8 speed automatic transmission jerks aggressively when shifted from Park to Drive. It only does it when the engine is cold or has sat over night. The car has 13,000 kms. I would greatly appreciate any advice before taking it to a garage.

Thank you
 
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Probably cold oil. Not something I have heard about before. Kind of difficult to quantify "jerk" I understand. If it is aggressive might be worth a trip to the dealership or preferred mechanic.
 
I had the same problem last year and took it to the dealership. The mechanic said the transmission had to be retrained and he reloaded the software.
That helped for a while but it comes back occasionally especially after driving the A8 in manual mode during deceleration etc.
If I drive it easy, it doesn't happen.
 
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A few weeks ago I've noticed that my 2015 C7, with 8 speed automatic transmission jerks aggressively when shifted from Park to Drive. It only does it when the engine is cold or has sat over night. The car has 13,000 kms. I would greatly appreciate any advice before taking it to a garage.

Thank you
It's what you get for not getting a stick...LOL. The jerk occurs when the trans fluid is not warmed up and circulating to all crevices of the tranny..
Sharkface
 
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When you first start the car it would be on a fast idle. Wait for it to come off fast idle before shifting.
Good advice, any automatic should not be shifted out of park at fast idle. kick the throttle down while in park to decrease the idle before shifting.

I recently posted a note about c7s acting up when the trans is cold. (automatics). I also think there is a defect with the trans software. You can reprogram it or retrain it, but this is not a permanent fix. I recently parked my vette C4, next to a c7 gran sport. A very nice yellow one. After meeting the owner, he said that with a six speed standard, you cant rev it up in first and hit second because the car is programmed to go from first to fourth when revving it up in first. I don't know why Corvette does this stuff? Anything to improve gas mileage ... (people don't buy Corvettes for good gas mileage...
 
Good advice, any automatic should not be shifted out of park at fast idle. kick the throttle down while in park to decrease the idle before shifting.

I recently posted a note about c7s acting up when the trans is cold. (automatics). I also think there is a defect with the trans software. You can reprogram it or retrain it, but this is not a permanent fix. I recently parked my vette C4, next to a c7 gran sport. A very nice yellow one. After meeting the owner, he said that with a six speed standard, you cant rev it up in first and hit second because the car is programmed to go from first to fourth when revving it up in first. I don't know why Corvette does this stuff? Anything to improve gas mileage ... (people don't buy Corvettes for good gas mileage...


That guy is FOS or has a problem with his car.
I had this feature on my last 3 manual Z06s. (1 C6 and 2 C7s) You can rev up as far as you want in 1st gear. That feature drops at 2000ish RPM and can be programmed out or a little "skip shift" device can be installed. It was so rarely a problem I did not bother doing either.

That fellow clearly is missing out on the info available right here on CCF, or in his manual, the internet...any forum. My god how could anyone be so oblivious to his own car....and live with that. :rofl:
 
That guy is FOS or has a problem with his car.
I had this feature on my last 3 manual Z06s. (1 C6 and 2 C7s) You can rev up as far as you want in 1st gear. That feature drops at 2000ish RPM and can be programmed out or a little "skip shift" device can be installed. It was so rarely a problem I did not bother doing either.

That fellow clearly is missing out on the info available right here on CCF, or in his manual, the internet...any forum. My god how could anyone be so oblivious to his own car....and live with that. :rofl:
Very True, I thought this dude would be better off driving a Honda Civic with a straight pipe...LOL He didn't seem very credible with mechanics. After researching c7 gran sports, while in the sport mode, you can rev it up in first and shift second. There is an idiot light on the dash that indicates its going from first to fourth when it is not in sport mode.
 
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A few weeks ago I've noticed that my 2015 C7, with 8 speed automatic transmission jerks aggressively when shifted from Park to Drive. It only does it when the engine is cold or has sat over night. The car has 13,000 kms. I would greatly appreciate any advice before taking it to a garage.

Thank you
This is a common issue with the C7 A8 transmissions. In fact if you go to the USA corvette forum there is entire thread dedicated to it. I had the same issue pretty much by end of first year I bought my '15. I ended up finding a local dealer with a head shop mechanic who investigated the current bulletins and there seems to be several bulletins trying to address the issue you are having now anywhere from torque converter replacement, issue with an O-ring, update to to software, to a triple flush and new transmission oil. The mechanic decided the best option would be to just have the transmission replaced and the differential replaced with a more updated version. This was 2 summers ago and last year I also descided to get the most recent software update and all of this has fixed issue and now runs perfect. I was lucky that all of this was at no cost but I'm assuming you might not have any warranty left so cheapest thing to do would be ask your dealer to reflash your software and check for updates. If are experiencing a shudder during acceleration try the triple flush and new recommended transmission oil Mobil 1 lv atf hp gm part 19417577 the bulliten for this is TSB 18-NA-355 (July 29, 2019 version 5.
 
My 2019 GMC 8 speed its a crappy transmission
When I was getting my transmission fixed the mechanic mentioned that they were seeing similar issues in the trucks as well. I think in general they try to do the software update first but I really feel it's just bad luck and the only fix is getting another transmission and the software update. It just seems like most people have no issues so just a bad part at the end of the day.
 
A few weeks ago I've noticed that my 2015 C7, with 8 speed automatic transmission jerks aggressively when shifted from Park to Drive. It only does it when the engine is cold or has sat over night. The car has 13,000 kms. I would greatly appreciate any advice before taking it to a garage.

Thank you
Check automatics. Linckage. sometimes minor adjustments. i'd go to a reliable transmission shop or dealership.
 
I apologize to the OP for not seeing this post back in August. Had I been aware of it I would have provided the appropriate info. However, the following may help other C7 owners should they experience this issue in future.

This is a well known failure affecting the 1st gen 8L90 (A8) transmissions installed in many GM products including 2015 and early 2016 MY C7's. The issue is with the transmission modulator valve body. The valving within the modulator valve body allows too much of the ATF to drain from the torque converter when the car sits for any length of time. When started there is insufficient ATF in the torque converter to allow for smooth power transmission to the gear box resulting in a harsh shift into 1st or reverse. The same problem can cause harsh up/down shifts under load in the upper rev range particularly in manual mode.

Replacement of the modulator valve body, along with a software update (Service Fast Learn, the re-learn procedure) solved the problem for most affected vehicles. The repair would have been covered under GM's 5 year/100,000 kl powertrain warranty. Unfortunately, some transmissions sustained severe damage as a result of this failure and had to be replaced but this was also covered under warranty.

2016 MY C7's produced in late September, 2015 had the updated components.

Hope this helps.

Best regards
Ross
 

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I have a 2016 corvette c7, still under warranty. 3 months ago I had a gear job done because the car is jerking when I shift the gear while engine is in cold conditions, they almost replaced the whole gear box, 1 month later same problem... I took it again to the workshop, they reporgramed the gear and peoblem was resolved. Tomorrow am taking my car again because the car is jerking again.

In conclusion, it obvious that there is a defect in their 8 speed transmission gear and this problem wont be resolved.

I love this car, but this is it... and no wonder that GM is facing a lawsuit because of their 8 transmission speed gearbox.
 
I have a 2016 corvette c7, still under warranty. 3 months ago I had a gear job done because the car is jerking when I shift the gear while engine is in cold conditions, they almost replaced the whole gear box, 1 month later same problem... I took it again to the workshop, they reporgramed the gear and peoblem was resolved. Tomorrow am taking my car again because the car is jerking again.

In conclusion, it obvious that there is a defect in their 8 speed transmission gear and this problem wont be resolved.

I love this car, but this is it... and no wonder that GM is facing a lawsuit because of their 8 transmission speed gearbox.
Sorry to hear of your problem. Have heard a few complaints here on the A8 tranny but not usually what you are describing. I can't really comment as I drive an M7. I'm sure there's a few around if you wanted to trade of for the manual trans that has been exemplary. Good luck either way.
 
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