C7 8 Auto cold start delay into Drive
Thread Starter
3rd Gear
Joined: Jun 2018
Posts: 3
Likes: 0
C7 8 Auto cold start delay into Drive
Greeting everyone! I have a 2015 Z51 2LT Auto 8 speed with 11K miles. At around 6K miles, the issue with the trans was getting worse. Cold start, let warm up about a minute, go from Park, then Reverse to back out of driveway, then place into Drive, About a full 2 second delay waiting for trans to get into gear. And when it does engage, it does it with a jerking clunk. After it warms up, doesn't do it. Took to dealership, and they reprogrammed the computer and checked the fluid. Seemed to help for a bit. Then started acting up again within a few hundred miles. Back to dealership. End result? Technician could NOT fix at this point and ordered a NEW transmission (supposedly tested and guaranteed 100% operational from GM). Well, it's acting up again doing the same thing. I've read that this might have something to do with fluid starvation with these 8 speed auto's. Any info I need before going back to the dealership? Anybody know what's really going on with these transmissions? Thanks all.
Melting Slicks
Joined: Oct 2009
Posts: 2,004
Likes: 392
From: Long Island New York
All the A8s do it on a cold start, just let it warm up like everyone else. I wouldn't want the dealer taking my car apart, I'd rather just let the car warm up.. it's because the trans fluid hasn't had time to circulate on the cold start.
Team Owner
Joined: Sep 2000
Posts: 25,019
Likes: 2,712
From: Far NW 'burbs of Chicago
St. Jude Donor '13
We've driven our 2017 Z51 A8 in temps down into the 20's (A/S tires), and there is no noticeable delay going into Reverse or Drive on the first start of the day or any other time.
However, whether you want the dealer to tear your car apart to fix the issue is another question.
Good luck with it!
However, whether you want the dealer to tear your car apart to fix the issue is another question.
Good luck with it!
Thread Starter
3rd Gear
Joined: Jun 2018
Posts: 3
Likes: 0
Thanks for the response! So, now, my next question; Why on earth would GM design a new transmission with a fluid starvation issue and let it be installed into an $80,000 sports car? I talked myself out of the manual trans car before I bought this, and now I wish I didn't. smh…..
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
As to the why, it's the same reason GM sells an M7 that it notchy and doesn't shift well until warmed up that everyone replaces the shifter on, I guess.
I wonder if it's somehow unique to the Corvette, or does it happen on trucks too? That would really surprise me.
I wonder if it's somehow unique to the Corvette, or does it happen on trucks too? That would really surprise me.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
My 16Z has no delay warm or cold. It does not clunk either.
2nd Gear
Joined: Jun 2018
Posts: 2
Likes: 0
From: Leonia NJ
I'm having the same issue on my 15 Z06. There is a delay even after the car is warm. Sometimes after driving for a while it goes away but most of the time the issue is there. I will attempt have the fluid changed being that the car has 33k miles on it. I bought the car used with 29k miles and I feel like the car always had the delay.
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Race Director
Joined: May 2001
Posts: 15,324
Likes: 2,079
From: Guelph, Ontario
False, all A8s do not do this at all. My 2018 doesn't do it and I really haven't heard of too many others with this issue. I think it would be unacceptable to have a trans that didn't engage properly until you warmed the car up for a little bit. I start my cars and immediately drive away with no warm up at all, I just drive them gently until the oil warms up.
Drifting
Joined: Apr 2015
Posts: 1,276
Likes: 317
The 2015 and early 2016 a8 has an early design stator support and allows converter drainback to the pan. Newer models have a checkball in a redesigned stator support that prevents the drainback. Trucks have the same problem.
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
False, all A8s do not do this at all. My 2018 doesn't do it and I really haven't heard of too many others with this issue. I think it would be unacceptable to have a trans that didn't engage properly until you warmed the car up for a little bit. I start my cars and immediately drive away with no warm up at all, I just drive them gently until the oil warms up.
