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2017 Grand Sport M7 won't go into reverse

 
Old 07-08-2019, 11:55 PM
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copjsd
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Default 2017 Grand Sport M7 won't go into reverse

Does anyone else have this following problem with their M7 Corvette transmission? Every time I take my 2017 Grand Sport to a track event, usually after three or four 20-25 minute runs, when I return to the paddock, I'm unable to get my car into reverse. It feels as though the reverse lockout is engaged (just the same as if you attempt to shift to reverse when you are traveling forward).

Then, after the event is over, and I've driven an hour or two on the street, although it's difficult to engage it the first time, once it is engaged, all subsequent engagements are smooth and easy as ever. I've taken to my dealer, however by the time I drive to the dealership, they will only witness the one extra high effort engagement, then it's back to smooth and easy and they say "see, it's fine now."
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Old 07-09-2019, 07:18 AM
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rrsperry
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Just a guess, but I'd try to center the shifter alignment. Look at the MGW shifter install videos and see. A slight misalignment not be a problem at normal temps, but after HARD use, heat may make the problem worse. If I were you, I'd install the MGW shifter anyway, it's just worlds better.. (and as a bonus, you have to align the shifter anyway...lol)
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Old 07-15-2019, 03:13 PM
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copjsd
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Originally Posted by rrsperry View Post
Just a guess, but I'd try to center the shifter alignment. Look at the MGW shifter install videos and see. A slight misalignment not be a problem at normal temps, but after HARD use, heat may make the problem worse. If I were you, I'd install the MGW shifter anyway, it's just worlds better.. (and as a bonus, you have to align the shifter anyway...lol)
Hello, rrsperry, thank you for your suggestions! I actually had the MGW shifter successfully installed and utilized in my 2017 GS for about 30 days before my first track event. Then on day one at Mid-Ohio reverse became inaccessible. So even though I knew that the only actual adjustment on both the factory OE or MGW shifter is actually just fore and aft I opened up to double check for alignment and the torque on the clamp bolt.

When I visited my dealer with the issue, they immediately condemned the MGW shifter, despite my explanation that the MGW doesn't have a rotational shaft adjustment, and that when the clamp bolt is installed, the rotational alignment is assured, just as it is with the OE shifter. In any case, I removed the MGW and reinstalled the OE shifter. Well of course the problem continues with the OE shifter.

I spoke with Tremec and learned that it is likely the normally very reliable device mounted atop the transmission called the Reverse Lockout Solenoid. Below three m.p.h., the solenoid remains "open" allowing the shifter to access reverse. Above three m.p.h. the solenoid "closes" the path to prevent an accidental engagement into reverse. His hunch is that the solenoid is hanging up in the "closed path" position, then later unsticks and resumes normal operation.

At present I'm hoping that it resolves it self, otherwise I have an appointment with my Chevy dealer for 7/23/19.
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