6l80 5/6 Shift Speed

[gmorris]

Hey folks,

For some reason I'm struggling to stop the 6l80 in my 2010 c6 vette from shifting to 5th and 6th way too soon. I have changed shift speeds on 6l80/90's plenty of times and never had a problem until now. All other gears shift exactly when I have them set to but no matter what I do to 5/6 they shift immediately after it shifts to 4th at part throttle. I always use S mode which is pattern b (confirmed though HPT logging) but I have changes pattern a as well as normal trying to get it to behave. Can someone take a look and see if I'm missing something obvious or has any ideas? It's all in kph but I want it to hit 5th at around 100 and 6th at 110...currently it will shift immediately after the 4-5 shift at 80 and will hold it all the way down into the 60's.

first tune.hpt

[DrLoch]

Cant open file, are you using BETA version? Are you doing a relearn after you do the write?

[gmorris]

Yes and yes...beta and doing a relearn every time. Forgot about the beta issue.

[gmorris]

Does the difference between upshift and downshift speeds have any effect on shifting? I did notice that at slightly higher throttle positions it does shift at higher speed but I have the same speed carried down from 40% to 0% so I don't understand why it's commanding 4-5 and 5-6 shifts the instant it completes the 3-4 shift.

[DrLoch]

Yes they do. Same with lock-up, look at those tables also. Mine weren't to my liking, it would shift and lock-up almost instantly which I didn't care for. In sport mode I don't let it lock-up at all.

[gmorris]

Aha! I didn't even think of tcc tuning affecting shift speeds for some reason...I didn't even touch tcc on my zl1 and it was fantastic. Thanks, I'll give it a try next.

[DrLoch]

I have a STS V and from the 1st drive I noticed the lockup thing. On light throttle it would shift to 4th then almost immediately lockup so I would feel a double chug. In normal mode I've spread the MPH from shift to 4th - 5th - 6th to lock-up so i don't feel it. And like I said I removed lockup in sport mode. I left it alone in TUTD for now but I need to modify those as well. It's the wifes car for the most part so I need to keep it somewhat tame. Big thing I've done is modify the lockup apply ramp, Regulator Offset, (TCC Adapt) Adapt Min and Adapt Max. When it goes into lockup now it feels likes changed a gear, also in the past I could see and feel when it was lowering the TCC lockup pressure till slip was seen and then raise the pressure again till slip was gone. Didn't like that at all. Those changes stopped all that nonsense.

[gmorris]

Well for now I just raised the TCC apply speeds to just above my new shift points and it solved my issue. Strange that despite it being nowhere near the shift speed (like 30 kph less) it would shift anyway when it hit the tcc apply speed. I would have thought that shift speed would override lockup speed but I guess not...I'm pretty sure it did in my zl1. I typically reduce shift times slightly, increase oncomming pressure preset a whole bunch and maybe bump line pressure 10% or so and I find these things are pretty solid. Thanks for pointing me in the right direction.