8 speed shifting - how fast is too fast?

[WS6FirebirdTA00]

So in attempts to play with desired shift time vs actual to see if it impacted my flare, my 3-4 shift is 0.20-0.23 seconds in some areas.

On the stock tune, I was seeing 0.28-0.30s in the same areas (around 300 Nm and 2500 RPM right before the 3-4 shift).

Stock commanded 0.35 and now I am at 0.28. The truck always seems to shift faster in 4th than commanded - especially in that load area.

So...how fast is too fast?

I have never really came across issues where it was going faster than commanded, but the newer adaptive stuff is new to me anyway. A lot of the factory tables are commanding 0.27-0.30 seconds in many areas.

The ratio change from 3-4 isn't huge and it isn't banging into gear. It feels fine, but I don't want to leave it at that without some feedback on what others see.

[5FDP]

I never went faster than like .2900 to .3000 command shift time in trucks. I would use the on-coming pressure presets and shift pressures to help with the shifts.

[WS6FirebirdTA00]

My thing is factory was faster than that in some spots. I also don't have oncoming pressure presets, just base line pressures which I don't even feel like they are doing much. Not sure if it is just the new transmissions and the new calibrations or what.

[RacnJsn95]

While not in a truck, and not in 8L90, I have an 8L40 in my 4 banger Camaro. I notice the same, the 3-4 upshift almost always happens faster than commanded. I spent a few months tuning my trans, and the fastest I was able to get it to shift was 0.125 (on the 3-4, commanded 0.150), most of my other gears are commanded 0.150, and are shifting 0.150 in the logs. IDK if this helps you or not, but I wouldn't be scared you're shifting too fast myself.

we REALLY REALLY NEED the oncoming/offgoing tables to be unlocked. They gotta be there, but they just haven't found them yet. If we get those, I'm confident I can get my shift times down even further, and it will probably help people with flare problems also.

[WS6FirebirdTA00]

I really want more TCC tables too. The TCC lockup rates make it odd (especially cold).

Most of my shifts 0.250-0.400 during active shifts, most commands are 0.300-0.400. Shifts nice but isn?t bangng gears. Not a huge fan of that in the truck.

[8850]

Might take a look at a Corvette file. Mine are well into the .2xx range in the upper torque values.

[5FDP]

A Corvette doesn't have the weight, so I'm a little more cautious. Me personally I don't want to possibly rebuild something in 50-70k miles because lighting speed shifts are something that could be done.

[mbray01]

These things shift so good, i rarely touch anything shift related in them. Dial in torque tables and they seem perfect to me. I only mess with tcc stuff to help with the shudder. Larger throttle bodies do require a little touch up in trans settings!