Which is best for setting Shift Points

[Kurt02GT]

I'll have 4.56 gears and I 'm going to reset my shift points on my 4R70W trans. Which is best for setting them using the MPH or RPM? I'm going pretty quick in first gear and I'm sure I'll have to command the shift 800-1000rpm before it does, lol

[nickmckinney]

IMHO - use RPM since thats the easiest to change.

[crosser]

I don't have an automatic in my mustang so I'm not familiar with the shift logic for SCT but I do transmission calibration for a living and the philosophy is fairly similar to the old strategy I used to work with.

RPM based is easier and is simpler to understand for most people. The biggest advantage of engine RPM based shift scheduling is consistency. The vehicle speed based schedule can some times be tricked a little bit and you can have some late shifts for different driving conditions (for example a 1-2 shift can vary based on if it's a launch from a stand still versus a 1-2 upshift after a 3-1 kickdown). To be honest it's what ever you are more comfortable using. With the vehicle speed base you may have to do some back calculation to make sure you don't go over redline at WOT.

If I was doing it, WOT (90% pedal and higher) would be based on engine RPM and the rest would be based on vehicle speed.

Make sure to watch the hysteresis between the upshift and downshift lines and you be good to go.