whitt1

I've switched from a 4L60E to a 4L80E and I'm having problems setting the shift points and converter lockup to function properly.I've got the speedo reading correctly and my part throttle shifts aren't bad,but when I try a full throttle shift into second gear it won't shift,it hits the rev limiter,if I'm running 60mph plus and apply full throttle the transmission downshifts to first and hits the rev limiter.At 2/3rds throttle the truck accellarates hard and the shifts bark the tires in 2nd and 3rd gears.Guys do you have any idea what I'm doing wrong?Any advice will be greatly appreciated.Thanks Whitt1

jimmyblue

iTrader: (11)

RPM shiftpoint must be less than rev limiter (- "windage" for shift time)
MPH shiftpoint at WOT and elsewhere must be less than rev limiter.
WOT against a loose converter will put you at less MPH for a given
top end RPM than partial throttle and possibly fail to satisfy the upshift
logic. Back down the MPH points incrementally until this quits happening.

deezel

Have you tried to look for another Edit file with a 4L80E and your gears? That seems like a good starting point for tuning the tranny swap...

whitt1

Thanks for the suggestions,I think that I've set my shift points to close to the rev limit and with the 4.56 gears the"windage" factor is pushing me into the limiter before the transmission can shift.I lowered my down shift points and that seems to have helped the highspeed downshifting.I'm going to lower my shift points slightly and raise my rev limit to see if that helps.