In a different thread there's an interesting discussion surrounding a fellow 4L60-E
owner trying to resolve a 'vicious 1-2 shift' issue. One of the guys just replied that his
transmission shop troubleshot it to an egg-shaped bore, and fixed it with the
slightly oversize throttle valve assembly:
what is the # on your accumulator housing? 94 should NOT have dual springs unless you are using a late housing. do you know the colours? with the piston against the separator plate a stiffer spring actually makes a softer shift in this instance... did you play around with the separator plate...
www.gmt400.com
This whole throttle valve subsystem in the 4L60-E looks to be an area where a
lot of concentrated voodoo is located, and can either make or break the driving
experience. No doubt that the original designers felt that the new throttle valve/cable
setup was the best solution to the problem at hand...but for me the old vacuum
modulator on the Turbo 400 just seemed to work flawlessly without any value
added by yours truly. :0)
Good luck getting that hard pedal issue sorted out without harming the existing
good behavior that the tranny is otherwise delivering. It's possible...just got to
get the exact right 700R4 whisperer involved.