I had the Corvette servo fitted to an otherwise stock auto at a trans shop and was very happy with the shift feel, almost too harsh and a day later code 81 popped up and the gearbox went into limp home mode. I replaced the A+B shift solenoids and the car is back to normal, so much so that the shift feel is almost standard, no more thump into second and no more chirp into second on the redline, I actually prefer the way it is now as it is a daily (not slack but not exactly firm either) but it has me thinking, why such the big change after replacing the solenoids? The fluid was burnt up too, was serviced at the same time the part was fitted, could it have burnt up in limp home mode?
I'm only guessing, but I'd guess the solenoid was sticking maybe for a split second before operating which maybe changed the shift pressures causing the servos to grab the clutches harshly...replacing it brought it back to opening immediately, but it's working so that's good. Re the burnt fluid, I'd say it's due to the amount of work you've been giving the box...most of the brown discoloration is usually due to very fine burnt clutch particles....a bit like disc brake dust...the harder you press, the more they produce. Driving in LHM probably added a bit more by heating the oil due to the slip involved. Might pay to put a heavy duty cooler on as well...
Along the lines of my thoughts. Maybe it was a coincidence that the gearbox shifter harder after the Corvette servo piston was fitted. To tell the truth I am doubting it was fitted now the gearbox is back to normal.
