A buddy and I took my Iroc out for a couple of Gtech runs today with the freshly checked out TH350, new 3500 stall, and 28X13.5X15 Et streets on. The 1-2 shift was perfect and the 2-3 shift would happen until I lifted of the throttle for a bit. Same problem as I was having earlier with this trans. I ran a 12.330 at 112.02 mph with two of us in the car and lifting to make the 2-3 shift. This problem is getting annoying.


If I do a part throttle run the shifts are great all the way up.

Any suggestions?

 

i'm not expert, not even very knowledgeable, but try a differant modulator. there are 3, i think, and all interchange, you want one found on a th400. not sure on the color code ,but i think it's black. do a search on here and you may find more info.