Mooseman, when you pulled the valve body down, did you get the check ball back in that is suspended above the seperator plate? There is one that will fall out and needs to go back in with a dab of vaseline to hold it in place.
After about 40K miles on my new seperator plate I'm just starting to experience and very slight soft shift from 1-2 when warm and more of a delayed harder shift when cold. I talked to someone today and he mentioned the filter in the seperator plate and the screen in the EPC solenoid...which is what controls the line pressure. Seems I have a very very slight derease in shift firmness but it's even across all gears.
I need to flush the fluid again and when I do I think I'm going to pull the valve body down and check the screens on the EPC solenoid....it's almost like the CPAS with tiny screens on the end. I will also install torlon check balls since these are much easier on the plate.
This is something that could be going on with the OP's trans, could very well be a line pressure issue from the start, who knows what went on with the trans rebuild, could have been a swap from a donor vehicle with different parameters including line pressures required for shifting, or an incorrect seperator plate that has incorrect hole sizing for fluid flow.....each vehicle is different. Just because it's a 4L60E doesn't mean it's setup for the vehicle you are putting it in. Not saying he had a trans swap instead of a rebuild, but the wrong plate could have gone in.
Moose, I wouldn't worry about the vette servo right now, if you add it it will likely shift even harsher, providing you have a shift kit installed. You can increase line pressure from the plate openings on the stock servo, or retain factory pressure on the vette servo, both will yield similar results. However with a kit or increasing the pressure as well as the increased area on the vette servo will really bang the shifts.
