Th400 with mild rebuild. late 2-3 upshift at light and heavy throttle. Used a PATC K7 kit with stock converter. Auto shift with Fairbanks trans action kit on lowest setting. Dual fed direct. Worse when cold. I bought a governor weight kit but found trans already has the heavy weights installed. While checking modulator operation I found the modulator valve outer large land sticking in case. Thinking this is my problem I carefully polished the land with 1500 grit sandpaper until it was free in the bore. Now the problem is worse. I didnt take any more than .001" off the land. Thank You for any ideas on this.

 

Trans also has new detent solenoid with rubber gasket built in. detent wire is disconnected.
Pressure readings @ idle
P=75
R=120
N=75
D=75
L2=160
L1=160
@ 60 MPH in 3rd 68 psi
Is this lower pressure in 3rd normal or an indication of a leak in the direct circuit?

 

Any opinions or elaboration on 3rd gear cutback mod to modulator valve? What application is this mod used for? How would this affect auto shift behaviour?