pressure drop!!!

[Lee Thompson]

Posted earlier about a spare trans I/m trying to build(BQ). Will not shift out of 1st gear @ wot. Finally got around to trying it with a gage installed on windshield. At wot from a stop--pressure goes to 250 psi--at about the time it should shift (5200)-- pressure drops to 100 psi. and it will hit the rev limiter if I don/t lift, shifts when I lift. Tried it with my GOOD BRF VB, Gov. and servo installed, same thing.
I am open to all suggestions.

BTW, this is with an extended pan and extended filter. So I don/t feel it is running out of fluid.

 

[Morkai]

Pressure drop

Sounds to me like it might be the slide spring in the pump. I think that's why most of the hardened ring kits come with the high rpm slide spring, for turning it over 5K. Does it do it in every gear? There are other possiblities too, but that came to mind first.