Ok so at the bottom of the stator in this picture we can see the spring. This spring is in between the PR valve and boost valve..
The upgrade parts we are installing will ensure good strong line pressure in this transmission and God willing prevent any slippage under all that load. Here is a side by side of old and new boost valves. The upgrade part has a larger orifice and limits the size of the passage to that orifice on the outside of the valve..
The PR valve wears against the casing of the stator which is only aluminum and it wears out. The upgraded part is a redesign that is meant to ride on different areas of the casing that aren't worn..
And here is the exploded view of the valve assembly..
We also need to redirect the flow of fluid around one side of the PR valve. First we beat a check ball into this hole to block the passage..
And then we can carefully drill our new path..
Making damn sure not to leave any metal shavings in that stator assembly..