Ok, here is my 3rd and final effort.
I've remade the cup with tighter tolerances.
This time I used an old stainless pump shaft and being better quality material it was much easier to machine.
The bottom bearing washer is now a press fit. There are two holes in the back of the cup if ever I need to press it back out.
I've also included a "wavy" washer to give a little preload. This should also help with hot tolerances.
The plug is also a press fit for the top bearing washer and the back was slightly undercut to make removal of it easier.
I intend to pack the cup with grease. If this is washed away by oil all well and good.
I'll see how this goes. It should be easy to inspect every few thousand miles (about 2 years of driving with this car)
Later I post some drawings with dimensions etc.
