If you have a vernier caliper you will be within a
few thou and that will be close enough...if your preload
is a couple of thousands off it wont matter... but .040
is getting quite a bit out of the range they want... I
dont think the tip of the caliper will go into the hole
at the bottom of the cup... just check it... that way you
wont need the 5/16" ball
I guess I can go out to the shop and see if the tip will
go in.... stand by.... I measured from the top to the bottom
of the seat(where the ball would sit)and the tip of MY calipers
didnt go into the hole..from the top on mine solid roller it
was .618...so their numbers must be from the bottom of the flat
to the inside at the seat...if you want just measure each one
the same way so you know the difference